Screening for fetal growth restriction with third trimester ...
Screening for fetal growth restriction with third trimester ultrasound: cohort study
Universal third trimester ultrasound improves detection of the small for gestation fetus compared with routine care, but still performs poorly as a screening test.
Sovio U, White IR, Dacey A, et al. Screening for fetal growth restriction with universal third trimester ultrasonography in nulliparous women in the Pregnancy Outcomes Prediction study: a prospective cohort study. Lancet 2015; 386:2089-9.
Fetal growth restriction is a major cause of perinatal morbidity and mortality. Detection of the baby with estimated fetal weight (EFW) < 10th centile (small for gestational age, SGA) with routine clinical care is poor, leaving many pregnancies at increased risk of adverse outcomes unrecognised.
This study aimed to determine the diagnostic performance of routine third trimester ultrasound for detecting babies with estimated fetal weight < 10th centile (SGA). It also aimed to determine whether the risk of morbidity in SGA fetuses was associated with other ultrasound markers of growth restriction.
In this prospective cohort study of nulliparous women with singleton pregnancies, clinically indicated ultrasounds and universal research ultrasounds at at 28 and 36 weeks were performed. The primary outcome for the study was ultrasound detection of SGA fetuses. Secondary outcomes included markers of fetal growth restriction involving biometric ratios, utero-placental Doppler and fetal growth velocity.
Data from 3977 women were eligible for analysis. Universal ultrasound detected 57% of SGA babies, compared to only 20% detected with routine clinical care. These pregnancies were at an increased risk of neonatal morbidity.
Those SGA fetuses with the lowest rate of growth in the abdominal circumference (in lowest decile) had a significant higher risk of neonatal morbidity.
Universal ultrasound was less specific than routine clinical care (90% vs 98%). For every additional SGA fetus identified, there were two fetuses with false positives results.
Universal third trimester ultrasound improves detection of the small for gestation fetus compared with routine care, but still performs poorly as a screening test. Combining fetal biometry analysis and abdominal growth velocity may identify a group at particularly increased perinatal morbidity risk.