The Prevalence and Clinical Impact of Transition Zone Anastomosis in Hirschsprung Disease: A Systematic Review and Meta-Analysis

Background: Hirschsprung disease (HD) is characterized by absent neuronal innervation of the distal colonic bowel wall and is surgically treated by removing the affected bowel segment via pull-through surgery (PT). Incomplete removal of the affected segment is called transition zone anastomosis (TZA). The current systematic review aims to provide a comprehensive overview of the prevalence and clinical impact of TZA. Methods: Pubmed, Embase, Cinahl, and Web of Sciences were searched (last search: October 2020), and studies describing histopathological examination for TZA in patients with HD were included. Data were synthesized into aggregated Event Rates (ER) of TZA using random-effects meta-analysis. The clinical impact was defined in terms of obstructive defecation problems, enterocolitis, soiling, incontinence, and the need for additional surgical procedures. The quality of studies was assessed using the Newcastle–Ottawa Scale. Key Results: This systematic review included 34 studies, representing 2207 patients. After excluding series composed of only patients undergoing redo PT, the prevalence was 9% (ER = 0.09, 95% CI = 0.05–0.14, p < 0.001, I(2) = 86%). TZA occurred more often after operation techniques other than Duhamel (X(2) = 19.21, p = <0.001). Patients with TZA often had obstructive defecation problems (62%), enterocolitis (38%), soiling (28%), and fecal incontinence (24%) in follow-up periods ranging from 6 months to 13 years. Patients with TZA more often had persistent obstructive symptoms (X(2) = 7.26, p = 0.007). Conclusions and Inferences: TZA is associated with obstructive defecation problems and redo PT and is thus necessary to prevent.