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. Aortic atresia is a rare defect that involves valves in the heart. 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: Tricuspid atresia and pulmonary atresia also involve valves in the heart. Choanal atresia is a defect of the nasal passages (choana). Biliary atresia is a defect in the liver or bile system. Anal atresia (imperforate anus) and esophageal atresia are defects of the digestive tract. 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. Back to Articles Related Articles When Your Baby Has a Birth Defect If your child has a birth defect, you don't have to go it alone - many people and resources are available to help you. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.