In order to understand the situation in which a patient will be asked to undergo a Coombs test, one needs to know the diseases that it helps detect. Hemolysis is the most prominent condition in which a coombs test will prove to be very beneficial in the diagnostic phase. This is characterized by premature red blood cell destruction. Under normal circumstances, red blood cells have a lifespan of about 110 to 120 days, after which they are broken down and removed from the body’s circulation by the spleen. As a result, the Coombs test helps look for the antibodies that work against the red blood cells.
Just as with any type of blood test, a Coombs test will require the doctor to have a blood sample taken from the patient which will then be analyzed to identify the quantities of each constituent. The sample of blood is taken from a vein, usually from the back of the hand or the inside of the elbow. The area where the needle will be inserted is first cleansed with the help of some kind of antiseptic. Once this has been done, the physician or nurse will wrap an elastic band around the upper part of the arm in order to apply added pressure that will cause the vein to swell with blood. Once the vein has become significantly prominent, a needle will be inserted into it and the blood collected into an air tight tube or vial that has already been attached to the syringe. The elastic band is then removed to allow the blood to flow more freely and the needle withdrawn when the blood has been collected. The puncture site is then covered to restrict any significant loss of blood.
Only once the blood has been withdrawn does the Coombs test commence. There are two types of coombs tests’: direct and indirect. The direct coombs test is concerned with detecting antibodies that are already bound to the surface of the red blood cells – more often than not, caused by medical conditions and medication. The indirect version of the Coombs tests analyzes the unbound and circulating antibodies against a set of standardized blood cells. This is really only used in the case of diagnosing medical conditions as well as identifying if a person is likely to react to blood transfusions. The risks faced with undergoing a coombs blood test are limited to some amount of blood loss and the likelihood of infection if medical standards are not followed.