Institute of Reproductive and Developmental Biology (IRDB), Imperial College London, Hammersmith Campus, London, UK.
Ultrasound Obstet Gynecol. 2011 Nov;38(5):503-9. doi: 10.1002/uog.10075. Epub 2011 Oct 13.
We studied changes in mean gestational sac diameter (MSD) and embryonic crown-rump length (CRL) in intrauterine pregnancies of uncertain viability (IPUVs). We aimed to establish cut-off values for MSD and CRL growth that could be definitively associated with either viability or miscarriage, and to establish the relationship between growth in MSD and appearance of embryonic structures in the gestational sac.
One thousand and sixty consecutive IPUVs were recruited prospectively from four London University hospitals: 462 with no yolk sac or embryo, 419 with a yolk sac but no embryo, and 179 with an embryo but no heartbeat visible. IPUV was defined as an empty gestational sac with or without a yolk sac but no embryo seen with MSD < 20 or < 30 mm (depending on center) or an embryo with no heartbeat and CRL < 6 mm or < 8 mm (depending on center). Scans were repeated 7-14 days later. The endpoint was viability at first-trimester screening ultrasonography between 11 and 14 weeks. Change in MSD and CRL between the first and second scans of each pregnancy was compared with respect to viability and appearance of embryonic structures using the two-sample t-test.
The study included 359 pregnancies in which a gestational sac with or without embryo was identified at the follow-up scan 7-14 days later. Of these, 192 were viable and 167 non-viable at the 11-14-week scan. MSD growth was significantly higher in viable than non-viable pregnancies (mean 1.003 vs. 0.503 mm/day; P < 0.001, 95% CI of difference 0.403-0.596). A difference in CRL growth was found between the two groups (mean 0.673 vs. 0.148 mm/day; P < 0.001, 95% CI of difference 0.345-0.703). MSD growth of 0.6 mm/day was associated with a specificity for diagnosing miscarriage of 90.1%, a sensitivity of 61.7% and 19 false-positive test results. A cut-off of CRL growth rate of 0.2 mm/day gave a sensitivity of 76.3% and there were no false-positive test results for miscarriage. On repeat scan the failure of either a yolk sac or embryo to be visualized was always associated with miscarriage.
There is an overlap in MSD growth rates between viable and non-viable IPUV. No cut-off exists for MSD growth below which a viable pregnancy could be safely excluded. A cut-off value for CRL growth of 0.2 mm/day was always associated with miscarriage. These data suggest that criteria to diagnose miscarriage based on growth in MSD and CRL are potentially unsafe. However, finding an empty gestational sac on two scans more than 7 days apart is highly likely to indicate miscarriage, irrespective of growth.
我们研究了不确定存活能力的宫内妊娠（IPUV）中平均孕囊直径（MSD）和胚胎头臀长（CRL）的变化。我们旨在确定与存活能力或流产明确相关的 MSD 和 CRL 生长的截止值，并确定 MSD 生长与孕囊中胚胎结构出现之间的关系。
从伦敦四所大学医院前瞻性地招募了 1060 例连续的 IPUV：462 例无卵黄囊或胚胎，419 例有卵黄囊但无胚胎，179 例有胚胎但无可见胎心。IPUV 定义为孕囊为空，MSD<20 或<30mm（取决于中心）或胚胎有不可见胎心和 CRL<6mm 或<8mm（取决于中心），伴有或不伴有卵黄囊。扫描后 7-14 天重复。终点是 11-14 周的早孕筛查超声检查时的存活能力。使用两样本 t 检验比较每个妊娠的第一次和第二次扫描之间的 MSD 和 CRL 变化与存活能力和胚胎结构的出现。
这项研究包括 359 例在随访扫描 7-14 天后发现有或没有胚胎的孕囊的妊娠。其中，192 例在 11-14 周的扫描时存活，167 例不可存活。MSD 生长在存活组明显高于非存活组（平均 1.003 比 0.503mm/天；P<0.001，差异的 95%置信区间为 0.403-0.596）。两组之间 CRL 生长存在差异（平均 0.673 比 0.148mm/天；P<0.001，差异的 95%置信区间为 0.345-0.703）。MSD 生长 0.6mm/天与流产特异性为 90.1%，敏感性为 61.7%和 19 例假阳性检测结果相关。CRL 生长速度的截止值为 0.2mm/天，流产的敏感性为 76.3%，且没有假阳性检测结果。在重复扫描时，卵黄囊或胚胎无法被可视化总是与流产相关。
在存活和非存活的 IPUV 之间存在 MSD 生长速率的重叠。没有 MSD 生长的截止值可以安全地排除存活妊娠。CRL 生长速度的截止值为 0.2mm/天总是与流产相关。这些数据表明，基于 MSD 和 CRL 生长来诊断流产的标准可能是不安全的。然而，两次扫描间隔超过 7 天发现空孕囊极有可能表明流产，无论生长情况如何。
