Clinical applications and techniques of cinedefecography

The American Journal of Surgery 182 (2001) 93–101

Review

Clinical applications and techniques of cinedefecography J. Marcio N. Jorge, M.D., Angelita Habr-Gama, M.D., Steven D. Wexner, M.D.* Department of Coloproctology, University of Sa˜o Paulo, Sa˜o Paulo, Brazil Department of Colorectal Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Boulevard, Weston, Florida 33331, USA Manuscript received October 17, 2000; revised manuscript January 28, 2001

Abstract Background: Cinedefecography is of value in routine examination of functional disorders of the pelvic floor. Interest in this technique has rapidly expanded owing to the increased availability of colorectal physiologic testing and better understanding of the multifactorial pathophysiology involving evacuation disorders. Methods: A summary of the available techniques, methodology, and indications for cinedefecography was undertaken. In addition, information was provided on interpretation of these images particularly in the context of anatomic abnormalities and clinical applications. Results: Cinedefecography can be rapidly and easily performed using standard radiographic equipment. Effective radiation dose is significantly lower than for other intestinal contrast studies. The technique has been found most useful for measurements of perineal descent, puborectalis length, and ascertaining the function of the puborectalis muscle and pelvic floor. Common diagnoses that can be made by this test include nonrelaxing puborectalis syndrome, perineal descent, rectocele, enterocele, sigmoidocele, and rectoanal intussusception. Conclusion: Cinedefecography provides a wide range of information to assist the surgeon with the evaluation and management of patients with evacuatory and other associated pelvic floor disorders. © 2001 Excerpta Medica, Inc. All rights reserved. Keywords: Defecography; Pelvic floor disorder; Obstructed defecation; Constipation

The interest in radiographic imaging of the pelvic dynamic changes during evacuation was triggered in 1952, when Lennart Wallde´n [1], in a comprehensive study, investigated the relationship among deep rectovaginal pouches, enterocele, and obstructed defecation. Despite its apparent simplicity, the technique of cinedefecography is multifaceted. Over the last 3 decades, several difficulties have been surpassed in order to achieve standardization [2–5]. More recently, interest in this technique has expanded owing to the increased availability of colorectal physiology testing and better understanding of the multifactorial pathophysiology involving disordered defecation [6 – 8]. Evidence has shown that cinedefecography is of value in routine evaluation of functional disorders of the pelvic floor [9]. Specifically, this study provides pelvic measurements at rest and during both squeeze and push, which are used to assess evacuation dynamics. As a result, disorders such as paradoxical puborectalis contraction syndrome, rectocele, intussusception, and perineal descent can be diagnosed. * Corresponding author. Tel.: ⫹1-954-659-5133; fax: ⫹1-954-6595757. E-mail address: [email protected]

Moreover, cinedefecography assesses both anatomical detail and rectal emptying.

Technique Although some authors maintain that an unprepared rectum is more adequate for colorectal physiologic testing [6], feces may obscure detailed rectal configuration and consequently hamper interpretation. Moreover, a limited bowel preparation will yield a more standardized examination and provide more comfort for both patient and investigator [5]. The current regimen of preparing a patient for cinedefecography includes a phosphate enema 30 minutes prior to the procedure. The patient is placed in the left lateral decubitus position and approximately 50 mL of barium suspension is injected into the rectum in order to coat the rectal mucosa and enhance the contrast imagery. After initial barium instillation, air is insufflated to outline the rectal mucosa. Subsequently, 250 cc (500 g) of thick barium paste, or less if the patient experiences rectal fullness prior to that point (Anatrast, E-Z-EM, Westbury, New York), is introduced using a caulking gun injector. Injection is continued

