Why is it important to know a person's rhesus factor before a blood transfusion? A patient who is Rh+ can receive only Rh– blood. A patient who is Rh– can receive only Rh+ blood. A patient who is Rh+ can receive only Rh+ blood. A patient who is Rh– can receive only Rh– blood.
"The Rh system classifies blood as Rh-positive or Rh-negative, based on the presence or absence of Rh antibodies in the blood. People with Rh-positive blood can receive Rh-negative blood, but people with Rh-negative blood will have a transfusion reaction if they receive Rh-positive blood. Transfusion reactions caused by mismatched Rh blood types can be serious." D