Rectal Duplication - PDF document

Rectal Duplication . . . 23113.1.1 Introduction . . . 23113.1.2 Pathology . . . 23113.1.3 Embryogenesis . . . 23113.1.4 Classication . . . 23213.1.5 Clinical Features . . . Introduction . . . 23413.2.2 Clinical Presentation . . . 23413.2.3 Investigations . . . 23513.2.4 Treatment . . . 23513.2.5 Management of Associated Anomalies . . . References EmbryogenesisMany hypotheses have been put forward to explain how alimentary duplications develop. Two of these are the Veeneklass theory and the Lewis–yng theory. e Veeneklass theory seems to be accepted by most authors for isolated duplications with no spinal involvement. According to Veeneklass, duplications result from a disorder during separation of the notochord due to defective adherence of the endoderm to the notochord [6]. Migration of cells during embryonic development and metaplasia of undierentiated cells (totipotent cells) of the embryonic gut could ex Devendra K. Gupta and Shilpa Sharma 234 be multilocular or have diverticula extending laterally or cephalad. Complete excision of at least all of the lining mucosa should be performed. Infected duplications may require initial drainage followed by a staged resection.ere are several surgical approaches, the decision being based primarily on the location of the duplication. A posterior sagittal approach is now the preferred approach for most of these since it allows good access for complete surgical removal. Large cysts may require a combined approach (abdominal with posterior sagittal or perineal approach). An abdominal approach is preferred for the high, anteriorly located and long tubular duplication cysts. Marsupialization is only indicated in cases with infection, to allow resolution of the sepsis before complete resection of the duplication can be performed. For transanal excision, the anus is dilated and retracted causing the lesion to bulge forward, an incision of the rectal mucosa with subsequent

stripping of the mucosal lining of the duplication cyst may then be accomplished by keeping the dissection in the submucosal plane. For the transcoccygeal or Kraske approach, a transverse incision is made posterior to the anus (similar to the Kraske approach to low rectal tumors). It may be necessary to remove the coccyx. Cyst excision using a transcoccygeal route was common prior to the development of the PSARP approach; it is not popular these days. e posterior sagittal approach with or without an additional abdominal/perineal approach is now the preferred approach. It provides better access and is similar to Peña’s approach for ARM. is approach is also useful for other types of retrorectal masses. e rectum may be dissected from the muscles and lied o or bisected to reach the lesion. is approach can be combined with an abdominal approach to remove long and large cysts that are not attainable by the posterior sagittal route. e additional abdominal and/or perineal approach is required in cases where the lesion is large, if it is in association with genitourinary malformations and ARM, and if there is extension of the cyst into the abdomen, especially in anterior duplication cysts SummaryRectal duplications are rare anomalies that present in a variable fashion. A suspicion of such an anomaly helps in investigative planning. A cyst of variable shape and oen distended with mucus, lying in the presacral space, forms the diagnosis. ese need to be dierentiated from other types of anorectal pathology. A single-stage excision of the cyst, usually by the transanal, perineal, or posterior sagittal route is curative in most cases. However, associated ARM and severe hypospadias with perineal duplication cysts, may require complex surgical procedures (involving repair of hypospadias, anorectum, and excision of the cyst) under a covering colostomy to achieve a successful repair. Anal Canal Duplication IntroductionAnal canal duplication can be an isolated

anorectal pathology or a part of caudal twinning syndrome that is characterized by the presence of twinning of the hindgut derivatives, giving rise to doubling of its derivatives, namely the colon, rectum, bladder, urethra, genital organs, and kidney. It usually occurs in association with colonic duplication. Cases of isolated colonic duplication without involving the anal canal have been excluded in this chapter. Clinical PresentationAer an extensive review of the previously reported cases, three anatomical patterns of anal canal duplications have been seen (Fig. 13.3 A–C). Two separate perineal openings externally giving rise to double perineal ani, occurring in association with colonic duplication. Colonic duplication with one normal and one imperforate anus terminating with or without a stula to the genitourinary tract. Colonic duplication with both imperforate ani terminating with or without a stula to the genitourinary tract. Fig. . Types of duplication of the anal canal 235  Rectal Duplication and Anal Canal Duplication Double perineal ani is extremely rare and only a few cases with true double anal openings in the perineum have been reported in the world literature. ere could even be a triplication of the colon, with or without any normal opening in the perineum. In case of double ani, these may lie on either side of the midline with the external corresponding genitalia, or may be located along the anteroposterior axis in the midline. One of them is, however, better developed than the other. e sites of the ani were initially reported to be seen more commonly on either side of the midline [21]. However, recent reports have found the openings to be anteroposterior in location [22]. e two ani may be separated only by a thin septum or may lie wide apart from each other for about 1.5 cm [21]. Each anal canal passes through the sphincter complex separately. Each is lined by normal anal canal lining epithelium (Fig. Double an

