SOP     : DIRECT ANTIGLOBULIN / COOMB’S TEST (DAT / DCT)

BLOOD CENTRE NAME

SCOPE AND APPLICATION

• This procedure is applied for detection of coating of red cells in vivo with antibody (IgG) & C3d

RESPONSIBILITY

• It is the responsibility of the resident doctor/Technician posted in Immunohaematology Lab to perform Indirect Antiglobulin Test and document the results

REFERENCES

• Modern Blood Banking and Transfusion Services, Denise M. Harmening 6^th edition
• Technical Manual of American Association of Blood Banks, 18^th edition

MATERIAL REQUIRED

Equipment:

• Tabletop centrifuge
• Microscope
• Incubator 

 Specimen:

• EDTA blood sample of the patients.

Reagents:

• Antihuman globulin reagent (AHG) (Polyspecific anti-IgG+anti-C3d) 
• Coomb’s control check cells (IgG Coated cells) 
• 0.9% Normal Saline. 

Glassware:

• Pasteur pipettes.
• Glass slides
• Glass Test tubes 

Miscellaneous:

• Rubber teats. 
• Disposal box
• plastic beakers
• Test tube Stand

PROCEDURE:

• Label the test tube with Patient’s Name or MRD or CR number
• Wash the EDTA blood sample 3 times using Normal Saline at 3000 rpm for 3 minutes
• Prepare 5% red cell suspension of the specimen using Normal Saline
• Add 1 drop of 5% red cell suspension to the labelled test tube
• Add 2 drops of AHG reagent and mix by shaking
• Centrifuge the tube at 1000rpm for 1 minute
• Observe for agglutination
• If the test is negative, add 1 drop of IgG sensitised control check cells 
• Centrifuge the tube at 1000 rpm for 1 minute
• Observe for agglutination

INTERPRETATION:

• The test is positive when agglutination is observed after centrifugation and the agglutination reaction is graded
• The test is negative when there is no agglutination after centrifugation, provided the check cells give a positive reaction
• The test is invalid when no agglutination is observed after adding Coomb’s check cells

DOCUMENTATION:

• Enter results in Immunohaematology register
• Report positive findings to the In-Charge

END OF DOCUMENT