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while simultaneously withdrawing the injector in order to outline the entire anal canal. The radiography table is tilted upright to a 90-degree angle, and the patient is comfortably seated on a water-filled radiolucent commode (Sunburst, Ladson, South Carolina). Lateral films of the pelvis are taken at rest and during both squeeze and push. The patient is then asked to evacuate the rectal contents, and with the aid of fluoroscopy, the process of defecation is recorded on videotape using a high-resolution recorder. Adequacy of the contrast medium consistency, conciliation between a seated position and the quality of obtained imagery, and the addition of an effective recording device were major challenges in the methodology of cinedefecography. Contrast medium consistency affects the rectal emptying rate; the ideal contrast material should simulate stool in weight and consistency [10]. Potato starch and fiber supplements such as psyllium were initially used to thicken the barium sulphate solution [6]. Subsequently, commercially available thick media preparations that can be easily assembled into a caulking gun to facilitate injection have been developed [11]. Static films of the patient in the seated position are frequently of poor quality due to the glare in the lower part of the image; this artifact may occasionally compromise adequate measurements of pelvic dynamics. A number of special commodes have been designed in order to improve imagery and reproduce normal physiology [12–14]. Additionally, radiographic filters such as copper strips and water containers have been developed to improve imagery [5]. Video recording is important in defecography to effectively study all phases of evacuation; the entire process can be reviewed and the effects of abnormalities such as rectocele, intussusception, and nonrelaxing puborectalis in rectal emptying can be better evaluated, by both the investigator and the referring physician. Additionally, “spot” films may not demonstrate enterocele and sigmoidocele because deep rectogenital pouches may contain bowel only intermittently, usually after prolonged straining [1].

Radiation dose The effective dose equivalent, considered as an expression of total patient risk for radiation exposure to limited areas of the body, is significantly lower for cinedefecography (3 to 7 mSv) than for barium enema studies (10 to 17 mSv) [15,16]. In fact, barium enema is considered a highdose procedure, probably because of the larger field of view required and consequently more tissue exposure for this study. Although the area exposed to the beam is smaller in cinedefecography, more radiation per unit area is used, and the local dose is therefore higher with cinedefecography. Consequently, the ovarian dose, which is important owing to the genetic risk for severe hereditary effects, is slightly higher for cinedefecography (10 to 20 mSv) compared with barium enema (3.8 to 16 mSv) [16,17]. Despite the rela-

tively high exposure to ionizing radiation involved in cinedefecography, the risk is acceptable when the examination is indicated. It has been demonstrated that for 1 minute and 40 seconds of videofluoroscopy, the radiation dose is approximately five times higher for a routine barium enema (750 mrads) than for cinedefecography (270 mrads) [6]. Therefore, exposure to radiation during cinedefecography can be significantly minimized by limiting the examination to under 5 minutes. Technical variations In order to improve physiological efficacy, gain better patient acceptance, reduce radiation exposure, and enhance imagery, numerous alternative techniques have been adapted to the basic technique. Although cinedefecography has become more widely available, to date no optimal patient position has been established. Most authors consider the standard seated position more physiological; however, this position may yield poor-quality static films [6]. The left lateral decubitus position offers better imagery, is better accepted by radiology personnel, and may provide a similar overall diagnostic rate compared with the conventional seated position [18]. Additionally, some authors consider the standard seated technique too sensitive and therefore potentially susceptible to overdiagnosis [19]. Nonetheless, there is no consensus. In a prospective study, reproducibility of cinedefecographic measurements and abnormal findings between the seated and left lateral decubitus positions was assessed in 105 patients [20]. Although static values of anorectal angle, perineal descent, and puborectalis length were significantly higher in the seated position, dynamic changes of all these measurements during evacuation were essentially the same for both positions. Consequently, the diagnosis of either dynamic increased perineal descent or nonrelaxing puborectalis syndrome were not affected by the patient’s position. However, as static values of perineal descent were significantly higher in the seated position, the diagnosis of fixed increased perineal descent was significantly more accurate in the seated position. Thirty-one (62%) of 50 patients with fixed increased perineal descent were diagnosed only in the seated position (P ⬍0.001). The weight of rectal and other abdominal contents probably contributes to the downward pull of a flaccid pelvic floor and may account for higher static values of perineal descent in the seated position. The seated position may be more sensitive for the diagnosis of increased fixed perineal descent based on the fact that it is a more physiological position and as such is preferred for patients with constipation. However, premature evacuation severe enough to hamper cinedefecographic measurements occurred only in the seated position, as noted in 6 (27%) of 22 patients with fecal incontinence. Therefore, for these patients, the left lateral decubitus position should be adopted to ensure better results. More importantly, given the statistically significant differences between the results

