Division of Fetal Imaging, Department of Obstetrics and Gynecology, Oakland University William Beaumont School of Medicine, Royal Oak, MI 48073-6769, USA.
Ultrasound Obstet Gynecol. 2009 Nov;34(5):556-65. doi: 10.1002/uog.7327.
The main goal of this study was to determine the accuracy and precision of new fetal weight estimation models, based on fractional limb volume and conventional two-dimensional (2D) sonographic measurements during the second and third trimesters of pregnancy.
A prospective cross-sectional study of 271 fetuses was performed using three-dimensional ultrasonography to extract standard measurements-biparietal diameter (BPD), abdominal circumference (AC) and femoral diaphysis length (FDL)-plus fractional arm volume (AVol) and fractional thigh volume (TVol) within 4 days of delivery. Weighted multiple linear regression analysis was used to develop 'modified Hadlock' models and new models using transformed predictors that included soft tissue parameters for estimating birth weight. Estimated and observed birth weights were compared using mean percent difference (systematic weight estimation error) and the SD of the percent differences (random weight estimation error). The proportion of newborns with estimated birth weight within 5 or 10% of actual birth weight were compared using McNemar's test.
Birth weights in the study group ranged from 235 to 5790 g, with equal proportions of male and female infants. Six new fetal weight estimation models were compared with the results for modified Hadlock models with sample-specific coefficients. All the new models were very accurate, with mean percent differences that were not significantly different from zero. Model 3 (which used the natural logarithms of BPD, AC and AVol) and Model 6 (which used the natural logarithms of BPD, AC and TVol) provided the most precise weight estimations (random error = 6.6% of actual birth weight) as compared with 8.5% for the best original Hadlock model and 7.6% for a modified Hadlock model using sample-specific coefficients. Model 5 (which used the natural logarithms of AC and TVol) classified an additional 9.1% and 8.3% of the fetuses within 5% and 10% of actual birth weight and Model 6 classified an additional 7.3% and 4.1% of infants within 5% and 10% of actual birth weight.
The precision of fetal weight estimation can be improved by adding fractional limb volume measurements to conventional 2D biometry. New models that consider fractional limb volume may offer novel insight into the contribution of soft tissue development to weight estimation.
本研究的主要目的是确定基于胎儿四肢段体积和二维（2D）超声测量的新胎儿体重估测模型在妊娠第二和第三阶段的准确性和精密度。
前瞻性的 271 例胎儿的横截面研究使用三维超声提取标准测量值，包括双顶径（BPD）、腹围（AC）和股骨骨干长度（FDL），以及分娩后 4 天内的四肢段体积（AVol）和大腿段体积（TVol）。使用加权多元线性回归分析建立“改良 Hadlock”模型和使用包括软组织参数的转换预测因子的新模型来估计出生体重。使用平均百分比差异（系统体重估测误差）和百分比差异的标准差（随机体重估测误差）比较估计和观察到的出生体重。使用 McNemar 检验比较估计出生体重在实际出生体重的 5%或 10%以内的新生儿比例。
研究组的出生体重范围为 235 至 5790 克，男女婴儿比例相等。将 6 种新的胎儿体重估测模型与具有样本特异性系数的改良 Hadlock 模型的结果进行比较。所有新模型都非常准确，平均百分比差异与零无显著差异。模型 3（使用 BPD、AC 和 AVol 的自然对数）和模型 6（使用 BPD、AC 和 TVol 的自然对数）提供了最精确的体重估测（随机误差=实际出生体重的 6.6%），而最佳原始 Hadlock 模型为 8.5%，使用样本特异性系数的改良 Hadlock 模型为 7.6%。模型 5（使用 AC 和 TVol 的自然对数）将另外 9.1%和 8.3%的胎儿分类为实际出生体重的 5%和 10%以内，模型 6 将另外 7.3%和 4.1%的婴儿分类为实际出生体重的 5%和 10%以内。
通过将四肢段体积测量值添加到常规 2D 生物测量中，可以提高胎儿体重估测的精密度。考虑四肢段体积的新模型可能为软组织发育对体重估测的贡献提供新的见解。
