imperforate anus, any of several congenital developmental malformations of the anorectal portion of the GI tract. ▪ OBSERVATIONS: The most common form is anal agenesis, in which the rectal pouch ends blindly above the surface of the perineum. An anal fistula is present in 80% to 90% of cases. Other forms include anal stenosis, in which the anal aperture is small, and anal membrane atresia, in which the anal membrane covers the aperture, creating an obstruction. ▪ INTERVENTIONS: The defect is usually discovered at birth; inspection reveals absence of the anus or the presence of a thin translucent membrane covering it. Digital and endoscopic examination allows identification of the anatomical character of the malformation. Radiographic examination is performed to outline the rectal pouch. A radiopaque marker is placed at the usual site of the anus, and the infant is held upside down. Air moving through the intestines into the distal portion of the bowel or the rectum is visible on the x-ray film. Anal stenosis is treated with daily digital dilation begun in the hospital and continued at home by the parents. An imperforate anal membrane is excised, and digital dilation is performed daily as the skin heals. Surgical reconstruction is performed to treat anal agenesis in infants in whom the pouch is below the puborectalis of the levator ani; an anus is created surgically by an anoplasty. Anal atresia in which the pouch at the end of the bowel is high above the perineum may require a colostomy. ▪ PATIENT CARE CONSIDERATIONS: Often it is the nurse who identifies the anal malformation during the routine newborn assessment. A newborn who does not pass any stool in the first 24 hours requires further evaluation for the possibility of the defect. The passage of meconium from the vagina or urinary meatus clearly indicates the presence of anal fistula and usually occurs in association with an imperforate anus. Postoperative care in the newborn treated surgically for any of these conditions requires scrupulous attention to the perineal area.
