Reoperative surgery for persistent anal fistulae

Author's Accepted Manuscript

“Reoperative Surgery For Persistent Anal Fistulae” Janice F. Rafferty MD, Jonathan R. Snyder MD

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S1043-1489(15)00072-X http://dx.doi.org/10.1053/j.scrs.2015.09.003 YSCRS521

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Seminars in Colon and Rectal Surgery

Cite this article as: Janice F. Rafferty MD, Jonathan R. Snyder MD, “Reoperative Surgery For Persistent Anal Fistulae”, Seminars in Colon and Rectal Surgery, http: //dx.doi.org/10.1053/j.scrs.2015.09.003 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

“Reoperative Surgery for Persistent Anal Fistulae”

Co-Author: Janice F. Rafferty, MD Professor of Surgery; Chief, Division of Colon and Rectal Surgery, Department of Surgery, University of Cincinnati; Cincinnati, Ohio

Co-Author: Jonathan R. Snyder, MD Assistant Professor of Surgery; Division of Colon and Rectal Surgery, Department of Surgery, University of Cincinnati; Cincinnati, Ohio

From the University of Cincinnati, Division of Colon and Rectal Surgery 2123 Auburn Avenue, Suite 524 Cincinnati, OH 45219 Phone: (513) 929-0104 Fax: (513) 929-4369 [email protected]

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Abstract Failure of treatment of a primary anal fistula is rarely life threatening, but the cost to the patient in terms of pain, discomfort, and interruption of daily life is substantial. Complex or recurrent fistulas must be methodically evaluated so a successful treatment strategy can be developed, and therapy completed, ideally without compromising fecal continence. Advanced imaging can be useful in identifying complex tracts and accumulated sepsis but is rarely indicated in the setting of a primary fistula. Multiple methods to repair complex, recurrent fistulas have been described, with varying success rates. Diversion of the fecal stream is often employed after repeat repair of a fistula, but is not universally beneficial. Treatment must be individualized according to pre-existing patient factors, number of internal openings, and condition of the tissues in and around the anus.

Key Words Reoperative anal fistula- Complex anal fistula –Fistulotomy – Rectal advancement flap – Ligation of intersphincteric fistula tract – Fistulectomy

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Body of Manuscript Introduction Failed management of an anal fistula rarely leads to death, and thus, as surgeons, we are faced with our failures over and over again. While anorectal fistula surgery is rarely life saving, the impact on the patient from a quality of life standpoint, and on society from an economic standpoint, cannot be overstated. There are direct medical and surgical costs to consider, as well as indirect costs including employment and opportunity lost, which are far more difficult to estimate. The options for surgical management of anal fistulae include simple in-office procedures and evaluations, to straightforward ambulatory operative procedures, to more complex flap reconstructions, fecal diversion and proctectomy. The use of a Seton for the treatment of anal fistulae dates back to 600 BC, when first described by the ancient Indian surgeon Sushruta1. Roughly 200 years later, Hippocrates described the application of raw lint and human hair as elements of a durable and effective Seton. He also described the act of opening the tract as the means for a cure2. For over two millennia, surgeons found themselves with a relative dearth of progress in the understanding and management of anal fistulae. The last two decades, in particular, have seen measured progress toward the goal of understanding

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and ultimately curing complex fistulae. It is these elements of progress and innovation that will comprise the bulk of this chapter.

Classification The most widely cited classification of anal fistulae was first articulated by Parks and colleagues in 19763. Although somewhat complex, this classification system provides a framework by which to approach most anal fistulae, particularly those of a complex, reoperative nature. Broadly speaking, Parks classified fistula into the following four categories: intersphincteric, transsphincteric, suprasphincteric and extrasphincteric. Intersphincteric fistulae account for 70% of those encountered in practice and lie within the plane between the internal and external sphincters. These most commonly originate from and/or are responsible for perianal abscesses. Less commonly, they can represent an extension from an infectious process within the pelvis. Transsphincteric fistulae account for 23% of fistulae and, arguably, a larger portion of those seen in reoperative and complex cases. In these cases, the tract traverses fibers of the external sphincter muscle prior to exiting the perianal skin. Appreciating the height at which this tract penetrates the external sphincter, as well as the orientation, i.e. anteriorly, laterally, or