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Fig. 1. Comparison of measurements among resting, squeeze and push values in the same patient.

obtained in the two positions and the lack of universal endorsement of one position, centers should elect the same position for a given diagnostic group. The standard lateral view of the pelvis used during cinedefecography may be insufficient to diagnose a lateral rectocele. A helpful technique is to rotate the patient under fluoroscopy in order to assess the pelvis from various angles. In addition, posteroanterior proctography has been proven helpful to validate the diagnosis of intra-anal intussusception [21]. Balloon proctography was introduced to document change in the anorectal angle during evacuation along with the inability to expel the balloon [22,23]. This technique was intended to reduce radiation exposure; however, it does not assess either anatomic detail of rectal configuration or completeness of evacuation. Furthermore, frequent displacement of the balloon results in inaccurate or dubious measurements [11]. Therefore, the conventional method using barium paste is preferred. Other technical variants have been proposed in an attempt to enhance the diagnostic capability of cinedefecography, specifically to assist delineation of deep cul-de-sac pouches, enterocele, and sigmoidocele. Oral ingestion of 150 mL of barium contrast 1 to 3 hours prior to the examination may assist in the delineation of pelvic small bowel loops [6,24]. More recently intraperitoneal instillation of 50 mL of nonionic contrast has been proposed. Despite the potential risk of complications, peritoneography combined with dynamic proctography can provide better assessment of pelvic floor pathology in selected cases [25]. The use of a tampon soaked in iodine contrast medium placed in the posterior fornix of the vagina either as an isolated method or combined with a voiding cystography (colpocystodefecography) also helps to assess the depth of the rectogenital fossa and the eventual interposition of intra-abdominal content between the rectum and vagina [24,26].

descent (PD), and puborectalis length (PRL). The anal canal length can also be measured; however, anal manometry, which provides the functional anal canal length or high pressure zone, is the preferred method for this purpose. The cinedefecographic measurements are taken at rest and during both squeeze and pushing. In order to assess the pelvic floor dynamics during evacuation, the difference between rest and maximal push is calculated for each measurement. There is a wide range of normal values for each of these parameters [4,6]. The exact value of any of these isolated parameters is of relatively little consequence, however, and comparison of an absolute measurement in a patient against a group of controls is frequently frustrating. Instead, the role of static proctography is to provide a basis for relative comparison among rest, squeeze, and push values in a single patient (Fig. 1). Evaluation of both absolute and dynamic (evacuation-rest) values of ARA, PD, and PRL allows diagnosis of excessive perineal descent and paradoxical puborectalis syndrome (Figs. 2 and 3). The ARA is the most often quoted measurement on cinedefecography [4,24]. The ARA is measured differently by different researchers. It is more frequently defined as the angle between the axis of the anal canal and the distal half of the posterior rectal wall [3,5,11]. In opposition to the anal canal component of the angle, the rectal axis has been drawn in several different ways, including the middle of the rectal ampulla, through the tip of the coccyx and the anterior rectal wall [27,28]. The resting ARA ranges from 70 to 140 degrees with a mean of 92 to 114 degrees; during evacuation, this angle becomes more obtuse, 110 to 180 degrees, and more acute during squeeze, ranging from 75 to 90

Interpretation Cinedefecographic measurements Essentially, static proctography has been used to measure the following parameters: anorectal angle (ARA), perineal

Fig. 2. Excessive perineal descent.

