Anal atresia, also known as imperforate anus, is a birth defect characterized by a malformed rectum. The cause of an imperforate anus is unknown. There are several forms of imperforate anus, including low lesion (the colon is near the skin with a narrow or missing anus), high lesion (the colon is high in the pelvis with a fistula (small connection to the rectum, bladder, urethra and/or the vagina), and a persistent cloaca (a single channel connecting the rectum, urinary tract and/or vagina).
Symptoms of an imperforate anus vary depending on whether or not the condition is high lesion, characterized by constipation and a loss of control of bowel function, or low lesion, characterized by effective bowel control and possible constipation. An imperforate anus is usually diagnosed at birth and is often accompanied by additional birth defects. Ultrasounds are used to determine additional defects and immediate surgery may be necessary. Treatment of a low lesion imperforate anus includes closure of any fistulae, creation of an opening for stool passage and repositioning the rectal pouch. A colostomy is often used to treat a high lesion imperforate anus. Normal recovery for treatment of an imperforate anus includes a hospital stay of a few days.