Anal canal duplication: experience at a single institution and literature review

Anal canal duplication (ACD) is an extremely rare congenital intestinal anomaly. There are not many reports in the English literature, with just a few from each institution. The aim of this study was to describe the clinical characteristics, surgical treatment, and outcome of ACD in pediatric cases at a single institution.

The medical records of ACD patients we treated from 1988 to 2009 were reviewed retrospectively.

There were ten cases, all females. Nine were asymptomatic without any history of perianal infection, identified only incidentally at routine check-up although one case had severe periproctal abscess. Mean age at diagnosis was 6 months (range 0-47 months). Concurrent pathology present were meningocele and presacral mass in one, presacral mass in one, and renal hypoplasia in one. In all cases, an extraneous perianal orifice opening in the midline posterior to the native anus was present, but in one case it was only identified at surgery because it had closed secondary to severe inflammation preoperatively. All had preoperative radiologic investigations, such as magnetic resonance imaging (MRI), barium contrast studies, and fistulography. Mean age at surgery was 14 months (range 1-48 months). All underwent surgical removal of the anal canal duplication, eight through a perineal approach and two through a posterior sagittal approach, depending on the length of the duplicated anal canal and the presence of concurrent anomalies. Histopathology of the excised anal canals showed squamous epithelium in all cases. The postoperative course was uneventful in all cases and all are well without complications at mean follow-up of 9.1 years (range 5-19 years).

This is the largest series of ACD at a single institution reported to date. For the clinician faced with an extraneous perianal orifice located posteriorly in the midline with respect to the native anus, ACD should be suspected. The treatment of choice in children is complete excision (perineal/posterior sagittal approach), even if asymptomatic. Morbidity is minimal, and outcome is excellent.