Longitudinal study of fetal middle cerebral artery flow velocity waveforms preceding fetal death

OBJECTIVE: To assess longitudinally fetal cerebral vasodilatation in small-for-gestational age fetuses to investigate whether intrauterine death might be predictable. DESIGN: Prospective observational study. SETTING: Ultrasound department in a university hospital. SUBJECTS: Five pregnancies with ultrasonographically confirmed small fetuses (abdominal circumference less than the 3rd centile) monitored longitudinally until time of intrauterine death. MAIN OUTCOME MEASURE: Time between last ultrasound examination and diagnosis of intrauterine death, and variation in middle cerebral artery pulsitility index prior to death. RESULTS: Two of the five fetuses showed a reversal of adaptation (as indicated by an elevation of the middle cerebral artery pulsitility index) within 48 hours of intrauterine death. The other three had their final ultrasound examination 3 to 7 days before death and showed no such reversal of adaptation. CONCLUSION: Reversal of adaptation in fetal hypoxaemia as indicated by a rise in the middle cerebral artery pulsitility index may be a predictor of intrauterine death within 48 hours. Whether delivery after reversal of adaptation would result in salvage of neurologically intact babies needs to be investigated.