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Fig. 3. Nonrelaxing puborectalis syndrome. Note overcapacious rectum with no significant change in the anorectal angle during resting, squeeze or push.

degrees [6]. This wide variation is, at least in part, due to discrepancies in technique. Additionally, patient position affects the absolute values of the ARA, which are higher at rest and during push in the seated position, compared with the left lateral decubitus position [20]. The dynamic changes of the ARA during evacuation are similar in both positions, however, and again, absolute values are not significant. Perineal descent is quantitatively defined by measuring the vertical distance between the position of the ARA and a fixed plane, which is usually represented by the pubococcygeal line as it seems to reflect a more exact relationship of the levator ani muscle to the pelvis [29]. The normal pelvic floor position is as much as 1.8 cm below the pubococcygeal line at rest and as much as 3.0 cm below the pubococcygeal line during maximal push effort; therefore, abnormally increased PD has been classically defined as descent of more than 3.0 cm during evacuation when compared with the value measured at rest [3,5,6,29]. The techniques of PD measurement are also varied as multiple observers have chosen different radiographic reference points. The distance from the anal canal opening to the ischial tuberosities has been suggested as the distance between the anal canal aperture and the tip of coccyx [10, 12,30,31]. A common alleged assumption is that since the position of the ARA is relative to any chosen fixed landmark, the exact relationships among ischial, coccygeal, and pubococcygeal planes are not relevant [10]. However, the dynamic changes in the pelvic floor during straining may not account for the diagnosis of abnormal PD in all cases. Patients may present with a flaccid and noncontractile pelvic floor. In this situation, although little change is seen during straining, an abnormally increased PD is already observed at rest. This “fixed increased PD,” considered when PD exceeds 4.0 cm at rest, has been particularly associated with advanced age [32]. The PRL is measured as the distance between the ARA and the pubic symphysis. The resting PRL ranges from 14 to 16 cm. During squeeze, the PRL is shorter (12 to 15 cm), and during evacuation the muscle length increases (15 to 18 cm) [7]. Comparison of the PRL measurement, along with the ARA, corroborates with the diagnosis of paradoxical puborectalis syndrome [7]. Predictors of a good outcome of biofeedback training at cinedefecography include prominent

puborectalis impression during straining and absence of excessive PD [33,34]. Anatomic abnormalities Cinedefecography also permits the diagnosis of causative or associated anatomical abnormalities such as nonrelaxing puborectalis (puborectalis indentation), rectocele, occult internal intussusception, sigmoidocele, and enterocele (Fig. 4). These findings, particularly a small rectocele and an intussusception may be found in 25% to 77% of asymptomatic patients [6]. Failure to recognize these variants of normal can easily lead to overdiagnosis and overtreatment. Therefore, a decision for treatment should be made based upon both clinical history and evaluation of rectal emptying during cinedefecography. Clinical applications Cinedefecography is particularly indicated for patients with chronic idiopathic constipation to exclude causes of obstructed defecation. In addition, for patients with idio-

Fig. 4. Association of (1) rectoanal intussusception, (2) sigmoidocele, and (3) rectocele in the same patient, at the maximal effort of defecation.

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pathic fecal incontinence, specifically if a history of chronic straining at stool is reported, cinedefecography can be helpful to exclude an internal rectal prolapse. Cinedefecography may uncover a causative disorder in patients with solitary rectal ulcer and chronic idiopathic rectal pain [35]. In addition, cinedefecography has been indicated to assess the functional results of procedures such as rectopexy, postanal repair, gracilis neosphincter, and ileoanal reservoir. The effect of the procedure on the mechanism of continence can be evaluated, including changes in pelvic dynamic measurements, rectal configuration, and rectal emptying rate. Nonrelaxing puborectalis syndrome Nonrelaxing puborectalis syndrome is a complex and poorly understood entity characterized by contraction rather than relaxation of the puborectalis and other striated pelvic floor muscles in a paradoxical fashion during attempted evacuation. Since its description by Wassermann [36] in 1964, this syndrome has received a number of appellations including rectal dyschesia [37], paradoxical external anal sphincter [38], spastic pelvic floor syndrome [39], anismus [40], rectoanal dyssynergia [41], and abdominolevator incoordination [42]. The etiology of this dysfunction also remains obscure; proposed theories include voluntary suppression of the normal inhibitory reflex, muscular dystonia, abuse of cathartics and sympathetic nerve abnormalities, spastic contraction due to local inflammatory perianal and pelvic conditions, partial denervation of the pelvic floor, generalized pelvic floor disorder, and psychological factors [36,43– 46]. The behavioral disorder theory, based upon lack of coordinated relaxation of the striated anal sphincters during defecation, is supported by the improvement in nonrelaxing puborectalis syndrome noted after biofeedback therapy [47– 49]. Although the exact incidence of nonrelaxing puborectalis syndrome remains unknown, it apparently represents an important etiologic factor in constipation, specifically in obstructed defecation. In a series of 180 patients with idiopathic chronic constipation, nonrelaxing puborectalis syndrome was found twice as often as was colonic inertia (33% versus 17%, respectively) [8]. The prevalence of this syndrome in a large series of patients who underwent cinedefecography for a variety of symptoms, including constipation, rectal pain, and fecal incontinence, was 3.9% [50]. Typical clinical manifestations of nonrelaxing puborectalis syndrome include symptoms of obstructed evacuation such as straining, tenesmus, and the sensation of incomplete evacuation as well as the frequent use of suppositories, enemas, or digitation. Often, these patients have a history of previous treatment for other anorectal conditions associated with straining such as solitary rectal ulcer syndrome, rectoanal intussusception or prolapse, descending perineal syndrome, or rectocele. Although the physical examination may be suggestive of paradoxical “reaction,” the diagnosis is usually reached

