Anorectal developmental anomalies

Abstract

Anorectal malformations include a wide range of conditions that can affect both sexes and involve the distal anus and rectum, as well as the urinary and genital tracts. An imperforate anus is a common birth defect that results from defects or delays in the development of the hindgut. The diagnosis of nonperforation of the anus is usually made shortly after birth through a routine medical examination. Patients have the best chance for a good functional outcome if the disease is diagnosed early and effective anatomic repair is started immediately. Most malformations in girls can only be correctly diagnosed on physical examination. An anus visible in the perineum with a normal vagina and urethra suggests a perineal fistula. A rectovestibular fistula occurs when the opening is in the posterior vestibule and beyond the hymen. If only one opening is visible between the labia, it is very likely a cloaca. Rectovaginal fistulae may initially appear as a non-perforating anus without a fistula (a normal-looking vagina and urethra, but no visible anus). Close examination usually reveals the presence of an opening in the back wall of the vagina or inside the hymenal ring. Radiological evaluation of a newborn with non-perforated anus should include abdominal ultrasound, using it to detect urological abnormalities. Sepsis, aspiration, abdominal distention, colonic perforation, respiratory distress, electrolyte imbalance are complications that can result from delayed diagnostic and therapeutic treatment of anorectal malforations. Accurate preoperative identification of an internal fistula between the distal part of the genitourinary tract is very important for optimal surgical treatment and prevention of possible damage to the genitourinary tract. Staged surgery, the most common approach for treating anorectal malformations, consists of three operations: a colostomy at birth, a definitive operation at 2–3 months of age, and closure of the colostomy at approximately 6 months of age.