Plateletpheresis: In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the platelets and returns the rest of the blood to the donor. Because donors get most of their blood back, they can safely give 8 to 10 times as many platelets during one of these procedures as they would give in a single donation of whole blood. Collecting platelets from a donor takes about 1 to 2 hours, compared with collecting whole blood, which takes about 10 minutes.

Autologous transfusion: In an autologous transfusion, donors are recipients of their own blood. For example, in the weeks before undergoing elective surgery, a person may donate several units of blood to be transfused if needed during or after the surgical procedure. The person takes iron pills after donating the blood to help the body replenish the lost blood cells before surgery. Also, during some types of surgery and in certain kinds of injuries, blood that is lost can be collected and immediately given back to the person (intraoperative blood salvage). An autologous transfusion eliminates the risks of incompatibility and blood-borne disease (unless the wrong blood is given by mistake). However, doctors do not use this technique as often as standard transfusion because the general blood supply is very safe due to rigorous donor screeing and testing. In addition, elderly patients may not tolerate donating blood before surgery because they are more likely to have side effects during donation such as low blood pressure and fainting. They are also more likely to have a low blood count to begin with. Also, autologous transfusion is somewhat more expensive than standard transfusion.

Controlling Diseases by Purifying the Blood
In apheresis, blood is removed from a person and then returned after fluid, substances in the fluid, blood cells, or platelets are selectively removed or reduced in quantity. Sometimes this process is used to obtain needed blood cells or platelets from a donor (for example, stem cell pheresis, granulocyte apheresis, or plateletpheresis). This process is also used to purify blood by removing harmful substances or excessive numbers of blood cells or platelets in people with serious illnesses who have not responded to other treatments. To be helpful for purifying blood, apheresis must remove the undesirable substance or blood cell faster than the body produces it. The two most common types of apheresis that are used to purify blood are plasma exchange and cytapheresis. In plasma exchange, the person's blood is removed, and the plasma is separated from the blood cells and platelets. The plasma is discarded and the blood cells and platelets are returned to the person along with a plasma-replacing fluid, such as albumin. Plasma exchange is used to treat such disorders as multiple sclerosis, myasthenia gravis and Guillain-Barré syndrome (neurologic disorders that cause muscle weakness), Goodpasture syndrome (an autoimmune disorder involving bleeding in the lungs and kidney failure), cryoglobulinemia (a type of abnormal antibody formation), and thrombotic thrombocytopenic purpura (a rare clotting disorder). In cytapheresis, excess numbers of certain blood cells are removed. Cytapheresis can be used to treat polycythemia (an excess of red blood cells), sickle cell anemia (a disorder in which red blood cells are abnormally shaped), certain types of leukemia (a type of cancer in which there are excess white blood cells), and thrombocythemia (an excess of platelets). Apheresis is repeated only as often as necessary because the large fluid shifts between blood vessels and tissues that occur as blood is removed and returned may cause complications in people who are already ill. Apheresis can help control some diseases but generally does not cure them. However, thrombotic thrombocytopenic purpura can be cured with apheresis.

Directed or designated donation: Family members or friends can donate blood specifically for one another if the recipient's and donor's blood types and Rh factors are compatible. For some recipients, knowing who donated the blood is comforting, although a donation from a family member or friend is not necessarily safer than one from an unrelated person. Blood from a family member is tested as are all blood samples and then treated with radiation to prevent graft-versus-host disease, which, although rare, occurs more often when the recipient and donor are related.

Hematopoietic stem cell apheresis: In hematopoietic stem cell apheresis, a donor gives only hematopoietic stem cells (undifferentiated cells that can develop into any type of blood cell) rather than whole blood. Before the donation procedure, the donor receives an injection of a special type of protein (growth factor) that stimulates the bone marrow to release stem cells into the bloodstream. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the hematopoietic stem cells and returns the rest of the blood to the donor. Stem cell donors and recipients must have compatible leukocyte types (human leukocyte antigen, or HLA), a type of protein found on certain cells, rather than blood type. Hematopoietic stem cells are sometimes used to treat people with leukemia, lymphoma, or other cancers of the blood. This procedure is called stem cell transplantation. The recipient's own stem cells can be obtained, or donated stem cells can be given.

Last full review/revision October 2012 by Ravindra Sarode, MD