The Extent of the Transition Zone in Hirschsprung Disease.

Retained transition zone is a leading cause of obstructive symptoms after pull-through operation in Hirschsprung's disease. We aimed to evaluate the extent of the histological transition zone in patients with Hirschsprung's disease. We performed an observational study. DAB + immunohistochemistry for Protein Gene Product 9.5 was used to evaluate the neuronal networks in serial sections of pull-through specimens obtained from children with Hirschsprung's disease (n = 12). Reference ranges for ganglion size/density and nerve trunk diameter were statistically determined using healthy controls obtained from colostomy specimens from children with anorectal malformations (n = 8). The transition zone was defined as ganglionic bowel exhibiting ganglion hypoplasia, hypertrophic nerve trunks, or partial circumference aganglionosis. The mean submucosal nerve trunk diameter in controls was 19.56 μm +/− 3.87 μm. The median age at pull-through for Hirschsprung's disease was 5 months (3–14 months). The median length of the transition zone across the population was 8 cm (4–22 cm). Median transition zone extent was significantly longer in patients with long-segment aganglionosis (n = 6) compared to rectosigmoid aganglionosis (n = 6, 13 cm vs 6 cm, p = 0.041). Due to the age of the patients enrolled, long-term follow-up of bowel function is not yet available. Our data suggest that, in children with rectosigmoid Hirschsprung's disease, the transition zone can extend for up to 13 cm. In children with long-segment disease, a longer transition zone is possible. Extended resection at a minimum 5 cm beyond the most distal ganglionic intra-operative biopsy and intra-operative histological examination of the proximal resection margin are required to minimize transition zone pull-through. 2. [ABSTRACT FROM AUTHOR]