MIDDLE CEREBRAL-ARTERY VELOCIMETRY AS A PREDICTOR OF HYPOXEMIA IN FETUSES WITH INCREASED RESISTANCE TO BLOOD-FLOW IN THE UMBILICAL ARTERY

About half of all fetuses with increased resistance to blood how, but with still detectable diastolic blood velocity in the umbilical artery (UA), show signs of imminent asphyxia during labour indicating a need for operative delivery. Fetal brain-sparing during hypoxia is charact erized by an increase in diastolic and mean blood flow velocity in the middle cerebral artery (MCA). The aim of this study was to assess whe ther MCA blood velocity in pregnancies with increased resistance to bl ood flow in the fete-placental circulation could predict the developme nt of fetal asphyxia during labour. Fifty pregnant women with signs of increased fete-placental vascular resistance between 31 and 42 weeks of gestation were studied serially by Doppler ultrasound and the last examination was correlated to perinatal outcome. The MCA pulsatility i ndex (PI), cerebroplacental PI ratio and mean MCA blood velocity were calculated and correlated to fetal outcome. Fetal brain-sparing was de fined as MCA PI < mean - 2 S.D., cerebroplacental PI ratio <1.08 and m ean MCA blood velocity >mean +2 S.D. No significant association was fo und between signs of fetal brain-sparing and the perinatal outcome. Am ong fetuses with signs of increased resistance to how in the umbilical artery, velocimetry of the middle cerebral artery did not identify th ose that would not withstand the strain of labour. (C) 1997 Elsevier S cience Ireland Ltd.