Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening blood disorder in which the blood cells that play a key role in blood clotting (platelets) are rapidly consumed by excessive clotting. In medical terms, "thrombotic" means the tendency to form blood clots, "thrombobytopenic" means a low count of platelets, and "purpura" describes skin discolorations caused by a bleeding condition. Thus, TTP is a state of reduced platelets caused by the formation of blood clots that can result in skin discoloration.

At one time, TTP was almost always fatal. More than 90 percent of patients who suffered from the condition died. However, due to new treatment techniques, more than 90 percent of people who suffer from TPP now survive. The standard treatment for TTP is called plasma exchange. In this procedure, plasma transfusions are coupled with removal of the platelets from the blood. After several days of this treatment, signs and symptoms should improve.