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posteriorly, is paramount in the decision making process as to whether the fistula is amenable to simple fistulotomy or requires a more complex strategy to achieve cure. Suprasphincteric and extrasphincteric fistulae account for the remaining 5% and 2%, respectively. Suprasphincteric fistulae typically begin as an intersphincteric abscess but then travel cephalad over the puborectalis muscle before following a caudal extension towards the perianal skin. Extrasphincteric fistulae are the outliers in terms of their site of origin, as they are not typically of cryptoglandular origin, but rather originate often within the rectum itself and pass above and outside of the levators and the sphincter muscles entirely, before draining onto the perianal skin. These fistulae are often caused by Crohn’s disease, malignancy, penetrating trauma to the rectum, or iatrogenic injury from aggressive probing of a lower fistula tract4.

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Initial Considerations For most subcutaneous, intersphincteric and low-transsphincteric fistulae in an otherwise continent patient, a primary fistulotomy, or lay-open technique, is typically employed as definitive surgical management. Aside from the time required for granulation and epithelialization of the tract, there is typically little morbidity with this approach. The term reoperative fistula implies a more complex tract not cured by simple fistulotomy. While the term, “complex fistula” is not always clearly defined, the general consensus remains that a fistula is complex when reoperation is required and/or when conventional fistulotomy would render the patient incontinent5. This typically involves a transsphincteric fistula traversing at least 30-50% of the external sphincter complex, or anterior transsphincteric fistulae particularly in the female patient, where the absence of the puborectalis muscle fibers leaves the patient more susceptible to poor functional outcomes. The principles of fistula surgery have been, and will continue to be: -

Control of local inflammation/sepsis

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Closure/healing of the fistula tract

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Maintenance of the sphincter complex and, therein, the mechanism of fecal continence

Initial assessment Clinical assessment must, in every case, involve a careful interrogation of the patient’s existing/pre-operative continence status, and thorough review of previous operative notes to determine if muscle has been divided, flaps advanced, or grafts used (biologic or other). Aside from cases where the patient is mistaking external fistula drainage for fecal incontinence, corrective surgery for anal fistulae, be it of conventional lay-open or sphincter-sparing technique, will do nothing to enhance a patient’s continence. If a patient has failed a prior repair, it may be wise to objectively assess residual anatomy and status of the sphincter complex with anal manometry, ultrasound, and pudendal nerve EMG. A woman with a complex fistula should be queried about any history of pelvic floor compromise by traumatic vaginal delivery. Finally, any patient with a history of pelvic radiation should be carefully evaluated for evidence of recurrent malignancy, or significant radiation proctitis that could compromise healing of any surgical repair of a complex fistula.

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During the initial evaluation of any patient with anal fistulae, recurrent or primary, careful inspection of the perineum, digital rectal examination, and anoscopy or proctoscopy are of paramount importance. Special attention should be directed at noting the location of perianal scars, the condition of the perianal skin, number and location of external fistula openings, as well as the presence of persistent perineal sepsis. Careful digital rectal exam can reveal presence of sphincter defects, complex or multiple internal openings, and presence of induration, tenderness and stricture. Probing of a fistula tract within the office is often limited by patient discomfort. The utility of a careful and thorough exam under anesthesia cannot be underestimated, especially in patients who are not amenable to inoffice exams due to anxiety, tenderness, inflammation of the perineum, and persistent fistulas. In patients with recurrent fistulae, and particularly those with symptoms or clinical findings suggestive of inflammatory bowel disease, endoscopic evaluation with biopsies as necessary should be considered prior to definitive surgical management. Extensive and expensive cross-sectional imaging is rarely indicated in the evaluation of most primary anal fistulae. However, for complex and recurrent fistulae, especially where previous efforts to correct the deformity

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and heal the patient have failed, dedicated imaging can aid the surgeon in planning therapy and decrease the incidence of yet another failed procedure.

