The Coombs test is a specific laboratory test that allows you to identify antibodies in the blood plasma or on the surface of an red blood cell. This procedure allows you to diagnose immune hemolytic anemia, including in newborns, as well as to identify hemolytic transfusion reactions. The Coombs test is actively used in forensic science and scientific genetics to determine red blood cell antigens. Compliance with all the rules for the implementation of such an analysis allows you to get the most reliable result.
The purpose of the antiglobulin test
A direct Coombs test allows you to detect anti-RBC antibodies that are fixed on red blood cells. 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 determine the autonomous substances in the blood serum.
How is the analysis carried out?
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venous blood sampling in 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 taken material at a temperature of 2 to 8 ° C for no longer than seven days. In order for the indicators of this study 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.
Decoding of totals
The Coombs test is a rather laborious research method that requires careful and accurate execution. When using this test, some difficulties may occur that are associated with an incorrect interpretation of the final results due to the weak manifestation of positive reactions. It should be noted that the inaccuracy of the analysis - namely, a positive Coombs test - may be the result of inefficient washing of red blood cells, contact with oily
surface, as well as neutralizing antiglobulin reagents with components
serum. Another disadvantage of this research method is the instability of the material taken, the storage of which has certain features.
The cause of a false negative result may be excessive shaking of the suspension of red blood cells during resuspension. Erroneous results can also be caused by the presence of impurities of anti-complementary antibodies, which are adsorbed upon incubation on the surface of the tested red blood cells, resulting in the appearance of a positive result. If you thoroughly wash the test samples and control the reaction conditions, these shortcomings can be easily eliminated, which will increase the chances of obtaining the most reliable Coombs test results.