i in association with colonic duplications are usually tubular. Of the 32 cases reported in the literature up till 1988, only two cases had communications at the lower end, starting from the rectum to the anal verge. e remaining cases all had proximal communications in the region of colon, cecum, or even in the ileum [21].Over 90% of cases are females, with the female:male ratio being 9:1 [21,22]. e anomaly is apparent in the newborn; however, its detection may be delayed if the additional colon is ending blindly in the perineum without external evidence. e age range in this group is from 1 to 24 months. Even the patients with perineal communications remain asymptomatic but may present with mucus discharge, infection, diarrhea, ulceration, and bleeding due to the presence of gastric heterotopy. Malignancy is rare but has been reported in adults. Both the ani function simultaneously and with normal continence as they pass through the puborectalis and levator ani muscle separately. However, the amount of fecal matter coming in each is variable. InvestigationsInvestigations such as stulogram, contrast enema, micturating cystourethrography (MCU), renogram, ultrasonography, and MRI, are performed to gain information about the location and communication of the double ani with the genitourinary and intestinal tracts. It may sometimes be dicult to dierentiate this anomaly from stula-in-ano, which mimics this condition closely. e stula-in-ano is also uncommon in the pediatric age group and, if present, would not open in the midline, unlike the double ani. Also, a solid mass would persist even aer drainage, a characteristic that is not seen with a stula.Diagnosis of double ani is made histologically, showing a smooth muscle wall with gastrointestinal epithelial lining and the presence of anal glands. Contrast studies performed through each anal orice and the urogenital orices show complete duplication of the rectum and colon as far as the ascending c

olon. Two separate bladders, vaginas and uteri may be seen. TreatmentTreatment for patients with double ani remains controversial and involves many considerations. In the present scenario, the decision would be in favor of surgery to provide the patient with as near a normal state of external genitalia and continence as possible, excising the unwanted component of the duplicated colon. In the past it was felt that if the second anus was not embarrassing to the patient it could be le untouched [21]. Also, if there is no neurogenic bladder or bowel problem (as with associated spina bida), a good continence and a normal function can be expected through both the ani and the urethrae. e levator and sphincter muscles, being mesodermal structures, are not related to hindgut development, Fig. . Double ani. e normal-located anus and the ectopically placed anus; both have independent anal sphincters (photograph courtesy of Professor Tahmina Banu, Bangladesh) Devendra K. Gupta and Shilpa Sharma 236 and are thus single structures (except if the spine and sacrum are also duplicated).e main reason for the excision of the extra anus is cosmetic and prevention of malignancy in the redundant rectal pouch in cases in whom the colon needs to be excised due to obstructive symptoms in the duplicated colon. Alternatively, the mucosa of the rectal stump may be evaginated to achieve its nonfunction.e thin septum between the ani can be resected, or the distal continuity with the colon can be excised and made into a single channel if obstructive symptoms arise, using a combined abdominal and PSARP approach.e colonic duplications that are associated with duplication of the genitalia are usually not fused and have a separate blood supply, so that resection of one colon from the other is usually possible [23]. Genital reconstruction is also performed only for cosmetic reasons. In females, construction of a single vulva provides a desirable external appearance in which the two uret

hrae and two vaginae open unimpeded [21]. Simultaneous continent streams prove no disadvantage if covered with a single vulva. Urethral removal or closure may only be required if its presence interferes with vulval reconstruction. Vaginal duplication does not interfere with menstruation, coitus, or parturition, unless there is stenosis. Fertility has been reported in patients with double ani and double vaginae.Most cases reported in the earlier literature had a very high mortality that was mostly due to severe associated anomalies and because of obstruction to one or both of the coli. However, with modern amenities available, the patient should have as near a normal perineum as possible, passing stool and urine at will through single orices.In cases of colonic duplication with one normal anus and one imperforate anus, the imperforate anus may or may not terminate as a stulous communication into the genital, urinary tract, rectum, or perineum. e appearance of the external genitalia is highly variable in this group. Most cases have nonduplicated external genitalia.ese patients present early because of complications of intestinal obstruction and sepsis. None reach adult age without surgery. If le untreated, the patients die of intestinal obstruction [21]. From the data available in the literature, patients in this group with one normal anus and one imperforate anus without a stula had the worst outcome.It has been observed that when the external genitalia are single, the double colons tend to be intimately fused, so that colonic resection of both coli together is necessary [23]. Treatment consists of anastomosis of the two coli together so that the fecal matter goes through the main anal canal, and the stulous connection is excised.Colonic duplication/triplication with two or more imperforate ani terminating with or without a stula to the genitourinary tract present in early infancy due to colonic obstruction [24]. External genital anomalies are rare in these patients, bu

t varying degrees of associated internal genitourinary anomalies requiring treatment are present. e treatment options for these patients are: colostomy followed by denitive repair later, total colectomy, and ileoanal anastomosis. Management of Associated AnomaliesAssociated anomalies occur frequently and are seen in 20–40% of cases and include cle lip and palate, cardiac anomalies, malrotation, lumbosacral dysgenesis, renal anomalies, omphalocele, meningomyelocele, and early cranial fusions [21–23, 25–27]. e most common associated anomaly is spina bida. External genitalia in association with anal duplication may have a varied presentation – double external and internal genitalia, double genitourinary tract.e urethral duplications may be complete or incomplete. In complete duplications the patient may void with a double stream. Epispadiac duplications are usually associated with signicant dorsal curvature of the penis. e most common type of urethral duplication is the Y-type, where the duplication arises from the prostatic urethra and the main urethra opens at the anal verge, through which most of the urine passes. e other urethra is very narrow and dysplastic and can not serve the purpose for micturition. ere is also a spindle duplication, where the duplication arises from the prostatic urethra and rejoins the urethra at some point along the sha of the penis.Most urethral duplications present with a double stream or a leak from the second orice. Diagnosis is by MCU and panendoscopy, although it is oen dicult to catheterize either of the two urethrae. No specic treatment will be required if both the urethrae are normal in caliber and serve their purpose well. However, as the ventral component is the normal urethra in almost all cases, and opens in the perineum just anterior to the anus, the urethral reconstruction is really technically demanding and requires staged procedures, even under the cover of a colostomy i