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only after anorectal physiology investigation [51]. Likewise, segmental colonic transit time may suggest the diagnosis, and outlet obstruction pattern has been associated with 75% to 92% of patients with cinedefecographic evidence of nonrelaxing puborectalis syndrome; however, it is not a specific test [39,45]. Electromyography and cinedefecography provide the best assessment of puborectalis muscle function. Electromyography provides data on external anal sphincter and puborectalis neuromuscular activity while cinedefecography allows measurement of the ARA, which is directly related to sphincter muscle activity. Cinedefecographic criteria of nonrelaxing puborectalis syndrome includes failure to open the ARA, persistence of the puborectalis impression, and poor rectal emptying. The prominent and persistent puborectalis impression during attempts to evacuate the rectum can be better evaluated with the aid of videorecording and probably represents the most important finding [52]. Other cinedefecographic findings suggestive of nonrelaxing puborectalis include an overly capacious rectum, a long and persistently closed anal canal, ballooning of the rectum, and the presence of compensatory anterior and posterior rectoceles. These findings of nonrelaxing puborectalis syndrome can be associated with nonemptying, incomplete emptying, or even total evacuation after a prolonged and difficult attempt [6]. Both cinedefecography and electromyography have their limitations. Voluntary contraction of the pelvic floor due to embarrassment may simulate a functional disorder on cinedefecography [39]. Similarly, inability to relax the sphincter may occur during push as a response to fear or pain during electromyographic assessment [35]. These factors could cause false positive findings of nonrelaxing puborectalis syndrome in patients without symptoms of obstructed evacuation. A recent study prospectively assessed the correlation between electromyography and cinedefecography in the diagnosis of nonrelaxing puborectalis syndrome in 112 patients with symptoms of obstructed evacuation [51]. Forty-two patients (37%) had evidence on cinedefecography (rectal emptying, 24; incomplete, 18). Twenty-eight (67%) of these 42 patients also had evidence of nonrelaxing puborectalis syndrome on electromyography. Electromyographic findings of nonrelaxing puborectalis syndrome were present in 12 (17%) of 70 patients with normal rectal emptying. Fourteen (19%) of 72 patients with normal puborectalis relaxation on electromyography had evidence of nonrelaxing puborectalis on cinedefecography. The sensitivity and specificity for the electromyographic diagnosis of nonrelaxing puborectalis syndrome were 67% and 83%, respectively, and the positive and negative predictive values were 70% and 80%, respectively. Conversely, if electromyography is considered as the ideal test for the diagnosis of nonrelaxing puborectalis syndrome, cinedefecography had sensitivity of 70%, specificity of 80%, and positive and negative predictive values of 66 and 82%, respectively. The association of these tests is necessary to permit

