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Anorectal Abscess and Fistula
7 Anorectal Abscess and Fistula Kasaya Tantiphlachiva DE P A R T M E N T OF S UR GE R Y , C H U L A L O N GKOR N UNIVERSITY, BANGKOK, THAILAND
7.1 Introduction Anorectal abscess (ARA) and fistula (ARF) are the acute and chronic form of anorectal infection, respectively.1 It is one of the most common anorectal problems.1 The major cause of the abscess is infection of the anal gland, which has become obstructed with debris known as the cryptoglandular theory.2 Generally, there are 4–12 anal glands situated around the anal circumference, predominantly in the posterior.3–5 In most people these glands are situated in the areolar tissue of the intersphincteric plane, which is rich in lymphatics3 and they drain into the anal crypts at the level of the dentate line.3 The presence of the lymphoid tissue around the glands may account for the other causes of anorectal inflammation, including tuberculosis and Crohn’s diseases.6 The suppuration spreads into adjacent spaces1 via the path of the least resistance.2 It may spread downwards to the anal margin, upwards along the rectal wall, or outwards through the external sphincter into the ischiorectal space.6 The overall incidence rate of ARA was 20.2 per 100,000. The rate of subsequent fistula formation was 15.5% in idiopathic cases and 41.6% in patients with inflammatory bowel disease (IBD).1,2,7 The median age at the time of first presentation is 40 (range 29–52) years.7 The overall incidence of ARF (or fistula-inano) in the general population is 8.6 per 100,000 per year (12.2 per 100,000 males and 5.5 per 100,000 female).1,3,8 The common age of presentation was between 20 and 60 years (mean 40).1 The median time to presentation of fistula following an abscess drainage was 7.0 months (range 6.9–7.1 months).7 Predictors of fistula formation were IBD, female gender, age at time of the first abscess (41–60 years), and intersphincteric/ischiorectal abscess location (compared to perianal location).7 The lifestyle risk factors that increased the risk of developing fistula are a body mass index of >25.0 kg/m2, high daily salt intake, history of diabetes, hyperlipidemia, dermatosis (urticaria, eczema, or contact dermatitis) within the last 6 months, anorectal surgery, smoking and alcohol intake, sedentary lifestyle, excessive intake of spicy/greasy food, little exercise, and prolonged toilet time.9 Besides the anal gland infection, other causes of ARA/ARF include IBD, fungal infection, mycobacterial infection, neoplasm, and trauma.2 Up to 30% of individuals with Crohn’s disease will develop perianal lesions8,10 and 18% present as ARF or ARAs.10 Ingested foreign bodies such as chicken or fish bones, pin perforation,11,12 penetrating trauma of anorectum, low rectal cancer, and anal-gland cancer are other possible causes of ARF.1 Anorectal Disorders. https://doi.org/10.1016/B978-0-12-815346-8.00007-2 © 2019 Elsevier Inc. All rights reserved.
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7.2 Classification ARAs are classified by the location in the perirectal space of the purulent collection: perianal abscess (located superficially around the anal verge), intersphincteric abscess (located in the intersphincteric space), ischiorectal abscess (located in the ischiorectal space), and supralevator abscess (located in the supralevator level).2 Most of a supralevator abscess is an extension of an intersphincteric abscess, which extends upwards along the intersphincteric plane.1,2 On a rare occasion a supralevator abscess may result from pelvic sepsis due to an appendicitis, diverticulitis, or gynecological infection.1 Fig. 7.1 demonstrates the types of ARA. Perianal, ischiorectal, intersphincteric, and supralevator abscesses are present in 43%, 23%, 21%, and 7% of the ARA patients, respectively.2,13 Hanley et al. described a type of abscess that originated from the anal gland, which connected to a crypt near the posterior midline and was located in the deep postanal space.14 This type of abscess has potential to spread to the ischiorectal space, unilaterally or bilaterally, as a so-called semihorseshoe or horseshoe abscess. ARFs are classified by their passage to the anal sphincter complex. The most widely used is the Parks classification1,6,8 which consists of four types: 1. Intersphincteric fistula—tracking from anal crypt through internal anal sphincter (IAS) and then between internal and external anal sphincter (EAS) down to perianal skin at anal verge.1,6,8 It is the most common type of ARF and is usually preceded by a perianal abscess.8 It can extend up high in the intersphincteric plane and presents as supralevator abscess.1,2,8 2. Transphincteric fistula—tracking through IAS and EAS into the ischiorectal fossa, then down to the skin below.1,6,8 It can be divided into high and low type.2
Rectum
Levator ani Puborectalis Superficial EAS Subcutaneous EAS IAS Intersphincteric abscess Perianal abscess FIG. 7.1 Types of anorectal abscess.
Supralevator abscess Ischioanal abscess
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3. Suprasphincteric fistula—originating from intersphincteric plane, extending up to the supralevator area and tracking over puborectalis muscle into the ischiorectal fossa and then to skin below.6,8 4. Extrasphincteric fistula—typically arise from the pelvis or rectum above the dentate line, cross the proximal to the sphincter complex, tracking through the levator ani into ischioanal fossa down to the perianal skin, without involvement of IAS or EAS.2,6,8 There is an additional subtype of ARF which courses in the submucosa without traversing either IAS or EAS called subcutaneous fistula15 or intersphincteric fistula.8 This type is often associated with anal fissures.8 Parks et al. estimated the frequencies of intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric fistula as being 70%, 23%, 2%, and 3%, respectively.6,15 A later report showed the percentage of subcutaneous, intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric as 16.4%, 55.9%, 21.3%, 3.4%, and 3%, respectively.16 ARF can also be classified as low and high types. Low-type fistulas pass through the lower third of the IAS and EAS muscles and high-type fistulas pass higher than lower third of the anal sphincters.8 The objective of these classifications is to predict the risk of incontinence after surgery.8 However, there are other risk factors that should be considered. For this purpose, ARF is divided into simple and complex types.8,17 Simple fistulas include intersphincteric fistula and low transsphincteric fistula that involves less than 30% of the sphincter complex.17 Complex fistulas include high transsphincteric, suprasphincteric, extrasphincteric, recurrent and horseshoe fistulas, fistula with multiple tracts, anterior tract in female, presence of IBD or malignancy, previous pelvic irradiation, presence of incontinence or chronic diarrhea, and involvement of other organs (e.g., vagina, base of scrotum, and urinary bladder).8,17 Fig. 7.2 Demonstrates types of anorectal fistula. The pathogenic organisms found in ARA and ARF are polymicrobial aerobic and anaerobic bacteria.13,18 The common isolated organisms are Escherichia coli (22%–25%), Enterococcus (16%–22%), and Bacteroides fragilis (20%–26%).13,18 The rarer organisms that can be found are Mycobacterium tuberculosis, Actinomycosis, Chlamydia trachomatis (lymphogranuloma venereum), and fungus.13,18 The presence of these gut-associated organisms is indicative of the presence of ARF.19
7.3 Clinical Presentation Patients with acute ARA present with perianal pain and are febrile with a hot, erythematous, fluctuant, tender, indurated swelling adjacent to the anus.1,3,20 Spontaneous drainage may occur.20 If untreated or inadequately treated, infection may involve the perineal soft tissue and fascia (Fournier’s gangrene), which can be fatal.2,20,21 This condition is likely to occur in patients with comorbid risk factors including diabetes, body mass index >30 kg/m2, hypertension, end-stage renal disease, liver failure, smoking, alcohol abuse, advanced age, and immunosuppressed states.21,22 Patients with ARF may complain of drainage, bleeding or pain, and fever.23
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Rectum
Levator ani Puborectalis Superficial EAS Subcutaneous EAS IAS Subcutaneous fistula Intersphincteric fistula Low transphincteric fistula High transphincteric fistula Suprasphincteric fistula Extrasphincteric fistula FIG. 7.2 Types of anorectal fistula.
Diagnosis of ARA and ARF is usually based on history and physical examination.17,24 A disease-specific history, emphasizing symptoms, risk factors, previous anal surgery, obstetric injury, gastrointestinal symptoms, and baseline fecal continence should be taken.8,24,25 Useful information can be obtained during a digital rectal examination.25 During inspection the practitioner should look for a bulging area, the location of an external opening, purulent discharge, the presence of secondary cellulitis, any scaring from previous surgery, and evidence of fecal incontinence.8,25 An external opening that is closed to the anal canal likely belongs to a superficial or intersphincteric fistula and an external opening that lies at 2–3 cm from the anus likely belongs to a transsphincteric, suprasphincteric, or extrasphincteric fistula.25 By palpation an internal opening and tract may be identified.8 Bidigital examination, with the index finger inside and the thumb outside the anal canal, may help identify the fistulous tract as a cord-like lesion under the skin.23 Anal sphincter bulk, tone, and defect should be assessed.8 Any point of tenderness should be noted. In an acute abscess, rectal examination and anoscopy should be gently performed and kept to a minimum as they could aggravate pain.26 A supralevator abscess may present as dull pain in the lesser pelvis or back, fever, and other nonspecific symptoms.26 An intersphincteric abscess may not have significant external findings24 but severe pain may preclude digital rectal examination and examination under anesthesia (EUA) may be more appropriate.2 Differential diagnosis of ARAs includes hidradenitis suppurativa, a skin furuncle, infections such as herpes simplex, HIV, tuberculosis, syphilis, and actinomycosis.17,24 The obtained clinical information may alert the physician to the possible etiology.8,24 Features suggestive of Crohn’s disease or atypical causes, including large skin tags or multiple fistulas, require a more detailed workup.24
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7.4 Preoperative Imaging For the preparation of an appropriate management plan, it is important to identify the location of the internal opening and to map the fistula course.8 This can be done by various methods. The classic Goodsall’s rule may be used to determine the location of an internal opening.8,17 According to the rule, an imaginary transverse line across the anus is drawn. If the external opening is located anterior to this line, the tract will run directly toward the anal canal. If the external opening is located posterior to this line, the tract will curve posteriorly toward an internal opening in the midline.8,23,25 The predictive accuracy of Goodsall’s rule is 90% for posterior fistula, but only 49% for anterior fistulas.8,13,23,25 High predictive accuracy was seen in superficial fistulas (97%) and intersphincteric fistula (84%), but decreased significantly for transsphincteric fistulas (69%).27 The reliability also decreases in the case of recurrent fistulas,17,24 long fistula tracts, fistulas with an external opening located >3 cm from the anal verge, and fistulas associated with Crohn’s disease, tuberculosis, or malignancy.8,24 Conventional fistulography, performed by injecting a water-soluble dye through the external opening and taking an X-ray,8 is not recommended for the diagnosis of ARF because of low accuracy (16%) and poorly tolerance of the patient.17,24 The technique does not provide information about the relationship between the tract and the anal sphincter complex.8 Also, it cannot be used for a fistula that has an external opening that has been closed or plugged.8 Because of the lack of sensitivity and visualization of the tract, patients had to undergo an EUA to determine the type of anorectal fistula.2 Tract injecting technique using hydrogen peroxide or methylene blue helps the surgeon in the identification of an internal opening2,24 with a success rate of 80%–90%.24 The subsequent procedure is then dictated by the location and the path of the tract.2 However, in complex cases additional investigations may help to improve preoperative planning, i.e., detect occult abscess and secondary tracts, or to assess the integrity and function of the anal sphincter muscles.17 Endoanal ultrasound (EAUS) is a cost-effective technique that may be the first-line method for imaging complex fistulas.17,23 The reported accuracy in detecting abscesses or fistulas was between 80% and 89%.17,24 The accuracy of EAUS is significantly better than physical examination in detecting the primary tract (88.8% vs 85.0%, P ¼ 0.023), horseshoe extension (85.7% vs 57.7%, P < 0.0001), and the location of the internal opening (85.5% vs 69.1%, P < 0.0001).28 Three-dimensional (3D) technique improved the accuracy for identification of the primary tract up to 94% and for the localization of the internal opening to 91%.23 Hydrogen peroxide (H2O2) enhancement, performed by injection through the external opening, further improve the diagnostic accuracy and identification of the internal opening up to 94%.17,29,30 When compared to EUA, peroxide-enhanced EAUS showed good to very good agreement with EUA in the classification of primary fistula tract (κ ¼ 0.93), identification of internal opening (κ ¼ 0.97), and detection of secondary fistula extensions (κ ¼ 0.71).29 Overall sensitivity and specificity of 3D-EAUS in the diagnosis of perianal sepsis was 98.3% and 91.3%, respectively.29 Peroxide-enhanced EAUS findings are comparable to magnetic resonance imaging (MRI) with close to 90% concordance.24
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EAUS is useful for planning the appropriate operation.29 The high diagnostic accuracy leads to successful operations in 98% of patients.31 With adjunctive volume render mode, the interpreter can better classify the type of fistula.32 The limitation of EAUS is that it cannot be performed in patients with anal stricture23 and it requires an experienced operator for diagnostic reliability.17,33 In the emergency setting, it may be difficult to localize the fistulous tract and the patient may not tolerate the anal probe.33 In such a situation EAUS under anesthesia can be performed. The suboptimal visualization of the levator plate may lead to limitation in the assessment of the secondary tract in the far field.17 Fig. 7.3 is an example of an EAUS examination of an anterior transsphincteric fistula using multiplanar views and volume render mode (Fig. 7.3D–F). The abscess and tract are heterogeneous hypoechoic lesions in the perianal space and through the anal sphincter complex. Fig. 7.4 demonstrates the use of EAUS with volume render mode and H2O2 enhancement in detecting a high transsphincteric fistula that has intersphincteric extension up to the supralevator level. Computed tomography (CT) scan may be useful in acute complex anorectal sepsis. In an emergency patients usually present with perineal pain, fever, and leukocytosis, and
FIG. 7.3 Endoanal ultrasonography (EAUS) views of an anterior transsphincteric fistula. (A–C) Normal EAUS views. (D–F) Volume render mode views. (A, D) The level of lower anal canal. (B, E) The level of mid anal canal. (C, F) Sagittal plane.
