Imperforate anus is the absence of a normal anal opening.
The diagnosis is usually made shortly after birth by a routine physical examination. Imperforate anus occurs in about 1 in 5000 births and its cause is unknown. Children who have imperforate anus may also have other congenital anomalies. The incidence of kidney and bladder problems increases with the severity of the imperforate anus, ranging from 5 to 20 percent with low lesions up to 60 to 90 percent with high lesions. While some of these anomalies may be noted on physical examination, others require further diagnostic tests.