The Junction Between the Peristaltic and Non-peristaltic Bowel (Shore Break) is Found in the Transition Zone in Hirschsprung's Disease

The junction between the peristaltic and non-peristaltic bowel, which is named the “shore break” (SB), observed on endoscopy is thought to be the boundary between normal and abnormal motility in Hirschsprung's disease (HD). The transition zone (TZ), which is the histopathological border, does not have normal motility and should be resected. This study aimed to evaluate the histopathological findings of the SB and determine the association between the SB and TZ. A retrospective review of surgical specimens of patients with HD who underwent preoperative SB marking was conducted. The TZ was defined if nerve hypertrophy, myenteric hypoganglionosis, or partial circumferential aganglionosis was detected. Ten patients (9 boys and 1 girl) were studied. The median age at surgery was 30 days. The median distance from the anal verge to the marked SB site was 14 cm. No patients manifested any obstructive symptoms resulting from a residual TZ bowel. In eight patients, nerve hypertrophy was identified at the proximal margin and at the SB. Myenteric hypoganglionosis was identified in three patients at the proximal margin and SB. Partial circumferential aganglionosis was identified at the SB in two patients. As a result, in all patients, the pull-through site and SB site had histopathological features indicating TZ. The SB is located in the TZ. Our results suggest that the proximal part of the TZ has normal motility and that functional border points may be present in the TZ. IV. •The actual motility of the transition zone in Hirschsprung's disease has not been well-documented.•The proximal part of the transition zone may have normal motility. Functional border points, which are impossible to identify histopathologically, may be present in the transition zone.