Some babies are born with malformations of the anus, rectum, or both. There are several general types. They have varying degrees of severity and are treated with surgery. These malformations are often specific to boys and girls. The malformation can come in the form of an absence of an opening where the anus should be; a fistula, or small opening from the rectum to the urinary tract or to the vagina; and many variations from these general categories. Depending on the exact nature and severity of the malformation, babies may be left completely continent, with full control over their bowel movements; partially continent; or incontinent. In general, surgeons will close the fistula and, in the case of a missing anus, create an opening and gently pull though the bottom of the bowel, creating a new anus.