A blood donation occurs when a person voluntarily has blood drawn and is used for transfusions and / or converted into biopharmaceutical drugs by a process called fractionation (separation of whole blood components). The donation can be whole blood (WB), or specific components directly (the latter called apheresis). Blood banks often participate in the collection process, as well as the procedures that follow it.
Today, in the developed world, most blood donors are unpaid volunteers who donate blood for a community supply. In poorer countries, established supplies are limited and donors often give blood when their family or friends need a transfusion (directed donation). Many donors donate as an act of charity, but in countries that allow paid donation, some donors are paid and in some cases there are incentives that are not money such as paid time off from work. Donors can also draw blood for their own future use (autologous donation). The donation is relatively safe, but some donors have bruises where the needle inserts or may feel weak.
Potential donors are evaluated for anything that may make their blood not safe to use. The test includes tests for diseases that can be transmitted by a blood transfusion, including HIV and viral hepatitis. The donor should also answer questions about the medical history and make a brief physical examination to make sure the donation is not hazardous to your health. The frequency with which a donor can donate varies from days to months depending on the component they donate and the laws of the country where the donation is made. For example, in the United States, donors must wait eight weeks (56 days) for donations of whole blood, but only seven days between donations of platelets and twice for seven days in plasmapheresis.
The amount of blood drawn and methods vary. The collection can be done manually or with automated equipment taking only specific blood components. Most of the blood components used for transfusions have a short shelf life and maintaining a constant supply is a persistent problem. This has led to a greater interest in auto-transfusion, so that a patient's blood is recovered during surgery for continuous reinfusion or alternatively "self-donated" before it is needed. (In general, the notion of "giving" does not refer to giving oneself, although in this context it has become something acceptably idiomatic).