Colonic atresia associated with annular pancreas: An extremely rare and previously unreported association.

Colonic atresia is the rarest entity among the all intestinal atresias and may be associated with anterior abdominal wall defect, small intestinal atresia, Hirschsprung's disease, and other anomalies. Here, we are reporting a case of colonic atresia associated with annular pancreas, which has not been reported previously to the best of our knowledge.

INTRODUCTION

Colonic atresia is contributing 1.8-15% of all intestinal atresias, with an incidence of 1:40,000 live birth.[1] The classical approach is staged operation: End colostomy and delayed anastomosis. Reported-associated anomalies are malfixation of the mesentery, Hirschsprung's disease, anterior abdominal wall defects, ocular and facial anomalies, and other atresias. The association of annular pancreas has not been reported till date in the available literature.

CASE REPORT

A 2-day-old term female baby presented with abdominal distention, bilious vomiting, and failure to pass meconium since birth. On rectal examination, a red rubber catheter could be passed up to 5 cm. Straight X-ray abdomen showed dilated gut loops with absence of gas shadow in the pelvic region [Figure 1]. A provisional diagnosis of distal ileal atresia/colonic atresia was made.

Figure 1

Per operative findings during re-laparotomy showing “Annular pancreas” causing duodenal obstruction

On exploration, we found colonicatresia at the level of transverse colon with a short segment of distal micro colon. After exclusion of other atresias, we performed an end colostomy along with a biopsy from the colostomy site. The baby recovered well and was discharged on 4th postoperative day (POD).

After three and a half months, the patient was readmitted with repeated bilious vomiting. Clinically, abdomen was not distended. Straight X-ray abdomen showed “double bubble” sign and Ultrasonography (USG) was normal. An upper gastrointestinal (GI) contrast study showed dilated stomach and duodenum up to D2 with the passage of contrast materials distally on delayed film. On re-exploration, we detected the duodenal obstruction was due to an annular pancreas. There was no evidence of duodenal atresia or stenosis. We performed duodeno-duodenostomy (diamond anastomosis). Post-operative recovery was uneventful. Oral feeding was started on 6th POD.

DISCUSSION

Neonatal intestinal obstruction with dilated gut loops and scanty or absent gas shadow in the pelvic region suggests a colonic pathology and may be due to Hirschsprung's disease, meconium plug syndrome, small left colon syndrome, and colonic atresia/ stenosis. Colonic atresia is rare and the transverse colon is the rarest site of all the colonic atresias. The most accepted theory of colonic atresia is an intrauterine vascular insult due to embolus in mesenteric circulation, fetal herniation, kinks, and intussusception of the gut and maternal use of cocaine. Other theories like failure of recanalization, intestinal perforation, drugs, and environmental factors have been proposed.[2] A provisional diagnosis of colonic atresia could be made on ultrasound if the colonic diameter is more than 18 mm. Contrast enema study is sometimes required to reach the diagnosis of colonic atresia. In most of the cases, primary resection and anastomosis is not possible due to the presence of distal short/ micro colon. The standard recommendation is staged operation: End colostomy and delayed anastomosis. Resection of dilated proximal colon and distal micro colon followed by primary anastomosis with or without proximal covering enterotomy also has been proposed as a favorable option. The prognosis is usually favorable unless associated with other anomalies like multiple small intestinal atresias and pyloric atresia.[3]

The name “Annular pancreas” was first suggested by Esker in 1862. It is a rare congenital anomaly (incidence is 1-3/20,000 live birth), and here the pancreatic tissue completely or partially wraps around the second part of the duodenum. It is thought to be due to incomplete rotation of the ventral pancreatic diverticulum with the duodenum. An alternate theory of Hypertrophy of ventral and dorsal buds resulting a band of pancreatic tissue around the second part duodenum has been published.[4] Although there is a fibrous constricting ring around the second part of the duodenum, the duodenal obstruction is usually due to an associated atresia or stenosis at the same level.[5] So the onset of symptoms of isolated annular pancreas may be delayed. There is early onset of vomiting with minimal or no abdominal distension. Classical double bubble in X-ray is enough to conclude the duodenal obstruction.[6] Duodeno-duodenostomy is the procedure of choice for annular pancreas which has evolved from a side-to-side anastomosis to a proximal transverse to distal longitudinal (“diamond shaped”) anastomosis. At the time of operative repair, distal obstruction should be evaluated, because a second mucosal web exists in 1% to 3% of cases. Duodeno-jejunostomy and gastro-jejunostomy are not favored as blind loop syndrome may develop.[7] Mortality is high if it is associated with other congenital anomalies like Down's syndrome, tracheoesophageal fistula, esophageal atresia, imperforate anus, and Hirschsprung's disease.[8]

In our case, the patient underwent a colostomy and biopsy for colonic atresia at the level of the transverse colon. The patient had to be readmitted for repeated bilious vomiting without any abdominal distension. A presumptive diagnosis of duodenal obstruction was made after straight X-ray abdomen, USG, and upper GI contrast study. Finally, annular pancreas was detected on exploration.

Even in an extensive search of the available literature, no case report of an association of colonic atresia with annular pancreas was found. Baglaj et al., reviewed 30 cases of colonic atresia over 30 years and found that out of 30 patients, 13 had associated anterior abdominal wall defects. In 2005, Cox et al., described small intestinal atresia associated with colonic atresia. Etensel et al., collected the data from all the available case series of CA from 1992-2002 and published their article emphasizing the etiology, demography, associated anomalies, treatment options, and overall prognosis, but this rare association has not been mentioned.[9]

CONCLUSION

After an extensive literature search, we have concluded that the association of colonic atresia with annular pancreas is one of the rarest and previously unreported. Although a rare entity, we must keep in mind the possibility of this association on finding colonic atresia on exploration and therefore inspect the whole small gut. Post-operative patients presenting with symptoms on follow-up, we must regard the possibility of a missed diagnosis and investigate. Also, the presence of rare association like annular pancreas did not alter the treatment algorithm of colonic atresia and so also its prognosis.