探讨联体双胎早孕期超声声像图特征，总结早孕期超声诊断联体双胎的技巧。

对2011年1月至2017年12月因早孕期先兆流产在深圳市妇幼保健院超声筛查发现颈项透明层（NT）增厚、规范化超声筛查诊断为联体双胎21例胎儿的超声声像特征、联体部位、联体类型、合并畸形及妊娠结局进行分析，总结早孕期超声诊断联体双胎的技巧。

早孕期超声诊断的21例联体双胎平均头臀径相当于平均孕周；8例获得较满意的NT测量，其中7例NT厚度大于0.3 cm；21例双胎联体部位及联体类型：胸脐联胎12例（12/21），头部联胎3例（3/21），双头联胎3例（3/21），脐部联胎2例（2/21），坐骨联胎1例（1/21）。21例联体双胎二维超声检出合并脊柱畸形、单心室、腹裂、膈疝、脐膨出、脊柱裂等其他畸形；三维超声对联体类型和范围及外观特征的观察更直观。妊娠结局：21例联体双胎中4例胎死宫内，17例超声检查后孕妇选择终止妊娠，产后标本检查证实21例均为联体双胎。

早孕期超声检查可对联体类型及合并畸形做出明确诊断，有利于孕妇进行产前咨询。

To analyze the ultrasonographic features of conjoined twins and summarize the diagnostic skills in early pregnancy.

The ultrasonographic features, sites of union, type of fusion, related abnormalities and pregnancy outcomes were analyzed in 21 cases of conjoined twins who were checked up for early vagina bleeding during the first trimester or for 11^th-13^{th+ 6} gestational week scanning between January 2011 and December 2017 Shenzhen Maternity and Child Healthcare Hospital. The diagnostic skills of conjoined twins in early pregnancy were summarized.

Twenty-one cases of conjoined twins were diagnosed in the first trimester, whose gestational age were estimated by crown-rump length. NT measurements were obtained in 8 cases, of which 7 cases had increased nuchal translucency over 3.0 mm. The prenatal ultrasonic results of conjoined twins: there were 12 cases (12/21) of thoraco-omphalopagus, 3 cases (3/21) of cephalopagus, 3 cases (3/21) of parapagus dicephalus, 2 cases (2/21) of omphalopagus and 1 case (1/21) of ischiopagus. All cases were associated with other anomalies, including rachis deformation, single cardiac ventricle, gastroschisis, diaphragmatic hernia, omphalocele and spina bifida. Three-dimensional ultrasound imaging was helpful to confirm the types of fusion and improve facial features, which could be understood more easily. Postpartum examination showed: four cases had intrauterine fetal death, in the other 17 cases parents chose to terminate the pregnancy after ultrasound examination. All cases were confirmed to be conjoined twins by postpartum specimens.

Ultrasound examination in early pregnancy can make a clear diagnosis of the type of fusion and related abnormalities of conjoined twins, which is conducive to pregnant women for prenatal consultation.