Anal canal duplication in infants.

Background/purpose: Anal canal duplication (ACD) is the most distal and the least frequent digestive duplication. A review of the English-language literature found 15 cases reported in the pediatric age group.

Methods: A retrospective chart review was performed for our experience from 1999 to 2001 with 6 patients who presented with a midline postanal opening.

Results: All of 6 patients were girls and included one set of twins. Patients were from 3 to 9 months of age at the time of diagnosis (mean, 4.5 months). The anal canal duplication was delineated clearly by contrast study of the tract. All were tubular structures, 10 to 12 mm in length. None of the patients had any other associated anomalies. Five of 6 patients underwent operation between the ages of 3 and 8 months (mean, 5.4 months). Excision of the ACD was accomplished through the posterior sagittal approach. The orifice of the ACD, measuring 1 to 2 mm in diameter located just behind anus, directed to the lumen of the anal canal by keeping in the midline and ended blindly 5 mm above the dentate line without luminal communication. Histology findings showed a squamous epithelium with smooth muscle bundles in 2 cases and pseudostratified columnar epithelium with focally squamous epithelial lining and adjacent smooth muscle bundles in 3 cases. The postoperative courses were uneventful with satisfactory anal function. One patient has not yet undergone operation and has been well on outpatient follow-up.

Conclusions: ACD is a congenital developmental lesion located in the midline posterior to the anus presenting as a tubular structure without communication with the anal canal, usually discovered in early infancy, and characteristically predominant in girls. The authors recommend that all ACDs, regardness of size and length, should be removed surgically to restore the normal anatomy and to avoid delayed presentation of infection such as perianal abscess or fistula formation.