Identifying fetal growth disorders using ultrasonography in women with diabetes

Objectives—We evaluated the ability of third-trimester ultrasonography (US) to diagnose disorders of fetal growth among women with diabetes mellitus. Methods—This work was a retrospective cohort study of women with diabetes who delivered term singleton neonates at a single academic medical center and who had a US examination within 5 weeks of delivery. We characterized the sensitivity, specificity, positive predictive value, and negative predictive value of US to detect largefor gestational age (LGA) and small-for-gestational age (SGA) infants. Large and small for gestational age were defined as a US estimated fetal weight of greater than 90% and less than 10%, respectively, based on the Hadlock formula (Radiology 1991; 181:129-133); US estimates of LGA or SGA were compared with postnatal findings of LGA or SGA based on gestational age-based weight percentiles. Test characteristics were analyzed for the total cohort and by the type of diabetes. We compared the areas under the curve for receiver operating characteristic curves for different types of diabetes. Results—Of 521 women, 3 (0.6%) screened positive for SGA, and 64 (12.3%) delivered an SGA neonate. In contrast, 129 (24.8%) screened positive for LGA, and 61 (11.7%) delivered an LGA neonate. The receiver operating characteristic curves did not differ significantly for different types of diabetes (P5.68). Conclusions—Ultrasonography in women with diabetes and term or late preterm pregnancies has high specificity but poor sensitivity for SGA and a low positive predictive value for LGA. The diagnostic capability of US to detect fetal growth abnormalities did not differ significantly by the type of diabetes.