Blood Basics To determine a person’s blood type, we add three different serums to blood samples and see if clumps form. Anti-A goes in the A well. Anti-B goes in the B well. Anti-Rh goes in the Rh well. Clumps = Positive (+) No Clumps = Negative (-) What would the blood type be for this sample? Add the 2 drops of blood and 3 drops of serum to the appropriate wells. Who:____________________________