IMPERFORATE ANUS REPAIR

Imperforate anus : Routine inspection of a newborn should note the position and patency of the anus. Anorectal malformations range from slight anterior displacement of the anal opening to a completely imperforate anus. Many children with imperforate anus have an abnormal sacral progression as well as internal fistulas between the rectum and the genitourinary structures. All children with an anorectal malformation are predisposed to constipation. A newborn with imperforate anus should undergo plain radiography 12-24 hours after birth to assess the distal extent of bowel gas.

Preoperative workup for imperforate anus is focused on the proximity of the distal rectum to the anal skin and sphincter complex. Lateral radiography with the child in a prone position, invertography, may be helpful in classifying the imperforate anus. Many newborns with imperforate anus have a fistulous tract to the skin or genitourinary system. Low lesions that have a fistulous connection between perianal or perineal body skin and rectum may be primarily repaired with a perineal anoplasty. If the distal rectum is several centimeters above the anal skin or has a fistula to the vagina or urinary bladder, the imperforate anus is classified as intermediate or high. In intermediate or high imperforate anus, colostomy is performed in the newborn period.

Following colostomy for intermediate or high imperforate anus, the infant undergoes a staged repair of the imperforate anus to pull down the rectum into the center of the anal sphincter complex. Continence has been achieved with both anterior and posterior approaches. Currently, the most widely performed procedure is a posterior sagittal anorectoplasty as described by Pena in 1998. Outcome is dependent upon the precision of the surgery, the severity of the sacral and perineal musculature anomaly, and the degree of colonic dysmotility.

Anorectal malformations are part of the VACTERL (vertebral, anal, cardiac, tracheal, esophageal, renal, limb) association of congenital anomalies. Diagnosis of an anorectal malformation requires an investigation for other associated midline anomalies. Cardiac echocardiography, renal and sacral ultrasonography, and plain radiography of the vertebrae and radii are recommended. Because esophageal atresia with tracheoesophageal fistula is part of the VACTERL spectrum, any infant with imperforate anus and respiratory distress should undergo full airway evaluation.