WS14‐04Improved fetal weight estimation by three‐dimensional ultrasound

Aim To investigate the value of 3D‐ultrasound in predicting fetal weight at delivery. Patients and methods The study group consisted of 251 pregnant women (formula‐finding group: n  = 125; evaluation group: n  = 126) with a singleton pregnancy and an ultrasound examination within seven days of delivery. Pregnancies with major structural or chromosomal anomalies were excluded. Ultrasound examinations included standard biometry as well as three‐dimensional volumetry of the upper arm, the thigh and the abdomen of the fetus. All examinations were performed with a Voluson 530D MT system (Kretztechnik, Zipf, Austria). The results were compared with commonly used weight formulas. Results All measurements were completed successfully. Polynomial regression analysis with standard biometric parameters and volumes of the upper arm, the thigh and the abdomen was employed to yield the best‐fit formula for prediction of fetal weight at birth. The new 3D formula (Estimated fetal weight (EFW) = – 1478.557 + 7.242 * thigh volume + 13.309 * upper arm volume + 852.998 * lg abdominal volume + 0.526 * BIP 3 ) proved to be superior to established two‐dimensional equations with the lowest mean error (25.8 ± 194.4 g), the lowest mean absolute error (155.2 ± 118.2 g) and the lowest mean absolute percentage error (6.1 ± 5.0%) when studied prospectively in the evaluation group. Conclusion Fetal weight estimation by 3D–ultrasound compares favourably with conventional 2D–formulas.