Doppler: more or less?

Clinical Opinion: The diagnosis and management of suspected fetal growth restriction: an evidence-based approach

This study reviewed the literature about the diagnosis, antepartum surveillance, and time of delivery of fetuses suspected to be small for gestational age or growth restricted. Several guidelines have been issued by major professional organizations, including the International Society of Ultrasound in Obstetrics and Gynecology and the Society for Maternal-Fetal Medicine. The differences in recommendations, in particular about Doppler velocimetry of the ductus venosus and middle cerebral artery, have created confusion among clinicians, and this review has intended to clarify and highlight the available evidence that is pertinent to clinical management. A fetus who is small for gestational age is frequently defined as one with an estimated fetal weight of <10th percentile. This condition has been considered syndromic and has been frequently attributed to fetal growth restriction, a constitutionally small fetus, congenital infections, chromosomal abnormalities, or genetic conditions. Small for gestational age is not synonymous with fetal growth restriction, which is defined by deceleration of fetal growth determined by a change in fetal growth velocity. An abnormal umbilical artery Doppler pulsatility index reflects an increased impedance to flow in the umbilical circulation and is considered to be an indicator of placental disease. The combined finding of an estimated fetal weight of <10th percentile and abnormal umbilical artery Doppler velocimetry has been widely accepted as indicative of fetal growth restriction. Clinical studies have shown that the gestational age at diagnosis can be used to subclassify suspected fetal growth restriction into early and late, depending on whether the condition is diagnosed before or after 32 weeks of gestation. The early type is associated with umbilical artery Doppler abnormalities, whereas the late type is often associated with a low pulsatility index in the middle cerebral artery. A large randomized clinical trial indicated that in the context of early suspected fetal growth restriction, the combination of computerized cardiotocography and fetal ductus venosus Doppler improves outcomes, such that 95% of surviving infants have a normal neurodevelopmental outcome at 2 years of age. A low middle cerebral artery pulsatility index is associated with an adverse perinatal outcome in late fetal growth restriction; however, there is no evidence supporting its use to determine the time of delivery. Nonetheless, an abnormality in middle cerebral artery Doppler could be valuable to increase the surveillance of the fetus at risk. We propose that fetal size, growth rate, uteroplacental Doppler indices, cardiotocography, and maternal conditions (ie, hypertension) according to gestational age are important factors in optimizing the outcome of suspected fetal growth restriction.

Predicting adverse neonatal outcome in severe fetal compromise: A pivotal role for estimated fetal weight Z scores

OBJECTIVE

To identify significant predictors for adverse neonatal outcome in severe by compromised fetuses.

METHODS

Consecutive premature fetuses at between 25 and 32 weeks' with severe placental insufficiency were examined prospectively. Inclusion criteria were: singletons; normal anatomy; abnormal umbilical artery Doppler pulsatility index; abnormal cerebroplacental ratio; middle cerebral artery pulsatility index (PI) <or=2 standard deviations. We considered as independent potential predicting variables: absent or reversed end diastolic flow in umbilical artery, abnormal ductus venosus S/A ratio, absent or reversed flow during atrial contraction in the ductus venosus, and estimated fetal weight (EFW) Z score. Outcome parameters were: neonatal mortality and severe neonatal morbidity (Periventricular-Intraventricular Hemorrhage grade 03 or 04, Retinopathy of Prematurity stage 3 or 4, Periventricular Leukomalacia or Broncopulmonary Dysplasia).

RESULTS

Univariate analysis for all potential predicting variables was performed. EFW Z score index showed the strongest association with mortality and there was no fetal death or Retinopathy of Prematurity in the group with EFW Z-score index below lower limit. There was no case of Cystic Periventricular Leukomalatia in these analyses. The area under receiver-operator characteristic curve was significant for EFW Z-score index.

CONCLUSION

Our study suggests that EFW Z score is the strongest predictor of adverse neonatal outcome in severely compromised fetuses.