Utility of third trimester sonographic measurements for predicting SGA in cases of fetal gastroschisis.

Objective: To assess the accuracy of different sonographic estimated fetal weight (EFW) cutoffs, and combinations of EFW and biometric measurements for predicting small for gestational age (SGA) in fetal gastroschisis.
Study Design: Gastroschisis cases from two centers were included. The sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated for different EFW cutoffs, as well as EFW and biometric measurement combinations.
Results: Seventy gastroschisis cases were analyzed. An EFW<10% had 94% sensitivity, 43% specificity, 33% PPV and 96% NPV for SGA at delivery. Using an EFW cutoff of <5% improved the specificity to 63% and PPV to 41%, but decreased the sensitivity to 88%. Combining an abdominal circumference (AC) or femur length (FL) z-score less than -2 with the total EFW improved the specificity and PPV but decreased the sensitivity.
Conclusion: A combination of a small AC or FL along with EFW increases the specificity and PPV, but decreases the sensitivity of predicting SGA.