Background: The transition zone (TZ) is defined by specific histological findings in patients with Hirschsprung Disease (HSCR). HSCR treatment includes surgical removal of the aganglionic zone (AZ). During the pull-through procedure, it is critical to resect the TZ. Given the TZ's wide histological heterogeneity, we wanted to know how extensive the histological transition zone is. Methods: A retrospective study of patients who had pull-through surgery for rectosigmoid HSCR between January 2010 and December 2020 was carried out. Demographics, length of TZ and AZ, age and symptoms upon presentation, and complications after surgery were also obtained. Results: The inclusion criteria were met by 50 patients. The mean age of all patients was 10 months (0.1-107.5 months), with a mean age at pull-through of 16.3 months (3-112 months). Thirty-one out of fifty patients (62%) received primary laparoscopic endorectal pull-through surgery (LEPT). The average TZ length of all patients was 2.6 cm (0-10 cm), and the AZ length was 9.6 cm (1-30 cm). The length of the AZ and TZ were shown to have no correlation (r² = 0.237). Conclusions: The current study found that the mean length of the TZ in individuals with rectosigmoid HSCR is less than 5 cm in most cases and has no correlation with the length of the AZ.
