The accuracy of Fetoplacental Doppler in distinguishing between growth restricted and constitutionally small fetuses.

Introduction: Fetoplacental Doppler is considered to be a key tool for the diagnosis of placenta-mediated fetal growth restriction(FGR). We aimed to determine the diagnostic accuracy of fetoplacental Doppler for specific placental diseases.

Methods: A retrospective cohort study of all women with a singleton pregnancy and an antenatal diagnosis of SGA fetus(estimated fetal weight <10th centile for gestational age), who underwent fetoplacental Doppler assessment within 2 weeks before birth. Primary exposure was any abnormal Doppler result, defined as an abnormal umbilical artery(UA) Doppler, middle cerebral artery(MCA) Doppler, cerebroplacental-ratio(CPR), or umbilico-cerebral ratio(UCR). Study outcomes were abnormal placental pathology: maternal vascular malperfusion(MVM), villitis of unknown etiology(VUE), or fetal vascular malperfusion(FVM).

Results: A total of 558 women with a singleton SGA fetus were included, of whom 239(42.8%) had an abnormal fetoplacental Doppler findings. UA Doppler had the lowest detection rate for abnormal placental pathology. MCA Doppler exhibited a significantly higher detection rate for all types of pathology. CPR and UCR exhibited highest detection rates for all types of placental pathology, however, were also associated with the highest false positive rate. The combination of fetoplacental Doppler with the severity of SGA and maternal hypertensive status achieved a high negative predictive value MVM lesions(97%). In contrast, fetoplacental Doppler did not improve the negative predictive value for non-MVM pathology(VUE or FVM).

Discussion: Among SGA fetuses, the combination of UA and MCA Doppler is highly accurate in ruling out FGR due to MVM placental pathology, but is of limited value in excluding FGR due to underlying non-MVM pathologies.