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FIG. 7.4 Endoanal ultrasound (EAUS) view of a right transsphincteric fistula with supralevator intersphincteric extension. (A, C, E, and G) Peroxide-enhanced normal EAUS views. (B, D, F, and H) Peroxide-enhanced volume render mode views. The bright white area is the fistula tract traced from the level of lower anal canal (A, B), mid anal canal (C, E), upper anal canal (E, F), and supralevator level (G, H). (I, J) Coronal views in different planes to show the high transsphincteric tract (yellow arrow) extending up in the right ischiorectal fossa and the intersphincteric extension of the abscess up to supralevator level (white arrow).
perineal examination without anesthesia may not be possible.24,33 A CT scan is readily available and effective.17,33 In nonemergency, CT fistulography provides a clear view of the fistulous tract and its relationship to the pelvic structure34 and has an advantage over MRI in allowing the visualization of an air-containing abscess.34 It is valuable to
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differentiate between supralevator and infralevator abscesses.17 In IBD, CT can help to delineate fistulas and abscesses from isolated rectal inflammation in patients with Crohn’s disease.24 Thin-slice spiral multiplanar CT scan is useful when MRI is not available or contraindicated (such as in claustrophobia).25 However, a limitation occurs when the external opening cannot be cannulated for contrast injection.34 Also, the poor resolution of the soft tissue makes it difficult to distinguish between the fistula tract, fibrotic material, and sphincter muscle.8,34 MRI with or without an endoanal coil is the gold standard for imaging the ARF.8,17 The accuracy was 90% for mapping fistula tract and identifying the internal opening.17,24,25 It can demonstrate the tract angulation related to the internal opening.2 The anal sphincter muscle, levator ani, and the tract branching are clearly demonstrated, therefore supralevator and infralevator abscesses can be differentiated.8 The sensitivity and specificity of MRI vs EAUS was 0.87 vs 0.87 and 0.69 vs 0.43, respectively.26 MRI is pain free, nonoperator dependent, and is preferred to EAUS when the lesion is far from the anus.26 However, the high cost and lack of availability may limit its usage.23,25,26 Preoperative imaging assists the surgeon in planning, counseling, and selecting the appropriate procedure.2 In patients who may require sphincter division, preoperative anorectal manometry can predict postoperative anal function17 and allow preoperative planning. The choice of investigation depends on the patient’s condition, availability of facilities, cost, and the physician’s personal experience.
7.5 Treatment The primary goal of ARA treatment is to drain the septic foci.1 An immediate operative trial to prevent future recurrence or fistula formation may not always be appropriate. Primary fistulotomy without careful evaluation of the etiology and the anal sphincter complex may lead to impaired continence without a cure for the ARA.17 The principal goal of treatment of ARF is to eradicate infection, eradicate the fistula tract, if possible, and decreased the risk of recurrence while preserving anal sphincter integrity and continence.1,3
7.5.1 Treatment of an ARA An ARA should be adequately drained in a timely manner.23,24 Delayed or inadequate treatment may lead to extensive life-threatening suppuration, tissue necrosis, and septicemia.24 Incision and drainage can be performed under local anesthesia and should be as close as possible to the anal verge17,24 to minimize the length of the potential fistula.16,35,36 With an adequate sized elliptical incision postoperative wound packing is not necessary and should be avoided, as it may lead to pain and delayed healing.24,35 Alternatively, an abscess can be drained with a small tube via a stab incision and this can be left in situ until drainage stops (3–10 days).24,35 If the abscess is complex, drainage should be performed in the operating room under sedation or regional or general anesthesia.17 An intersphincteric abscess can be drained into the anal canal via internal
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sphincterotomy.35 A supralevator abscess that has originated from the upward extension of the intersphincteric abscess may be drained into the rectum or via the transanal insertion of a drain.35 An ischiorectal abscess with or without supralevator extensions should be drained through the perianal skin.35 In the presence of a horseshoe abscess, a contralateral incision over the perianal skin overlying the ischiorectal fossa should also be made to allow adequate drainage from both sides.17 If the internal opening is identified, insertion of a seton through the fistula tract allows drainage and facilitates the second-stage of the procedure, which may be performed 8 weeks later.17 A modified Hanley technique, which is a partial sphincterotomy combined with seton, can be used to resolve a horseshoe abscess while minimizing the risk to analsphincter function.35 A primary fistulotomy for simple fistula that has an identified internal opening should be used with caution to avoid iatrogenic damage to anal sphincter.17,35 In the first occurrence group, the recurrence rate was reduced by 83% (relative risk 0.17, P < 0.001) but a high risk of fecal incontinence to flatus and soiling was seen (relative risk 2.46, P ¼ 0.140).37 Postoperative fecal incontinence has been reported as high as 44%.17,35 The overall recurrence rate after ARA drainage ranges from 3% to 44%.35 A fistula developed in 37% of patients and 10% developed a recurrent abscess.38 Being female and suffering from a horseshoe abscess were associated with higher recurrence rates.35,38 The surgeon should weigh the possible decreased recurrence rate with the potentially increased risk of continence disturbance.24 Antibiotic therapy is unnecessary in an uncomplicated ARA undergoing drainage.17,35 It should be considered in patients with cellulitis, concomitant systemic disease, HIV, underlying immunosuppression, or atypical anorectal infection.17,24,35 Preoperative antibiotics before incision and drainage should be given in patients with previous bacterial endocarditis, prosthetic valve, congenital heart disease, and heart transplant recipients with valve pathology.17,24,33 In immunocompromised patients, with an absolute neutrophil count of >1000/mL and fluctuance on examination had higher resolution rates with incision and drainage but in patients with a lower absolute neutrophil count (<500–1000/mL) and/or lack of fluctuance on examination may be successfully treated with antibiotics alone in 30%–88%.24,35
7.5.2 Treatment of ARF Secondary fistulas related to IBD, cancer, irradiation, or iatrogenic injury should be treated accordingly. The treatment of primary cryptogenic ARF is primarily surgery,2 which is tailored to match the classification and the patient’s continence status. The key to a successful operation is excision or destruction of the infected anal gland in the intersphincteric space39 and obliteration of the internal opening2,24 and any associated epithelialized tracks with minimal sphincter division.24 Watchful waiting in a patient with minimal symptoms or with a prohibitive operative risk can be performed.2 The risks associated with observation include recurrent ARA or fistula and, rarely, malignancies arising in this long-standing tract.2 Surgical options for
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ARF can be divided into two major types: a sphincter-preserving operation and a nonsphincter-preserving operation. The selection of technique should be based on the etiology, anatomy of the fistula, degree of symptoms, patient’s comorbidity, baseline anal sphincter function, and the surgeon’s experience.35
7.5.2.1 Nonsphincter-Preserving Operation A. FISTULOTOMY Simple ARF can be treated by fistulotomy with a high success rate ranging from 79% to 100%.17,24,35 Increased risks of recurrence are associated with complex fistulas, failure to identify the internal opening, and Crohn’s disease.24,35 Postoperative alterations in continence were reported to be between 0% and 73%,24 which is dependent on patient selection.35 It is suitable for a low submucosal fistula or one that involves the anal sphincter complex <30%.8 The risk factors for postoperative anal incontinence include preoperative incontinence, recurrent fistula, female gender, complex fistulas, and previous fistula or anorectal surgery.35 Contraindications for fistulotomy are anterior fistula (especially in females), fecal incontinence, IBD, and previous pelvic radiation.8 Marsupialization of the wound edges was associated with less pain and fewer postoperative complications.35,40 B. FISTULECTOMY Excision of the entire fistula tract also involves the removal of a part of the anal sphincter resulting in a large sphincter defect. Fistulectomy was associated with prolonged healing time and a higher risk of incontinence.35,41 This procedure should not be undertaken for simple anal fistula.17 C. SETON Seton is a foreign material (suture, rubber band, silastic vessel loop) placed through the fistula tract that can be tightened sequentially at regular intervals until it eventually cuts through the entire tissue thickness.23 These sequential intervals allow the process of foreign body reaction to cause fibrotic healing of the recently cut area to re-ensure continuity of the anorectal ring.23,24 The healing rate of the cutting seton has been reported to be up to 90%–94%.35 A recurrence rate of 2%–8% has been reported.8,23 This procedure involves the division of the anal sphincter to some extent and there is no agreement as to its safety.17 A fecal incontinence rate of 12%–60% (2%–3% incontinence for solid stool) following this procedure was found.8,23 Due to the high postoperative incontinence rate, it should therefore be reserved for cases where no other alternatives are available8 and should be performed meticulously.35 Drainage or loose seton can be used to control sepsis8,24 in the emergency setting, which is followed by a secondary procedure (endoanal advancement flap, fibrin glue, anal plug) or, in Crohn’s disease, during the medical management.8 This kind of seton is a thin,
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nonabsorbable suture that is placed along the tract through the anus.8 It provides drainage, prevents abscess recurrence, and is a marker for future fistula surgery.1,8 Fig. 7.5 shows the classic procedures for the treatment of ARF and the amount of the anal sphincter that is sacrificed during the operations.
