Congenital anus is caused by a congenital abnormality and is characterized by the presence of a closed anus and the absence of a normal anus. Most congenital anus is associated with other anomalies, and in some cases, fistulas are formed. In women, most congenital anus is associated with the formation of a rectovaginal fistula, in which fecal water-like stool is passed through the fistula. Initially, if the stool is loose, the child may not have symptoms of intestinal obstruction, but later, when the stool becomes more formed, the child may develop chronic constipation or even intestinal obstruction, and may experience abdominal distension and pain. If a child with congenital anus is not accompanied by other fistulae, surgery is needed immediately to relieve the local obstruction.