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. Biliary atresia, a defect in the liver or bile system, means the ducts that carry bile from the liver to the gallbladder are blocked. This can lead to liver damage and cirrhosis of the liver. 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: Choanal atresia is a defect of the nasal passages (choana). Anal atresia (imperforate anus) and esophageal atresia are defects of the digestive tract. 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. Back to Articles Related Articles A to Z: Jaundice Learn about jaundice, when the skin and whites of the eyes appear yellow due to excess bilirubin in the blood. Read More A to Z: Cholangitis Learn more about infections and problems of the liver and biliary tract. Read More When Your Child Needs a Liver Transplant If your child needs a liver transplant, you're probably feeling lots of emotions. Fortunately, most kids who have liver transplants go on to live normal, healthy lives. Read More Ultrasound: Abdomen Doctors order abdominal ultrasounds when they're concerned about symptoms such as abdominal pain, repeated vomiting, abnormal liver or kidney function tests, or a swollen belly. Read More X-Ray Exam: Abdomen An abdominal X-ray can help find the cause of many abdominal problems, such as pain, kidney stones, intestinal blockage, a hole in the intestine, or an abdominal mass such as a tumor. 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.