The usefulness of fetal Doppler evaluation in early versus late onset intrauterine growth restriction. Review of the literature.

Intrauterine growth restriction (IUGR) represents a serious condition that can lead to increased perinatal morbidity, mortality and postnatal impaired neurodevelopment. There are two distinct phenotypes of IUGR: early onset and late onset IUGR with different onset, patterns of evolution and fetal Doppler profile. In early onset preeclampsia the main Doppler modifications are at the level of umbilical artery, with progressive augmentation of the pulsatility index to absent or reverse end diastolic flow. The modifications of the cerebral, cardiac and ductus venosus circulation are generally present, but with different sequences. The late onset IUGR is determined by third trimester placental insufficiency that entails fetal hypoxia. The cerebro-placental ratio (CPR) and the pulsatility index of the middle cerebral artery (PI MCA) seems to be the main markers for both diagnosis and obstetrical management while umbilical Doppler PI is frequently normal. Also the sequence of Doppler alterations is neither specific nor complete. New protocols for the diagnosis and management of late onset IUGR need to be implemented.