Blood donation and will screen for antibodies to less common antigens. More testing, including a crossmatch, is usually done before a transfusion. Type O negative is often cited as the "universal donor" but this only refers to red cell and whole blood transfusions. For plasma and platelet transfusions the system is reversed: AB positive is the universal platelet donor type while both AB positive and AB negative are universal plasma donor types. Most blood is tested for diseases, including some STDs. The tests used are high-sensitivity screening tests and no actual diagnosis is made. Some of the test results are later found
Jehovah's Witnesses and blood transfusions eating blood to prohibit the medical transfusion of human blood. Osamu Muramoto has argued that the refusal by Jehovah's Witnesses of "life-saving" blood treatment creates serious bio-medical ethical issues. He has criticized the "controlling intervention" of the Watch Tower Society by means of what he claims is information control and its policy of penalising members who accept blood transfusions or advocate freedom to choose blood-based treatment. He says the threat of being classified as a disassociated Witness and subsequently shunned by friends and relatives who are members coerces Jehovah's Witnesses to accept and obey the prohibition on blood transfusions. In