7.5.2.2 Sphincter-Preserving Procedures A. ADVANCEMENT FLAP Treatment of complex FIA should not involve sphincter cutting in order to avoid postoperative fecal incontinence. The endorectal advancement flap is a technique that uses a partial or full thickness anal mucosal-submucosa-muscle flap to cover the internal opening.8,24 The mean success rate of this technique is 70% (range 57%–90%)17,24 with a recurrence rate of about 13%–56%.24,42,43 Full-thickness flaps have the lowest recurrence rate (7.4%) compared to partial-thickness flaps (19%), and mucosal flaps (30%).43 The risk factors for failure include increased age, history of surgical abscess drainage, suprasphincteric fistula, horseshoe abscess, and high body mass index.24,42 Mild or moderate incontinence was reported in 7%–38% with decreased resting and squeeze anal pressure, which may be due to the inclusion of the IAS into the flap.24,43 Mucosal-, partial-, and full-thickness flaps had incontinence rates of 9.3%, 10.2%, and 20.4%, respectively.43
Low fistula
Loose seton
Fistulotomy
Cutting seton
FIG. 7.5 Low fistula and the classic procedures for treatment of anorectal fistula.
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The additional treatments for the fistula tract, i.e., core-out or curettage, have similar rates of recurrence and incontinence.42,43 The potential complications from the flaps are rectal dissection and scarring of anorectal area.8 The anodermal advancement flap is an alternative to the mucosal advancement flap.25 It is performed by raising an anoderm and perianal skin flap, which includes the internal opening, and moving this up to suture it to the proximal rectal mucosa.25 Fig. 7.6 shows the procedure for the mucosal advancement flap and the anodermal advancement flap. B. FIBRIN GLUE INJECTION This procedure is performed by simultaneously injecting thrombin and fibrinogen from a two-chambered syringe into the fistula tract through the external opening.17 The patient should then be supine for several hours and avoid excessive movement during the first operative month.44 The obliteration of the tract is supposed to prevent the constant re-introduction of luminal bacterial from entering3 without the need for division of the anal sphincter. The aim is to reduce the complications from surgical procedures. The host cells will eventually lyse the fibrin plug and replace it with scar tissue.44 A success rate of 25%–94% (10%–67% for complex fistula) and recurrence rate of up to 26%–59% have been report.17,23,3544 As it is relatively ineffective,35 it should be used as second- or third-line treatment.23 The advantages of the use of fibrin glues are low morbidity, no risk of incontinence, simplicity, shorter hospital stays, less postoperative pain, repeatability, and it does not preclude the possible use of other techniques.17,23–25
High fistula
Mucosal advancement flap
Anodermal advancement flap FIG. 7.6 Mucosal advancement flap and anodermal advancement flap. The mucosal advancement flap (upper; raised from rectal mucosa) and anodermal advancement flap (lower; raised from anoderm and perianal skin) are used to cover the internal opening of the anorectal fistula.
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C. ANAL FISTULA PLUG An anal fistula plug (AFP) is a cone-shaped porcine acellular collagen matrix bioprosthesis (Surgisis AFP, Cook Biotech Inc., United States) that is used to close the internal opening of the fistula.24,44 It is fixed to the submucosa and IAS44 to avoid migration. Physical activity should be limited in the early postoperative period.44 The overall success rates range between 24% and 92%8 (70%–100% for low fistula and 80%–83% for complex fistula).24 A failure rate of up to 87% has been reported.45 Factors that may influence failure include early dislodgement, multiple previous surgery, fistula between pelvic organs (anovaginal fistula), Crohn’s disease, short fistula tract, HIV infection, and active smoking.25,46 The drawbacks of this technique are the high cost44,46 and moderate risk of infection (21% abscess formation).44 Newer materials have been developed to improve the outcome, including bioabsorbable synthetic fistula plug (GOREBIO-A, Gore medical, United States; 67% polyglycolide, 33% trimethylene carbonate), with success rates ranging from 16% to 73%.17,47 Deterioration of continence was found in 6%.47 Compared to the mucosal advancement flap, AFP had less postoperative pain, shorter healing time and hospital stay without difference in healing rates, fewer complications, and lower rates of recurrence.48 Although in a recent randomized controlled study high recurrence rates (66%) after AFP were found.49 Autologous cartilage had also been used as an AFP, but this technique has not been popularized.50 Recently, a new material combining the silicone plug and cylindrical collagen matrices (Curaseal AF device) was used to close the internal opening and form a scaffold for natural healing. A healing rate of 70% without disturbance of continence has been shown.51 D. LIGATION OF INTERSPHINCTERIC FISTULA TRACT This technique of ligation and division of the fistula tract in the intersphincteric space was reported in 2006 with a success rate of up to 94%.52 The aim is to eliminate the source of infection by obliterating the entrance from the anal canal44 and removing the intersphincteric nidus.52 Success rates of 57%–94% (mean 74.6%) with a healing time of 4–8 weeks, minimal morbidity, and no de novo incontinence were report.24,44,53 The recurrence rate was 6%–18%. The postoperative complication rate was only 1.8%–5.5% (minor: persistent pain, anal fissure, thrombosed hemorrhoid, wound infection, wound dehiscence, perianal hematoma, secondary bleeding).24,54 The patient satisfaction rate was 72%–100%.53 The risk factors for failure were obesity, smoking, multiple previous surgery, and the length of the fistula tract >3 cm.35,53 Preoperative seton drainage was not associated with increased success rates.55 The advantages of the ligation of intersphincteric fistula tract (LIFT) technique are the preservation of the anal sphincters, minimal tissue injury, and short healing time.54 The technique is easy-to-learn, inexpensive,3,24,54 repeatable, and can be used in both simple and complex ARF,35,56 including those associated with Crohn’s disease.57 Modification of the LIFT technique included omission of fistula tract division, excision of the lateral aspect of the tract, and the combined use of a seton, fistula plug, or biological mesh interposition.35 Up to now no additional benefit of combining procedures has been demonstrated.55
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E. VIDEO-ASSISTED ABLATION OF THE FISTULA TRACT This technique uses a 3.3 4.7 mm-diameter fiber-optic fistuloscope, which is inserted through the external opening to identify the internal opening, irrigate the tract with the glycine-mannitol solution, and destroy the tract with a unipolar electrode.8,17,54 Closure of the internal opening can be performed using semicircular or linear staplers or a mucosal flap.8,17,54 Synthetic cyanoacrylate glue can also be applied to reinforce the closure.54 Secondary tracts or abscesses can be debrided and irrigated.17 The healing rate was between 58% and 87%, which may be the effect of the technique of closure of the internal opening.17,25 The mean complication rate was 4.8% (perianal sepsis, bleeding, pain, urinary retention) and the recurrence rates were 16%–18% at the median follow-up at 9 months.58 The main benefit of video-assisted ablation of the fistula tract (VAAFT) is the precise identification of the fistula tract,54 minimal risk of incontinence, short hospital stays (1–4 days), and early return to work (1–11 days).59 However, the cost for the special instrument is high and the success rate has not been consistent.25 F. ADIPOSE-DERIVED STEM CELLS Mesenchymal stem cells (MSCs) derived from the adipose tissue of the patient have been used to auto-injected into the anal fistula. These cells can be obtained from the subcutaneous fat by liposuction,59 which provides 100 times more stem cells than bone marrow aspiration.54 After purification and expansion in the laboratory, the cells are prepared for implantation.59 An alternative method is to centrifuge the aspirated fat in a special automated system for 90–120 min to get the fresh concentrated lipoaspirate.60 The fistulous tract should be thoroughly curetted prior to injecting the adipose-derived stem cells (ASC) suspension, via a long, fine needle, into the tract walls.59 The multipotent MSCs have the potential to regenerate damaged tissue while inhibiting inflammation and fibrosis.61 The healing rate was reported to be between 35% and 90%.26 For cryptogenic fistula, the available studies involved only a small number of patients and further information is awaited. The main advantage of the ASC injection may be that continence is unaffected.60 However, the cost is high26 and the preparation requires additional procedures (e.g., liposuction) and instruments. In patients with Crohn’s disease, ASC was associated with a significant improvement in healing without increased adverse events.61,62 A combination of ASC and fibrin glue or acellular dermal matrix (ADM) has been used to plug the internal opening.17,44,59 Addition of stem cells did not significantly improve the healing rate compared with fibrin glue-injection alone.17,44,54 Other novel materials that have been used for fistula treatment are platelet-rich plasma, ADM, and acellular extracellular matrix (AEM), which showed high success rates of 54%–100% in early follow-up.17,63 G. OVER-THE-SCOPE-CLIP These specialized 14 mm-nitinol clips with applicator have been used to close internal openings from within the anal canal. Success rates of 70%–90% have been report without postoperative pain or discomfort.44,64 The healing rate as a first-line treatment was 79%, for recurrent fistula was 26%, and for fistula associated with IBD was 45%.64 In long-term
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follow-up a recurrence rate of 41% was found.65 Time to recurrence was 7 months (range 3–11 months).65 However, the cost is high and the infected gland is left untreated.44 H. LASER ABLATION For recurrent fistula, a radial emitting laser probe (FiLaC) is inserted into the external opening to destroy the fistula tract continuously during probe withdrawal. The aim is to “burn” the tract in a controlled manner.66 The laser wavelength used is 1470 nm and the energy level is 100–120 J/cm.66,67 The probe is withdrawn at a speed of 1 cm/6 s.65 The internal opening is closed by endoanal advancement flap3 or the internal opening may be left open.17 As a first-line treatment a success rate of 82% was reported in early follow-up.17,66 In a study that included both first-occurrence and recurrent fistulas, a success rate of 71% was found on long-term follow-up.67 The median healing time was 5 weeks (range 3–8 weeks).67 Postoperative complications included temporary pain or anismus (18%), and moderate bleeding (6%).67 A failure rate of 24% and recurrence rate of 4% were reported.67 The contraindication to laser treatment is the presence of an abscess.66,67 Although the procedure has had promising results, is easy-to-perform, and is repeatable, the disposable laser probe and the equipment are expensive.63 Newer modifications using photodynamic therapy that have improved the specificity of the burn area by using an intralesional injection of 2% 5-aminolevulinic acid, have been reported with a healing rate of 80%.68 Further study is awaited. Fig. 7.7 demonstrates the novel sphincter preservation techniques that are discussed in this chapter.
