14 March 2019 They are named by looking at the ABO classification (A, B, AB and O blood) and the presence of the rhesus factor (Rh+ and Rh-). What are the different blood types? Blood types classified according to the ABO system have the following characteristics: Type A - has A antigens in the red blood cells and anti-B antibodies in plasma; Type B - has B antigens in the red blood cells and anti-A antibodies in plasma; Type AB - has A and B antigens in the red blood cells and no antibodies in plasma; Type O - has no antigens in the red blood cells and anti-A and anti-B antibodies in plasma. The rhesus factor or antigen may or may not be present in red blood cells. Therefore, blood may be: Rh+ or Rhesus positive; Rh- or rhesus negative. So, taking ABO classification and the presence of the rhesus factor into account, blood types can be: A Rh+ (or A+); A Rh- (or A-); B Rh+ (or B+); B Rh- (or B-); AB Rh+ (or AB+); AB Rh- (or AB-); O Rh+ (or O+); O Rh- (or O-). Are all blood types compatible? Not all blood types are compatible with one other. Therefore, it is important that everybody knows what their blood group is and the significance of blood type in transfusions. What are the general rules for transfusions? Blood types classified according to the ABO system have the following specific characteristics and consequences with regard to transfusions: People with type A blood may only receive type A and type O blood; People with type B blood may only receive type B and type O blood; People with type AB blood may receive types A, B, AB and O blood; People with blood type O can only receive type O blood. Because people who have type AB blood can receive any of the other types, they are called universal recipients . Because people who have type O blood can donate blood to any of the other types, they are called universal donors . The consequences of the presence of the rhesus factor on the compatibility of blood used in transfusions are: People with Rh+ blood can only receive Rh+ blood; People with Rh- blood can only receive Rh- blood. This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
