Department of Gynecology, Obstetrics and Gynecological Endocrinology, Kepler University Hospital, Johannes Kepler University Linz, Altenberger Strasse 69, Krankenhausstrasse 26-30, 4040, Linz, Austria.
Arch Gynecol Obstet. 2020 Jan;301(1):129-135. doi: 10.1007/s00404-019-05410-7. Epub 2019 Dec 27.
Estimating fetal weight using ultrasound measurements is an essential task in obstetrics departments. Most of the commonly used weight estimation formulas underestimate fetal weight when the actual birthweight exceeds 4000 g. Porter et al. published a specially designed formula in an attempt to improve detection rates for such macrosomic infants. In this study, we question the usefulness of the Porter formula in clinical practice and draw attention to some critical issues concerning the derivation of specialized formulas of this type.
A retrospective cohort study was carried out, including 4654 singleton pregnancies with a birthweight ≥ 3500 g, with ultrasound examinations performed within 14 days before delivery. Fetal weight estimations derived using the Porter and Hadlock formulas were compared.
Of the macrosomic infants, 27.08% were identified by the Hadlock formula, with a false-positive rate of 4.60%. All macrosomic fetuses were detected using the Porter formula, with a false-positive rate of 100%; 99.96% of all weight estimations using the Porter formula fell within a range of 4300 g ± 10%. The Porter formula only provides macrosomic estimates.
The Porter formula does not succeed in distinguishing macrosomic from normal-weight fetuses. High-risk fetuses with a birthweight ≥ 4500 g in particular are not detected more precisely than with the Hadlock formula. For these reasons, we believe that the Porter formula should not be used in clinical practice. Newly derived weight estimation formulas for macrosomic fetuses must not be based solely on a macrosomic data set.
使用超声测量估计胎儿体重是妇产科的一项基本任务。当实际出生体重超过 4000 克时，大多数常用的体重估计公式会低估胎儿体重。波特等人发表了一个专门设计的公式，试图提高对这种巨大儿的检测率。在这项研究中，我们质疑波特公式在临床实践中的有用性，并提请注意关于此类专门公式推导的一些关键问题。
进行了一项回顾性队列研究，纳入了 4654 例出生体重≥3500 克的单胎妊娠，在分娩前 14 天内进行了超声检查。比较了使用波特公式和哈多克公式得出的胎儿体重估计值。
在巨大儿中，哈多克公式识别出 27.08%，假阳性率为 4.60%。所有巨大儿均通过波特公式检测，假阳性率为 100%；使用波特公式的所有体重估计值的 99.96%均落在 4300 克±10%的范围内。波特公式仅提供巨大儿的估计值。
波特公式不能成功区分巨大儿和正常体重儿。特别是出生体重≥4500 克的高危胎儿并没有比哈多克公式更精确地检测到。基于这些原因，我们认为波特公式不应在临床实践中使用。用于巨大儿的新体重估计公式不能仅基于巨大儿数据集。
