Three-dimensional ultrasound first trimester fetal volume measurement and its relation to pregnancy outcome

Abstract

Aim of work: To determine whether fetal volume (FV) measured by three-dimensional (3D) ultrasound was able to detect fetuses at risk of low birth weight (primary outcome) and/or preterm labor (secondary outcome).

Methods: One hundred pregnant women carrying a singleton living pregnancy who were sure of dates, and had a dating scan, with gestational age between 11 weeks and 13 weeks+6 days coming for routine first trimester nuchal translucency (NT) were examined by both two-dimensional (2D) and 3D ultrasound (Vocal System) for crown-rump length (CRL) and FV then followed up regularly every 4 weeks until 28 weeks then biweekly until 36 weeks then weekly until delivery both clinically and by ultrasound biometry.

Findings: Eighty-seven cases had a normal outcome, while the remaining 13 cases had either preterm labor (four cases) or low-birth weight (nine cases). FV positively correlated with CRL (P=0.026), gestational age in weeks (P=0.002), neonatal body weight in grams (P=0.018) and neonatal body length at birth (P=0.04). A mean FV of 8.3 mm3 was association with neonatal complications (P=0.045). A cut-off point of 9 mm3 for FV was associated with 100% sensitivity for detection of the date of birth, while a cut-off point of 9.15 mm3 for FV was associated 100% sensitivity for detection of neonatal birth weight.

Conclusion: 3D assessment of FV in the first trimester provides an accurate method for predicting pregnancy outcome namely low birth weight and neonatal complications, however, it is a better positive predictor than a negative one.

Keywords: 3D ultrasound; fetal volume; pregnancy outcome.