Hirschsprung's disease: problems with transition-zone pull-through

It is generally accepted that if surgery for Hirschsprung's disease is to be successful, ganglionic bowel must be anastomosed to the lower rectum or anal canal. Above the aganglionic distal bowel lies a transition zone (TZ) where more subtle abnormalities of innervation are apparent. The significance of this transition zone in respect to the functional outcome of surgery has received little attention. The aim of this study was to identify the incidence of transition zone pull-through (TZPT) in a cohort of children who underwent surgery for Hirschsprung's disease, to identify the reasons why TZPTs occurred, and to identify the functional consequences. The authors report the long-term outcome of these children with emphasis on bowel function and the results of subsequent surgery.

A Retrospective study was conducted of children treated at a single institution from 1979 through 1994. TZPT patients were subject to detailed review of surgical records and histopathologic material.

Thirteen children were identified with a TZPT. In 12 cases, histopathologic errors contributed to the TZPT: in 5 cases this was caused by single point biopsies missing an asymmetrical TZ, whereas in 7 cases the histopathologic features of the TZ were not recognized. In 1 case the TZPT was caused by surgical error. As a consequence of the TZPT 7 children underwent repeat pull-through. One child is fully continent, one has daytime fecal continence, and 2 others are incontinent. Two children have permanent stomas. One child is clean with antegrade colonic washouts. Repeat pull-throughs were not attempted in 6 children. Two children have achieved full continence, 2 have permanent stomas, 1 is clean with antegrade colonic washouts, and 1 child receives regular suppositories.

Transition zone pull-throughs occurred because of a combination of surgical and histopathologic errors. The transition zone may follow an asymmetric course around the circumference of the bowel and may be missed if single-point extramucosal biopsy specimens are taken. Recognition of the subtle histologic features of the transition zone requires an experienced pathologist. The functional consequences of a TZPT are severe, with symptoms of constipation, diarrhea, and incontinence. The results of revisional pull-through were disappointing. Serious consideration should be given to alternative procedures such as the antegrade continence enema operation.