Anorectal malformation without fistula: a defect with unique characteristics

Anorectal malformations (ARMs) without fistula occur in approximately 5 % of all cases of ARM. The high frequency of Trisomy 21 associated to this type of malformation has been previously described. A review of the literature revealed only one previous publication discussing ARM without fistula with or without Trisomy 21; all other publications focused their discussion in patients with Trisomy 21. We felt that ARM without fistula has very specific characteristics and therapeutic implications that deserved a special discussion, which prompted us to review our experience.

A retrospective review of the medical records of patients with ARM without fistula was performed between September 1980 and March 2014. From a series of 2,189 cases of ARMs, 92 had no fistula identified. Information related to demographic, anatomic, and prognostic factors, as well as outcome variables was obtained and compared to those results obtained from other types of ARMs.

Seventy-six patients were males and 16 females. Thirty-seven patients (40 %) had Trisomy 21. Eighty-six patients were primarily operated on and six had a reoperation after a failed attempted repair at another institution. Of the six patients that were reoperated, five had an attempted repair in the newborn period without a colostomy and the operation was aborted after the rectum could not be found. The location of the blind rectum was at the level of the bulbar urethra in males or 1–2 cm from the perineal skin in females in 80 patients; and in 9 patients it was found at the level of the prostatic urethra. In five patients, during the repair, there was an incidental opening of the urethra, which was repaired with uneventful recovery. The sacrum was normal in 61 patients; 4 patients had a sacral ratio <0.4, which indicated poor prognosis for fecal continence. Sixty-four patients had normal urinary tract, four patients had an absent kidney, ten had bilateral hydronephrosis, and three unilateral. Long-term outcomes related to bowel control were available in 52 cases: 11 of 18 patients with Trisomy 21(61 %) had voluntary bowel movements and 29 of 34 (85 %) without Trisomy 21 had voluntary bowel movements. All patients without Trisomy 21 had urinary control.

Anorectal malformation without fistula is a unique defect. In our series, it occurs in 4 % of all ARMs. Even when patients do not have a fistula, the operation is not technically easier due to the presence of an extensive common wall between the rectum and urethra in males or vagina in females. The ARM with no fistula has a good reasonable functional prognosis, even in patients with associated Trisomy 21 and conveys a low frequency of associated urologic defects.