Overview: Direct Coombs (DCT) Test
Introduction: The Direct Coombs Test detects antibodies on red blood cells to diagnose autoimmune hemolytic anemia, causing fatigue or jaundice. Aligned with 2023 ASH guidelines, it uses an immunoassay for high specificity, aiding in hematological screening. This test is critical for guiding diagnosis, treatment, and improving outcomes in hematology for patients with suspected autoimmune hemolytic anemia.

Other Names: Coombs Direct Assay, Anti-Globulin Test.

FDA Status: Laboratory-developed test (LDT), meeting hematology standards for diagnostic accuracy.

Historical Milestone: Coombs testing began in the 1940s with blood transfusion research. Direct Coombs assays emerged in the 1950s, and by the 2000s, automated methods improved accuracy.

Purpose: Diagnoses autoimmune hemolytic anemia, guides treatment, and monitors antibody presence in patients with fatigue or jaundice.

Test Parameters: 1. Direct Coombs

Pretest Condition: No fasting required. Collect whole blood at any time. Report symptoms like fatigue or jaundice, and list medications like immunosuppressants.

Specimen: 2-5 mL whole blood (EDTA). Transport in a biohazard bag within 8 hours.

Sample Stability at Room Temperature: 8 hours

Sample Stability at Refrigeration: 7 days

Sample Stability at Frozen: 6 months

Medical History: Document fatigue, jaundice, or history of autoimmune diseases. Include current medications, especially steroids or chemotherapy.

Consent: Written consent required, detailing the tests purpose, diagnostic implications, and potential need for immunosuppressive therapy.

Procedural Considerations: Uses an immunoassay to detect antibodies on red blood cells. Results are available in 1-2 days, enabling rapid clinical decisions.

Factors Affecting Result Accuracy: Recent transfusions or improper storage can affect results. Hemolysis may cause false positives.

Clinical Significance: Positive results confirm autoimmune hemolytic anemia, prompting immunosuppressive therapy. Negative results may require further testing.

Specialist Consultation: Consult a hematologist for result interpretation. A rheumatologist referral is advised for autoimmune involvement.

Additional Supporting Tests: Indirect Coombs test, reticulocyte count, or haptoglobin test to confirm hemolytic anemia.

Test Limitations: False positives may occur with recent transfusions. Results require clinical correlation.

References: ASH Hemolytic Anemia Guidelines, 2023; Blood, Hill QA, 2022.