Overview: Indirect Coombs (ICT) TestIntroduction: The Indirect Coombs Test detects antibodies in blood to diagnose transfusion reactions or hemolytic disease, causing jaundice or anemia. Following 2023 ASH guidelines, it uses an immunoassay for high specificity, aiding in hematological screening. This test is critical for guiding transfusion compatibility, treatment, and improving outcomes in hematology for patients with suspected transfusion issues.
Other Names: Coombs Indirect Assay, Antibody Screen Test.
FDA Status: Laboratory-developed test (LDT), meeting hematology standards for diagnostic accuracy.
Historical Milestone: Coombs testing began in the 1940s with transfusion research. Indirect Coombs assays emerged in the 1950s, and by the 2000s, automated methods improved accuracy.
Purpose: Diagnoses transfusion reactions or hemolytic disease, guides transfusion planning, and monitors antibodies in patients with jaundice or anemia.
Test Parameters: 1. Indirect Coombs
Pretest Condition: No fasting required. Collect serum at any time. Report symptoms like jaundice or anemia, and list recent transfusions or pregnancies.
Specimen: 2-5 mL serum (SST). Centrifuge within 1 hour. 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 jaundice, anemia, or history of transfusions/pregnancies. Include current medications, especially immunosuppressants.
Consent: Written consent required, detailing the tests purpose, implications for transfusion safety, and potential need for specialized care.
Procedural Considerations: Uses an immunoassay to detect antibodies in serum. Results are available in 1-2 days, enabling rapid clinical decisions.
Factors Affecting Result Accuracy: Improper storage or hemolysis can degrade samples. Recent transfusions may cause false positives.
Clinical Significance: Positive results indicate antibodies, prompting careful transfusion matching. Negative results support safe transfusion.
Specialist Consultation: Consult a hematologist for result interpretation. A transfusion medicine specialist referral is advised for complex cases.
Additional Supporting Tests: Direct Coombs test, blood typing, or antibody identification to confirm transfusion reactions.
Test Limitations: False positives may occur with recent transfusions. Results require clinical correlation.
References: ASH Transfusion Guidelines, 2023; Transfusion, Cohn CS, 2022.