Imaging techniques Magnetic resonance imaging (MRI) Of the imaging modalities available, pelvic MRI has the greatest sensitivity and specificity and is considered by many to be the diagnostic test of choice in defining the anatomy of complex or recurrent fistulae6. Buchanan et al prospectively studied 104 patients with anal fistula, and evaluated each with digital examination, 10-MHz anal endosonography and MRI, and compared these results with the operative findings at the time of definitive surgery as the standard for accuracy7. Clinical exam alone was accurate in 61%, endosonography in 81%, and pelvic MRI in 90%. The accuracy of MRI increased to 97% in the identification of internal openings and more complex fistulae with horseshoe extensions. In terms of true clinical and surgical applications, the use of MRI has been shown to alter surgical decision making in 10 to 20 percent of cases. This increases to 40 percent in the setting of Crohn’s fistulae8,9. Within the realm of reoperative anal fistulae specifically, MRI has been shown to be of particular benefit. Buchanan et al followed a cohort of patients with reoperative fistulae in

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whom MRI was used, and compared the recurrence rate of cases in which the surgeon followed the MRI findings versus those in which the surgeon ignored the MRI findings10. The authors found that following the MRI findings decreased the incidence of fistula recurrence from 57% to 16%, resulting in a 75% decrease in recurrence when MRI was correctly used. The type of coil used in MRI, e.g. endoanal coil, body coil and phase array coil, have various implications in the diagnostic yield of this modality, but institutional and equipment limitations are often key in deciding which approach to use. The injection of gadolinium mixed with hydrogen peroxide into the fistula tract, referred to as HPMRI, has shown promise in more accurate identification of complex fistulae11.

Endoanal ultrasound / Endosonography Endosonography has been demonstrated to be superior to clinical exam alone, yet inferior to MRI in the delineation of complex fistulae, and accurate identification of the internal opening. Some of the initial literature demonstrated marginal, if any, improvement in the ability to correctly identify the internal opening of anal fistulae when using this modality12. In particular, endosonography was limited in its ability to correctly identify primary superficial, suprasphincteric or extrasphincteric tracts, as well as

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secondary supralevator and infralevator tracts. Modification of this technique to employ use of a 10mHz probe and simultaneous tract injection with dilute hydrogen peroxide or LevovistTM has been shown to increase accuracy in delineation of the anatomy and proper identification of the internal opening in up to 93% of cases13,14. The use of this technique is, of course, operator-dependent and may be somewhat limited in the evaluation of reoperative fistulae due to the presence of scarring and fibrosis from previous surgery.

Computed tomography (CT) scanning The use of CT scans in the evaluation of anal fistulae is limited by its inability to demonstrate the relationship of the fistula tract to the levator complex and sphincter muscles. It is often employed in the identification of unattended suppuration, or inflammation and thickening of the distal rectum and anus. The broader scope and poorer resolution of CT, as compared to MRI and endosonography, has limited its application in evaluation of anal fistulae, be they primary or recurrent.

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Fistulography A fistulogram involves fluoroscopic evaluation of the fistula tract during injection of a contrast medium via the external opening. This approach is limited by the inability to visualize appropriate soft tissue landmarks and the potential for reflux of contrast into the rectum via entry into the anus. These difficulties, as well as the potential for dissemination of sepsis due to injection under pressure, has rendered fistulography rather limited – particularly as MRI and endosonography have been further refined and standardized.

Surgical Treatment Fistulotomy The utility of a fistulotomy in the context of a reoperative anal fistula is rather limited. Certainly, for complex fistulae traversing more than 3050% of the external sphincter, or for fistulae in patients with Crohn’s disease or an immunocompromised state such as HIV infection, the experienced surgeon must hesitate to perform a fistulotomy given the risk of fecal incontinence and prolonged wound healing. When reoperation is required due to initial lack of identification of the true internal opening, and the recurrent/persistent fistula is ultimately found to be intersphincteric or low-

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transsphincteric, a fistulotomy may be reasonable. Of course, in these instances, great care must be given to counseling the patient regarding the possibility of post-operative fecal incontinence. In the standard execution of a primary fistulotomy, the patient is positioned on the operating table in prone jackknife position. Pre-operative antibiotics are not routinely given15. This is often performed under MAC anesthesia with intra-operative local anesthetic infiltration and performance of a pudendal nerve block. The trajectory and internal opening of the fistula tract are established with use of a fistula probe. Identification of the internal opening can be aided by instillation of dilute hydrogen peroxide through an angiocath into the external opening. If inspection and palpation confirm this fistula to be of subcutaneous, intersphincteric or low-transsphincteric, then a fistulotomy can be performed along the axis of the fistula probe. The base of the fistula tract is then curetted free of all granulation tissue and often cauterized. The wound is either left open in this state or the edges marsupialized using absorbable suture. This may be described by some as a fistuloplasty and involves suturing the cut edges of the anal mucosa and anoderm to the fibrotic lateral boundaries of the fistula tract. The rationale behind performance of marsupialization is to promote more rapid healing of the

