Bleeding or clotting disorders that cause bruising

When you cut or injure yourself, your body uses special blood cells, called platelets, and other chemicals, called clotting factors, to form a blood clot and control your bleeding. Bleeding disorders sometimes occur when the platelets or clotting factors are not working properly and do not form clots. Common bleeding or clotting disorders include:

• Disseminated intravascular coagulation (DIC), a condition that comes on quickly. Small blood clots form and move through the bloodstream, blocking small blood vessels and using up the clotting factors that are needed to stop bleeding. Emergency treatment is needed to stop bleeding and save the person's life.
• Idiopathic thrombocytopenic purpura (ITP, also known as primary or autoimmune thrombocytopenic purpura), a disorder in which a low platelet count causes abnormal bleeding. The cause of ITP in adults is not known. In children, ITP may be an autoimmune disease that is triggered by a viral infection. Symptoms include red spots on the skin, unexplained bruises, bleeding from the gums and nose, and blood in the stool. The condition may appear suddenly or gradually.
• Thrombocytopenic purpura, a rare disorder in which small blood clots form throughout the body, leading to a sharp drop in the number of platelets and red blood cells. Symptoms develop suddenly and include fever, bruising, abdominal pain, blood in the urine, and an irregular heartbeat. A person who has symptoms of thrombocytopenic purpura needs emergency treatment.
• Hemolytic uremic syndrome, a serious and often fatal disorder in which the number of platelets suddenly drops, red blood cells are destroyed, and the kidneys stop working. The cause is not known, but the syndrome may be triggered by a bacterial infection or medication use.
• Henoch-Schonlein purpura, also known as allergic purpura, an uncommon inflammatory disease of the small blood vessels that most often affects children. The cause is not known, but it may be the result of an autoimmune disease or a severe allergic reaction. Symptoms may include sudden headache, fever, loss of appetite, abdominal cramping, joint pain, and bruising. Abnormal bruising is most often seen in the lower legs.