Congenital Pouch Colon with Rectal Atresia Revisited.

We are adding two cases of congenital pouch colon with rectal atresia (RA) to the already published five cases. The presentation of RA is often delayed owing to the presence of normal anus, however, clinical evaluation, plain abdominal radiograph, and urine examination for meconuria, may help in detecting this rare association early.

Introduction

Congenital pouch colon (CPC) is a rare form of high anorectal malformation (ARM) in which part of or the entire colon is replaced by a pouch with a fistula to the genitourinary tract. The majority of cases of CPC have been reported from North India.[1] The rectal atresia (RA) itself is a rare entity. The association of CPC anomaly with RA has been described in only five cases, and we are adding two more cases along with review of pertinent literature.[23456] On clinical evaluation, our patients were diagnosed with RA, and on radiological evaluation, they were found to be associated with CPC.

Case Reports

Case 1

A 4-day-old preterm (36 weeks) male baby, weighing 2 kg, 1st in birth order, born by normal vaginal home delivery, presented with marked abdominal distension and nonpassage of meconium since birth. On physical examination, the baby was moderately dehydrated. The abdomen was distended with prominent veins all over the abdomen [Figure 1]. Perineum examination revealed meconuria, and normal urethral and anal openings, but infant feeding tube could not be inserted beyond 2 cm from the anal verge [Figure 1]. A preliminary diagnosis of RA was made. Abdominal radiograph suggested CPC Type 4 [Figure 1]. After preoperative optimization, laparotomy was performed with left hockey stick incision which confirmed the diagnosis of CPC Type 4 with colovesical fistula associated with RA. Excision of pouch colon with ligation of colovesical fistula and sigmoid end colostomy was performed at the distal end of the incision. Other associated gastrointestinal anomalies were ruled out and meticulous hemostasis was achieved before abdominal closure. Feeds were initiated on the 4th day and discharged in stable condition. The patient is awaiting evaluation of other associated genitourinary anomalies in follow-up.

Figure 1

Photograph showing a neonate with visible veins and marked abdominal distension particularly on the right side; the figure has been marked to show the presence of congenital pouch colon, arrow shows the direction of the pouch pointing to the right side, stomach, and intestines on the left side (a); normal anus and perineum with number 10 infant feeding tube, which could be inserted only 2 cm through anus (b); a single, wide air-fluid level on upright abdominal radiograph suggestive of congenital pouch colon Type 4 with apex pointing to right side as shown by red arrow, displacing small bowel loops to left side along with the absence of rectal air (c)

Case 2

A 2-day-old full-term male baby, weighing 2.25 kg, 2nd in birth order, born by normal delivery, presented with marked abdominal distension and nonpassage of meconium since birth. The abdomen was distended. Perineum examination revealed meconuria, and normal urethral and anal openings, but infant feeding tube could not be inserted beyond 2 cm through the anus. A preliminary diagnosis of RA was made. Babygram revealed the presence of CPC. On exploration, CPC Type 4 was found; pouch excision and sigmoid end colostomy were performed. The postoperative period was uneventful. On a follow-up visit, echocardiography revealed small PDA (patent ductus arteriosus) 2.5 mm with left to right shunting. Micturating cystourethrogram (MCU) suggested Grade II vesicoureteral reflux (VUR) on the right side. A combined abdomino-posterior sagittal anorectoplasty (A-PSARP) was performed at 5 months of age. Endoscopic treatment of VUR with injectable dextranomer/hyaluronic acid copolymer was performed for Grade II VUR in a further follow-up visit.

Discussion

CPC is a rare form of high ARM. The majority of cases of CPC have been reported from North India.[1] CPC was placed in the group of “rare/regional variants” of the Krickenbeck International classification.[7] The RA itself is a rare entity. The association of CPC anomaly with RA is even rarer and has been described in only five cases in the literature.[23456]

This rare association embryologically is best explained by combined Stephen's[8] (incomplete downward growth of cranial fold [Tourneux] with failure of lateral fold [Retterer] fusion) and vascular insult theories[2] (intrauterine obliteration of inferior mesenteric artery and branches of internal iliac artery).

CPC has been classified into five types, based on anatomic morphology.[1] In the abdominal radiograph, a single, large, dilated bowel loop with an air-fluid level occupying more than half of the total width of the abdominal cavity and displacing the small bowel to one side is usually diagnostic of CPC. Mathur et al. attempted to predict the type of CPC on plain abdominal radiography.[1] In Type 1 and Type 2 CPC, the apex of the dilated pouch is directed toward the left hypochondrium while in Type 3 and in most of the cases of CPC Type 4, the apex lies to the right hypochondrium.[1] During a 7-year period from 2009 to 2015, a total of 1463 patients of ARM were surgically managed in the neonatal period at our institute. A total of 252 (17.22%) were identified with CPC malformation, out of which 185 were males and 67 were females (M:F ratio of 3:1). The types of CPC found during the study were Type 1 - 55 (21.82%), Type 2 - 40 (15.87%), Type 3 - 11 (4.36%), Type 4 - 144 (57.14%), and Type 5 - 02 (0.79%).

Of all the reported cases of CPC with RA including the present series, the majority of the neonates were males (6/7).[23456] Preoperative plain abdominal radiograph was suggestive of CPC in 5 out of 7 cases. On exploration, CPC Type 4 was found in 5 cases and CPC Type 2 in 2 cases. Although colovesical fistula was demonstrated in 5 out of 7 cases, meconuria was seen in only 3 cases. The outcome was favorable in all cases, except our first reported case in the literature.[23456]

There are no published data about the incidence of VUR in CPC from a single center, yet. However, this has been observed in significant percentage of cases of CPC (Prof. Rao KLN, personal communication, April 26, 2016). The inherent defective musculature of CPC might have also involved the bladder musculature, resulting in high incidence of VUR in CPC. We have limited experience about endoscopic management of VUR in CPC. We recommend MCU in all neonates with CPC in follow-up and low threshold for endoscopic treatment.

We believe that presentation of RA is often delayed owing to the presence of normal anus. The presence of RA in any patient with nonpassage of meconium or abdominal distension since birth should always be ruled out by passing soft red rubber catheter or infant feeding tube. The condition of the child should dictate the surgical management. There is precedence of a single case of primary surgical repair (combined A-PSARP),[3] but owing to the late presentation of CPC with RA, we would recommend staged surgery.

Conclusion

The three diagnostic modalities for this rare association (CPC with RA) are (a) clinical - (i) nonpassage of meconium and/or abdominal distension since birth (ii) failure of passage of red rubber catheter beyond 2–3 cm from the anal verge, (b) radiological - plain abdominal radiograph (to detect CPC and its type), and (c) laboratory - urine examination for meconuria (colovesical fistula). In other words, RA, if associated with meconuria, suspect CPC. We recommend MCU in all neonates with CPC in follow-up to detect VUR early owing to its high incidence in CPC.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.