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There are two forms of the Coombs' test: direct and indirect.
The direct Coombs' test is used to detect autoantibodies on the surface of red blood cells. Many diseases and drugs (quinidine, methyldopa, and procainamide) can lead to production of these antibodies. These antibodies sometimes destroy red blood cells and cause anemia
. This test is sometimes performed to diagnose the cause of anemia or jaundice
The indirect test looks for anti-RBC antibodies that flow freely in blood serum, which is the clear yellowish fluid left after red blood cells and clotting materials are removed. The indirect Coombs' test is only rarely used to diagnose a medical condition. More frequently, it is used to determine whether a person might have a reaction to a blood transfusion.
Erythroblastosis fetalis develops in an unborn infant because the mother produces antibodies
that attack the fetus' red blood cells. This happens when the mom and the baby have different blood types. The most common form is called is ABO incompatibility, which can vary in its severity. The less common form is called Rh incompatibility
, which more often causes a very severe anemia in the baby.
The severity of this condition can vary widely. In some instances, the baby has no symptoms of the disease. In other cases, it can lead to death of the baby before or shortly after birth. It can be treated in utero (before birth) by intrauterine
When the child is born, signs may include an enlarged liver
or spleen, generalized edema
, and anemia
. After birth, depending on the severity, a transfusion
usually needs to be performed.
The most severe form of this disease, Rh incompatibility, can be prevented if the mother takes a medicine called RhoGAM at certain times during and after pregnancy. If you have had a baby with this disease, be sure to talk with your doctor if you plan on having another baby.