Validity of common ultrasound methods of fetal weight estimation in late pregnancy among women in Kwale, Niger Delta region, Nigeria

Background: Accuracy of some ultrasound equations used in our locality for fetal weight estimation is doubtful. Objective : To assess the accuracy of common ultrasound equations used for fetal weight estimation. Subjects and Methods: A longitudinal study was conducted on selected Nigerian obstetric population at Central Hospital, Kwale between March, 2009 and January, 2011. Sonography was performed on 412 women with advanced singleton cyesis and measurements of BPD, HC, AC, and FL were obtained and figured into 12 common ultrasound equations for the estimation of fetal weight. The actual birth weight at delivery was recorded. Results : The highest intraclass correlation coefficient was generated by the Hadlock 5 and Hsieh 2 equations. The least mean absolute percent error was obtained with Hsieh 2 equation, followed by Woo 3, and Hadlock 5. These equations also had the least percentage error and the least range of limits of agreement in the same order with no significant difference between their mean fetal weight estimates and that of the actual birth weight (p > 0.05). All twelve equations had strong positive correlation with the actual birth weight with Nzeh 2 equation the least. Conclusion: Hsieh 2 equation has the best accuracy in fetal weight estimation studied. Key Words : Validation; Fetal Weight; Sonography; Advanced Cyesis; Nigerian Population