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fistula tract. In a randomized controlled trial looking primarily at the safety and efficacy of incision and drainage of perianal abscesses versus fistulotomy at the time of the index operation, Ho et al reported improved outcomes in patients when wounds were marsupialized as compared to those simply laid open16 . Healing time was improved from 10 weeks to 6 weeks; incontinence to liquid stool was improved from 12% to 2%, and anal manometric studies demonstrated increased maximal squeeze pressure.

Fistulectomy Fistulectomy, or surgical excision of the entire fistula tract with or without primary surgical closure of the wound, is a technique not widely practiced. A single randomized trial comparing fistulotomy to fistulectomy demonstrated more rapid healing and fewer reports of fecal incontinence following fistulotomy. Re-operative rates for failures were similar between the two groups17. These results were reiterated in a subsequent Cochrane review, although sparse data could be found in the interim to support or refute these findings18. Nonetheless, the understanding that fistulectomy involves greater disruption of the sphincter muscle fibers and possibly a greater threat to continence has led to recommendation against this practice19. The practice of a core fistulectomy, however, particularly when

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combined with creation of an advancement flap, has demonstrated excellent healing rates – from 77% to 98.4%, with disturbance in continence in up to 8%20,21.

Anal Fistula Plug The anal fistula plug seems attractive for a reoperative fistula, since the risk for worsening patient continence or perineal sepsis is low. However, this modality has been used with varying rates of success by different authors. The plug was initially developed in an effort to simplify management of transsphincteric (or higher) anal fistulae, obviating the need for painful surgery, prolonged recovery and the potential for impairment of continence. With these goals in mind, an anal fistula plug was fashioned from a bioabsorbable xenograft (Surgisis®, Cook Surgical, Inc., Bloomington, IN) made from lyophilized porcine small intestinal submucosa. Healing after fistula plug placement compared favorably to injection of fibrin glue in the initial report (87% vs. 40%, p <0.05) 22. Enthusiasm grew when the same authors achieved similar results in prospective studies23,24, despite the inclusion of Crohn’s fistulae. Unfortunately, these results were not reproducible by other investigators, who reported success rates varying from 14% to 88%, with a

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median range of 40%25-30. A prospective randomized controlled trial comparing anal fistula plug to rectal advancement flap was closed early due to the vast difference in success rate between the two groups seen at 12 months follow-up with 12 of 15 fistula plug patients experiencing failure, compared to only 2 of 16 patients in whom an advancement flap was performed30. Many failures were blamed on implant extrusion and lack of fixation. In an effort to further refine and perhaps improve upon the concept of plugging the complex fistula, a second synthetic fistula plug was developed and is composed of composed of a bioabsorbable monofilament copolymer – polyglycolic acid:trimethylene carnonate (PGA:TMC) (GORE® BIO-A® Fistula Plug, W.L. Gore & Associates, Elkton, MD). Results with this plug are highly variable as well31-34. The largest study of the synthetic plug in the treatment of cryptoglandular transsphincteric anal fistulae was recently published35. The authors reported on 93 patients with complex fistulae repaired with the plug and followed at 1, 3, 6, and 12 months postoperatively. Healing rates at 6 and 12 months were 41% and 49%, respectively. Somewhat surprisingly, incontinence scores were significantly improved by 6 months. The authors postulated that this might be clouded by the patients’ misinterpretation of external drainage for fecal leakage.

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Despite moderate success rates that appear to be heavily userdependent, a fistula plug can be considered for use in the reoperative setting given the low risk and technical ease of use. Both the patient and surgeon must be fully aware of and willing to accept the potential for failure and need for future interventions.

