(bud-kee-AR-ee SIN-drome) A blood clot blood clot: A mass of blood that forms when platelets stick together. Harmful blood clots are more likely to happen in PNH. The term thrombus describes a blood clot that develops and attaches to a blood vessel. The term embolus describes a blood clot or other foreign matter that gets into the bloodstream and… in the major vein that leaves the liver (hepatic vein). The liver and the spleen may become enlarged. Budd-Chiari syndrome can occur in PNH.