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optimal data accrual. However, cinedefecography is probably superior in that it can detect associated abnormalities and demonstrate the exact dynamics of evacuation. It has been suggested that artifactually false positive results may ensue owing to reluctance to evacuate in front of others. If it is suspected that the patient’s embarrassment is preventing evacuation, the privacy of a bathroom is suggested, followed by fluoroscopic reassessment of the evacuated rectum. At cinedefecography, predictors of a good outcome include prominent puborectalis impression during straining and absence of excessive PD [10,41]. Anal pressures and abnormalities of rectal sensation are not relevant to determine the results after biofeedback therapy [51]. In addition, cinedefecography may help to stratify nonrelaxing puborectalis syndrome in different subtypes. Recent reports have shown better response to biofeedback in patients with both, prominent puborectalis impression and less PD on cinedefecography [33,34]. Based on cinedefecographic findings, Park et al [34] have demonstrated that anismus can be subdivided into two types, type A with a flattened ARA without definite puborectalis indentation but with anal canal hypertonia, and type B with clear persistent puborectalis indentation, narrow ARA, and a closed anal canal. Biofeedback was successful in treating 86% of patients with type B anismus and only 25% of patients with type A anismus. Finally, the diagnosis of nonrelaxing puborectalis syndrome should be given only to patients whose clinical symptoms of pelvic outlet obstruction are supported by physiologic confirmation of their significance. Perineal descent syndrome The “syndrome of the descending perineum” was first observed by Porter in 1962 [53] and subsequently recognized as a definite entity by Parks and colleagues in 1966 [54]. This syndrome was considered by these authors as a component of a viscous cycle involving excessive and repeated straining, protrusion of the anterior rectal wall into the anal canal, sensation of incomplete evacuation, weakness of the pelvic floor musculature, more straining and further pelvic floor weakness. The perineometer, an instrument that consists of a freely moving graduated cylinder within a steel frame positioned on the patient’s ischial tuberosities, has been designed to measure perineal descent. This technique, similar to the traditional method of simple observation of the position of the perineum during the physical examination, is used with the patient in the left lateral decubitus position [54,55]. Evidence has shown that the most physiologically appropriate position in which to measure PD is the seated position with both hips and knees flexed. Cinedefecography offers a more accurate assessment of PD, mainly because of the standard seated position adopted during the study [20]. A further advantage is that actual rather than feigned expulsion of intrarectal contents occurs. Increased dynamic PD is considered when during maximal push effort, PD exceeds

values of 3 cm from those measured at rest, whereas increased fixed PD is considered when PD exceeds 4 cm at rest [6,12]. Excessive PD is a physical sign indicative of pelvic floor weakness. Patients with abnormally increased PD may present with rectal prolapse, partial or major incontinence, obstructed evacuation, solitary rectal ulcer syndrome, or vague symptoms of incomplete evacuation or rectal pain [55–57]. However, PD may merely represent one facet in a constellation of varied symptoms and findings. Abnormally increased PD, both at rest and during evacuation, is found in approximately 75% of patients with fecal incontinence as well as in patients who habitually strain at stool but have no significant incontinence [58]. The exact clinical and neurophysiological significance of increased PD remains unknown. Because excessive PD and pudendal neuropathy are commonly present in patients with defecatory disturbances, Parks et al [54] postulated that descent of the pelvic floor during childbirth or secondary to chronic prolonged difficult evacuation can result in stretch injury of the pudendal nerves, as they are tightly bound by connective tissue when they exit from the pelvis to the pudendal canal. Over the last 15 years the entrapment and stretch theory has gained widespread acceptance [55,59,60]. This often espoused relationship between increased PD and pudendal neuropathy was not supported by a recent prospective study of 213 consecutive patients with pelvic floor disorders [32]. The lack of a relationship was seen for the entire group, regardless of sex or diagnosis, as well as for those patients with either neuropathy or increased PD. Although increased PD and prolonged pudendal nerve terminal motor latency are frequently observed in patients with pelvic floor functional disorders, they may represent independent findings. Therefore, unlike an abnormally prolonged pudendal nerve latency, the isolated radiographic finding of increased PD should not be considered as a predictive factor of pelvic neuromuscular function. Rectocele Rectocele represents herniation of the rectal wall with a higher prevalence of anterior rectocele than posterior rectocele. This condition is more common in women, and factors such as multiparity and traumatic vaginal deliveries, which cause weakness of the rectovaginal septum, are usually implicated. The clinical history can be highly suggestive when patients recount the need to either press the posterior vaginal wall or use rectal digitation in order to assist defecation. Prior to establishing treatment of a rectocele, it is crucial to assess both its clinical significance and concomitant functional disorders. Rectoceles are present in as many as 70% of asymptomatic women; however, rectoceles of greater diameter (ⱖ4 cm), with prolonged or even absent emptying are more likely to cause symptoms of constipation [6]. The

