Estimation of fetal weight before delivery in low-resource setting of North-west Nigeria: can we rely on our clinical skills?

Abstract

Objective: To compare the accuracy of sonographic versus clinical methods of fetal weight estimation in a low-resource setting.

Methods: This was a prospective study. Ethical clearance and informed consent were obtained. Two hundred (200) women admitted for delivery were assessed. Questionnaires and data collection forms were used to obtain socio-demographic and other clinical information. The actual weight was determined at birth. Estimated fetal weight (EFW) was compared with the actual weight (BW). The data obtained were analyzed using SPSS version 16.0 statistical software. The accuracy of clinical and sonographic fetal weight estimation was compared using Students' t-test, Chi-square test and Pearsons' coefficient of correlation and p < 0.05 was considered statistically significant.

Results: The mean of absolute percentage error was smaller for ultrasonic (9.8 ± 7.2) than clinical (10.5 ± 7.5) estimation, but the difference was not statistically significant (p = 0.083). In the 2.5-3.99 kg group there was no statistically significant difference between the mean absolute percentage errors for the two methods (p = 0.096). In the <2.5 kg group, clinical method overestimated birth-weight while in ≥4.0 kg, the sonographic method underestimated the birth weight. For birth weight 2.5-3.99 kg, sensitivity, specificity, positive predictive value and negative predictive value were 96.9, 76.9, 98.1, 66.7% and 96.8, 75, 96.8, 75% for sonographic and clinical estimates, respectively. The predictive powers of sonographic and clinical methods were better for low birth weight and macrosomic fetuses, respectively.

Conclusion: Clinical method of fetal weight estimation can only be recommended for use as screening tool for normal weight and macrosomic fetuses.

Keywords: Clinical; Nigeria; North-west; estimation; fetal weight; low-resource; sonographic.