Rectal advancement flap The rectal advancement flap is known by many names, including: transanal advancement flap, anorectal advancement flap, endoanal/endorectal advancement flap, anal/rectal mucosal advancement flap, among others. This is regarded by some as the gold standard for surgical repair of complex or recurrent anal fistulae. Advancement flap has been well studied, both in the primary repair as well as reoperative repair of anal fistulae. Considerable debate exists regarding the optimal depth of flap development, under the postulate that while a thinner flap may be more mobile, a thicker flap will confer better blood supply and more tissue to serve as an interposition between the remaining fistula tract and repair. In general, patients are prepared with mechanical bowel preparation and perioperative antibiotics. Under a general or regional anesthetic, the patient is positioned most commonly in the prone jackknife position,

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although lithotomy position can be used for fistulae with posterior internal openings. The external and internal openings of the fistula are identified and a flap consisting of mucosa, submucosa and a portion of the internal sphincter is then raised, beginning 1cm distal to the internal opening and continuing several centimeters above the internal opening. The fistula tract is identified and transected, and dissection continues for 4-6cm proximally. The flap is designed so that the base (proximal) is broad, in general twice as wide as the tip (distal). The exposed deep aspect of the internal opening of the fistula is closed with absorbable suture. The portion of the flap containing the fistula tract is then excised sharply and, after ensuring adequate mobility and vascularity the tip of the flap is secured to the neodentate line (1cm distal to the internal fistula opening) and to the lateral aspects of the divided anorectal tissue using interrupted absorbable suture. The external opening of the fistula is dilated slightly and debrided. The external opening is then either left open to close by secondary intent; or, if the tract is long or complex, a Pezzer catheter is placed and secured. If placed, the drain is left in for several weeks, until drainage has ceased and evidence of healing of the internal opening is present. There is not consensus about the ideal depth of an endorectal advancement flap. Some authors describe appropriate flap thickness as

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involving mucosa and submucosa only36. The largest body of published surgical experience endorses the use of a flap consisting of mucosa, submucosa and a portion of the internal sphincter muscle37-43. Considerable experience has also been reported in the creation of full-thickness flaps, involving all layers of the rectal wall and dissection into the mesorectal fat44,45,46. There is a tendency towards poorer functional outcome but improved fistula cure rate when a partial or full thickness flap is used, as compared to a flap consisting of mucosa and submucosa only. In a prospective randomized trial involving 40 patients with “high anal fistulae,” Khafagy et al studied the outcomes of a mucosal/submucosal flap (limited thickness) versus those involving the superficial internal sphincter (partial-thickness). Success rates were 60% for the limited-thickness flap and 90% when partial-thickness flaps were used. Ten percent of patients in the partial-thickness group developed incontinence to flatus versus none in the limited-thickness group, although this did not achieve statistical significance46. A retrospective analysis of seventy patients undergoing advancement flap found no difference in the full- or partial-thickness approach versus the limited thickness technique, but also noted a trend toward poorer functional outcomes with thicker flaps47. A smaller retrospective analysis of fifty-four

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patients found a 95% success rate for full-thickness flaps versus a 65% success rate in the mucosal flaps with no difference in minor incontinence between the two groups45. Those with four or more prior operations were identified as those with the highest potential for recurrence. Of all of the techniques available for persistent anal fistulae, redo advancement flaps carry the greatest body of published data36,49,50,51. In two retrospective analyses, Zimmerman et al have demonstrated no evidence of decreased success when using advancement flap in the treatment of reoperative anal fistulae41,51. In a randomized controlled trial comparing the use of fibrin glue to conventional techniques for reoperative fistulae, Lindsey et al cited the presence of a prior flap repair as a limiting factor in the performance of a repeat procedure52, but this is not otherwise supported in the literature. Anal stenosis, regardless of the cause, may prove to be a rate-limiting factor in the technical feasibility of performing a rectal advancement flap, given the resultant inability to place adequate retraction and visualize and manipulate the anorectal wall. This determination should be made at the time of in-office evaluation in order to facilitate appropriate surgical planning of a more suitable procedure – e.g. LIFT, biologic or interpositionflap repair.

