A bleeding disorder is a condition that affects the way your blood normally clots. The clotting process, also known as coagulation, changes blood from a liquid to a solid. When you’re injured, your blood normally begins to clot to prevent a massive loss of blood. Sometimes, certain conditions prevent blood from clotting properly, which can result in heavy or prolonged bleeding. Bleeding disorders can cause abnormal bleeding both outside and inside the body. Some disorders can drastically increase the amount of blood leaving your body. Others cause bleeding to occur under the skin or in vital organs, such as the brain. Bleeding disorders often develop when the blood can’t clot properly. For blood to clot, your body needs blood proteins called clotting factors and blood cells called platelets. Normally, platelets clump together to form a plug at the site of a damaged or injured blood vessel.