Lab method
Direct antiglobulin (Coombs) test
Detects antibody/complement coating red cells
KOOMZ
High-yield clue
Agglutination after adding antihuman globulin means antibody or complement is already coating the red cells (positive direct Coombs).
Overview
An immunohematology concept where antihuman globulin reagent bridges antibody or complement already bound to red blood cells, causing visible agglutination to show in-vivo cell coating.
Classification
- Agglutination-based assay
- Immunohematology concept
- Direct (DAT) vs indirect format
- Qualitative
Lab & identification clues
- Antihuman globulin cross-links coated cells
- Direct test detects in-vivo coated RBCs
- Indirect test detects free serum antibody vocabulary
- Positive result = visible agglutination
Associations
- Autoimmune and immune hemolysis workup vocabulary
- Certain infection-associated hemolysis study association
- Mycoplasma cold-agglutinin framing
Commonly confused with
- Latex agglutination
- Lateral flow assay
Frequently asked questions
What is Direct antiglobulin (Coombs) test?
An immunohematology concept where antihuman globulin reagent bridges antibody or complement already bound to red blood cells, causing visible agglutination to show in-vivo cell coating.
What is the high-yield clue for Direct antiglobulin (Coombs) test?
Agglutination after adding antihuman globulin means antibody or complement is already coating the red cells (positive direct Coombs).
What is Direct antiglobulin (Coombs) test associated with?
Direct antiglobulin (Coombs) test is associated with Autoimmune and immune hemolysis workup vocabulary, Certain infection-associated hemolysis study association, and Mycoplasma cold-agglutinin framing.
What is Direct antiglobulin (Coombs) test commonly confused with?
Direct antiglobulin (Coombs) test is commonly confused with Latex agglutination and Lateral flow assay.
Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.