Direct Antiglobulin test (DAT) (COOMBS)

CPT: 86880

Expected Turnaround Time

24 Hours

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Specimen Requirements


Whole Blood


EDTA (Lavender Top Tube)

Storage Instructions

Room Temp., Refrigerated (2-8 C)

Stability Requirements

Room temp. 72hrs., Refrigerated 7 days

Test Details

Additional Information

Antiglobulin testing, also known as the Coombs test, is an immunology laboratory procedure used to detect the presence of antibodies against circulating red blood cells (RBCs) in the body, which then induce hemolysis. The destruction of these red blood cells (RBCs) by antibodies directed against them is described diagnostically as autoimmune hemolytic anemia (AIHA). Many etiologies fall under this classification.   

Antiglobulin testing can be either direct antiglobulin testing (DAT) or indirect antiglobulin testing (IAT). The principle of DAT is to detect the presence of antibodies attached directly to the RBCs, which takes place by washing a collected blood sample in saline to isolate the patient’s RBCs; this procedure removes unbound antibodies that may otherwise confound the result. IAT, by contrast, is used to detect unbound antibodies to RBCs, which may be present in the patient’s serum. With direct antiglobulin testing, a monospecific or Poly-specific reagent is then added to the washed RBCs to detect bound IgG and/or complement C3.

In practice, many laboratories will first use the Poly-specific reagent that can detect both IgG and C3; a positive result will then be followed with monospecific testing to characterize the antibody further. For indirect antiglobulin testing, serum from a blood sample gets isolated, and native RBCs are removed. The isolated serum sample then gets incubated with foreign RBCs of known antigenicity. Antiglobulin reagent is then added, and the presence of agglutination indicates a positive result. 

A normal result is called a negative result. It means there was no clumping of cells, and there were no antibodies to red blood cells. 

An abnormal (positive) direct Coombs test means there are antibodies that act against red blood cells. This may be due to: 

  • Autoimmune hemolytic anemia 
  • Chronic lymphocytic leukemia or similar disorder 
  • Blood disease in newborns called erythroblastosis fetalis (also called hemolytic disease of the newborn) 
  • Infectious mononucleosis 
  • Mycoplasma infection 
  • Syphilis 
  • Systemic lupus erythematosus 
  • Transfusion reaction, such as one due to improperly matched units of blood 

The test result may also be abnormal without any clear cause, especially among older people. 

An abnormal (positive) indirect Coombs test means there are antibodies that will act against red blood cells that the body views as foreign. This may suggest: 

  • Erythroblastosis fetalis 
  • Incompatible blood match (when used in blood banks 


  1. Zupańska B, Thompson E, Brojer E, Merry AH. Phagocytosis of erythrocytes sensitized with known amounts of IgG1 and IgG3 anti-Rh antibodies. Vox Sang. 1987;53(2):96-101. [PubMed] 
  2. Leaf RK, O’Brien KL, Leaf DE, Drews RE. Autoimmune hemolytic anemia in a young man with acute hepatitis E infection. Am J Hematol. 2017 May;92(5):E77-E79. [PubMed] 
  3. Win N, Islam SI, Peterkin MA, Walker ID. Positive direct antiglobulin test due to antiphospholipid antibodies in normal healthy blood donors. Vox Sang. 1997;72(3):182-4. [PubMed] 

Statement on Medical Necessity
All ordered tests should be medically necessary for the diagnosis or detection of disease, illness, impairment, symptom, syndrome, or disorder and the results should be used in the medical management and treatment decisions for the patient. Solaris requires ICD-10 codes with each order for lab testing and both the tests ordered and the diagnosis should be documented in the provider’s medical record for the patient. The United States Department of Health and Human Services, Office of Inspector General, takes the position that a provider who orders medically unnecessary tests may be subject to civil penalties.

Panels and Profiles
Solaris offers Providers the convenience of ordering test combinations in a group at times with the flexibility to choose appropriate test(s) for individual patients. Providers should only order those tests that he or she believes are medically necessary for each patient, and a lesser inclusive profile or individual tests should be ordered if not all tests in the test combination/profile are medically necessary. All tests offered in a test combination/profile may be ordered separately as individual tests. Solaris encourages clients to contact their Solaris representative if the testing configurations shown do not meet individual needs for any reason, or if some other combination of procedures is needed.

CPT Codes
CPT Codes listed are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are the responsibility of the billing party and are listed here for informational purposes. Correct coding may vary from one carrier to another. Solaris may bill specific carriers using codes other than what is shown.


For questions or inquiries related to testing please reach out to or contact us by phone at (844) 550-0308.