Burd Irina, Srinivas Sindhu, Paré Emmanuelle, Dharan Vanita, Wang Eileen
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Pennsylvania, 2000 Courtyard, 3400 Spruce St, Philadelphia, PA 19104-6142 USA.
J Ultrasound Med. 2009 Aug;28(8):1019-24. doi: 10.7863/jum.2009.28.8.1019.
Several published formulas exist for the determination of estimated fetal weight (EFW), with limited data on their comparative accuracies. The aims of our study were to assess and compare the performance of different EFW formulas in predicting actual birth weight (BW) in an urban population.
Patients with an EFW determined within 7 days of delivery were considered eligible for the study. Fourteen published formulas, derived from populations comparable to ours, were used to recalculate EFWs from the same initial measurements. The accuracy of the EFWs obtained from the different formulas were compared by percentage error methods using bias and precision and Bland-Altman limits of agreement methods. Sensitivity and specificity for prediction of being small for gestational age (SGA) were calculated.
Eighty-one fetuses were included in the study. Formula C of Hadlock et al [Hadlock C; log(10) BW = 1.335 - 0.0034(abdominal circumference [AC])(femur length [FL]) + 0.0316(biparietal diameter) + 0.0457(AC) + 0.1623(FL); Am J Obstet Gynecol 1985; 151:333-337] had the best performance according to the bias and precision method. Bland-Altman limits of agreement confirmed these results. Among the formulas, the sensitivity for detection of SGA ranged from 72% to 100%, and specificity was 41% to 88%. Hadlock C had the optimal sensitivity/specificity trade-off for detection of SGA.
Fourteen formulas showed considerable variation of bias and precision in our population as well as a wide range of sensitivities and specificities for SGA. The choice of the appropriate formula for EFW in a given population should be based on objective and explicit criteria. Consideration of bias and precision for the formula in the population being assessed is critical and may affect clinical care.
目前已有多个已发表的公式用于估算胎儿体重（EFW），但关于它们相对准确性的数据有限。我们研究的目的是评估和比较不同的EFW公式在预测城市人群实际出生体重（BW）方面的性能。
在分娩7天内确定EFW的患者被认为符合研究条件。使用从与我们相似的人群中得出的14个已发表公式，根据相同的初始测量值重新计算EFW。通过使用偏差和精密度的百分比误差方法以及Bland-Altman一致性界限方法，比较从不同公式获得的EFW的准确性。计算预测小于胎龄（SGA）的敏感性和特异性。
81例胎儿纳入研究。根据偏差和精密度方法，Hadlock等人的公式C（Hadlock C；log(10) BW = 1.335 - 0.0034（腹围[AC]）（股骨长度[FL]）+ 0.0316（双顶径）+ 0.0457（AC）+ 0.1623（FL）；《美国妇产科杂志》1985年；151：333 - 337）表现最佳。Bland-Altman一致性界限证实了这些结果。在这些公式中，检测SGA的敏感性范围为72%至100%，特异性为41%至88%。Hadlock C在检测SGA方面具有最佳的敏感性/特异性权衡。
14个公式在我们的人群中显示出偏差和精密度的显著差异，以及对SGA的广泛敏感性和特异性。在特定人群中选择合适的EFW公式应基于客观明确的标准。考虑所评估人群中公式的偏差和精密度至关重要，可能会影响临床护理。
