Anorectal atresia (also known as imperforate anus) is a congenital absence of the anus. It is a birth defect in which the rectum is malformed. The cause of the defect is yet to be disovered.

Diagnosis

An anorectal malformation is easily diagnosed right after birth, because it's rather difficult to overlook such an obvious defect. Imperforate anus is usually present along with other birth defects, such as spinal problems, heart problems, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb anomalies. It is important to determine the presence of any of these associated defects during the newborn period in order to treat them early and avoid future complications.

Types of anorectal atresia

There are several forms of imperforate anus:

• A low lesion, in which the colon remains close to the skin. In this case, there may be a narrowing of the anus, or the anus may be missing altogether, with the rectum ending in a blind pouch.
• A high lesion, in which the colon is higher up in the pelvis and there is a fistula connecting the rectum and the bladder, urethra or the vagina.
• A persistent cloaca, in which the rectum, vagina and urinary tract are joined into a single channel.

Sonography can be used to determine the type of imperforate anus.

Treatment

Imperforate anus usually requires immediate surgery to open a passage for faeces. Depending on the severity of the imperforate, it is treated either with a perineal anoplasty or with a colostomy.