A 26-year-old primigravida with blood group B Rh negative attends her routine antenatal visit at 28 weeks gestation. Her indirect Coombs test is negative and she has had no bleeding episodes. What is the appropriate next step?
- A No intervention required unless a sensitising event occurs
- B Anti-D immunoglobulin 300 microgram intramuscularly now, repeated at 34 weeks ✓
- C Intrauterine transfusion if the MCA peak systolic velocity rises above 1.5 MoM
- D Anti-D immunoglobulin only within 72 hours of delivery if the baby is Rh positive
Correct answer: B. Anti-D immunoglobulin 300 microgram intramuscularly now, repeated at 34 weeks
Explanation
An unsensitised Rh negative woman receives routine antenatal anti-D prophylaxis, 300 microgram (1500 IU) intramuscularly at 28 weeks, repeated around 34 to 36 weeks, because occult fetomaternal haemorrhage occurs most often in the third trimester. Option D alone leaves the antenatal window unprotected and is incomplete prophylaxis. The Coombs test is negative, so she is unsensitised and prophylaxis rather than monitoring applies.
Reference: DC Dutta's Textbook of Obstetrics, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.