What does a positive result in an indirect Coombs test indicate?

A positive result in an indirect Coombs test indicates the presence of unbound Rh antibodies in the serum. This test is primarily used during pregnancy or prior to blood transfusions to assess for the presence of antibodies that could lead to hemolytic disease. In the context of pregnancy, for example, if a mother is Rh-negative and her blood is tested, a positive result would suggest that she has developed antibodies against Rh-positive blood cells, which could pose a risk if the fetus is Rh-positive.

Understanding this is crucial for clinical decisions, such as monitoring the pregnancy for potential complications like anemia or jaundice in the newborn, due to the mother’s immune response against the fetal blood cells. The indirect Coombs test is an important diagnostic tool to ensure safe transfusions and manage pregnancies effectively, particularly for Rh incompatibility scenarios.