A pregnant woman attends her first antenatal visit. She is Rh negative and her husband is Rh positive. Which serological investigation is performed on her blood to detect anti-Rh (anti-D) antibodies in her serum?
- A Direct Coombs test
- B Indirect Coombs test ✓
- C Rose-Waaler test
- D Paul-Bunnell test
Correct answer: B. Indirect Coombs test
Explanation
The indirect Coombs (indirect antiglobulin) test detects free, unbound antibodies in serum by incubating the serum with known Rh-positive red cells and then adding anti-human globulin to reveal sensitisation. It is used antenatally to screen Rh-negative mothers for anti-D antibodies and also for pre-transfusion compatibility testing. The direct Coombs test is different: it detects antibodies already bound to red cells in vivo, as in haemolytic disease of the newborn or autoimmune haemolytic anaemia.
Reference: Ananthanarayan and Paniker Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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