Rolo Liliam Cristine, Nardozza Luciano Marcondes Machado, Araujo Júnior Edward, Nowak Paulo Martin, Moron Antonio Fernandes
Department of Obstetrics, São Paulo Federal University, SP, Brazil.
Arch Gynecol Obstet. 2009 Jun;279(6):821-7. doi: 10.1007/s00404-008-0828-8. Epub 2008 Nov 1.
Establish normative data for gestational sac volume (GSV) between 7 and 10 weeks gestation using three-dimensional ultrasonography (3DUS).
A cross-sectional study involving 74 normal pregnancies was performed to assess GSV between 7 and 10 weeks gestation. All measurements were performed using an endocavitary volumetric transducer. The virtual organ computer-aided analysis (VOCAL) method was used for volumetric calculations, with a 30 degrees rotation angle. To analyze the correlation between GSV and gestational age, regression models were constructed and adjustments were made using the determination coefficient (R (2)). For each week the mean, median, standard-deviation, minimum and maximum GSV values were calculated. The method proposed by Royston and Wright was used to calculate the reference intervals according to crown-rump length (CRL). The interclass correlation coefficient (ICC) and Bland-Altman graph were used to evaluate intraobserver variability.
There was a high correlation between GSV and gestational age (R (2) = 0.816). Mean GSV increased from 8.50 cm(3) at 7 weeks to 44.35 cm(3) at 10 weeks. There was also a significant correlation between GSV and CRL (R (2) = 0.693) with mean GSV increasing from 5.00 to 50.28 cm(3) for CRL between 9 and 40 mm. Intraobserver variability was excellent with an ICC = 0.9997 (95% CI, 0.9994-0.9998), with an average difference between measurements of 0.5 cm(3).
There is a correlation between GSV and CRL and this is a reproducible first trimester parameter. Reference limits for GSV using 3DUS were generated for pregnancies between 7 and 10 weeks.
使用三维超声（3DUS）建立妊娠7至10周时妊娠囊体积（GSV）的规范数据。
进行了一项涉及74例正常妊娠的横断面研究，以评估妊娠7至10周时的GSV。所有测量均使用腔内容积探头进行。采用虚拟器官计算机辅助分析（VOCAL）方法进行容积计算，旋转角度为30度。为分析GSV与孕周之间的相关性，构建回归模型并使用决定系数（R²）进行调整。计算每周GSV的均值、中位数、标准差、最小值和最大值。采用Royston和Wright提出的方法根据头臀长度（CRL）计算参考区间。使用组内相关系数（ICC）和Bland-Altman图评估观察者内变异性。
GSV与孕周之间存在高度相关性（R² = 0.816）。平均GSV从妊娠7周时的8.50 cm³增加到妊娠10周时的44.35 cm³。GSV与CRL之间也存在显著相关性（R² = 0.693），CRL在9至40 mm之间时，平均GSV从5.00 cm³增加到50.28 cm³。观察者内变异性极佳，ICC = 0.9997（95% CI，0.9994 - 0.9998），测量之间的平均差异为0.5 cm³。
GSV与CRL之间存在相关性，这是一个可重复的孕早期参数。生成了妊娠7至10周使用3DUS的GSV参考限值。
