An Rh-negative woman with a spontaneous first-trimester miscarriage at 9 weeks undergoes suction evacuation. She is unsensitized and the blood group of the conceptus is unknown. What is the recommended dose of anti-D immunoglobulin?

• A 50 micrograms (250 IU) ✓
• B 100 micrograms (500 IU)
• C 300 micrograms (1500 IU)
• D No anti-D is required before 12 weeks

Explanation

For potentially sensitising events before 12 weeks of gestation, the total fetomaternal haemorrhage volume is small enough that a standard small dose of 50 micrograms (250 IU) suffices. From 12 weeks onward, the full 300 microgram (1500 IU) dose is used because fetal blood volume and bleeding potential increase. Option D is wrong because sensitisation can occur even in early pregnancy, particularly after instrumentation such as evacuation.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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