Coombs test

What is a Coombs Test?

A Coombs Test is a laboratory test used to detect and measure antibodies attached to the surface of red blood cells. It is used to detect autoimmune hemolytic anemia, to determine the cause of a newborn's anemia, and to identify which red cell antigens might be causing a reaction in someone receiving a blood transfusion.

Types

There are two types of Coombs tests: direct and indirect. A direct Coombs test detects the presence of antibodies that are already attached to the red blood cells. An indirect Coombs test can detect the presence of antibodies that may be circulating in the blood, even if they are not attached to any red blood cells.

Preparation

No special preparation is needed before undergoing a Coombs test. If the test is being conducted on a patient already in the hospital, a care provider or doctor may order additional blood tests to check for other matters that may be interfering with the Coombs test results.

Procedure

A blood sample is taken from the patient and placed into a tube containing a special preservative. The tube is then sent to the lab for analysis. The lab techs use a microscope to examine the cells for any antibodies attached to the surface of the red blood cells.

Risks

A Coombs test is a low-risk procedure, and there are no serious side effects to expect.

Why it’s Done?

A Coombs test is done to diagnose conditions like autoimmune hemolytic anemia, in which the body produces antibodies that target and attach to red blood cells, destroying them prematurely. It is also used to determine the cause of a newborn’s anemia and to identify which red cell antigens might be causing a reaction in someone receiving a blood transfusion.

When it’s Done?

A Coombs test is typically ordered by a doctor when a patient is showing signs of anemia, such as fatigue, shortness of breath, and paleness of the skin. It may also be ordered if a patient is receiving a blood transfusion and exhibiting signs of an allergic reaction.