7.6 Treatment of ARA/ARF in Patients With Crohn’s Disease Perianal involvement occurs in 40%–80% of patients with Crohn’s disease.24 In 18% of cases, the presentation is ARA or ARF.68 Primary treatment is medical.24,35 In an asymptomatic Crohn’s fistula, no surgical treatment is required.24,35 In patients with symptomatic perianal disease, proctosigmoidoscopy is mandatory to check for the presence of rectosigmoid involvement, which predicts a more aggressive course.69 MRI or EAUS is preferred to CT/fistulogram/EUA to define the inflammatory character of the lesion, especially after failure of previous medical and/or surgical treatments.69,70 When symptomatic, antibiotics (metronidazole 750–1500 mg/d and fluoroquinolones; ciprofloxacin 1 g/d) can improve symptoms in over 90% of patients.23,35,69 The mainstay of treatment is the use of tumor necrosis factor-alpha inhibitor (anti-TNFs, e.g., infliximab, adalimumab).23,69 For low-lying simple FIA, fistulotomy is safe and effective.23,35,69 Healing rates were 56%–100% with a mild incontinence rate of 6%–12%.23,35 However, the extent of disease, presence of active proctitis, sphincter integrity, previous anorectal operations, gender, anterior fistula location, and stool consistency should be taken into consideration.10,35 In the presence of abscess or complex Crohn’s fistula, placement of setons for drainage of sepsis and to prevent closure of the external opening has been recommended.10,23,35 It can be left in place throughout the course of anti-TNF therapy, as too early removal may result in abscess recurrence.10,35 Cutting seton should not be
96
LIFT
Mesenchymal stem cell injection
Fistula plug
VAAFT
Fibrin glue injection
FiLaC
FIG. 7.7 Sphincter preservation techniques for treatment of anorectal fistula. LIFT, ligation of intersphincteric fistula tract; FiLaC, FiLaC-fistula-tract laser closure; VAAFT, video-assisted ablation of fistula tract.
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High fistula
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used as this was followed by incontinence in two-thirds of the patients.69 Fibrin glue and bioprosthesis plug demonstrated a success rate of fistula closure in only 25% and 31.5%, respectively.10 The mucosal advancement flap has shown a better success rate of 64% (range 33%–93%), and an incontinence rate of 9.4% (range 0%–29%).10,35 LIFT in Crohn’s disease had shown a 67% healing rate without new onset of fecal incontinence,10,35 but this requires further study.69 A promising treatment for perianal Crohn’s disease is MSC injection. From the meta-analysis, MSC injection was associated with improved healing at both early (OR ¼ 3.06 (95% CI 1.05–8.90), P ¼ 0.04) and long-term follow-up (OR ¼ 2.37 (95%CI 0.90–6.25), P ¼ 0.08).62 There was no significant increase in adverse events.62 Diverting stoma may be required to control severe perianal sepsis with insufficient response to drainage, long-term seton placement, and medical management.10,35 Diversion rates range from 31% to 49%.35 The initial response to diversion was up to 81% but dropped later.35 Proctectomy was required in 10%–20% of perianal Crohn’s disease patients to control refractory symptoms.10 This should be considered after a careful team discussion consisting of patients, gastroenterologist, and surgeons.35 The predictive factors are concomitant colonic disease, persistent perianal sepsis, prior temporary diversion, fecal incontinence, and anal canal stenosis.35 A postproctectomy complication rate of 25% was reported, which included poor wound healing and formation of perineal sinus.10
7.7 Conclusion ARF and ARA are common problems. Cryptoglandular infection is the etiology in the major group of patients. Preoperative imaging with MRI or EAUS provides the anatomical information for the disease and the anal sphincter. Various treatments have been proposed to provide drainage, obturation of the internal opening, and obliteration of the tract. The aim is to cure, reduce recurrence, and preserve anal-sphincter function. Classic operations include fistulotomy and seton (loose or cutting). The sphincter-preserving procedures to close the internal opening are endoanal advancement flap, anodermal advancement flap, LIFT, fibrin glue, AFP, and over-the-scope-clip. The procedures to desiccate the tract are VAAFT, FiLaC, and photodynamic therapy. The novel materials that are used to assist local wound healing include ASC, platelet rich plasma, ADM, and AEM. Perianal Crohn’s disease is a different entity for which the primary treatment is medication. A surgical procedure is used to control sepsis, improve healing, and salvage the refractory cases.
References 1. Abcarian H. Anorectal infection: abscess-fistula. Clin Colon Rectal Surg. 2011;24:14–21. 2. Rizzo JA, Naig AL, Johnson EK. Anorectal abscess and fistula-in-ano: evidence-based management. Surg Clin N Am. 2010;90:45–68. 3. Pigot F. Treatment of anal fistula and abscess. J Visc Surg. 2015;152:S23–S29.
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4. Kaiser AM, Ortega AE. Anorectal anatomy. Surg Clin N Am. 2002;82:1125–1138. 5. Billingham RP, Isler JT, Kimmins MH, Nelson JM, Schweitzer J, Murphy MM. The diagnosis and management of common anorectal disorders. Curr Probl Surg. 2004;41:586–645. 6. Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg. 1976;63:1–12. 7. Sahnan K, Askari A, Adegbola SO, et al. Natural history of anorectal sepsis. BJS. 2017;104:1857–1865. 8. Zubaidi AM. Anal fistula: past and present. Saudi Med J. 2014;35:937–944. 9. Wang D, Yang G, Qiu J, et al. Risk factors for anal fistula: a case-control study. Tech Coloproctol. 2014;18:635–639. 10. Panes J, Rimola J. Perianal fistulizing Crohn’s disease: pathogenesis, diagnosis and therapy. Nat Rev Gastroenterol Hepatol. 2017;14:652–664. 11. Cash DJ, Sadat MM, Abu-Own AS. Anorectal abscess and fistula caused by an ingested chicken bone. Am J Gastroenterol. 2004;99:1617–1618. 12. Delikoukos S, Zacharoulis D, Hatzitherogilou C. Perianal abscesses due to ingested foreign bodies. Int J Clin Pract. 2005;59:856–857. 13. Wright WF. Infectious diseases perspective of anorectal abscess and fistula-in-ano disease. Am J Med Sci. 2016;351:427–434. 14. Hanley PH, Ray JE, Pennington EE, Grablowsky OM. Fistula-in-ano: a ten-year follow-up study of horseshoe-abscess fistula-in-ano. Dis Colon Rectum. 1976;19:507–515. 15. Sun MR, Smith MP, Kane RA. Current techniques in imaging of fistula in ano: three-dimensional endoanal ultrasound and magnetic resonance imaging. Semin Ultrasound CT MRI. 2008;29:454–471. 16. Michalopoulos A, Papadopoulos V, Tziris N, Apostolidis S. Perianal fistulas. Tech Coloproctol. 2010;14 (suppl 1):S15–S17. 17. Amato A, Bottini C, De Nardi P, et al. Evaluation and management of perianal abscess and anal fistula: a consensus statement developed by the Italian Society of Colorectal Surgery (SICCR). Tech Coloproctol. 2015;19:595–606. 18. Seow-Choen F, Hay AJ, Heard S, Phillips RK. Bacteriology of anal fistulae. Br J Surg. 1992;79:27–28. 19. Eykyn SJ. Use of bacteriology in anorectal sepsis as an indicator of anal fistula: experience in a district general hospital. J R Soc Med. 1991;84:319. 20. Nelson R. Anorectal abscess fistula: what do we know? Surg Clin N Am. 2002;82:1139–1151. 21. Faria SN, Helman A. Deep tissue infection of the perineum: case report and literature review of Fournier gangrene. Can Fam Physician. 2016;62:405–407. 22. Wroblewska M, Kuzaka B, Borkowski T, Kuzaka P, Kawecki D, Radziszewski P. Fournier’s gangrenecurrent concepts. Pol J Microbiol. 2014;63:267–73.3. 23. Schubert MC, Sridhar S, Schade RR, Wexner SD. What every gastroenterologist needs to know about common anorectal disorders. World J Gastroenterol. 2009;15:3201–3209. 24. Steele SR, Kumar R, Feingold DL, Rafferty JL, Buie WD. Practice parameters for the management of perianal abscess and fistula-in-ano. Dis Colon Rectum. 2011;54:1465–1474. 25. Willams JG, Farrands PA, Williams AB, et al. The treatment of anal fistula: ACPGBI position statement. Colorectal Dis. 2007;9(suppl 4):18–50. 26. Ommer A, Herold A, Berg E, Furst A, Sailer M, Schiedeck T. German S3 guideline: anal abscess. Int J Colorectal Dis. 2012;27:831–837. 27. Jayarajah U, Samarasekera DN. Predictive accuracy of Goodsall’s rule for fistula-in-ano. Ceylon Med J. 2017;62:97–99. 28. Toyonaga T, Tanaka Y, Song JF, et al. Comparison of accuracy of physical examination and endoanal ultrasonography for preoperative assessment in patients with acute and chronic anal fistula. Tech Coloproctol. 2008;12:217–223.
