What is this test?
This laboratory test is performed on a blood sample to detect antibodies or anti-globulins that are reactive against red blood cells. This is an abnormal function of antibodies. Normally, antibodies are proteins that react against harmful objects in the body. Indirect Coombs test detects the antibodies circulating freely in the liquid part of blood called serum.
Why is this test performed?
This test is performed:
- To determine the safety of blood transfusion
- As a part of routine pregnancy lab tests
- After the delivery if the baby is determined to be Rh-positive.
- What is the difference between direct and indirect coombs test?
There are two types of coombs test:
- Direct coombs test
- Indirect coombs test
Direct coombs test detects the presence of antibodies reactive against RBCs stuck to the surface of RBCs while indirect coombs test detects the presence of antibodies roaming freely in the serum.
- How to prepare for this test?
No special preparations are required for this test. However, inform your doctor about your complete medical history.
- What are the risks of this test?
Collecting blood from a vein is a very easy procedure and pose only minimum risk, including:
- Bruising
- Bleeding
- Infection
- What happens if the fetus is Rh-positive?
If an Rh-negative mother is pregnant with an Rh-positive fetus, the mother can become sensitized to Rh-negative blood and produce antibodies against it when exposed. These antibodies attack the RBCs of the fetus.
- How to prevent Rh-sensitization?
Rh-sensitization can be prevented by ordering an indirect coombs test at the 28th week of pregnancy to know the status of sensitization. If the mother is not sensitized, an Rh immune globin injection is administered to prevent the complications from sensitization.
Interpretation of test results:
- Negative: A negative indirect coombs test means that there are no antibodies harmful to RBCs in the serum. You can safely get blood from the donor and there are no risks to the unborn child.
- Positive: A positive indirect coombs test means that your blood is incompatible with the donor’s blood. If the Rh-antibody titer test is positive in pregnant females it means she has antibodies against Rh-positive blood, close monitoring is required in fetus with Rh-positive blood to prevent problems to the red blood cells.