Budd-Chiari syndrome is a rare medical condition characterized by the obstruction of blood flow from the liver, typically due to the blockage or narrowing of the hepatic veins. As blood backs up, the liver grows larger, leading to liver damage, portal hypertension, cirrhosis, and other complications. It can result from various causes, including sickle cell disease, blood and bone marrow diseases, blood cancer, inflammatory bowel disease, and pregnancy.