Comparison of three methods of fetal weight estimation in patients with severe and morbid obesity: a prospective study

The aim of this study was to compare ultrasonographic, maternal subjective and clinical estimations of fetal weight in women with severe/morbid obesity (BMI≥35) at term. A prospective study on multiparous women with singleton gestation was conducted. An US estimate (US-EFW) was performed in our ultrasound unit and based on Hadlock's 4 formula. For maternal subjective estimate (subjective-EFW), patients were asked to give a fetal weight estimation. Clinical-EFW was performed by a trained professional physician using Leopold's manoeuvres. All physicians were blinded to the documentation of the weight of prior deliveries and the Results of the other method of fetal weight estimation. The study included 60 patients, median BMI = 38.1 (35.1-47.8), median parity = 2 (2-8) and gestational age at delivery of 39.4 ± 1.3 weeks. The mean absolute error was 222.3 ± 161.3g in US-EFW, 265.9 ± 190.8g in subjective-EFW and 294.3 ± 241.4g in clinical-EFW. The mean absolute error was higher in US-EFW compared with clinical-EFW (p = 0.03). The absolute % error was higher in clinical-EFW compared with US-EFW (6.4% vs. 8.5%, p = 0.02). The absolute % error >15 was higher in clinical-EFW compared with US-EFW (16.7% vs. 3.3%, p = 0.02). The absolute % error >20 was higher in clinical-EFW compared with subjective-EFW and US-EFW (10.0%,1.7%,1.7%, p = 0.03). The absolute error >500g was higher in clinical-EFW compared with US-EFW (18.3% vs. 5.0%, p = 0.008). US-EFW has superior accuracy in patients with severe/morbid obesity when compared to clinical-EFW. Our results suggest that subjective-EFW can be used as an additional tool supporting the standard use of ultrasound. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.