Congenital malformations of anus and rectum: Report of 162 cases

One hundred sixty-two cases of anal and rectal abnormalities were reported from the Boston Children's Hospital.The embryology of the anorectal region is reviewed. The malformations under discussion are believed to represent arrests or aberrations in development of the anus or rectum in the seventh or eighth week of fetal life.The cases are classified into four groups which had the following characteristics: (1) Stenosis of the anus; (2) membranous obstruction of the anus; (3) imperforate anus, but with separation of the rectum from the anus; (4) anus and anal canal normal, but separation of the rectum from the anal pouch. The external anal sphincter muscle was present in all four types. Associated with these anal and rectal obstructions there were fistulae in 52 per cent of the patients, connecting the rectum with the bladder, urethra, vagina, fossa navicularis, or the perineum.The symptoms and physical signs were essentially those of acute bowel obstruction when there was an imperforate anus or atresia of the rectum. In those cases of anal stenosis or in those instances of rectal atresia in which there was a large associated fistula, there was less evidence of intestinal obstruction. Fistulae with the urinary tract were manifested by the presence of urinary infection or by the passage of fecal material and flatus through the urethra.X-ray examination was a valuable aid in determining the distal extent of the rectal pouch in cases of imperforate anus or rectal atresia. This could be readily accomplished by taking a flat plate with the baby in the inverted position, thus allowing gas to outline the rectum. Due to the fact that some time was required for gas to reach the lower intestinal tract, the method was not wholly reliable in the first fifteen to twenty hours of life.The essential in treatment of these rectal and anal abnormalities was to establish a continuity of epithelium between the rectum and skin and thus prevent scar formation with constriction. To provide adequate anal control, the external sphincter muscle was always employed. In the stenoses (Type 1) repeated dilatations were usually all that was necessary, but when the anal canal was unyielding, it had to be excised and the rectal mucosa brought down to cover the defect. In the membranous imperforate anus (Type 2) simple cruciate incision and dilatations sufficed. The rectal atresias (Types 3 and 4) were treated by a perineal operation (when the pouch was low enough) and the rectum was brought down to the skin through the anal sphincter muscle. When the pouch was high and prohibited a successful perineal operation, a colostomy was resorted to. In Type 3 atresias 86 per cent of the cases were amenable to treatment by the perineal approach. In Type 4 atresias, 66 per cent of the cases were amenable to treatment by the perineal operation.There were 43 deaths in the series, giving a mortality of 26 per cent. At least 12 of these deaths were directly due to other associated congenital abnormalities, leaving an expected mortality rate of about 19 per cent for anorectal abnormalities and their complications. By groups the mortality rates were: Type 1, 9.5 per cent; Type 2, 16.6 per cent; Type 3, 24.8 per cent; Type 4, 61.6 per cent.The lower fistulae (rectoperineal, rectofossa navicularis, and rectovaginal) were relatively easy to close when the rectal obstruction was corrected in the first few days of life. The higher fistulae (rectourethral and rectovesical), however, were very difficult to reach through a perineal incision in a newborn infant, hence it was found best to delay treatment of such communications until the patient attained an age of eight or nine years.