What blood type is the universal recipient?
AB positive (AB+) is the universal recipient for red blood cells, as individuals with this type can receive blood from all eight blood types (O+, O−, A+, A−, B+, B−, AB+, AB−). This is because AB+ red cells carry all major antigens and the body does not produce antibodies against them.
Can a person with Rh negative blood receive Rh positive blood?
No — an Rh− recipient should not receive Rh+ blood. Their immune system may produce anti-Rh antibodies, which can cause a serious hemolytic transfusion reaction, especially upon a second exposure. This is particularly important for Rh− women of childbearing age.
What happens if incompatible blood is transfused?
An incompatible transfusion triggers a hemolytic transfusion reaction, where the recipient's immune system attacks and destroys the donated red blood cells. Symptoms range from fever and back pain to kidney failure and, in severe cases, death. This is why blood typing and crossmatching are performed before every transfusion. You might also find our Serum Osmolality Calculator useful.
What blood type will my baby have?
A baby's blood type is determined by the ABO and Rh genes inherited from each parent. For example, if both parents are O, the child will always be O. If both parents are B, the child can be B or O. Rh factor is inherited independently — an Rh+ parent carrying one Rh− gene has a 50% chance of passing the Rh− gene to the child.
Can a child have a different blood type than both parents?
Yes, this is possible. For example, two parents who are both A or both B can have an O-type child if each parent carries an O allele alongside their dominant allele. Blood type genetics follow Mendelian inheritance, so recessive alleles may be hidden in parents but expressed in children.
What are the rarest blood types?
AB negative (AB−) is the rarest blood type, found in roughly 1% of the population. Other relatively rare types include B− (~2%) and A− (~6%). Blood type frequency also varies significantly by ethnicity and region.
Is blood type compatibility the same for plasma and platelets as for red cells?
Not exactly. For plasma transfusions, compatibility rules are reversed — AB plasma is the universal donor plasma. For platelet transfusions, ABO compatibility is preferred but not always strictly required, depending on clinical circumstances. This calculator focuses on red cell (whole blood) compatibility.