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Anocutaneous advancement flap The general principle of an anocutaneous (or anodermal) advancement flap is similar to that of a rectal advancement flap, only in reverse orientation. There are several variations of this technique, including dermal island flap creation and Y-V advancement flaps. The general technique was first described as a pioneering effort to mitigate the risk of incontinence following fistulotomy, and of anal ectropion following advancement flap53. The initial reports demonstrated promising results, with short-term success in 7 of 8 patients without Crohn’s disease (recurrence in 2 of 3 patients with Crohn’s). Shortly thereafter results from seventy-three dermal island flap anoplasties were published, and cited closure of the internal sphincter defect as improving success, while simultaneous injection of fibrin glue decreased the rate of successful healing54. Other variations on this technique have involved creation of a diamond-shaped flap55, as well as a V-Y advancement flap56,57, with success rates from 80-90% and no reports of alteration in fecal continence. Proponents of the anocutaneous flap technique report the technical feasibility of re-advancing the flap in cases of failure. Although limited in

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total number, reports demonstrate healing in redo procedures in 69-100% of cases performed.

Ligation of the intersphincteric fistula tract (LIFT technique) The varied success rates of flap repairs as well as the desire to avoid disturbing continence encountered during aggressive fistulotomies drove surgeons to pursue alternative methods of repair – via an external incision and dissection through the intersphincteric plane. The initial description of this technique was in 1993 and included 13 patients with high anal fistulae58. The authors described an approach of total sphincter preservation in which a partial fistulectomy and excision of the culprit anal gland was achieved via an intersphincteric approach. Complete success was achieved in seven patients (54%), while two (15%) required subsequent division of the internal sphincter, and four patients (31%) failed repair altogether. While not widely adopted, it was subsequently mentioned in a textbook of colon and rectal surgery59. The initial technique was initially believed to have a relatively high failure rate due to disruption of the internal sphincter muscle fibers during partial fistulectomy and susceptibility of breakdown of a now-ischemic portion of the anal mucosa in spite of careful repair. In an effort to preserve yet further refine this intersphincteric approach, Rojanasakul published a

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description of the LIFT procedure in 2007, based on a prospective observational study of eighteen patients where a refined procedure was employed60. An impressive rate of healing was described (94.4% success), with an average time to healing of four weeks and no disturbance in fecal continence. Further refinement of the technique was published in 200961. The key steps of the procedure were described follows: as incision along the intersphincteric groove, successful identification of the fistula tract within this plane, ligation of the tract close to the internal sphincter muscle, removal of the intersphincteric tract with debridement of the remainder of the tract, and suture closure of the defect at the external sphincter muscle. Adding a partial core fistulectomy to the level of the external sphincters has been described as the “LIFT Plus” technique and, in small numbers, has not been shown to be independently superior to conventional technique62. A patient with a badly scarred perineum and/or previous fistulotomy at the same site may prove to be a far more challenging candidate for a LIFT repair, given the local fibrosis and loss of normal subcutaneous and intersphincteric tissue planes. Early failures often manifest as an intersphincteric fistula, which represents a medialization of the initial fistula and subsequently simplified management of the remaining tract. In most cases, this is amenable to simple fistulotomy or silver nitrate application63.

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To perform a LIFT procedure, patients are typically positioned on the operating table in prone jackknife position under a heavy MAC (monitored anesthesia care) with local anesthesia or a general anesthetic. Bowel prep can be limited to rectal enemas before the procedure. An anal retractor is placed and the internal opening identified with a fistula probe inserted via the external opening. This probe is then left in place until the tract is ready for division later in the procedure. In many cases, a previous indwelling loose seton will have been in place for 6-12 weeks prior to surgery, although some authors have reported no association between pre-LIFT drainage seton and success of LIFT64. With appropriate tension being placed on the sphincter complex via the anal retractor, the intersphincteric groove overlying the fistula tract is then marked and a 3-4 cm curvilinear incision is made in the intersphincteric groove over the probe. Dissection is typically initiated with a needle-tip cautery device and radial retraction on the wound is then provided with a retractor (Lone Star® Retractor System, Cooper Surgical Inc, Trumbull, Connecticut). Care is taken to stay within the relatively avascular intersphincteric plane and avoid injury to the internal and external sphincter muscles. The fistula tract is frequently palpated with the probe still in place and the dissection continues beyond the tract, as the tract is circumferentially dissected. Prior to division of the tract, the fistula