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size of the rectocele as an isolated parameter has not been consistently correlated with the severity of symptoms [61]. This controversy may be related to the common association of other abnormalities including excessive PD, colonic inertia, and nonrelaxing puborectalis syndrome. Rectoceles can be found in up to 45% of patients with emptying disorders due to nonrelaxing puborectalis syndrome [62]. This type of rectocele usually represents a compensatory mechanism due to the functional closure of the anal canal during attempted defecation and consequent high intrarectal pressure. This finding is of primary importance as in this situation surgical treatment of the rectocele will fail, and therefore biofeedback is indicated. Cul-de-sac hernias: enterocele and sigmoidocele The portion of the pelvic cavity known as cul-de-sac or pouch of Douglas can eventually extend caudally between the rectum and vagina in varying degrees even as far as the perineum and become the site of a cul-de-sac or vaginal hernia [63]. More commonly, the small bowel and omentum will constitute the hernia contents, probably owing to the long longitudinal axis of these structures that allows them to descend this far. Occasionally, an elongated loop of sigmoid can extend caudally into the deep rectovaginal fossa [1]. Sigmoidocele, similar to enterocele, is usually related to a complex entity known as pelvic laxity or pelvic relaxation, resulting from weakening of the supporting tissues of the vagina and pelvic diaphragm [64]. As such, several defects may coexist, including anterior rectocele, rectoanal intussusception, cystocele, and vaginal or uterine prolapse. Enteroceles have been classified as primary when factors such as multiparity, advanced age, general lack of elasticity, obesity, constipation, or increased abdominal pressure are present; and secondary after gynecological procedures, specifically vaginal hysterectomies [65]. The incidence of enterocele at 1 year or more after vaginal hysterectomy ranges from 6% to 25%; however, it can be significantly reduced by obliterating the cul-de-sac with suture of the uterosacral ligaments [66,67]. The pathophysiology of sigmoidocele in obstructed defecation is complex, and several mechanisms may be involved including collapse of the rectum, direct compression by the hernia contents, and stasis in the sigmoid. The content of a cul-de-sac hernia splits the fascia of Denonvilliers and weakens the rectovaginal septum. Consequently, in these patients the anterior rectal wall is exposed to the direct action of the abdominal pressure. Therefore, a collapse of the rectal ampulla, which is also influenced by factors such as the gradient of pressure and rate of flow, occurs during straining. In addition to a deep rectogenital pouch and slackening of the supporting structures of the uterus, intraoperative findings in these patients frequently include a long sigmoid loop and eventually elongation of the proximal mesorectum [1]. As opposed to the small bowel, the herniated sigmoid, because of its larger diameter and more solid

