Role of plain abdominal radiographs in predicting type of congenital pouch colon

Congenital pouch colon (CPC) is a rare form of high ano-rectal malformation (ARM) in which part of or the entire colon is replaced by a pouch with a fistula to the genito-urinary tract. According to the Saxena-Mathur classification CPC is divided into five types. Although plain abdominal radiographs are taken in infants with suspicion of CPC to detect large dilatation of the pouch, the determination of the type of CPC is made during surgical exploration. Since large variations in the length of normal colon are present in the various types, management strategy options can be determined only at the time of surgery.

The aim of this study was to review abdominal radiographs of children with congenital pouch colon (CPC) and evaluate their value in determining the type of CPC prior to surgical exploration to assist pre-operative planning.

Over a 12-year period (1995-2007), CPC was documented in 80 children (52 boys and 28 girls, age range 1 day-9 years, median 2.4 days) and retrospective analysis of plain abdominal radiographs of 77 children at the time of presentation was performed. Radiographic findings were correlated with surgical findings.

Of 77 children, 5 were excluded from the study since the pouch colon was perforated. The direction of the pouch apex was correlated with surgical findings to determine the CPC type (P<0.0001, Fisher exact test). Type 1 (17/18) and type 2 CPC (18/18) were characterized by a single large pouch with the apex positioned in the left hypochondrium. In type 3 CPC (2/2) the pouch apex was directed towards the right hypochondrium. In type 4 CPC the apex of the pouch was directed towards the right hypochondrium (28/33); however in 5 children it was towards the left hypochondrium. In type 5 CPC (n=1) the radiograph was inconclusive.

Plain abdominal radiographs have a predictive value in determining the type of CPC and obviating the need for an invertogram.