Imperforate anus may occur in several forms:
The rectum may end in a pouch that does not connect with the colon.
The rectum may have openings to other structures. These may include the urethra, bladder, base of the penis or scrotum in boys, or vagina in girls.
There may be narrowing (stenosis) of the anus or no anus.
It is caused by abnormal development of the fetus. Many forms of imperforate anus occur with other birth defects.