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contents, is more prone to stasis. Consequently, symptoms of pelvic discomfort, sensation of incomplete evacuation, and prolonged straining can be more severe in patients with sigmoidocele. Although a severe cul-de-sac hernia can be diagnosed during physical examination as a prolapse of the upper posterior vaginal wall during Valsalva’s maneuver, more accurate assessment of this entity, especially sigmoidocele, became possible only after the advent of cinedefecography. Adequate technique to optimize the diagnosis of sigmoidocele on defecography includes the use of videorecording, systematic instillation of air and barium suspension, and injection of a substantial amount of barium paste. If necessary, the test may be performed 1 to 3 hours after ingestion of barium contrast medium to delineate small bowel loops [6]. Other technical modifications recommended include the association of colpocystography [26] and peritoneography [25]. Despite advances in diagnosing sigmoidocele, this entity has been mainly regarded as an incidental finding on cinedefecography. Ekberg et al [24] studied 83 patients with dyschezia and observed deepening of the rectovaginal fossa associated with herniation of either a loop of small bowel or sigmoid in 16 patients; sigmoidocele as the only abnormality was seen in only 5 of the 83 patients. More definite cinedefecographic criteria are required in order to differentiate a mere finding from an obstructing cul-de-sac hernia. A study was undertaken to assess the incidence and clinical significance of sigmoidocele as a finding during cinedefecography [68]. Twenty-four (5.2%) sigmoidoceles were noted in a total of 463 cinedefecographic studies. Sigmoidocele was classified based on the degree of descent of the lowest portion of the sigmoid loop during maximum straining in relation to the following pelvic anatomic landmarks: pubis, coccyx, and ischium. First-degree sigmoidocele was considered when an intrapelvic loop of sigmoid was observed on cinedefecography but the sigmoid did not surpass the pubococcygeal line; second-degree sigmoidocele was considered when the sigmoid loop was situated below the pubococcygeal line but remained above the ischiococcygeal line; and third-degree sigmoidocele, when the sigmoid loop transcended the ischiococcygeal line. In this study, symptoms of constipation were present in 20 (83%) of the 24 patients. The most common symptoms were incomplete evacuation, straining, bloating, sensation of rectal pressure or fullness, infrequent bowel movements, and abdominal pain. Two thirds (67%) of these patients reported assisted defecation including use of laxatives, enemas, digitation, and suppositories. One patient reported the need to press the lower abdomen in the left lower quadrant and suprapubic areas in order to have a bowel movement. Nine patients had first-degree, 7 had second-degree, and 8 had third-degree sigmoidocele. This proposed classification system yielded excellent correlation between the mean level of the sigmoidocele, the degree of sigmoid redundancy, and the clinical symptoms. The clinical significance of third-

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degree sigmoidocele is supported by the fact that all 8 patients of this group were women with severe disturbances of defecation and 7 of these patients (87%) had impaired rectal emptying on cinedefecography. Furthermore, all 5 patients with third-degree sigmoidocele who underwent colonic resection reported symptomatic improvement at a follow-up ranging from 14 to 60 months. Therefore, sigmoidocele may account for symptoms of obstructed defecation, and the staging of sigmoidocele is useful in determining both clinical significance and an objectively planned therapy. Intussusception Intrarectal and rectoanal intussusception represent initial phases of rectal prolapse when a fold develops in the rectal wall during push, prolapsing into the rectum; subsequently, the intussusception descends to obstruct the anal canal and finally becomes an external prolapse [5]. Internal intussusception can be difficult to diagnose during cinedefecography. Firstly, prolapse of anal cushions and variations of fold patterns due to some degree of asymmetry of the rectum during its emptying may confuse interpretation. Secondly, as seen in rectocele, intussusception can represent a mere cinedefecographic finding or the cause of obstructed defecation. Criteria of clinical importance include the presence of transverse or oblique infolding of more than 3-mm thickness formed by invagination of the rectal wall causing obstruction to rectal evacuation. These findings must be interpreted in the light of the clinical history. More advanced degrees of intussusception can cause rectal pain or even lead to solitary rectal ulcer syndrome with elimination of blood or mucus through the rectum. Solitary rectal ulcer syndrome The solitary rectal ulcer syndrome is characterized by the triad of rectal discharge of blood and mucus, lower-anterior benign rectal ulcer, and disordered defecation. Apparently the etiology of the ulcer is trauma due to excessive straining. Cinedefecography will demonstrate intussusception or nonrelaxing puborectalis syndrome in most of these patients. Excessive straining against a contracting pelvic floor is the most common mechanism imputed in the origin of the solitary rectal ulcer syndrome [37]. As cinedefecography can uncover the causative defecation disorder, it is the method of choice in the assessment of this condition [69].

Conclusion Standard examinations such as colonoscopy and barium enema detect essentially anatomic abnormalities, whereas functional disorders require a dynamic study to demonstrate the physiological process involved during rectal evacuation. Specifically, cinedefecography provides pelvic dynamic measurements during evacuation, and consequently pro-

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