[Characteristics of the anorectal atresia without fistula. Based on 12 cases]

Imperforate anus without fistula is an uncommon anorectal malformation, in association to Down syndrome in 50% of cases. This anomaly is described as a lack of annus, with a blind rectal pouch, located about 2 cm above perineal skin, and sharing a common wall with the urethra or vagina. The aim of this work is to present our experience in this condition and to determine the differences between the diagnosis, treatment and long-term outcome of these patients in relation to other forms of anorectal malformation.

We reviewed the medical records of 12 patients treated in our department from 1998 to 2008. Eight were boys and 4 girls. Eleven of these patients had significant associated congenital diseases: Down syndrome (6), cardiovascular anomalies (6), urinary tract malformations (5), esophageal atresia (1). In all cases neonatal colostomy was performed, being 7 months (range between 1 and 19 months) the average age of the definitive surgery through posterior sagital approach. In one case a laparotomy was performed. The distance from the rectal pouch to the skin ranged from 1 to 5 cm, founding a very dilatated rectum in 4 patients.

The postoperative outcome was favorable. Four patients required removal of a small anal prolapse. All patients older than 2 years (7) have urinary continence, while 5 of them have a significant constipation, resistant to treatment with diet and laxatives, requiring medical management with enemas.

Our study confirms the high incidence of Down syndrome in patients with imperforate anus without fistula, and shows a higher incidence of other congenital comobidities. A colostrogram prior to definitive repair seems to be mandatory taking into account the intraopetative findings (height and diameter of rectal pouch). The incidence of anal prolapse is very high and may be related to the hypotonia present in patients with Down syndrome. Since the constipation is very severe in these patients, it should be controlled early in the follow up.