Original Article
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Role of enterocele in obstructed defecation syndrome: proposal of a new radiological and surgical classification

Original article by CLAUDIO MORANDI - BEATRICE BREVEGLIERI - CLAUDIO MORATTI - LUCA VERGANTI - PIETRO TORRICELLI
Department of Radiology, University of Modena and Reggio Emilia, Italy

Abstract:This study proposes a new classification of enterocele based on its functional role as a cause of constipation in patients with ODS (obstructed defecation syndrome). We retrospectively evaluated 597 patients (551 F, 46 M) with symptoms of obstructed defecation syndrome, who had undergone a cinedefecography between November 2001 and November 2005. We classified enterocele into three groups based on the presence of a radiological pattern of obstructed defecation and the presence of any other functional or anatomical abnormality. An enterocele was found in 127 females (23%) and 1 male. We recognised prolapse of the small bowel in 103 females and in one male while in 24 females the sigmoid colon descended into the Pouch of Douglas. We found 38 patients ( 6.9% ) with a functional enterocele, 38 patients (6.9%) with a non obstructive enterocele and 27 (4.9%) with an obstructive enterocele. All the 23 patients with sigmoidoceles were classified as symptomatic non obstructive. In the group with obstructive enterocele the finding of a radiological pattern of obstructed defecation was higher (26/27) than in the group without an obstructive enterocele (23/100) (p < 0.001). In patients with obstructive enterocele the occurrence of concurrent anatomical and functional abnormalities was lower (p < 0.05) than in patients with other classes of enterocele. From this study we can infer that obstructive enterocele impairs rectal evacuation and it can be considered the main cause of obstructed defecation in patients with obstructed defecation syndrome. This new classification can be useful to determine which cases would be likely to benefit from pelvic surgery.
Key words: enterocele, Obstructed defecation syndrome, Cinedefecography, Sigmoidocele.

INTRODUCTION

Obstructed defecation syndrome (ODS) is clinically defined as a prolonged (more than 6 months) history of difficult rectal evacuation, including excessive straining, feeling of incomplete evacuation or inability to evacuate without digitation. It is usually related to a functional disorder and it occurs most exclusively in females.

Many authors 1-4 have reported an incidence of enterocele from 19% to 35% in patients with Obstructed defecation syndrome. However, the role of enterocele (defined as prolapse of the small bowel into the rectogenital space) in this syndrome is still controversial. According to Wexner,7 the etiological classification of enterocele is: primary when factors such as multiparity, advanced age, general lack of elasticity, obesity, constipation and increased abdominal pressure are present, and secondary when it occurs after gynecological surgical procedures, especially hysterectomy.

Another classification of enterocele proposed by Nichols 8 is based on its origin:

  1. congenital (unusual deep Pouch of Douglas),
  2. pulsion-mediated (caused by chronic increase of abdominal pressure),
  3. by traction (associated with a loss of support of the pelvic floor),
  4. iatrogenic (after surgical procedures that change the normally-horizontal vaginal axis to vertical).

In patients with a uterus, the hiatus between the proximal edges of the fascial layers (anteriorly the pubocervical fascia and posteriorly the rectovaginal fascia) is bridged by the cervix and the uterine fundus. One of the most common causes of enterocele in non-hysterectomized patients is an unusually deep Pouch of Douglas. 5 In hysterectomized patients failure to reattach these layers results in a fascial defect so the peritoneum comes into direct contact with the Pouch of Douglas. 6

A grading system, proposed by Hale et al., classifies enterocele as small when the bowel extends 2 to 4 cm below the vaginal apex, moderate when extension reaches 4-6 cm, and large when this distance is greater than 6 cm. Extension up to 2 cm below the vaginal apex is considered to be within the normal range. 9 The most common symptoms of enterocele are a dragging sensation in the pelvis and pain in the lower abdomen. Many patients report outlet obstruction 3 and assisted defecation. Some develop faecal incontinence.

Detection of enterocele is difficult: up to 84% are missed at clinical examination. 11 Its presence and extent can be diagnosed by endo-ultrasonography and by dynamic magnetic resonance imaging,12-14 otherwise the functional relevance of an enterocele is diagnosed only in the late evacuation phase during cinedefecography. 15, 16 Defecography or evacuation proctography is a dynamic radiologic technique that involves imaging of the elimination of a barium paste enema from the rectum in order to assess changing anatomic relationships of the pelvic floor and associated organs during evacuation. The main indication to perform cinedefecography is constipation and rectal outlet obstruction. 7, 8

The aim of our study is to demonstrate in patients with clinical symptoms of Obstructed defecation syndrome the incidence of enterocele, the variable relationship between herniated small bowel, peritoneum and rectal ampulla (the enterocele may sink into the bottom of the cul-de-sac or float within the Pouch of Douglas) and finally to assess the correlation between different groups of enterocele and obstructed defecation syndrome.