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29. Brillantino A, Iacobellis F, Di Sarno G, et al. Role of tridimensional endoanal ultrasound (3D-EAUS) in the preoperative assessment of perianal sepsis. Int J Colorectal Dis. 2015;30:535–542. 30. Navarro-Luna A, Garcia-Domingo MI, Rius-Macias J, Margco-Molina C. Ultrasound study of anal fistulas with hydrogen peroxide enhancement. Dis Colon Rectum. 2004;47:108–114. 31. Ratto, Grillo E, Parello A, Costamagna G, Doglietto GB. Endoanal ultrasound-guided surgery for anal fistula. Endoscopy. 2005;37:722–728. 32. Sudol-Szopinska I, Kolodziejczak M, Szopinski TR. The accuracy of a postprocessing techniquevolume render mode—in three-dimensional endoanal sonography of anal abscesses and fistulas. Dis Colon Rectum. 2011;54:238–244. 33. Khati NG, Lewis NS, Frazier AA, Obias V, Zeman RK, Hill MC. CT of acute perianal abscesses and infected fistulae: a pictorial essay. Emerg Radiol. 2015;22:329–335. 34. Liang C, Lu Y, Zhao B, Du Y, Wang C, Jiang W. Imaging of anal fistulas: comparison of computed tomographic fistulography and magnetic resonance imaging. Korean J Radiol. 2014;15:712–723. 35. Vogel JD, Johnson EK, Morris AM, et al. Clinical practice guideline for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula. Dis Colon Rectum. 2016;59:1117–1133. 36. Lohsiriwat V. Anorectal emergencies. World J Gastroenterol. 2016;14:5867–5878. 37. Quah HM, Tang CL, Eu KW, Chan SY, Samuel M. Meta-analysis of randomized clinical trials comparing drainage alone vs. primary sphincter-cutting procedures for anorectal abscess-fistula. Int J Colorectal Dis. 2006;21:602–609. 38. Hamalainen K-PJ, Sainio AP. Incidence of fistulas after drainage of acute anorectal abscesses. Dis Colon Rectum. 1998;41:1357–1362. 39. Aluwihar A. Finding the source of a fistula. Colorectal Dis. 2005;7:528–529. 40. Sahakitrungruang C, Pattana-Arun J, Khomvilai S, Tantiphlachiva K, Atittharnsakul P, Rojanasakul A. Marsupialization for simple fistula in ano: a randomized controlled trial. J Med Assoc Thai. 2011;94:699–703. 41. Malik AI, Nelson RL. Surgical management of anal fistulae: a systematic review. Colorectal Dis. 2008;10:420–430. 42. Boenicke L, Karsten E, Zirngibl H, Ambe P. Advancement flap for treatment of complex cryptoglandular anal fistula: prediction of therapy success or failure using anamnestic and clinical parameters. World J Surg. 2017;41:2395–2400. 43. Balciscueta Z, Uribe N, Balciscueta I, Andreu-Ballester JC, Garcia-Granero E. Rectal advancement flap for the treatment of complex cryptoglandular anal fistulas: a systematic review and meta-analysis. Int J Colorectal Dis. 2017;32:599–609. 44. Pommaret E, Benfredi P, Soudan D, de Parades V. Sphincter-sparing techniques for fistulas-in-ano. J Visc Surg. 2015;152:S31–S36. 45. Tan KK, Kaur G, Byrne CM, Young J, Wright C, Solomon MJ. Long-term outcome of the anal fistula plug for anal fistula of cryptoglandular origin. Colorectal Dis. 2013;15:1510–1514. 46. Thekkinkattil DK, Botterill I, Ambrose NS, et al. Efficacy of the anal fistula plug in complex anorectal fistulae. Colorectal Dis. 2009;11:584–587. 47. Narang SK, Jones C, Alam NN, Daniels IR, Smart NJ. Delayed absorbable synthetic plug (GORE® BIO-A®) for the treatment of fistula-in-ano: a systematic review. Colorectal Dis. 2015;18:37–44. 48. Xu Y, Tang W. Comparison of an anal fistula plug and mucosa advancement flap for complex anal fistulas: a meta-analysis. ANZ J Surg. 2016;86:978–982. 49. Bondi J, Avdagic J, Karlbom U, et al. Randomized clinical trial comparing collagen plug and advancement flap for trans-sphincteric anal fistula. GJS. 2017;104:1160–1166. 50. Ozturk E. Treatment of recurrent anal fistula using an autologous cartilage plug: a pilot study. Tech Coloproctol. 2015;19:301–307.
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51. Ratto C, Litta F, Donisi L, Parello A. Prospective evaluation of a new device for the treatment of anal fistulas. World J Gastroenterol. 2016;22:6936–6943. 52. Rojanasakul A, Pattanaarun J, Sahakitrungruand C, Tantiphlachiva K. Total anal sphincter saving technique for fistula-in-ano; the ligation of intersphincteric fistula tract. J Med Assoc Thai. 2007;90:581–586. 53. Vergara-Fernandez O, Espino-Urbina LA. Ligation of intersphincteric fistula tract: what is the evidence in a review? World J Gastroenterol. 2013;19:6805–6813. 54. Limura E, Giordano P. Modern management of anal fistula. World J Gastroenterol. 2015;21:12–20. 55. Hong KD, Kang S, Kalaskar S, Wexner SD. Ligation of intersphincteric fistula tract (LIFT) to treat anal fistula: systematic review and meta-analysis. Tech Coloproctol. 2014;18:685–691. 56. Xu Y, Tang W. Ligation of intersphincteric fistula tract is suitable for recurrent anal fistulas from followup to 16 months. Biomed Res Int. 2017;2017.3152424. https://doi.org/10.1155/2017/3152424 [Epub 2017 Feb 8]. 57. Kaminsk JP, Zaghiyan K, Fleshner P. Increasing experience of ligation of the intersphincteric fistula tract for patients with Crohn’s disease: what have we learned? Colorectal Dis. 2017;19:750–755. 58. Emile SH, Elfeki H, Shalaby M, Sakr A. A systematic review and meta-analysis of the efficacy and safety of video-assisted anal fistula treatment (VAAFT). Surg Endosc. 2018;32:2084–2093. 59. Garcia-Olmo D, Guadalajara H, Rubio-Perez I, Herreros MD, de-la-Quintana P, Garcia-Arranz M. Recurrent anal fistulae: limited surgery supported by stem cells. World J Gastroenterol. 2015;21:3330–3336. 60. Borowski DW, Gill TS, Agarwal AK, Tabaqchali MA, Garg DK, Bhaska P. Adipose tissue-derived regenerative cell-enhanced lipofilling for treatment of cryptoglandular fistulae-in-ano: the ALFA technique. Surg Innov. 2015;22:593–600. 61. Voswinkel J, Francois S, Simon JM, et al. Use of mesenchymal stem cells (MSC) in chronic inflammatory fistulizing and fibrotic diseases: a comprehensive review. Clin Rev Allergy Immunol. 2013;45:180–192. 62. Lightner AL, Wang Z, Zubair AC, Dozois EJ. A systematic review and meta-analysis of mesenchymal stem cell injections for the treatment of perianal Crohn’s disease: progress made and future direction. Dis Colon Rectum. 2018;61:629–640. 63. Narang SK, Keogh K, Alam NN, Pathak S, Daniels IR, Smart NJ. A systematic review of new treatments for cryptoglandular fistula in ano. Surgeon. 2017;15:30–39. 64. Prosst RL, Joos AK. Short-term outcomes of a novel endoscopic clipping device for closure of the internal opening in 100 anorectal fistulas. Tech Coloproctol. 2016;20:753–758. 65. Dango S, Antonakis F, Schrader D, Radzikhovskiy A, Ghadimi MB, Hesterberg R. Long-term efficacy and safety of a nitinol closure clip system for anal fistula. Minim Invasive Ther Allied Technol. 2017;26:227–231. 66. Ozturk E, Gulcu B. Laser blation of fistula tract: a sphincter-preserving method for treating fistula-inano. Dis Colon Rectum. 2014;57:360–364. 67. Giamundo P, Esercizio L, Geraci M, Tibaldi L, Valente M. Fistula-tract Laser Closure (FiLaC™): longterm results and new operative strategies. Tech Coloproctol. 2015;19:449–453. 68. Arroyo A, Moya P, Rodriguez-Prieto MA, et al. Photodynamic therapy for the treatment of complex anal fistula. Tech Coloproctol. 2017;21:149–153. 69. Sica GS, Di Carlo S, Tema G, et al. Treatment of peri-anal fistula in Crohn’s disease. World J Gastroenterol. 2014;20:13205–13210. https://doi.org/10.3748/wjg. v20.i37.13205. 70. Bouchard D, Abramowitz L, Bouguen G, et al. Anoperineal lesions in Crohn’s disease: French recommendations for clinical practice. Tech Coloproctol. 2017;21:683–691.
7.1 Introduction Anorectal abscess (ARA) and fistula (ARF) are the acute and chronic form of anorectal infection, respectively.1 It is one of the most common anorectal problems.1 The major cause of the abscess is infection of the anal gland, which has become obstructed with debris known as the cryptoglandular theory.2 Generally, there are 4–12 anal glands situated around the anal circumference, predominantly in the posterior.3–5 In most people these glands are situated in the areolar tissue of the intersphincteric plane, which is rich in lymphatics3 and they drain into the anal crypts at the level of the dentate line.3 The presence of the lymphoid tissue around the glands may account for the other causes of anorectal inflammation, including tuberculosis and Crohn’s diseases.6 The suppuration spreads into adjacent spaces1 via the path of the least resistance.2 It may spread downwards to the anal margin, upwards along the rectal wall, or outwards through the external sphincter into the ischiorectal space.6 The overall incidence rate of ARA was 20.2 per 100,000. The rate of subsequent fistula formation was 15.5% in idiopathic cases and 41.6% in patients with inflammatory bowel disease (IBD).1,2,7 The median age at the time of first presentation is 40 (range 29–52) years.7 The overall incidence of ARF (or fistula-inano) in the general population is 8.6 per 100,000 per year (12.2 per 100,000 males and 5.5 per 100,000 female).1,3,8 The common age of presentation was between 20 and 60 years (mean 40).1 The median time to presentation of fistula following an abscess drainage was 7.0 months (range 6.9–7.1 months).7 Predictors of fistula formation were IBD, female gender, age at time of the first abscess (41–60 years), and intersphincteric/ischiorectal abscess location (compared to perianal location).7 The lifestyle risk factors that increased the risk of developing fistula are a body mass index of >25.0 kg/m2, high daily salt intake, history of diabetes, hyperlipidemia, dermatosis (urticaria, eczema, or contact dermatitis) within the last 6 months, anorectal surgery, smoking and alcohol intake, sedentary lifestyle, excessive intake of spicy/greasy food, little exercise, and prolonged toilet time.9 Besides the anal gland infection, other causes of ARA/ARF include IBD, fungal infection, mycobacterial infection, neoplasm, and trauma.2 Up to 30% of individuals with Crohn’s disease will develop perianal lesions8,10 and 18% present as ARF or ARAs.10 Ingested foreign bodies such as chicken or fish bones, pin perforation,11,12 penetrating trauma of anorectum, low rectal cancer, and anal-gland cancer are other possible causes of ARF.1 Anorectal Disorders. https://doi.org/10.1016/B978-0-12-815346-8.00007-2 © 2019 Elsevier Inc. All rights reserved.
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7.2 Classification ARAs are classified by the location in the perirectal space of the purulent collection: perianal abscess (located superficially around the anal verge), intersphincteric abscess (located in the intersphincteric space), ischiorectal abscess (located in the ischiorectal space), and supralevator abscess (located in the supralevator level).2 Most of a supralevator abscess is an extension of an intersphincteric abscess, which extends upwards along the intersphincteric plane.1,2 On a rare occasion a supralevator abscess may result from pelvic sepsis due to an appendicitis, diverticulitis, or gynecological infection.1 Fig. 7.1 demonstrates the types of ARA. Perianal, ischiorectal, intersphincteric, and supralevator abscesses are present in 43%, 23%, 21%, and 7% of the ARA patients, respectively.2,13 Hanley et al. described a type of abscess that originated from the anal gland, which connected to a crypt near the posterior midline and was located in the deep postanal space.14 This type of abscess has potential to spread to the ischiorectal space, unilaterally or bilaterally, as a so-called semihorseshoe or horseshoe abscess. ARFs are classified by their passage to the anal sphincter complex. The most widely used is the Parks classification1,6,8 which consists of four types: 1. Intersphincteric fistula—tracking from anal crypt through internal anal sphincter (IAS) and then between internal and external anal sphincter (EAS) down to perianal skin at anal verge.1,6,8 It is the most common type of ARF and is usually preceded by a perianal abscess.8 It can extend up high in the intersphincteric plane and presents as supralevator abscess.1,2,8 2. Transphincteric fistula—tracking through IAS and EAS into the ischiorectal fossa, then down to the skin below.1,6,8 It can be divided into high and low type.2
Rectum
Levator ani Puborectalis Superficial EAS Subcutaneous EAS IAS Intersphincteric abscess Perianal abscess FIG. 7.1 Types of anorectal abscess.
