In a woman with Rh sensitization (anti-D titer 1:32), weekly middle cerebral artery-peak systolic velocity (MCA-PSV) Doppler monitoring is used to detect fetal anemia. The threshold value of MCA-PSV that indicates need for fetal blood sampling (or intrauterine transfusion in a hydropic fetus) is:
- A >1.0 MoM (multiples of the median)
- B >1.29 MoM
- C >1.5 MoM ✓
- D >2.0 MoM
Correct answer: C. >1.5 MoM
Explanation
The Mari criteria (NEJM 2000) established MCA-PSV >1.5 MoM for gestational age as the threshold predicting moderate-to-severe fetal anemia with high sensitivity (100%) and acceptable false-positive rate (~12%). Values above this threshold warrant fetal blood sampling (cordocentesis) to confirm fetal hemoglobin and, if anemia is confirmed (Hb <0.84 MoM), intrauterine transfusion is performed. This Doppler-based monitoring has largely replaced amniocentesis for OD450 (Liley curve) in modern practice.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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