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A blood donation occurs when a person voluntarily has blood drawn and used for transfusions and/or made into biopharmaceutical medications by a process called fractionation (separation of whole-blood components). Donation may be of whole blood (WB), or of 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 usually give blood when 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 other than money such as paid time off from work. Donors can also have blood drawn for their own future use (autologous donation). Donating is relatively safe, but some donors have bruising where the needle is inserted or may feel faint. Potential donors are evaluated for anything that might make their blood unsafe to use. The screening includes testing for diseases that can be transmitted by a blood transfusion, including HIV and viral hepatitis. The donor must also answer questions about medical history and take a short physical examination to make sure the donation is not hazardous to his or her health. How often a donor can give varies from days to months based on what he or she donates and the laws of the country where the donation takes place. For example, in the United States, donors must wait eight weeks (56 days) between whole blood donations but only seven days between platelet pheresis donations. The amount of blood drawn and the methods vary. The collection can be done manually or with automated equipment that only takes specific portions of the blood. Most of the components of blood used for transfusions have a short shelf life, and maintaining a constant supply is a persistent problem. This has led to some increased interest in autotransfusion, whereby a patient's blood is salvaged during surgery for continuous reinfusion — or alternatively, is "self-donated" ''prior'' to when it will be needed. (Generally, the notion of "donation" does not refer to giving to one's ''self'', though in this context it has become somewhat acceptably idiomatic.) == Types of donation == Blood donations are divided into groups based on who will receive the collected blood.〔M. E. Brecher, Editor (2005), ''AABB Technical Manual'', 15th edition, Bethesda, MD: AABB, ISBN 1-56395-196-7, p.98-103〕 An 'allogeneic' (also called 'homologous') donation is when a donor gives blood for storage at a blood bank for transfusion to an unknown recipient. A 'directed' donation is when a person, often a family member, donates blood for transfusion to a specific individual. Directed donations are relatively rare when an established supply exists. A 'replacement donor' donation is a hybrid of the two and is common in developing countries such as Ghana.〔T. Brown "Strengthening Blood Systems In Africa: Progress Under PEPFAR and Remaining Challenges" ''AABB News''. April, 1998:page 30〕 In this case, a friend or family member of the recipient donates blood to replace the stored blood used in a transfusion, ensuring a consistent supply. When a person has blood stored that will be transfused back to the donor at a later date, usually after surgery, that is called an 'autologous' donation.〔(【引用サイトリンク】title=Autologous (self-donated) Blood as an Alternative to Allogeneic (donor-donated) Blood Transfusion )〕 Blood that is used to make medications can be made from allogeneic donations or from donations exclusively used for manufacturing.〔(【引用サイトリンク】title=Recovered Plasma )〕 Blood is sometimes collected using similar methods for therapeutic phlebotomy, similar to the ancient practice of bloodletting, which is used to treat conditions such as hereditary hemochromatosis or polycythemia vera. This blood is sometimes treated as a blood donation, but may be immediately discarded if it cannot be used for transfusion or further manufacturing. The actual process varies according to the laws of the country, and recommendations to donors vary according to the collecting organization.〔(【引用サイトリンク】 title=The Donation Experience )〕〔(【引用サイトリンク】 title=Tips for a Good Donation Experience )〕 The World Health Organization gives recommendations for blood donation policies,〔(【引用サイトリンク】WHO Blood Safety and Donation )〕 but in developing countries many of these are not followed. For example, the recommended testing requires laboratory facilities, trained staff, and specialized reagents, all of which may not be available or too expensive in developing countries.〔(【引用サイトリンク】title= World Blood Donor Day 2006 )〕 An event where donors come to donate allogeneic blood is sometimes called a 'blood drive' or a 'blood donor session'. These can occur at a blood bank, but they are often set up at a location in the community such as a shopping center, workplace, school, or house of worship.〔(【引用サイトリンク】title=Sponsoring a Blood Drive )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「blood donation」の詳細全文を読む スポンサード リンク
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