Plateletpheresis (more accurately called thrombocytapheresis or thrombapheresis, though these names are rarely used) is the process of collecting thrombocytes, more commonly called platelets, a component of blood involved in blood clotting. The term specifically refers to the method of collecting the platelets, which is performed by a device used in blood donation that separates the platelets and returns other portions of the blood to the donor. Platelet transfusion can be a life-saving procedure in preventing or treating serious complications from bleeding and hemorrhage in patients who have disorders manifesting as thrombocytopenia (low platelet count) or platelet dysfunction. This process may also be used therapeutically to treat disorders resulting in extraordinarily high platelet counts such as essential thrombocytosis. Platelet transfusion Platelet transfusions are traditionally given to those undergoing chemotherapy for leukemia, multiple myeloma, those with aplastic anemia, AIDS, hypersplenism, idiopathic thrombocytopenic purpura (ITP), sepsis, bone marrow transplant, radiation treatment, organ transplant or surgeries such as cardiopulmonary bypass. Platelet transfusions should be avoided in those with thrombotic thrombocytopenic purpura (TTP) because it can worsen neurologic symptoms and acute renal failure, presumably due to creation of new thrombi as the platelets are consumed. It should also be avoided in those with heparin-induced thrombocytopenia (HIT) or disseminated intravascular coagulation (DIC). In adults, platelets are recommended in those who have levels less than 10,000/µL, or less than 20,000/µL if a central venous catheter is being placed, or less than 50,000/µL if a lumbar puncture or major surgery is required. Whole blood platelets Not all platelet transfusions use platelets collected by automated apheresis. The platelets can also be separated from donations of whole blood collected in a traditional blood donation, but there are several advantages to separating the platelets at the time of collection. The first advantage is that the whole-blood platelets, sometimes called "random" platelets, from a single donation are not numerous enough for a dose to give to an adult patient. They must be pooled from several donors to create a single transfusion, and this complicates processing and increases the risk of diseases that can be spread in transfused blood, such as human immunodeficiency virus. Collecting the platelets from a single donor also simplifies human leukocyte antigen (HLA) matching, which improves the chance of a successful transfusion. Since it is time-consuming to find even a single compatible donor for HLA-matched transfusions, being able to collect a full dose from a single donor is much