An Rh-negative unsensitized multigravida at 31 weeks presents with antepartum hemorrhage from a confirmed placental abruption. She receives anti-D immunoglobulin. Within what time window from the bleeding episode must anti-D be administered to remain effective?
- A Within 72 hours ✓
- B Within 48 hours
- C Within 24 hours
- D Within 7 days
Correct answer: A. Within 72 hours
Explanation
Anti-D must be given within 72 hours of every potentially sensitizing event, including each episode of antepartum hemorrhage, external cephalic version, trauma, and amniocentesis. If more than 72 hours have elapsed it should still be given up to 10 days, but efficacy falls sharply. The dose is guided by the Kleihauer-Betke test estimating fetomaternal hemorrhage size.
Reference: RCOG Green-top Guideline No. 65, The Management of Women with Red Cell Antibodies, 2014 revision ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.