Coombs Test During Pregnancy

Submitted by Nick on October 19, 2012

The Coombs test is an antibody test that is used to detect the presence of antibodies that attack the red blood cells in your system. Antibodies are basically proteins produced by your body’s immune system. These are a natural defense against infections in the body. Under normal circumstances these antibodies attack harmful bacteria and viruses, but certain diseases and autoimmune conditions cause the antibodies to attack healthy cells.

There are two types of coombs test, the direct coombs test and the indirect coombs test. The direct Coombs test looks for antibodies attached to red blood corpuscles, which could be those produced naturally to fight off disease or those received in a blood transfusion. More relevant to the connection of coombs test and pregnancy tests would be the use of the test on newborn babies with Rh positive blood, when the mother has Rh negative blood. The test helps reveal if the mother’s immune system has produced antibodies, and if they have travelled to the placenta, reaching the baby. Rh is an antigen and its full name is Rhesus factor. If sensitization occurs and these antibodies start to destroy the red blood cells of the baby before or after birth it could create severe problems.

The indirect Coombs test helps in the detection of antibodies present in blood serum, which can attack red blood corpuscles, but are unattached to any red blood corpuscles. This test is done early in the pregnancy and is extremely useful as it helps determine whether the mother has Rh positive or negative blood. If the results find it to be Rh negative then preventive action can be taken to protect the baby.

Rh sensitization occurs if there is a mix of the mother’s and baby’s blood either during delivery. This gives rise to a problem in future pregnancies as it causes the mother’s immune system to attack the baby’s red blood cells with antibodies. This response is termed as Rh sensitization and the effects of red blood cell destruction may occur before or after birth. In instances where sensitization does occur the fetus or newborn may develop problems that can vary in severity, from mild to serious and the condition is termed as Rh disease or Rhesus disease.

Most Rh diseases can in fact be prevented by providing the mother with prompt treatment during the pregnancy or within 72 hours of delivery. A Coombs test is therefore an important antibody test that helps in detection and treatment of the condition.

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