Dudley N J
Medical Physics Department, Nottingham City Hospital, Hucknall Road, Nottingham NG5 1PB, UK.
Ultrasound Obstet Gynecol. 2005 Jan;25(1):80-9. doi: 10.1002/uog.1751.
The range and use of ultrasound fetal measurements have gradually been extended. Measurements have been combined to estimate fetal weight by mathematically based non-linear regression analysis or physically based volumetric methods. Fetal weight estimation is inaccurate, with poor sensitivity for prediction of fetal compromise. Several authors have shown the unacceptable level of intra- and interobserver variability in fetal measurement and the impact of errors on growth assessment. The aims of this study were to review the available methods and possible sources of inaccuracy.
Four databases were searched for studies comparing ultrasound estimated fetal weight (EFW) with birth weight. Studies meeting the inclusion criteria evaluated 11 different methods. Errors were graphically summarized.
No consistently superior method has emerged. Volumetric methods provide some theoretical advantages. Random errors are large and must be reduced if clinical errors are to be avoided.
The accuracy of EFW is compromised by large intra- and interobserver variability. Efforts must be made to minimize this variability if EFW is to be clinically useful. This may be achieved through averaging of multiple measurements, improvements in image quality, uniform calibration of equipment, careful design and refinement of measurement methods, acknowledgment that there is a long learning curve, and regular audit of measurement quality. Further work to improve the universal validity and accuracy of fetal weight estimation formulae is also required.
超声胎儿测量的范围和应用逐渐得到扩展。测量结果已通过基于数学的非线性回归分析或基于物理的容积法相结合来估计胎儿体重。胎儿体重估计并不准确，对胎儿窘迫的预测敏感性较差。几位作者已经表明，胎儿测量中观察者内和观察者间的变异性水平令人无法接受，以及误差对生长评估的影响。本研究的目的是回顾现有的方法以及可能存在不准确的来源。
检索了四个数据库，以查找比较超声估计胎儿体重（EFW）与出生体重的研究。符合纳入标准的研究评估了11种不同的方法。以图表形式总结了误差。
尚未出现始终更优的方法。容积法具有一些理论优势。随机误差很大，如果要避免临床误差，就必须减少这些误差。
观察者内和观察者间的巨大变异性损害了EFW的准确性。如果EFW要在临床上有用，就必须努力将这种变异性降至最低。这可以通过多次测量的平均值、图像质量的改善、设备的统一校准、测量方法的精心设计和完善、认识到存在较长的学习曲线以及定期审核测量质量来实现。还需要进一步开展工作，以提高胎儿体重估计公式的普遍有效性和准确性。
