Anus, Imperforate

**Definition:** A congenital abnormality characterized by the persistence of the anal membrane, resulting in a thin membrane covering the normal ANAL CANAL. Imperforation is not always complete and is treated by surgery in infancy. This defect is often associated with NEURAL TUBE DEFECTS; MENTAL RETARDATION; and DOWN SYNDROME.

**Tree numbers:** - C06.198.050 - C16.131.314.094

**Synonyms:** - Anal Atresia - Atresia, Anal