Reliability of Sonographic Estimation of Fetal Weight: A Study of Three Tertiary Hospitals in Nigeria

CONTEXT: There is a dearth of sonologists in Nigeria, yet sonographic estimation of actual birth weight (ABW) is important in antenatal care. AIM: To determine the reliability of estimated fetal weight (EFW) by sonographers and sonologists in Lagos Nigeria. SETTINGS AND DESIGN: In the cross-sectional study, a convenience sample of 663 healthy women with singleton pregnancy at term was selected. Ethical approval for the study design and consent of participants were obtained. SUBJECTS AND METHODS: Three sonographers and three sonologists used a single ultrasound scanner with Hadlock-3 algorithm to measure biparietal diameter, abdominal circumference, and femur length in three centers while three midwives used a single neonatal weighing scale to measure ABW. STATISTICAL ANALYSIS USED: Medical(®) statistical software version 12.5 was used to analyze data. Descriptive and inferential statistics, as well as Bland/Altman plots were used to determine reliability of EFWs. Results were tested for statistical significance at P ≤ 0.05. RESULTS: Majority (76.2%) of babies had normal weight while mean EFW and ABW were 3.50 ± 0.10 kg and 3.45 ± 0.12 kg, respectively and the difference between them is not statistically significant (P > 0.05). For sonographers and sonologists in each center, mean error and coefficient of variation were very small while Pearson's correlation coefficient as well as intra- and interclass correlation coefficients was very high. CONCLUSION: Independent estimation of ABW by sonographers in Lagos metropolis was very reliable. Sonography was also highly reliable in predicting macrosomia.