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probe is removed and the tract is suture ligated with absorbable suture at the innermost aspect of the external sphincter and the external aspect of the internal sphincter. The tract is then sharply divided (or partially excised, depending on length) and complete closure of the tract is ensured by instilling dilute hydrogen peroxide into the external fistula opening. The internal closure is confirmed by filling the wound with dilute hydrogen peroxide and inspection within the anus for efflux through the internal opening. Either end of the tract is repeatedly ligated until complete closure is achieved. The external opening of the fistula is then enlarged and either curettage or a partial core fistulectomy (avoiding the external sphincter muscle) is performed. Gentle curettage of the internal opening can be performed through the anus. The external wound is left open and the intersphincteric incision is then closed in layers using absorbable suture. Support of this approach has grown as favorable success rates continue to accrue. In 2014, a meta-analysis was published65 that included twenty case series, three case control studies and one randomized control trial. In total, 1,110 patients were included in this review. Most cases involved transsphincteric fistulae or complex fistulae not otherwise amenable to fistulotomy. Mean follow-up was 10.3 months, with a mean success rate of 76.4%. Intra-operative complications and incontinence

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occurred in 0% of the pooled mean, while post-operative complications (including bleeding, external hemorrhoidal thrombosis, and wound separation) occurred in 5.5%. The use of pre-operative indwelling seton use did not correlate with a higher rate of success, yet the nature of the studies being reviewed prevented the authors from drawing any definitive conclusions regarding predictors of success or failure. Other investigators have added variations to the LIFT technique in an effort to improve success66,67,68 with variable outcomes. Another review of much of the same literature also looked at factors predictive of LIFT failure, identifying obesity, smoking, multiple prior attempts at repair and length of the fistula tract as factors that negatively impact on success69.

LIFT versus advancement flap for complex fistulae To date, two randomized control trials comparing LIFT technique to rectal advancement flap have been published. In the first, patients with high anal fistulae and an existing indwelling Seton were randomized to either rectal advancement flap or LIFT repair70. Twenty-five patients were included in the LIFT arm and fourteen patients in the advancement flap arm of the study. Outcomes were measured on the basis of successful healing of the fistula, operative time, complications, readmissions and fecal

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incontinence. The average time to return to normal activities was one week for the LIFT patients and two weeks for the advancement flap patients. Success rates at nineteen months were similar between the two groups, with two failures in the LIFT group (92% success) and one in the advancement flap group (93% success). Complications were similar between the two groups, with the only patient suffering minor fecal incontinence being in the advancement flap group. In 2014, a randomized control trial of seventy patients was published, comparing the results of LIFT versus advancement flap repair71. The authors reported shorter healing times in the LIFT group when compared to advancement flap (22.6 vs. 32.1 days, p=0.01). The initial post-operative pain scores at one week favored the LIFT group, but no difference was seen at four weeks. Success rates at one year were similar between LIFT and advancement flap (74.3% vs. 65.7%, p=0.58). There were no significant differences in post-operative Wexner incontinence scores and Cleveland Global Quality of Life scores between the two groups. In a retrospective analysis, another group found superior healing in the use of advancement flaps (93.5%) when compared to the LIFT technique (62.5%, p = 0.006) 72. Of the 31 patients in the advancement flap group, 59% had previous attempts at repair, while only 25% of those in the LIFT group

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had previous surgery for the fistula. Both groups were managed with indwelling setons for similar periods prior to surgery.

Tissue Interposition and Coloanal anastomosis Local Tissue Interposition Grafts Originally described by Henri Martius in 192873, the use of a bulbocavernosus muscle and labial fat pad graft as an interposition has been used as a means to treat refractory or complex rectovaginal fistulae. This approach was elegantly modified and described in 1990 to incorporate only the labial adipose tissue and leave the bulbocavernosus muscle in situ, thus reducing the morbidity and operative time74. Its use has since been extrapolated to the treatment of complex anal fistulae, specifically suprasphincteric anal fistulae, with excellent results, albeit in small numbers75. In brief, the technique employs the use of creation of an interposition labial fat pad graft, maintaining blood supply from the perineal branch of the internal pudendal artery, as an adjunct to fistulectomy with layered repair and reapproximation of the sphincter muscles. Additionally, gracilis, rectus abdominus, latissimus dorsi, dartos, and gluteus maximus muscle flaps as well as omental flaps have been used as means of harvesting well-vascularized tissue to serve as local interposition as

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an adjunctive repair for complex perineal fistulae. However, the greatest body of literature on these techniques reports on their use in the management of fistulae to the genitourinary structures76. These techniques should be considered in reoperative anterior fistulae, particularly in the female patient.

