Anal duplication: is surgery indicated? A report of three cases and review of the literature.

Abstract

Anal canal duplications (ACDs) are extremely rare with only approximately 90 cases described in the literature. We report on three additional patients. Cases were analyzed to evaluate presenting symptoms, physical exam and MRI findings. A comprehensive literature review was performed to compare our patients to previously described cases. IRB approval was obtained for this study (19-0394). The first female patient presented with an asymptomatic ACD at 2years old. The second patient was a 13-year-old female with perianal drainage that was initially mistaken for a fistula-in-ano and ultimately found to have an ACD associated with a dermoid cyst. Both posterior midline duplications shared a common wall with the rectum, but did not communicate with it. The ACDs and dermoid cyst were successfully excised through a posterior sagittal approach with no postoperative complications. Histology demonstrated the presence of both squamous epithelium and transitional anal epithelium in each case. The third patient was 8months old and had a tethered cord, hemisacrum, presacral mass, and anal duplication that was initially undiagnosed. These results corroborate patterns identified in other reports of ACDs with over 90% being female and in the posterior midline. The majority are asymptomatic, but may present with symptoms of local or even systemic infection. An opening in the midline posterior to the anus should raise clinical suspicion for anal canal duplication. An associated presacral mass must be ruled out. Complete excision through a posterior sagittal approach is recommended upon diagnosis to avoid symptomatic presentations. The key part of the operation is the separation of the ACD from the posterior rectal wall.