Concordance Rates Between Resident-Performed Ultrasound Measurements and Certified Sonographer Measurements

To evaluate the accuracy of ultrasound (US) estimated fetal weight (EFW) measurement compared with neonatal birth weight when performed by residents versus certified sonographers. The hypothesis tested was that residents and certified sonographers would not differ significantly in EFW or in EFW compared with neonatal birth weight.

A retrospective chart review of 142 inpatients from July 2010 to May 2011 was conducted. Ultrasound examinations were performed by a resident physician and a certified sonographer within 7 days after the resident. Standard US measurements obtained were head circumference, biparietal diameter, abdominal circumference, femur length, estimated gestational age, and EFW. Gestational age ranged from 20 to 39 weeks. The time from US to delivery, residency year, and birth weight were collected. Measurements were compared by paired t tests, the Wilcoxon signed rank test, and repeated-measures analysis of variance.

The US EFW by residents and sonographers showed excellent concordance with each other regardless of the neonatal birth weight. The resident and sonographer EFW each showed excellent concordance with the neonatal birth weight, and this concordance did not differ significantly between residents and sonographers for neonates weighing less than 1000 g (P = .61) and neonates weighing greater than or equal to 1000 to less than 2000 g (P = .93). The resident EFW (P < .05) and sonographer EFW (P < .01), however, were less than the neonatal birth weight for larger neonates (≥2000 g), but the degree of underestimation was not significantly different between residents and sonographers (P = .51).

Accurate EFW is critical for prenatal management. These data support the value of a dedicated month of US training in residency programs.