Congenital Pouch Colon associated with Anorectal Malformation: A Case Report and Review of Literature

Introduction

Congenital pouch colon (CPC) is an unusual abnormality in which a pouch like dilatation of a shortened colon is associated with an anorectal malformation (ARM).^1-5

It is rare worldwide but frequently reported in Asian regions, predominantly from Northern India.^4-6 Based on rarity of this disease, a case of congenital pouch colon is reported with review of literature on anorectal malformations.

Case Report

A one- day male baby was brought with absent anal opening, and meconuria to our department. There was history of conception of child after 15 years of marriage following infertility treatment. Antenatal ultrasound at 30 weeks of pregnancy was suggestive of enteric duplication. Clinically anal opening was absent with flat perineum. There was meconium in the urine and left undescended testis. Postnatal ultrasound showed large cystic lesion in lower abdomen which was interpreted by Radiologist as enteric duplication cyst (Fig.1), Postnatal X-ray and Invertogram had shown high anorectal malformation with air filled cystic area in lower abdomen (Fig. 2).

The baby was operated on day 2 of life. Intraoperatively we found a pouch-like dilatation of the colon. It was located at a distance of 10-12 cm of normal colon (Fig. 3). The distal end of the pouch opened into the dome of the bladder forming a fistula between pouch and the bladder. Divided diversion colostomy proximal to the pouch was performed with preservation pouch as first stage of the operative procedure. The baby was discharged on 6th day of life. Colonorraphy and pull through have been planned as second stage 4 months later.

Discussion

Congenital Pouch Colon (CPC) is known as an anomaly in which all or part of the colon is substituted by a pouch-like dilatation, which is connected distally with the urogenital tract through a fistula.^1-6

The name ‘CPC syndrome’ was introduced by Narsimha Rao and colleagues in 1984.¹   CPC has been categorized into four subtypes based on the length of normal colon proximal to the colonic pouch.1   In Type I CPC, normal colon is absent, and the ileum opens directly into the colonic pouch while in Type II CPC, a short segment of caecum is present between the ileum and the pouch. Type III CPC has a significant length of normal proximal colon (7–8 cm in the newborn) while with Type IV CPC, only the terminal portion of the colon (rectum and a varying length of sigmoid colon) is converted into the colonic pouch.¹ Recently Type V CPC has been proposed by Chadha et al⁷ and they have described it as “double pouch colon with short normal interposed colon segment” in which a proximal segmental dilatation of the colon communicates distally via a short segment of normal colon with a colonic pouch terminating in a fistula with the genitourinary tract.⁷ In our case child had type III CPC.

Many associated anomalies with CPC are reported in literature (Table 1)^5,7-12 Genitourinary and gastrointestinal systems are most commonly involved.^5,7-12 In our case child had left sided undescended testis.

Our case was a male baby and it is reported that CPC is more common in males.^1-6

The exact incidence of CPC associated with ARM is not known even if it is certain that it is rare worldwide. It is much more commonly reported in India than in the rest of world.^1-6 The reason of this unique geographical distribution has not yet been ascertained.^1-6

The terminal fistula of the colonic pouch opens at variable levels of genitourinary  system. In male, it can open into the urethra or bladder (at different sites); in female, it opens in the vestibule, in the vagina, uterus, in perineum or in a persistent cloaca.^3-5 In our case fistula was opened at the dome of the bladder.

In a classical case, the diagnosis is made with an abdomen X-ray (anteroposterior and lateral views) and an invertogram. The radiographic hallmark is a large loop of bowel with a single air-fluid level that occupies most of the abdominal cavity and causes a shift of small bowel to one side (usually right). In the invertogram, the image of the pouch is at the level pubo-coccygeal line.⁴⁶ The pouch is structurally, histologically and functionally different from the normal colon.^5,11,13 The management involves a diversion colostomy at birth with or without the excision of the pouch followed by pull through.^5,11,13 In our case also we followed same protocol of management.

Gupta and Sharma⁵ reported a mortality of 8.8% in the neonatal period.  Shinde et al¹³ assessed nutritional status in operated cases of CPC and found that children specially with type I and type II CPC have very short functional colon and suffer with malnutrition, stunting, anaemia and exhibit a  high incidence of Vitamin D, Vitamin B¹² and folate deficiency.¹³

Conclusion

We have to consider CPC in all patients with high ARM especially if they come from the Asian region. The knowledge of disease permits an early diagnosis and an appropriate surgical approach to ensure survival and good quality of life to these children.