Anal canal duplication: case reviews and summary of the world literature.

Anal canal duplication (ACD) is a rare entity that is difficult to recognize. After the presentation of two patients, a review of the literature found 45 reported patients with ACD. This article presents the largest collection of known patients ACD in the literature. Of the 47 patients, 43 were female. The mean age at presentation was 28 months (range 0-24 years). The majority of the duplications were discovered incidentally (n = 21). Several presented with infectious complications such as epidural abscess with sepsis. Forty-two patients manifested an opening in the midline posterior to the native anus. Eighteen patients had associated anomalies, the majority of which were midline. Thirty-five of the patients underwent successful resection with rare complications. ACDs characteristically appear in females as incidental findings of an extra perineal orifice. They are frequently associated with additional congenital anomalies. Generally, ACDs are resectable with excellent outcomes.