REVERSAL OF DIASTOLIC FLOW IN THE MIDDLE CEREBRAL-ARTERY OF THE FETUSDURING THE 2ND-HALF OF PREGNANCY

This study obtained data on 22 fetuses in whom reversal of diastolic f low in the middle cerebral artery (MCA) was seen. In 59% of cases ther e was normal heart function and in 28% there was isolated tricuspid va lve regurgitation. The majority (73%) of cases presented with normal f etal anatomy aid most (82%) had a normal amniotic fluid index and norm al fetal growth. In all cases, Doppler results of the umbilical artery and vein were normal. Of the women, 65% were on no medication and 73% did not smoke during pregnancy. The reversal of diastolic flow in the MCA was seen temporarily in the majority of cases (for 2-30 min); how ever, in one case with rhesus factor disease and a rim of ascites, it was observed for a longer period (about 2 h) and on the following day intrauterine demise was recorded In most of the cases without structur al malformations, the neonatal outcome was normal. We conclude that re versed diastolic flow in the MCA is a rare and usually transient event . In one of our cases prolonged reversed pow preceded intrauterine dem ise, Therefore, this may be an ominous sign and careful fetal surveill ance should be undertaken when this observation is made. There are a f ew Possible pathomechanisms of reversed diastolic flow in the MCA, In the majority of cases the cause of the observed phenomenon remains unk nown, but an increased pressure in the right ventricle and possible tr icuspid regurgitation should be considered.