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Atresia (ah-TREE-zhah) is a condition in which a baby is born with a missing or closed valve or tube somewhere in his or her body.

Anal atresia (imperforate anus) is a defect of the digestive tract in which the opening to the anus is missing or blocked.

More to Know

Air, blood, bodily fluids, and waste products travel throughout the body in a system of vessels, tubes, and chambers that are often separated by valves. When a child is born with atresia, it means that a valve is missing or a tube is closed off. This interrupts the normal flow of blood, fluid, waste, or air, which can lead to a number of complications.

Most kinds of atresia are serious and can be fatal if they go untreated. Treatment usually involves surgery while the child is still an infant.

Atresia can affect many body parts, including the nose, ears, organs, digestive tract, and heart. The types of atresia are named for the body parts they affect:

• Esophageal atresia is another defect of the digestive tract.
• Biliary atresia is a defect in the liver or bile system.
• Choanal atresia is a defect of the nasal passages (choana).
• Tricuspid atresia, pulmonary atresia, and aortic atresia involve valves in the heart.

Keep in Mind

Most kinds of atresia can be treated successfully with surgery; some cases may require more than one operation.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.