Aye Christina Y L, Stevenson Gordon N, Impey Lawrence, Collins Sally L
Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Women's Centre, John Radcliffe Hospital, Headington, Oxford, United Kingdom.
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Headington, Oxford, United Kingdom.
Ultrasound Med Biol. 2015 Mar;41(3):734-40. doi: 10.1016/j.ultrasmedbio.2014.10.001. Epub 2015 Jan 22.
Ultrasound estimation of placental volume (PlaV) between 11 and 13 wk has been proposed as part of a screening test for small-for-gestational-age babies. A semi-automated 3-D technique, validated against the gold standard of manual delineation, has been found at this stage of gestation to predict small-for-gestational-age at term. Recently, when used in the third trimester, an estimate obtained using a 2-D technique was found to correlate with placental weight at delivery. Given its greater simplicity, the 2-D technique might be more useful as part of an early screening test. We investigated if the two techniques produced similar results when used in the first trimester. The correlation between PlaV values calculated by the two different techniques was assessed in 139 first-trimester placentas. The agreement on PlaV and derived "standardized placental volume," a dimensionless index correcting for gestational age, was explored with the Mann-Whitney test and Bland-Altman plots. Placentas were categorized into five different shape subtypes, and a subgroup analysis was performed. Agreement was poor for both PlaV and standardized PlaV (p < 0.001 and p < 0.001), with the 2-D technique yielding larger estimates for both indices compared with the 3-D method. The mean difference in standardized PlaV values between the two methods was 0.007 (95% confidence interval: 0.006-0.009). The best agreement was found for regular rectangle-shaped placentas (p = 0.438 and p = 0.408). The poor correlation between the 2-D and 3-D techniques may result from the heterogeneity of placental morphology at this stage of gestation. In early gestation, the simpler 2-D estimates of PlaV do not correlate strongly with those obtained with the validated 3-D technique.
超声测量孕11至13周胎盘体积（PlaV）已被提议作为筛查小于胎龄儿的一项检查内容。一种半自动三维技术，经与手工描绘的金标准验证，发现在此孕周阶段可预测足月时的小于胎龄儿情况。最近，当在孕晚期使用时，发现采用二维技术获得的估计值与分娩时的胎盘重量相关。鉴于二维技术更简便，它可能作为早期筛查检查的一部分更有用。我们研究了这两种技术在孕早期使用时是否产生相似结果。在139例孕早期胎盘中评估了两种不同技术计算的PlaV值之间的相关性。采用曼-惠特尼检验和布兰德-奥特曼图探讨了PlaV及衍生的“标准化胎盘体积”（一种校正孕周的无量纲指数）的一致性。胎盘被分为五种不同形状亚型，并进行了亚组分析。PlaV和标准化PlaV的一致性均较差（p<0.001和p<0.001），与三维方法相比，二维技术对两个指标的估计值都更大。两种方法标准化PlaV值的平均差异为0.007（95%置信区间：0.006 - 0.009）。规则矩形胎盘的一致性最佳（p = 0.438和p = 0.408）。二维和三维技术之间的相关性较差可能是由于此孕周阶段胎盘形态的异质性所致。在孕早期，二维技术对PlaV的较简单估计与经验证的三维技术获得的估计值相关性不强。