MATERIALS AND METHODS

We retrospectively evaluated 597 patients (551 women, 46 men) who underwent a cinedefecography from November 2001 to November 2005. All patients had a full physical examination by a surgeon and completed a questionnaire regarding: age, presence of symptoms of obstructed defecation (defecation frequency, use of laxatives, severe and prolonged straining, perineal dragging sensation, feeling of incomplete evacuation, alimentary disorders), incontinence, parity, history of a previous hysterectomy or cystocele repair or any pelvic surgery for Obstructed defecation syndrome.

The indication for cinedefecography was obstructed defecation in 95% and incontinence in 5% of the cases. Females' mean age was 51 years (range 20-79) and males' mean age was 49 years (range 25-79 ). In the female group twenty-eight patients (5.08%) had a previous operation for obstructed defecation syndrome (Tab. 1); table 180 patients (32.67%) had hysterectomy, 35 (6.36%) had a cystocele repair (Tab. 2). table All patients gave written informed consent to the study.

Cinedefecography

Cinedefecography was performed using the standard technique described by Kelvin et al. in 1992. 17 The rectum was emptied by administration of glycerin suppositories or an enema. Approximately one hour before the examination 300 ml of diluted barium suspension at 60% (Prontobario® 60%- Bracco s.p.a.Milan-Italy) was given orally to opacify the small bowel. 11-18 Patients were asked to empty the bladder. Later the rectum was filled with 200 ml of thick barium sulphate paste at 113% w/v ( Prontobario® esofago-Bracco s.p.a-Milan-Italy ) injected with a syringe with the patient in the left lateral position on the fluoroscopy table (GE Prestige VH). Cinedefecography can be divided in three steps: pre-evacuation, evacuation and post-evacuation. Initial radiographs of the pelvis with the patient in the lateral position are taken at rest and with voluntary contraction of the pelvic floor muscles in order to record the pre-evacuation anorectal configuration and pelvic floor position.

Then the patient is moved into the upright position and seated on a commode placed on the footrest of an examination table in front of a fluoroscopy unit. 7 While the patient was seated on the commode lateral radiographs were taken during rest and squeezing as a point of reference to locate bone landmarks and to assess the degree of filling of pelvic ileum. A left lateral view of the pelvis was recorded during the evacuation phase (overall the entire fluoroscopic period is limited to 50 seconds). 7 The entire examination was recorded on videotape and each videoclip was analyzed using a computer video capture combined with an image analysis program (Microprint ®).

Definitions and radiographic analysis

The following parameters were considered: the anorectal angle (ARA), the pubococcygeal line (PCL), the bi-ischiatic line, the antero-posterior anal canal width, the evacuation time, and the post-evacuation barium trapping. An enterocele was diagnosed when the barium contrast which filled small bowel loops descended below the pubo-coccygeal line. Sigmoidocele (Fig. 1, 2) image was diagnosed by the presence of gas-filled sigmoid loops in the Pouch of Douglas. 10
Any other concomitant functional and anatomical abnormality was also recorded. A rectal prolapse was defined as a circumferential descent of the entire thickness of the rectal wall above the anal canal (rectal-ampullar prolapse), involving the anal canal (intracanalicular prolapse) or coming out through the anal verge (external full-thickness rectal prolapse). 19 We diagnosed a rectocoele when the anterior rectal and posterior vaginal wall herniated into the lumen of the vagina; its depth was assessed by the length of the segment drawn from this axis to the maximum anterior convexity point of the rectocoele. 19

Pelvic floor descent was defined as the drop of the ano-rectal junction during straining more than 3.5 cm from its resting position at the inferior plane of the ischial tuberosities. 20 Anismus was diagnosed as a persistent or excessive indentation of the puborectalis sling posteriorly on the rectum at or just above the anorectal junction without an appropriate widening of ARA.20 Obstructed evacuation was defined as the inability to evacuate 2/3 of the sulphate paste within 30 seconds. 21

Based upon cinedefecography we radiologically distinguished two types of enterocele: a functional enterocele (Fig. 3), image when the small bowel descends to PCL at straining and without compressing the rectal ampulla and symptomatic enterocele when small bowel or sigmoid colon compresses the rectal ampulla and rises with it at the end of straining. Furthermore, we divided the symptomatic enterocele into non obstructive and obstructive enterocele. Non obstructive (Fig. 4, 5) image enterocele permits rectal evacuation because it occupies the Pouch of Douglas only at the end of evacuation and allows normal function of the rectal ampulla.