Supralevator abscess Ischioanal abscess
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3. Suprasphincteric fistula—originating from intersphincteric plane, extending up to the supralevator area and tracking over puborectalis muscle into the ischiorectal fossa and then to skin below.6,8 4. Extrasphincteric fistula—typically arise from the pelvis or rectum above the dentate line, cross the proximal to the sphincter complex, tracking through the levator ani into ischioanal fossa down to the perianal skin, without involvement of IAS or EAS.2,6,8 There is an additional subtype of ARF which courses in the submucosa without traversing either IAS or EAS called subcutaneous fistula15 or intersphincteric fistula.8 This type is often associated with anal fissures.8 Parks et al. estimated the frequencies of intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric fistula as being 70%, 23%, 2%, and 3%, respectively.6,15 A later report showed the percentage of subcutaneous, intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric as 16.4%, 55.9%, 21.3%, 3.4%, and 3%, respectively.16 ARF can also be classified as low and high types. Low-type fistulas pass through the lower third of the IAS and EAS muscles and high-type fistulas pass higher than lower third of the anal sphincters.8 The objective of these classifications is to predict the risk of incontinence after surgery.8 However, there are other risk factors that should be considered. For this purpose, ARF is divided into simple and complex types.8,17 Simple fistulas include intersphincteric fistula and low transsphincteric fistula that involves less than 30% of the sphincter complex.17 Complex fistulas include high transsphincteric, suprasphincteric, extrasphincteric, recurrent and horseshoe fistulas, fistula with multiple tracts, anterior tract in female, presence of IBD or malignancy, previous pelvic irradiation, presence of incontinence or chronic diarrhea, and involvement of other organs (e.g., vagina, base of scrotum, and urinary bladder).8,17 Fig. 7.2 Demonstrates types of anorectal fistula. The pathogenic organisms found in ARA and ARF are polymicrobial aerobic and anaerobic bacteria.13,18 The common isolated organisms are Escherichia coli (22%–25%), Enterococcus (16%–22%), and Bacteroides fragilis (20%–26%).13,18 The rarer organisms that can be found are Mycobacterium tuberculosis, Actinomycosis, Chlamydia trachomatis (lymphogranuloma venereum), and fungus.13,18 The presence of these gut-associated organisms is indicative of the presence of ARF.19
7.3 Clinical Presentation Patients with acute ARA present with perianal pain and are febrile with a hot, erythematous, fluctuant, tender, indurated swelling adjacent to the anus.1,3,20 Spontaneous drainage may occur.20 If untreated or inadequately treated, infection may involve the perineal soft tissue and fascia (Fournier’s gangrene), which can be fatal.2,20,21 This condition is likely to occur in patients with comorbid risk factors including diabetes, body mass index >30 kg/m2, hypertension, end-stage renal disease, liver failure, smoking, alcohol abuse, advanced age, and immunosuppressed states.21,22 Patients with ARF may complain of drainage, bleeding or pain, and fever.23
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Rectum
Levator ani Puborectalis Superficial EAS Subcutaneous EAS IAS Subcutaneous fistula Intersphincteric fistula Low transphincteric fistula High transphincteric fistula Suprasphincteric fistula Extrasphincteric fistula FIG. 7.2 Types of anorectal fistula.
Diagnosis of ARA and ARF is usually based on history and physical examination.17,24 A disease-specific history, emphasizing symptoms, risk factors, previous anal surgery, obstetric injury, gastrointestinal symptoms, and baseline fecal continence should be taken.8,24,25 Useful information can be obtained during a digital rectal examination.25 During inspection the practitioner should look for a bulging area, the location of an external opening, purulent discharge, the presence of secondary cellulitis, any scaring from previous surgery, and evidence of fecal incontinence.8,25 An external opening that is closed to the anal canal likely belongs to a superficial or intersphincteric fistula and an external opening that lies at 2–3 cm from the anus likely belongs to a transsphincteric, suprasphincteric, or extrasphincteric fistula.25 By palpation an internal opening and tract may be identified.8 Bidigital examination, with the index finger inside and the thumb outside the anal canal, may help identify the fistulous tract as a cord-like lesion under the skin.23 Anal sphincter bulk, tone, and defect should be assessed.8 Any point of tenderness should be noted. In an acute abscess, rectal examination and anoscopy should be gently performed and kept to a minimum as they could aggravate pain.26 A supralevator abscess may present as dull pain in the lesser pelvis or back, fever, and other nonspecific symptoms.26 An intersphincteric abscess may not have significant external findings24 but severe pain may preclude digital rectal examination and examination under anesthesia (EUA) may be more appropriate.2 Differential diagnosis of ARAs includes hidradenitis suppurativa, a skin furuncle, infections such as herpes simplex, HIV, tuberculosis, syphilis, and actinomycosis.17,24 The obtained clinical information may alert the physician to the possible etiology.8,24 Features suggestive of Crohn’s disease or atypical causes, including large skin tags or multiple fistulas, require a more detailed workup.24
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7.4 Preoperative Imaging For the preparation of an appropriate management plan, it is important to identify the location of the internal opening and to map the fistula course.8 This can be done by various methods. The classic Goodsall’s rule may be used to determine the location of an internal opening.8,17 According to the rule, an imaginary transverse line across the anus is drawn. If the external opening is located anterior to this line, the tract will run directly toward the anal canal. If the external opening is located posterior to this line, the tract will curve posteriorly toward an internal opening in the midline.8,23,25 The predictive accuracy of Goodsall’s rule is 90% for posterior fistula, but only 49% for anterior fistulas.8,13,23,25 High predictive accuracy was seen in superficial fistulas (97%) and intersphincteric fistula (84%), but decreased significantly for transsphincteric fistulas (69%).27 The reliability also decreases in the case of recurrent fistulas,17,24 long fistula tracts, fistulas with an external opening located >3 cm from the anal verge, and fistulas associated with Crohn’s disease, tuberculosis, or malignancy.8,24 Conventional fistulography, performed by injecting a water-soluble dye through the external opening and taking an X-ray,8 is not recommended for the diagnosis of ARF because of low accuracy (16%) and poorly tolerance of the patient.17,24 The technique does not provide information about the relationship between the tract and the anal sphincter complex.8 Also, it cannot be used for a fistula that has an external opening that has been closed or plugged.8 Because of the lack of sensitivity and visualization of the tract, patients had to undergo an EUA to determine the type of anorectal fistula.2 Tract injecting technique using hydrogen peroxide or methylene blue helps the surgeon in the identification of an internal opening2,24 with a success rate of 80%–90%.24 The subsequent procedure is then dictated by the location and the path of the tract.2 However, in complex cases additional investigations may help to improve preoperative planning, i.e., detect occult abscess and secondary tracts, or to assess the integrity and function of the anal sphincter muscles.17 Endoanal ultrasound (EAUS) is a cost-effective technique that may be the first-line method for imaging complex fistulas.17,23 The reported accuracy in detecting abscesses or fistulas was between 80% and 89%.17,24 The accuracy of EAUS is significantly better than physical examination in detecting the primary tract (88.8% vs 85.0%, P ¼ 0.023), horseshoe extension (85.7% vs 57.7%, P < 0.0001), and the location of the internal opening (85.5% vs 69.1%, P < 0.0001).28 Three-dimensional (3D) technique improved the accuracy for identification of the primary tract up to 94% and for the localization of the internal opening to 91%.23 Hydrogen peroxide (H2O2) enhancement, performed by injection through the external opening, further improve the diagnostic accuracy and identification of the internal opening up to 94%.17,29,30 When compared to EUA, peroxide-enhanced EAUS showed good to very good agreement with EUA in the classification of primary fistula tract (κ ¼ 0.93), identification of internal opening (κ ¼ 0.97), and detection of secondary fistula extensions (κ ¼ 0.71).29 Overall sensitivity and specificity of 3D-EAUS in the diagnosis of perianal sepsis was 98.3% and 91.3%, respectively.29 Peroxide-enhanced EAUS findings are comparable to magnetic resonance imaging (MRI) with close to 90% concordance.24
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EAUS is useful for planning the appropriate operation.29 The high diagnostic accuracy leads to successful operations in 98% of patients.31 With adjunctive volume render mode, the interpreter can better classify the type of fistula.32 The limitation of EAUS is that it cannot be performed in patients with anal stricture23 and it requires an experienced operator for diagnostic reliability.17,33 In the emergency setting, it may be difficult to localize the fistulous tract and the patient may not tolerate the anal probe.33 In such a situation EAUS under anesthesia can be performed. The suboptimal visualization of the levator plate may lead to limitation in the assessment of the secondary tract in the far field.17 Fig. 7.3 is an example of an EAUS examination of an anterior transsphincteric fistula using multiplanar views and volume render mode (Fig. 7.3D–F). The abscess and tract are heterogeneous hypoechoic lesions in the perianal space and through the anal sphincter complex. Fig. 7.4 demonstrates the use of EAUS with volume render mode and H2O2 enhancement in detecting a high transsphincteric fistula that has intersphincteric extension up to the supralevator level. Computed tomography (CT) scan may be useful in acute complex anorectal sepsis. In an emergency patients usually present with perineal pain, fever, and leukocytosis, and
FIG. 7.3 Endoanal ultrasonography (EAUS) views of an anterior transsphincteric fistula. (A–C) Normal EAUS views. (D–F) Volume render mode views. (A, D) The level of lower anal canal. (B, E) The level of mid anal canal. (C, F) Sagittal plane.
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FIG. 7.4 Endoanal ultrasound (EAUS) view of a right transsphincteric fistula with supralevator intersphincteric extension. (A, C, E, and G) Peroxide-enhanced normal EAUS views. (B, D, F, and H) Peroxide-enhanced volume render mode views. The bright white area is the fistula tract traced from the level of lower anal canal (A, B), mid anal canal (C, E), upper anal canal (E, F), and supralevator level (G, H). (I, J) Coronal views in different planes to show the high transsphincteric tract (yellow arrow) extending up in the right ischiorectal fossa and the intersphincteric extension of the abscess up to supralevator level (white arrow).
perineal examination without anesthesia may not be possible.24,33 A CT scan is readily available and effective.17,33 In nonemergency, CT fistulography provides a clear view of the fistulous tract and its relationship to the pelvic structure34 and has an advantage over MRI in allowing the visualization of an air-containing abscess.34 It is valuable to
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differentiate between supralevator and infralevator abscesses.17 In IBD, CT can help to delineate fistulas and abscesses from isolated rectal inflammation in patients with Crohn’s disease.24 Thin-slice spiral multiplanar CT scan is useful when MRI is not available or contraindicated (such as in claustrophobia).25 However, a limitation occurs when the external opening cannot be cannulated for contrast injection.34 Also, the poor resolution of the soft tissue makes it difficult to distinguish between the fistula tract, fibrotic material, and sphincter muscle.8,34 MRI with or without an endoanal coil is the gold standard for imaging the ARF.8,17 The accuracy was 90% for mapping fistula tract and identifying the internal opening.17,24,25 It can demonstrate the tract angulation related to the internal opening.2 The anal sphincter muscle, levator ani, and the tract branching are clearly demonstrated, therefore supralevator and infralevator abscesses can be differentiated.8 The sensitivity and specificity of MRI vs EAUS was 0.87 vs 0.87 and 0.69 vs 0.43, respectively.26 MRI is pain free, nonoperator dependent, and is preferred to EAUS when the lesion is far from the anus.26 However, the high cost and lack of availability may limit its usage.23,25,26 Preoperative imaging assists the surgeon in planning, counseling, and selecting the appropriate procedure.2 In patients who may require sphincter division, preoperative anorectal manometry can predict postoperative anal function17 and allow preoperative planning. The choice of investigation depends on the patient’s condition, availability of facilities, cost, and the physician’s personal experience.
