Sydney Institute for Women, Children and Their Families, Sydney Local Health District, Sydney, New South Wales, Australia,
Monash IVF-Sydney Ultrasound for Women, Sydney, New South Wales, Australia,
Fetal Diagn Ther. 2020;47(4):321-327. doi: 10.1159/000504049. Epub 2020 Jan 21.
Monochorionic diamniotic (MCDA) twins are at increased risk of adverse outcome due to unequal placental sharing and placental vascular communications between the fetal circulations. Most centres perform ultrasound examination every 2-3 weeks to identify these complications. Identifying a high-risk cohort of MCDA twins in the first trimester would allow more efficient surveillance. We have attempted to validate first-trimester ultrasound characteristics as predictive tools for twin-twin transfusion syndrome (TTTS) and selective intrauterine growth restriction (sIUGR) in MCDA twins.
This is a prospective cohort study including MCDA twins enrolled at the time of first-trimester combined screening. Differences in crown-rump length (CRL), nuchal translucency (NT) thickness, ductus venosus pulsatility index for veins (DV PIV), presence or absence of tricuspid regurgitation and right ventricular E/A ratio were assessed. Receiver operating characteristic (ROC) curves were used to assess the potential value of these measures as predictive tools for identifying a cohort of MCDA pregnancies at high risk of adverse pregnancy outcome.
Sixty-five MCDA pregnancies were included in the analysis. Nine (14%) developed TTTS, 17 (26%) developed sIUGR. The best predictive marker for TTTS was NT discordance of ≥20% (ROC AUC = 0.79; 95% CI 0.59-0.99). Combining measures did not improve performance (AUC = 0.80; 95% CI 0.62-0.99).
NT discordance was the most effective characteristic at predicting TTTS but still had a relatively poor positive predictive value (36%). Intertwin differences in CRL, DV PIV and E/A ratio were not predictive of subsequent pregnancy complications. None of these characteristics have sufficient efficacy to be used to triage MCDA twin pregnancies ongoing obstetric surveillance.
由于胎盘间的不平等分配和胎儿循环之间的胎盘血管连通，单绒毛膜双羊膜（MCDA）双胞胎发生不良结局的风险增加。大多数中心每 2-3 周进行一次超声检查，以发现这些并发症。在孕早期识别 MCDA 双胞胎的高危队列将允许更有效的监测。我们试图验证孕早期超声特征作为预测 MCDA 双胞胎双胎输血综合征（TTTS）和选择性宫内生长受限（sIUGR）的工具。
这是一项前瞻性队列研究，包括在孕早期联合筛查时纳入的 MCDA 双胞胎。评估了头臀长（CRL）、颈项透明层（NT）厚度、静脉导管搏动指数（DV PIV）、三尖瓣反流的存在与否以及右心室 E/A 比值的差异。使用受试者工作特征（ROC）曲线评估这些指标作为预测工具，以识别 MCDA 妊娠中具有不良妊娠结局高风险的队列的潜在价值。
共纳入 65 例 MCDA 妊娠进行分析。9 例（14%）发生 TTTS，17 例（26%）发生 sIUGR。预测 TTTS 的最佳预测标志物是 NT 差异≥20%（ROC AUC = 0.79；95% CI 0.59-0.99）。联合测量并不能提高性能（AUC = 0.80；95% CI 0.62-0.99）。
NT 差异是预测 TTTS 最有效的特征，但阳性预测值仍相对较低（36%）。CRL、DV PIV 和 E/A 比值的双胞胎间差异不能预测随后的妊娠并发症。这些特征都没有足够的疗效用于 MCDA 双胎妊娠的产科监测。
