is a rare disorder characterized by narrowing and obstruction of the veins of the liver. This narrowing or obstruction slows or prevents blood from flowing out of the liver and back to the heart which can lead to liver damage. While some people experience no symptoms, many experience fatigue, abdominal pain, nausea, and jaundice. Other associated findings include an accumulation of fluid in the abdomen (ascites), an enlarged spleen and/or liver, and severe bleeding in the esophagus. The severity of the disorder varies from case to case, depending on the site and number of affected veins. Drugs may be used to dissolve or decrease the size of the obstruction (if it is a clot). In some cases surgery is performed. In most cases, the cause of Budd-Chiari syndrome is unknown. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.