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Gestational diabetes treatment — USMLE Step 3 MCQ

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HardOB/GYN (prenatal care, contraception, screening)Gestational diabetes treatmentUSMLE Step 3

A 27-year-old at 26 weeks has anti-Kell alloimmunization and a prior pregnancy complicated by fetal anemia. Two technically adequate middle-cerebral-artery Doppler studies show peak systolic velocities of 1.61 and 1.66 multiples of the median. There is no hydrops. What is the most appropriate next step?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Refer for fetal blood sampling with preparation for intrauterine transfusion

The best answer is “Refer for fetal blood sampling with preparation for intrauterine transfusion”. Repeated MCA peak systolic velocity above 1.5 multiples of the median identifies substantial risk of severe fetal anemia. At a preterm gestation when delivery is less favorable, SMFM recommends referral to an invasive fetal-therapy center for fetal blood sampling with preparation to transfuse. Anti-Kell titers correlate poorly with disease severity, delta OD450 has been replaced by Doppler surveillance, and waiting for hydrops risks irreversible injury.

Reference: SMFM Clinical Guideline #8: The Fetus at Risk for Anemia—Diagnosis and Management: https://publications.smfm.org/publications/586-society-for-maternal-fetal-medicine-clinical-guideline-8/