Measurement difficulty and accuracy of ultrasound estimation of fetal weight during labour

Summary Ultrasound estimation of fetal weight has been advocated in the management of high risk pregnancy and labour but, as with other methods, large errors may occur and can result in inappropriate management. To test the hypothesis that the ease with which measurements are made correlates with accuracy of fetal weight estimation, we have used a 10 cm linear analogue to quantify the perceived measurement difficulty during ultrasound examination. In the fifty-one pregnancies studied, accuracy was significantly better in those scans made with ease than those made with some difficulty. of the 14 errors of 20 per cent or greater, 12 (86 per cent) were identified using the linear analogue as an indicator of difficulty. Our preliminary results suggest that some index of measurement difficulty be considered when interpreting ultrasound estimated fetal weights.