Balsyte Dalia, Schäffer Leonhard, Zimmermann Roland, Kurmanavicius Jouzas, Burkhardt Tilo
Clinic of Obstetrics, University Hospital Zurich, Switzerland.
Clinic of Obstetrics, Baden Cantonal Hospital, Baden, Switzerland.
Ultraschall Med. 2017 Jan;38(1):60-64. doi: 10.1055/s-0035-1553252. Epub 2015 Sep 30.
The Hadlock et al. formula tends to underestimate fetal weight, in particular > 3500 g. At the high end of the range, the Merz et al. formula is more accurate, but becomes less so in smaller fetuses. This study was designed to improve fetal weight estimation in fetuses > 3500 g by identifying the fetal biometric parameter providing the most reliable guidance to optimal formula selection. Regression analysis of 12 032 pregnancies showed that multiplication of abdominal circumference by femur length (AC × FL) gave the best choice of appropriate formula: Hadlock for AC × FL < 24 600, Merz for those ≥ 24 600. We then tested this rule, ('Zurich method'), prospectively in 4073 pregnancies, comparing it with the Hadlock, Merz and the Kehl formulas. Birth weights were merged into 7 categories (< 1500 to ≥ 4000 g, interval of 500 g). The percentage error (PE) and absolute percentage error (APE) were calculated. The PE using the Zurich method was lower in both > 3500 g groups than with the Hadlock formula alone (3500 - 3999 g: 0.9 % vs. - 5.3 %, > 4000 g: - 3.2 % vs. - 8.6 %), similar to that with the Merz formula alone, and lower than with the Kehl formulas (3500 - 3999 g: - 9.0 % vs. - 3.2 %, > 4000g: - 5.1 % vs. 0.9 %). The Zurich method and Hadlock formula also shared the lowest PE in the < 1500 g group: 0.2 % vs. 6.8 % (Kehl) vs. 9.6 % (Merz). In terms of APE the Zurich method performed almost as well as the Merz formula in the > 4000 g group, while sharing the lowest value with the Hadlock formula in the < 1500 g group (8.2 % vs. 10.5 % [Kehl], 23.6 % [Merz]). The Zurich method uses a pivotal value of the biometry parameter AC × FL to switch between formulas and corrects for the errors of the Hadlock formula in fetuses ≥ 3500 g and those of the Merz formula in fetuses < 3500 g.
哈德洛克等人的公式往往会低估胎儿体重，尤其是体重超过3500克的胎儿。在体重范围的上限，默茨等人的公式更为准确，但对于较小的胎儿，其准确性会降低。本研究旨在通过确定能为最佳公式选择提供最可靠指导的胎儿生物测量参数，来改善对体重超过3500克胎儿的体重估计。对12032例妊娠进行的回归分析表明，腹围乘以股骨长度（AC×FL）能为合适公式的选择提供最佳依据：AC×FL＜24600时采用哈德洛克公式，AC×FL≥24600时采用默茨公式。然后，我们在4073例妊娠中对这一规则（“苏黎世方法”）进行了前瞻性测试，并将其与哈德洛克、默茨和凯尔公式进行比较。出生体重被合并为7个类别（＜1500克至≥4000克，间隔500克）。计算了百分比误差（PE）和绝对百分比误差（APE）。在两个体重超过3500克的组中，使用苏黎世方法的PE均低于单独使用哈德洛克公式（3500 - 3999克：0.9%对 - 5.3%，＞4000克： - 3.2%对 - 8.6%），与单独使用默茨公式时相似，且低于凯尔公式（3500 - 3999克： - 9.0%对 - 3.2%，＞4000克： - 5.1%对0.9%）。在体重＜1500克的组中，苏黎世方法和哈德洛克公式的PE也最低：0.2%对6.8%（凯尔）对9.6%（默茨）。在APE方面，苏黎世方法在体重＞4000克的组中表现几乎与默茨公式一样好，而在体重＜1500克的组中与哈德洛克公式共享最低值（8.2%对10.5%[凯尔]，23.6%[默茨]）。苏黎世方法使用生物测量参数AC×FL的一个关键值在公式之间进行切换，并校正了体重≥3500克胎儿中哈德洛克公式的误差以及体重＜3500克胎儿中默茨公式的误差。
