A Rh-negative woman at 28 weeks is found to have anti-D titer of 1:32. Fetal Doppler shows MCA-PSV of 1.58 MoM. According to current management guidelines, the next step is:
- A Cordocentesis (fetal blood sampling) and intrauterine transfusion (IUT) if fetal Hb <10 g/dL ✓
- B Repeat MCA-PSV Doppler in 1-2 weeks and deliver at 32 weeks
- C Amniocentesis for delta OD 450 (Liley curve) to assess severity
- D Maternal plasma exchange to reduce anti-D titers before intervention
Explanation
MCA-PSV >1.5 MoM (peak systolic velocity in fetal middle cerebral artery) indicates significant fetal anemia requiring intervention. This has replaced amniocentesis (delta OD 450 / Liley curve) as the primary non-invasive tool for predicting severe fetal anemia, with sensitivity ~88-100% for severe anemia. When MCA-PSV is >1.5 MoM, fetal blood sampling by cordocentesis is performed to measure fetal hematocrit/hemoglobin, and intrauterine transfusion (IUT) is given if fetal Hb is significantly reduced (<10 g/dL at <34 weeks, or <30% hematocrit). Anti-D titer 1:32 is above the critical titer of 1:16, mandating intensive monitoring. IUT is performed every 2-3 weeks until 34-36 weeks, then delivery.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.