Obstructive enterocele (Fig. 6, 7) image descends in the early phase of voiding and compresses the rectal ampulla to prevent passage of stool. We then describe three classes of enterocele: functional enterocele, symptomatic non obstructive enterocele and symptomatic obstructive enterocele The three categories of enterocele were then evaluated for the presence of a radiological pattern of obstructed defecation and any other functional or anatomical abnormalities. Differences between these groups were considered statistically significative for a p value < 0.05. SPSS 12 ( SPSS Inc. Chicago, Illinois, USA ) software was used for calculation.


RESULTS

An enterocele was found in 128 patients (21.44%), 127 females (23.05%) and 1 male (2.2%). One hundred and three females (81%) had a prolapse of the small bowel into the rectogenital space (enterocele), while the remaining 24 (19%) had a sigmoid colon descent into the Pouch of Douglas (sigmoidocele). A functional enterocele was diagnosed in 38 patients (6.9% of all females - mean age 55 years and range 27-79). The patients in this group had a mean number of pregnancies of 1.4, while 3 (7.89%) had undergone hysterectomy. No patients had undergone a cystocele repair.

The frequency of obstructed defecation in this group was 37% (14/38) (Fig. 8). image Five patients (13.18%) had an isolated enterocele, while in 33 (86.82%) it was associated with other conditions, as reported in Table 3. table

Four patients had a combined functional enterocele with sigmoidocele. Perineal descent was present in 10 of 38 patients (26.32%). Thirty-eight patients (6.9% of females with obstructed defecation syndrome) had a symptomatic non obstructive enterocele. Their mean age was 57yrs (range 38-73). Hysterectomy had been performed in 47.37% and was associated with cystocele repair in 3 cases (7.89%). cystocele repair alone had been performed in 3 patients (7.89%). Obstructed defecation syndrome was found in 7 patients (18%) (Fig. 8). image An isolated enterocele was noted in 5 patients (13.16%) and associations with other condition are shown in Table 3. table

Perineal descent was detected in 24 patients (68%). Symptomatic obstructive enterocele was found in 27 patients (4.9% of all females - mean age 56 years). Ten of these patients had undergone hysterectomy (37.04%), while 4 patients had undergone cystocele repair (14.81%). Radiologic obstructed defecation was found in 26 of the patients (96.3%) while 1 patient was incontinent (Fig. 8). image Obstructive enterocele was found as an isolated finding in 13 patients (41.15%), while in the remaining 14 (58.85%) we recognised additional findings (Tab. 3). table

Pelvic floor descent was present in 4 patients (14.81%). The only male with an enterocele had an obstructive enterocele. Sigmoidocele was found in 24 patients (4.35% of all females - mean age 52 years and range 20 -77 years). The mean number of pregnancies in this group was 1.7. Three patients (12.5%) had undergone a hysterectomy, while 2 patients (8.33%) had undergone a cystocele repair and 5 patients (20%) had both procedures. Only 2 patients (8%) had obstructed defecation (Fig. 8). image Five patients (20.83 %) had an isolated sigmoidocele, while 19 patients (79.17%) had additional findings on defecography (Tab.3). table

The most frequent finding was perineal descent(46%). In the group with obstructive enterocele the frequency of a radiological pattern of obstructed defecation was statistically significant (p < 0.001). In patients with obstructive enterocele the occurrence of concomitant anatomical-functional abnormalities was lower (p < 0.05) than in patients with other classes of enterocele.

DISCUSSION

Obstructed defecation syndrome is a multi-compartment pelvic disorder due to the presence of recto ampullar dysfunction such as rectal prolapse, rectocoele, paradoxic puborectalis muscle contraction, enterocele and pelvic floor descent. 22,23

The clinical role of enterocele is controversial. In many studies it has been considered to be associated with obstructed defecation and constipation. In 1952 Wallden et al. 24 postulated that the anterior pressure on rectum from an enterocele may cause a defecation disorder characterized by obstruction. They termed the disorder mechanical rectal obstruction or defecation block. However, Halligan et al. 25 demonstrated that most of the patients with enterocele evacuate more rapidly and completely suggesting that enterocele is not necessarily associated with impaired rectal evacuation indicating that these pouches do not mechanically obstruct defecation; on the contrary, they found a higher incidence of incontinence in patients with enterocele.

