Direct antiglobulin test (polyclonal)

Clinical information

Diagnostic Utility:

This test detects the presence of IgG antibodies or the complement component C3d coating red blood cells. This situation may occur, fundamentally, in the context of:

• Autoimmune hemolytic anaemia.
• Drug-induced hemolytic anaemia.
• Hemolytic transfusion reactions.
• Feto-maternal incompatibility and hemolytic disease of the newborn.

Method:                                              

Direct antiglobulin test (Direct Coombs test) with polyspecific antiglobulin. Hemagglutination.

Reference Values

Possible results are: Negative, Positive.

Diagnostic Algorithm:

In case of a positive result, test 9993 Differential direct Coombs is performed, which allows differentiation between IgG- and C3d-coated red blood cells.

*Although these tests can be ordered separately, the laboratory needs to know that the sample has a positive Direct Coombs. That's why a polyspecific Direct Antiglobulin Test is always performed initially.  

Turnaround Time:

1 day when the screening is negative.
1 day when the screening is positive and identification is unequivocal.
Several days may be needed when the identification is complex (mixtures of antibodies or uncommon specificities)

Specimen information

Sample: Whole blood
Tube: EDTA K3 10 ml tube
Minimum volume: 6 ml (1 ml in infants)
Stability:

• At room temperature: 2 days
• In refrigeration: 2 days

Transport instructions: Preferably at room temperature
Reason for rejection: Sample highly hemolyzed

Administrative information

BST Code: 0012
Test Description: Direct Antiglobulin Test (DAT) Synonyms: Direct Coombs Test
Section: Immunohematology
BST Rate: Check the updated rates by clicking here.

Profiles:

Test 0012 Direct Antiglobulin Test can be requested individually. It is also performed within the following profiles:

References

AABB Technical Manual. 19th edition. Editat per MK Fung, AF Eder, SL Spitalnik, CM Westhoff: AABB 2017