Coombs testDirect antiglobulin test; Indirect antiglobulin test; Anemia - hemolytic
The Coombs test looks for antibodies that may stick to your red blood cells and cause red blood cells to die too early.
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...Read Article Now Book Mark Article
How the Test is Performed
A blood sample is needed.
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.Read Article Now Book Mark Article
How to Prepare for the Test
No special preparation is necessary for this test.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
There are two types of the Coombs test:
The direct Coombs test is used to detect antibodies that are stuck to the surface of red blood cells. Many diseases and drugs can cause this to happen. These antibodies sometimes destroy red blood cells and cause anemia. Your health care provider may recommend this test if you have signs or symptoms of anemia or jaundice (yellowing of the skin or eyes).
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. Different type...Read Article Now Book Mark Article
The indirect Coombs test looks for antibodies that are floating in the blood. These antibodies could act against certain red blood cells. This test is most often done to determine if you may have a reaction to a blood transfusion.
A normal result is called a negative result. It means there was no clumping of cells and you have no antibodies to red blood cells.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
An abnormal (positive) direct Coombs test means you have antibodies that act against your red blood cells. This may be due to:
Autoimmune hemolytic anemia
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. Normally, red ...Read Article Now Book Mark Article
- Chronic lymphocytic leukemia or similar disorder
Chronic lymphocytic leukemia
Chronic lymphocytic leukemia (CLL) is cancer of a type of white blood cells called lymphocytes. These cells are found in the bone marrow and other p...Read Article Now Book Mark Article
Blood disease in newborns called erythroblastosis fetalis (also called hemolytic disease of the newborn)
Hemolytic disease of the newborn (HDN) is a blood disorder in a fetus or newborn infant. In some infants, it can be fatal. Normally, red blood cells...Read Article Now Book Mark Article
- Infectious mononucleosis
Mononucleosis, or mono, is a viral infection that causes fever, sore throat, and swollen lymph glands, most often in the neck.Read Article Now Book Mark Article
- Mycoplasma infection
- Systemic lupus erythematosus
Systemic lupus erythematosus
Systemic lupus erythematosus (SLE) is an autoimmune disease. In this disease, the immune system of the body mistakenly attacks healthy tissue. It c...Read Article Now Book Mark Article
- Transfusion reaction, such as one due to improperly matched units of blood
A hemolytic transfusion reaction is a serious complication that can occur after a blood transfusion. The reaction occurs when the red blood cells th...Read Article Now Book Mark Article
The test result may also be abnormal without any clear cause, especially among the older people.
An abnormal (positive) indirect Coombs test means you have antibodies that will act against red blood cells that your body views as foreign. This may suggest:
- Erythroblastosis fetalis
- Incompatible blood match (when used in blood banks)
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Fainting or feeling lightheaded
Fainting is a brief loss of consciousness due to a drop in blood flow to the brain. The episode most often lasts less than a couple of minutes and y...Read Article Now Book Mark Article
- Multiple punctures to locate veins
- Hematoma (blood buildup under the skin)
Bleeding into the skin can occur from broken blood vessels that form tiny red dots (called petechiae). Blood also can collect under the tissue in la...Read Article Now Book Mark Article
- Excessive bleeding
- Infection (a slight risk any time the skin is broken)
Elghetany MT, Banki K. Erythrocytic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 33.
Michel M. Autoimmune and intravascular hemolytic anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 151.
Review Date: 1/25/2022
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.