Ultrasound Evaluation of Fetal Hemodynamics and Perinatal Complications

In case of fetal weight below the 10th centile for gestational age, it is important to distinguish SGA and IUGR. SGA is defined as a fetal weight below the 10th centile. IUGR correspond to a pathologic reduction of growth velocity and it is a major determinant of perinatal mortality and morbidity. Even if SGA have long time been considered to be constitutionally small without adverse outcomes, recent evidence has demonstrated that a proportion of SGA, with normal UA Doppler, could be associated with neonatal adverse outcomes, probably related to a late-onset IUGR. Therefore, it seems essential to differentiate several categories of fetuses presenting abnormal fetal weight or intrauterine growth: fetuses SGA without any Doppler abnormalities, fetuses affected by early or late-IUGR. In case of late-IUGR, an important part of these fetuses is initially considered as PAG with a normal umbilical Doppler. In case of fetal weight below the 10th centile for gestational age, longitudinal assessment of the fetal weight and umbilical artery (UA) Doppler is recommended. In case of abnormal UA Doppler, Middle Cerebral Artery (MCA) Doppler is recommended to research a "brain-sparing" effect. If UA and MCA Doppler findings seem to become abnormal in the early stages of IUGR, Ductus Venosus (DV) flow abnormalities have been described as a late marker of fetal decompensation related to an acute myocardial impaired relaxation and acidemia which is a major contributor to adverse perinatal outcome and neurological. The aortic isthmus (AoI) Doppler is an indicator of the progression of fetal hemodynamic deterioration in IUGR and recent data confirm that AoI and DV abnormalities are correlated but AoI Doppler abnormalities would occur earlier than DV Doppler. AoI Doppler could identify abnormalities suggestive of right ventricular dysfunction before DV Doppler and anticipate obstetrical management. In conclusion, Doppler examination could not be reduced to UA Doppler in case of SGA and