7.5 Treatment The primary goal of ARA treatment is to drain the septic foci.1 An immediate operative trial to prevent future recurrence or fistula formation may not always be appropriate. Primary fistulotomy without careful evaluation of the etiology and the anal sphincter complex may lead to impaired continence without a cure for the ARA.17 The principal goal of treatment of ARF is to eradicate infection, eradicate the fistula tract, if possible, and decreased the risk of recurrence while preserving anal sphincter integrity and continence.1,3
7.5.1 Treatment of an ARA An ARA should be adequately drained in a timely manner.23,24 Delayed or inadequate treatment may lead to extensive life-threatening suppuration, tissue necrosis, and septicemia.24 Incision and drainage can be performed under local anesthesia and should be as close as possible to the anal verge17,24 to minimize the length of the potential fistula.16,35,36 With an adequate sized elliptical incision postoperative wound packing is not necessary and should be avoided, as it may lead to pain and delayed healing.24,35 Alternatively, an abscess can be drained with a small tube via a stab incision and this can be left in situ until drainage stops (3–10 days).24,35 If the abscess is complex, drainage should be performed in the operating room under sedation or regional or general anesthesia.17 An intersphincteric abscess can be drained into the anal canal via internal
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sphincterotomy.35 A supralevator abscess that has originated from the upward extension of the intersphincteric abscess may be drained into the rectum or via the transanal insertion of a drain.35 An ischiorectal abscess with or without supralevator extensions should be drained through the perianal skin.35 In the presence of a horseshoe abscess, a contralateral incision over the perianal skin overlying the ischiorectal fossa should also be made to allow adequate drainage from both sides.17 If the internal opening is identified, insertion of a seton through the fistula tract allows drainage and facilitates the second-stage of the procedure, which may be performed 8 weeks later.17 A modified Hanley technique, which is a partial sphincterotomy combined with seton, can be used to resolve a horseshoe abscess while minimizing the risk to analsphincter function.35 A primary fistulotomy for simple fistula that has an identified internal opening should be used with caution to avoid iatrogenic damage to anal sphincter.17,35 In the first occurrence group, the recurrence rate was reduced by 83% (relative risk 0.17, P < 0.001) but a high risk of fecal incontinence to flatus and soiling was seen (relative risk 2.46, P ¼ 0.140).37 Postoperative fecal incontinence has been reported as high as 44%.17,35 The overall recurrence rate after ARA drainage ranges from 3% to 44%.35 A fistula developed in 37% of patients and 10% developed a recurrent abscess.38 Being female and suffering from a horseshoe abscess were associated with higher recurrence rates.35,38 The surgeon should weigh the possible decreased recurrence rate with the potentially increased risk of continence disturbance.24 Antibiotic therapy is unnecessary in an uncomplicated ARA undergoing drainage.17,35 It should be considered in patients with cellulitis, concomitant systemic disease, HIV, underlying immunosuppression, or atypical anorectal infection.17,24,35 Preoperative antibiotics before incision and drainage should be given in patients with previous bacterial endocarditis, prosthetic valve, congenital heart disease, and heart transplant recipients with valve pathology.17,24,33 In immunocompromised patients, with an absolute neutrophil count of >1000/mL and fluctuance on examination had higher resolution rates with incision and drainage but in patients with a lower absolute neutrophil count (<500–1000/mL) and/or lack of fluctuance on examination may be successfully treated with antibiotics alone in 30%–88%.24,35
7.5.2 Treatment of ARF Secondary fistulas related to IBD, cancer, irradiation, or iatrogenic injury should be treated accordingly. The treatment of primary cryptogenic ARF is primarily surgery,2 which is tailored to match the classification and the patient’s continence status. The key to a successful operation is excision or destruction of the infected anal gland in the intersphincteric space39 and obliteration of the internal opening2,24 and any associated epithelialized tracks with minimal sphincter division.24 Watchful waiting in a patient with minimal symptoms or with a prohibitive operative risk can be performed.2 The risks associated with observation include recurrent ARA or fistula and, rarely, malignancies arising in this long-standing tract.2 Surgical options for
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ARF can be divided into two major types: a sphincter-preserving operation and a nonsphincter-preserving operation. The selection of technique should be based on the etiology, anatomy of the fistula, degree of symptoms, patient’s comorbidity, baseline anal sphincter function, and the surgeon’s experience.35
7.5.2.1 Nonsphincter-Preserving Operation A. FISTULOTOMY Simple ARF can be treated by fistulotomy with a high success rate ranging from 79% to 100%.17,24,35 Increased risks of recurrence are associated with complex fistulas, failure to identify the internal opening, and Crohn’s disease.24,35 Postoperative alterations in continence were reported to be between 0% and 73%,24 which is dependent on patient selection.35 It is suitable for a low submucosal fistula or one that involves the anal sphincter complex <30%.8 The risk factors for postoperative anal incontinence include preoperative incontinence, recurrent fistula, female gender, complex fistulas, and previous fistula or anorectal surgery.35 Contraindications for fistulotomy are anterior fistula (especially in females), fecal incontinence, IBD, and previous pelvic radiation.8 Marsupialization of the wound edges was associated with less pain and fewer postoperative complications.35,40 B. FISTULECTOMY Excision of the entire fistula tract also involves the removal of a part of the anal sphincter resulting in a large sphincter defect. Fistulectomy was associated with prolonged healing time and a higher risk of incontinence.35,41 This procedure should not be undertaken for simple anal fistula.17 C. SETON Seton is a foreign material (suture, rubber band, silastic vessel loop) placed through the fistula tract that can be tightened sequentially at regular intervals until it eventually cuts through the entire tissue thickness.23 These sequential intervals allow the process of foreign body reaction to cause fibrotic healing of the recently cut area to re-ensure continuity of the anorectal ring.23,24 The healing rate of the cutting seton has been reported to be up to 90%–94%.35 A recurrence rate of 2%–8% has been reported.8,23 This procedure involves the division of the anal sphincter to some extent and there is no agreement as to its safety.17 A fecal incontinence rate of 12%–60% (2%–3% incontinence for solid stool) following this procedure was found.8,23 Due to the high postoperative incontinence rate, it should therefore be reserved for cases where no other alternatives are available8 and should be performed meticulously.35 Drainage or loose seton can be used to control sepsis8,24 in the emergency setting, which is followed by a secondary procedure (endoanal advancement flap, fibrin glue, anal plug) or, in Crohn’s disease, during the medical management.8 This kind of seton is a thin,
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nonabsorbable suture that is placed along the tract through the anus.8 It provides drainage, prevents abscess recurrence, and is a marker for future fistula surgery.1,8 Fig. 7.5 shows the classic procedures for the treatment of ARF and the amount of the anal sphincter that is sacrificed during the operations.
7.5.2.2 Sphincter-Preserving Procedures A. ADVANCEMENT FLAP Treatment of complex FIA should not involve sphincter cutting in order to avoid postoperative fecal incontinence. The endorectal advancement flap is a technique that uses a partial or full thickness anal mucosal-submucosa-muscle flap to cover the internal opening.8,24 The mean success rate of this technique is 70% (range 57%–90%)17,24 with a recurrence rate of about 13%–56%.24,42,43 Full-thickness flaps have the lowest recurrence rate (7.4%) compared to partial-thickness flaps (19%), and mucosal flaps (30%).43 The risk factors for failure include increased age, history of surgical abscess drainage, suprasphincteric fistula, horseshoe abscess, and high body mass index.24,42 Mild or moderate incontinence was reported in 7%–38% with decreased resting and squeeze anal pressure, which may be due to the inclusion of the IAS into the flap.24,43 Mucosal-, partial-, and full-thickness flaps had incontinence rates of 9.3%, 10.2%, and 20.4%, respectively.43
Low fistula
Loose seton
Fistulotomy
Cutting seton
FIG. 7.5 Low fistula and the classic procedures for treatment of anorectal fistula.
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The additional treatments for the fistula tract, i.e., core-out or curettage, have similar rates of recurrence and incontinence.42,43 The potential complications from the flaps are rectal dissection and scarring of anorectal area.8 The anodermal advancement flap is an alternative to the mucosal advancement flap.25 It is performed by raising an anoderm and perianal skin flap, which includes the internal opening, and moving this up to suture it to the proximal rectal mucosa.25 Fig. 7.6 shows the procedure for the mucosal advancement flap and the anodermal advancement flap. B. FIBRIN GLUE INJECTION This procedure is performed by simultaneously injecting thrombin and fibrinogen from a two-chambered syringe into the fistula tract through the external opening.17 The patient should then be supine for several hours and avoid excessive movement during the first operative month.44 The obliteration of the tract is supposed to prevent the constant re-introduction of luminal bacterial from entering3 without the need for division of the anal sphincter. The aim is to reduce the complications from surgical procedures. The host cells will eventually lyse the fibrin plug and replace it with scar tissue.44 A success rate of 25%–94% (10%–67% for complex fistula) and recurrence rate of up to 26%–59% have been report.17,23,3544 As it is relatively ineffective,35 it should be used as second- or third-line treatment.23 The advantages of the use of fibrin glues are low morbidity, no risk of incontinence, simplicity, shorter hospital stays, less postoperative pain, repeatability, and it does not preclude the possible use of other techniques.17,23–25
High fistula
Mucosal advancement flap
Anodermal advancement flap FIG. 7.6 Mucosal advancement flap and anodermal advancement flap. The mucosal advancement flap (upper; raised from rectal mucosa) and anodermal advancement flap (lower; raised from anoderm and perianal skin) are used to cover the internal opening of the anorectal fistula.
