An Rh negative unsensitized woman undergoes suction evacuation for a missed abortion at 9 weeks gestation. What is the recommended minimum dose of anti-D immunoglobulin according to current guidance?
- A 300 micrograms intramuscularly
- B 120 micrograms intramuscularly
- C 50 micrograms intramuscularly ✓
- D No anti-D is needed before 12 weeks
Correct answer: C. 50 micrograms intramuscularly
Explanation
Before 12 weeks gestation the fetal blood volume is small and fetomaternal haemorrhage rarely exceeds 2.5 mL, so a mini dose of 50 micrograms (250 IU) suffices for abortion, ectopic pregnancy or molar evacuation in unsensitized women. Beyond 12 weeks the standard 300 microgram dose applies. Claiming no anti-C is needed ignores documented sensitization risk even in early pregnancy.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.