Context: Antiglobulin (Coombs) test is very important test in
the detection of incomplete (IgG) antibodies in the blood, either
in free form (Indirect coombs test) or bound to the red blood cell
(Direct coombs test). There is a possibility that anticoagulants like
Ethylenediaminetetraacetic acid (EDTA), Citrate, etc used for the
collection of blood sample, may effect the end result of the test.
Aims: The present study is aimed at comparison of the end result
(the clarity of agglutination) between the coombs test performed on
plain blood and anti- coagulated blood (EDTA and Citrate). Settings
and Design: Blood samples collected from blood donors at the time
of blood donation in plain and anti- coagulated blood (EDTA and
Citrate). Samples were subjected to coombs test at various dilutions
and agglutination was observed under the microscope. Methods and
Material: 6 ml. of blood samples will be collected from the 100 blood
donors at the time of blood donation in and 2 ml each transferred
into; EDTA bottle, Citrate bottle and Plain bottle. The sample thus
collected was used for performing the Anti-globulin test. 10% red
cell suspension was sensitized with Anti D IgG (as supplied by
Tulip Diagnostics) at different dilutions (1/10, 1/20, 1/30, 1/40).
The washed saline suspension of RBC’s is treated with Anti- human
globulin serum and agglutination is observed under a microscope
at 5X objective. Statistical analysis used: Friedman test. Results: The
degree of agglutination obtained by using plain blood samples at
various dilutions, tend to be higher compared to the same obtained
by using citrate and EDTA blood samples. The citrate blood samples
gives intermediate pattern between plain blood samples and EDTA
blood samples. Conclusions: The use of plain blood was found to give
better results compared to citrate and EDTA blood in performing the
antiglobulin test. The chances of missing the detection of low titres
of anti-D IgG is more with EDTA blood samples when compared to
citrate blood samples and least with plain blood samples.
Keywords: Antiglobulin; Coombs; Anticoagulants,
Ethylenediaminetetraacetic acid (EDTA), Citrate