Comparison of the accuracy of ultrasonic fetal weight estimation by using the various equations.

OBJECTIVE: To compare the accuracy of ultrasonic fetal weight estimation using the Hadlock's, Shepard's, Tongsong's and Hansmann's equations. MATERIAL AND METHOD: The analytical-cross sectional study was conducted on 102 pregnant women who were admitted for delivery in the Labor Room at Srinagarind Hospital, Faculty of Medicine, Khon Kaen University between January 1, 1999 and June 30, 1999. The fetal parameters, including biparietal diameter, abdominal circumference, transverse trunk diameter and femur length, were measured by ultrasound. The estimated fetal weight was calculated by those four equations. The mean absolute error was calculated from the absolute of the difference between the estimated fetal weight and the actual birth weight. RESULTS: The mean absolute error and standard deviation of the estimated fetal weight by the Hadlock's, Shepard's, Tongsong's and Hansmann's equations were 8.09 +/- 4.18, 7.94 +/- 4.63, 7.77 +/- 3.70 and 7.83 +/- 4.35 per cent respectively and there were no statistically significant differences at 95 per cent confidence interval (p>0.05). CONCLUSION: Apart from having comparable accuracy in the estimation of fetal weight to those of Hadlock, Shepard and Tongsong, Hansmann's equation employed at Srinagarind Hospital was more convenient to use than the others.