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C. ANAL FISTULA PLUG An anal fistula plug (AFP) is a cone-shaped porcine acellular collagen matrix bioprosthesis (Surgisis AFP, Cook Biotech Inc., United States) that is used to close the internal opening of the fistula.24,44 It is fixed to the submucosa and IAS44 to avoid migration. Physical activity should be limited in the early postoperative period.44 The overall success rates range between 24% and 92%8 (70%–100% for low fistula and 80%–83% for complex fistula).24 A failure rate of up to 87% has been reported.45 Factors that may influence failure include early dislodgement, multiple previous surgery, fistula between pelvic organs (anovaginal fistula), Crohn’s disease, short fistula tract, HIV infection, and active smoking.25,46 The drawbacks of this technique are the high cost44,46 and moderate risk of infection (21% abscess formation).44 Newer materials have been developed to improve the outcome, including bioabsorbable synthetic fistula plug (GOREBIO-A, Gore medical, United States; 67% polyglycolide, 33% trimethylene carbonate), with success rates ranging from 16% to 73%.17,47 Deterioration of continence was found in 6%.47 Compared to the mucosal advancement flap, AFP had less postoperative pain, shorter healing time and hospital stay without difference in healing rates, fewer complications, and lower rates of recurrence.48 Although in a recent randomized controlled study high recurrence rates (66%) after AFP were found.49 Autologous cartilage had also been used as an AFP, but this technique has not been popularized.50 Recently, a new material combining the silicone plug and cylindrical collagen matrices (Curaseal AF device) was used to close the internal opening and form a scaffold for natural healing. A healing rate of 70% without disturbance of continence has been shown.51 D. LIGATION OF INTERSPHINCTERIC FISTULA TRACT This technique of ligation and division of the fistula tract in the intersphincteric space was reported in 2006 with a success rate of up to 94%.52 The aim is to eliminate the source of infection by obliterating the entrance from the anal canal44 and removing the intersphincteric nidus.52 Success rates of 57%–94% (mean 74.6%) with a healing time of 4–8 weeks, minimal morbidity, and no de novo incontinence were report.24,44,53 The recurrence rate was 6%–18%. The postoperative complication rate was only 1.8%–5.5% (minor: persistent pain, anal fissure, thrombosed hemorrhoid, wound infection, wound dehiscence, perianal hematoma, secondary bleeding).24,54 The patient satisfaction rate was 72%–100%.53 The risk factors for failure were obesity, smoking, multiple previous surgery, and the length of the fistula tract >3 cm.35,53 Preoperative seton drainage was not associated with increased success rates.55 The advantages of the ligation of intersphincteric fistula tract (LIFT) technique are the preservation of the anal sphincters, minimal tissue injury, and short healing time.54 The technique is easy-to-learn, inexpensive,3,24,54 repeatable, and can be used in both simple and complex ARF,35,56 including those associated with Crohn’s disease.57 Modification of the LIFT technique included omission of fistula tract division, excision of the lateral aspect of the tract, and the combined use of a seton, fistula plug, or biological mesh interposition.35 Up to now no additional benefit of combining procedures has been demonstrated.55
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E. VIDEO-ASSISTED ABLATION OF THE FISTULA TRACT This technique uses a 3.3 4.7 mm-diameter fiber-optic fistuloscope, which is inserted through the external opening to identify the internal opening, irrigate the tract with the glycine-mannitol solution, and destroy the tract with a unipolar electrode.8,17,54 Closure of the internal opening can be performed using semicircular or linear staplers or a mucosal flap.8,17,54 Synthetic cyanoacrylate glue can also be applied to reinforce the closure.54 Secondary tracts or abscesses can be debrided and irrigated.17 The healing rate was between 58% and 87%, which may be the effect of the technique of closure of the internal opening.17,25 The mean complication rate was 4.8% (perianal sepsis, bleeding, pain, urinary retention) and the recurrence rates were 16%–18% at the median follow-up at 9 months.58 The main benefit of video-assisted ablation of the fistula tract (VAAFT) is the precise identification of the fistula tract,54 minimal risk of incontinence, short hospital stays (1–4 days), and early return to work (1–11 days).59 However, the cost for the special instrument is high and the success rate has not been consistent.25 F. ADIPOSE-DERIVED STEM CELLS Mesenchymal stem cells (MSCs) derived from the adipose tissue of the patient have been used to auto-injected into the anal fistula. These cells can be obtained from the subcutaneous fat by liposuction,59 which provides 100 times more stem cells than bone marrow aspiration.54 After purification and expansion in the laboratory, the cells are prepared for implantation.59 An alternative method is to centrifuge the aspirated fat in a special automated system for 90–120 min to get the fresh concentrated lipoaspirate.60 The fistulous tract should be thoroughly curetted prior to injecting the adipose-derived stem cells (ASC) suspension, via a long, fine needle, into the tract walls.59 The multipotent MSCs have the potential to regenerate damaged tissue while inhibiting inflammation and fibrosis.61 The healing rate was reported to be between 35% and 90%.26 For cryptogenic fistula, the available studies involved only a small number of patients and further information is awaited. The main advantage of the ASC injection may be that continence is unaffected.60 However, the cost is high26 and the preparation requires additional procedures (e.g., liposuction) and instruments. In patients with Crohn’s disease, ASC was associated with a significant improvement in healing without increased adverse events.61,62 A combination of ASC and fibrin glue or acellular dermal matrix (ADM) has been used to plug the internal opening.17,44,59 Addition of stem cells did not significantly improve the healing rate compared with fibrin glue-injection alone.17,44,54 Other novel materials that have been used for fistula treatment are platelet-rich plasma, ADM, and acellular extracellular matrix (AEM), which showed high success rates of 54%–100% in early follow-up.17,63 G. OVER-THE-SCOPE-CLIP These specialized 14 mm-nitinol clips with applicator have been used to close internal openings from within the anal canal. Success rates of 70%–90% have been report without postoperative pain or discomfort.44,64 The healing rate as a first-line treatment was 79%, for recurrent fistula was 26%, and for fistula associated with IBD was 45%.64 In long-term
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follow-up a recurrence rate of 41% was found.65 Time to recurrence was 7 months (range 3–11 months).65 However, the cost is high and the infected gland is left untreated.44 H. LASER ABLATION For recurrent fistula, a radial emitting laser probe (FiLaC) is inserted into the external opening to destroy the fistula tract continuously during probe withdrawal. The aim is to “burn” the tract in a controlled manner.66 The laser wavelength used is 1470 nm and the energy level is 100–120 J/cm.66,67 The probe is withdrawn at a speed of 1 cm/6 s.65 The internal opening is closed by endoanal advancement flap3 or the internal opening may be left open.17 As a first-line treatment a success rate of 82% was reported in early follow-up.17,66 In a study that included both first-occurrence and recurrent fistulas, a success rate of 71% was found on long-term follow-up.67 The median healing time was 5 weeks (range 3–8 weeks).67 Postoperative complications included temporary pain or anismus (18%), and moderate bleeding (6%).67 A failure rate of 24% and recurrence rate of 4% were reported.67 The contraindication to laser treatment is the presence of an abscess.66,67 Although the procedure has had promising results, is easy-to-perform, and is repeatable, the disposable laser probe and the equipment are expensive.63 Newer modifications using photodynamic therapy that have improved the specificity of the burn area by using an intralesional injection of 2% 5-aminolevulinic acid, have been reported with a healing rate of 80%.68 Further study is awaited. Fig. 7.7 demonstrates the novel sphincter preservation techniques that are discussed in this chapter.
7.6 Treatment of ARA/ARF in Patients With Crohn’s Disease Perianal involvement occurs in 40%–80% of patients with Crohn’s disease.24 In 18% of cases, the presentation is ARA or ARF.68 Primary treatment is medical.24,35 In an asymptomatic Crohn’s fistula, no surgical treatment is required.24,35 In patients with symptomatic perianal disease, proctosigmoidoscopy is mandatory to check for the presence of rectosigmoid involvement, which predicts a more aggressive course.69 MRI or EAUS is preferred to CT/fistulogram/EUA to define the inflammatory character of the lesion, especially after failure of previous medical and/or surgical treatments.69,70 When symptomatic, antibiotics (metronidazole 750–1500 mg/d and fluoroquinolones; ciprofloxacin 1 g/d) can improve symptoms in over 90% of patients.23,35,69 The mainstay of treatment is the use of tumor necrosis factor-alpha inhibitor (anti-TNFs, e.g., infliximab, adalimumab).23,69 For low-lying simple FIA, fistulotomy is safe and effective.23,35,69 Healing rates were 56%–100% with a mild incontinence rate of 6%–12%.23,35 However, the extent of disease, presence of active proctitis, sphincter integrity, previous anorectal operations, gender, anterior fistula location, and stool consistency should be taken into consideration.10,35 In the presence of abscess or complex Crohn’s fistula, placement of setons for drainage of sepsis and to prevent closure of the external opening has been recommended.10,23,35 It can be left in place throughout the course of anti-TNF therapy, as too early removal may result in abscess recurrence.10,35 Cutting seton should not be
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LIFT
Mesenchymal stem cell injection
Fistula plug
VAAFT
Fibrin glue injection
FiLaC
FIG. 7.7 Sphincter preservation techniques for treatment of anorectal fistula. LIFT, ligation of intersphincteric fistula tract; FiLaC, FiLaC-fistula-tract laser closure; VAAFT, video-assisted ablation of fistula tract.
ANORECTAL DISORDERS
High fistula
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used as this was followed by incontinence in two-thirds of the patients.69 Fibrin glue and bioprosthesis plug demonstrated a success rate of fistula closure in only 25% and 31.5%, respectively.10 The mucosal advancement flap has shown a better success rate of 64% (range 33%–93%), and an incontinence rate of 9.4% (range 0%–29%).10,35 LIFT in Crohn’s disease had shown a 67% healing rate without new onset of fecal incontinence,10,35 but this requires further study.69 A promising treatment for perianal Crohn’s disease is MSC injection. From the meta-analysis, MSC injection was associated with improved healing at both early (OR ¼ 3.06 (95% CI 1.05–8.90), P ¼ 0.04) and long-term follow-up (OR ¼ 2.37 (95%CI 0.90–6.25), P ¼ 0.08).62 There was no significant increase in adverse events.62 Diverting stoma may be required to control severe perianal sepsis with insufficient response to drainage, long-term seton placement, and medical management.10,35 Diversion rates range from 31% to 49%.35 The initial response to diversion was up to 81% but dropped later.35 Proctectomy was required in 10%–20% of perianal Crohn’s disease patients to control refractory symptoms.10 This should be considered after a careful team discussion consisting of patients, gastroenterologist, and surgeons.35 The predictive factors are concomitant colonic disease, persistent perianal sepsis, prior temporary diversion, fecal incontinence, and anal canal stenosis.35 A postproctectomy complication rate of 25% was reported, which included poor wound healing and formation of perineal sinus.10
7.7 Conclusion ARF and ARA are common problems. Cryptoglandular infection is the etiology in the major group of patients. Preoperative imaging with MRI or EAUS provides the anatomical information for the disease and the anal sphincter. Various treatments have been proposed to provide drainage, obturation of the internal opening, and obliteration of the tract. The aim is to cure, reduce recurrence, and preserve anal-sphincter function. Classic operations include fistulotomy and seton (loose or cutting). The sphincter-preserving procedures to close the internal opening are endoanal advancement flap, anodermal advancement flap, LIFT, fibrin glue, AFP, and over-the-scope-clip. The procedures to desiccate the tract are VAAFT, FiLaC, and photodynamic therapy. The novel materials that are used to assist local wound healing include ASC, platelet rich plasma, ADM, and AEM. Perianal Crohn’s disease is a different entity for which the primary treatment is medication. A surgical procedure is used to control sepsis, improve healing, and salvage the refractory cases.
References 1. Abcarian H. Anorectal infection: abscess-fistula. Clin Colon Rectal Surg. 2011;24:14–21. 2. Rizzo JA, Naig AL, Johnson EK. Anorectal abscess and fistula-in-ano: evidence-based management. Surg Clin N Am. 2010;90:45–68. 3. Pigot F. Treatment of anal fistula and abscess. J Visc Surg. 2015;152:S23–S29.
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