Accuracy of prenatal sonography performed by family practice residents

Sonographic evaluation of the fetus is a common procedure in modern antepartum management. This study investigates the accuracy of family physicians at different levels of training in performing common prenatal sonographic measurements.

Records of prenatal sonographic measurements of gestational age (279 scans) and estimated birth weight (62 scans) performed by family practice residents and family medicine teaching faculty at Silas B. Hays Army Community Hospital were compared to actual gestational age and birth weight. Associations between sonographically predicted gestational age and weight, Dubowitz-determined gestational age, actual birth weight, and training level of the operator were examined using analysis of variance.

The mean measurement difference in weeks between ultrasound-estimated gestational age and Dubowitz-determined gestational age on sonograms performed between 6 and 20 weeks of gestation was 1 week. The mean measurement difference on sonograms performed between 21 and 30 weeks of gestation was 1.3 weeks, and the mean measurement difference on sonograms performed between 31 and 42 weeks was 1.6 weeks. No significant difference was found between any of the resident year groups and family medicine faculty in accuracy of measuring gestational age. Sonograms estimating fetal weight within 10 days of delivery were within 10% of the actual birth weight. Faculty sonographic estimates were slightly more accurate than resident estimates.

The psychomotor skills necessary to perform accurate prenatal sonographic biometric measurements are easily learned within the confines of a 3-year family practice residency.