Coombs' test is a specific laboratory test that detects antibodies present in blood plasma or on the surface of red blood cells. This procedure allows diagnosing immune hemolytic anemia, including in newborns, as well as detecting hemolytic transfusion reactions. The Coombs test is actively used in forensic medicine and scientific genetics to determine erythrocyte antigens. Compliance with all the rules for the implementation of such an analysis allows you to get the most reliable result.
Purpose of the antiglobulin test
Direct Coombs test allows you to detect anti-erythrocyte antibodies that are fixed on erythrocytes. A positive reaction in such a study indicates the development of autoimmune hemolytic anemia. It should be noted that a negative result does not exclude the presence of an autoimmune disease, since antibodies are often in free form, that is, they have no connection with red blood cells. In such cases, it is advisable to conduct an indirect Coombs test, which will allow you to determine the autonomoussubstances in blood serum.
How is the analysis done?
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Venous blood sampling from a patient is carried out in the morning on an empty stomach, despite the fact that no significant factors affecting the final result of such a test were found. It is allowed to store the material taken at a temperature of 2 to 8 ° C for no longer than seven days. In order for the results of this test to be as accurate as possible, whole blood must be delivered to the laboratory within the first two hours. Ideally, the Coombs test should show a negative result, which indicates the absence of hemolytic changes in the body.
Transcript of totals
Coombs test is a rather time-consuming research method that requires careful and accurate performance. When using such a test, there may be some difficulties that are associated with incorrect interpretation of the final results due to the weak manifestation of positive reactions. It should be noted that the unreliability of the analysis - namely, a positive Coombs test - may be the result of ineffective washing of erythrocytes, contact with a greasysurface, as well as neutralization of antiglobulin reagents by components
serum. Another disadvantage of this research method is the instability of the material taken, the storage of which has certain features.
False-negative results may be caused by excessive shaking of red cell suspension whenresuspension. Erroneous results may also be due to the presence of anti-complementary antibody contaminants that adsorb during incubation on the surface of the tested erythrocytes, resulting in the appearance of a positive result. If the test samples are thoroughly washed and the reaction conditions are controlled, these shortcomings can be easily eliminated, which will increase the chances of obtaining the most reliable Coombs test values.