Coloanal Anastomosis Similar to tissue interposition flaps, coloanal anastomosis has been employed as a means of treating complex fistulae, particularly to the vagina and urethra. The coloanal sleeve anastomosis (Soave procedure) has been described particularly in the setting of rectourethral fistulae with somewhat favorable results77. The Parks coloanal sleeve anastomosis has been used most commonly for treatment of rectovaginal fistulae following previous radiation injury, primarily for prior gynecologic malignancy78. While either approach has limited role in the management of most complex anal fistulae, consideration may be given in the appropriate clinical setting, such as in rectovaginal/rectourethral fistulae and/or prior radiation exposure.

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Additional Therapies The use of fibrin glue has largely been abandoned in the management of anal fistulae due to low rates of success79. Additional novel therapies are under study and include fistula laser closure, video-assisted anal fistula treatment (VAAFT), and the use of adipose-derived stem cells. The requirement for highly-specialized and rather costly equipment required in the implementation of these latter three therapies may ultimately stand in the way of their widespread acceptance.

Adjuncts to Fistula Repair Diversion of the fecal stream As fistulae recur and manifest themselves in an increasingly complex fashion, common sense would suggest that healing would be enhanced by diversion of the fecal stream at the time of fistula repair. The majority of published data is retrospective in nature and reflects the use of ostomy creation on a case-by-case basis at the discretion of the surgeon. As such, one might assume that such cases represent more severe cases of complex fistulae in which perianal sepsis is poorly controlled, or patients in whom the quality of life is poor due to the severity of their disease. Unfortunately, no

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randomized control trials or prospective analyses dedicated to the study of the impact of a covering stoma prior to fistula repair exist. In an attempt to identify predictors of failure, Mizrahi and colleagues published their experience with 106 patients undergoing advancement flap repair – either recurrent or primary80. They found no difference in success rates with or without the use of a diverting ostomy. The use of perioperative antibiotics or steroids also did not predict success or failure. Only the presence of Crohn’s disease conferred a significantly higher failure rate (57% vs. 33% failure, p=0.027). Additional retrospective data support the findings that a diverting stoma does not enhance the successful healing rates in fistula repair49. In spite of their retrospective data, Sonoda, et al suggested that the use of a covering stoma may be reserved for more severe cases and may allow the healing rates in complex reoperative fistulae to approach the rates seen in cases of primary repair. While the use of fecal diversion in complex fistula repair may not be supported in retrospective analyses, its use should remain within the armamentarium of a surgeon faced with a particularly challenging reoperative fistula. At the very least it may serve to enhance patient comfort and decrease soiling during the healing phase.

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The Effect of Smoking and Obesity Patients who smoke appear to be at increased risk for failure of fistula repair, particularly in the setting of an advancement flap. In 2003, Zimmerman and colleagues reported on their experience with 105 consecutive patients undergoing transanal advancement flap repair for high transsphincteric anal fistulae51. In looking at a multitude of factors – age, gender, the number of previous repairs, body mass index, the use of preoperative setons, anatomy of the fistula and associated abscesses, and the number of cigarettes smoked per day – the only variable of any significance was the number of cigarettes smoked. Smokers experienced nearly a twenty percent decrease in their likelihood of successful healing. Evaluation of mucosal blood flow by laser Doppler flowmetry has demonstrated decreased perfusion in smokers when compared to non-smokers41. While these studies found no difference in the healing rates for obese versus non-obese patients, additional data exist to support the idea that obese patients fare worse in terms of healing rates following surgery for complex fistulae81. In 205 patients who underwent advancement flap for complex anal fistulae, and in whom obesity was defined as a BMI >30, multivariate analysis found obesity to be an independent predictor of success

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or failure, with obese patients experiencing a healing rate of 72% as compared to a rate of 86% in patients with a BMI less than 30.

Conclusion The treatment of a recurrent anal fistula is challenging for even the most experienced of surgeons. Methodical evaluation of patient factors, fistula anatomy, condition of pelvic and perineal tissues, and pre-existing fecal incontinence is important to good functional outcome and cure of the fistula. The experienced surgeon should have a full armamentarium of techniques available when operatively approaching a complex, recurrent fistula in ano.

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