The development of transanal resection as a treatment for outlet obstruction 26 has underlined the importance of assessing the presence of an enterocele. Patients were also asked to empty the bladder before rectal imaging because the presence of a cystocele may prevent the recognition of an enterocele.27 Some authors perform a post evacuation image after the proctographic phase to detect an enterocele. We prefer to document a late evacuation phase during cinedefecography with the patient straining maximally for almost 40 seconds to observe the herniation of intestinal loops in a dynamic setting. In our study the rate of enterocele in patients with Obstructed defecation syndrome was 21.44%, while the incidence of sigmoidocele was 4.35%. These data are comparable to those reported in the literature, where the incidence is reported as 19% to 35%4 and from 4% to 5.2% respectively. 10-17

 In the group with obstructive enterocele the number of patients with a radiological pattern of obstructed defecation is higher (26/27 vs 23/100; p< 0.001) than the number of patients without an obstructive enterocele. The same results can be observed comparing patients with an obstructive enterocele to those patients who belong to any other class of enterocele. Obstructed enterocele is more likely than non obstructive enterocele to be an isolated pathological condition (41.15% vs 13.16%, p < 0.05). Anatomical and functional abnormalities are less frequent in obstructive enterocele (58.85% vs 86.84%; p <0.05) than in other classes of enterocele.

This data confirms the hypothesis that an obstructed enterocele, often isolated, may be the real cause of Obst0ructed defecation syndrome in these patients. Our conclusions differ from those of Halligan et al.25 The reason could be that in Halligan's population the majority of patients probably had only functional and non obstructive enteroceles, as defined by our classification, without having a true obstructive enterocele. The identification of obstructive enterocele, which seems to be the main cause of obstructed defecation, is important in determining which patient to refer to pelvic surgery. The presence of clinical and radiological signs of incontinence 1-19 associated with the diagnosis of enterocele can be explained by the high incidence of perineal descent (58%) in patients with symptomatic non obstructive enterocele. This is the most frequent type of enterocele detected. The same condition is found in patients with sigmoidocele who have pelvic relaxation that results from weakening of the supporting vaginal tissues and the pelvic diaphragm.7

This is demonstrated by the increased incidence of perineal descent (46%), the association with a functional enterocele (16.6%) and by the presence of an external full-thickness rectal prolapse (25%). The association between sigmoidocele and enterocele was also observed in 3 of 9 sigmoidoceles in Fenner's study 28 whereas in our study we found it in 4/24 patients (16.66%). In the group of patients with sigmoidocele we found a very low incidence of obstructed defecation (2/24: 8.33%). This group has a higher rate of previous hysterectomy and cystocele repair. However, we found even younger patients (mean age 52 years old) with a past history of gastrointestinal disorders and poor pelvic floor function. These factors probably weakened the muscular fibers of the pelvic floor with subsequent loss of support. 7

 It is clear from imaging that a sigmoidocele compresses the rectal ampulla only in the late phase of defecation. In our classification this condition is called "symptomatic non obstructive" enterocele. Otherwise, the frequency of hysterectomized patients (i.e. secondary enterocele) is very high in obstructive and non obstructive enterocele (respectively 51% and 47%); the frequency of cystocele repair is similar. These results may suggest a possible role also for hysterectomy and cystocele repair in the pathogenesis of symptomatic enterocele (obstructive and not obstructive).

CONCLUSIONS

We propose a new classification of enterocele based on its causative role in obstructed defecation in patients with Obstructed defecation syndrome. In fact, we believe that it is possible to identify a functional enterocele which does not compress the rectal ampulla and a symptomatic one that does compress the rectal ampulla. enterocele can be further classified as either an obstructive or non obstructive enterocele.

The first one is often associated with a radiological pattern of obstructed defecation and it's usually present as an isolated condition, probably being the only cause of obstruction in these patients. The second one, which is less associated with obstructive defecation, is usually related to other pathological conditions. Once validated, this classification could define the role of enterocele in the pathogenesis of the obstructed defecation syndrome and allow the surgeon to design the best procedure and consequently improve the chances of a successful outcome.

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Correspondence to: Morandi Claudio - Dipartimento Integrato Servizi Diagnostici e per Immagine Struttura Complessa di Radiologia 1. - Azienda Ospedaliera Universitaria, Policlinico di Modena Via Del Pozzo, 71 - 41100 Modena Tel. +39 059 4225266 - Fax. +39 059 4224290 - Email:info @defecografia .it