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1.
O-
One of the rarest forms of blood type among humans. A Universal donor.

O Negative
Blood type is very important because it can potentially be transfused to any patient regardless of their blood type. In emergency situations, when there isn’t enough time to determine a patient’s blood type, O negative blood is often used.

Best blood type to donate:
O +, O - (i.e. Son), B-, A- (i.e. ME) RH-
Only about 7% of all people have Type O negative blood
Type O negative blood is the preferred type for accident victims and babies needing exchange transfusions
There is always a need for Type O donors because their blood may be transfused to a person of any blood type in an emergency
O- is Universal donation for the masses. What is yours?
by KWatlonTyUniverseal April 18, 2010