Wapner R J
Department of Obstetrics and Gynecology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107, USA.
Semin Perinatol. 1995 Oct;19(5):351-62. doi: 10.1016/s0146-0005(05)80013-8.
A twin gestation presents unique problems in both genetic counseling and prenatal diagnosis. This article describes the specific genetic counseling concerns for a twin gestation and outlines the available techniques for genetic prenatal diagnosis. The technical aspects, risks and benefits to the pregnancy of amniocentesis and of chorionic villi sampling are compared. Although the risk of miscarriage after amniocentesis in a twin gestation is at least double that for a singleton, much of this additional risk is secondary to the inherent hazards of twins and not procedure-related. In experienced centers, chorionic villi sampling is equally safe and efficacious, and allows an earlier diagnosis that may be beneficial when discordant results are found. The aspects of serum screening unique to twin gestations are also outlined. Prenatal diagnosis by both chorionic villus sampling and amniocentesis can be safely performed in twin gestations and higher-order multiple gestations. Serum screening is also useful, but appears to have a lower sensitivity and specificity than in singletons.
双胎妊娠在遗传咨询和产前诊断方面都存在独特的问题。本文描述了双胎妊娠具体的遗传咨询要点，并概述了现有的遗传产前诊断技术。比较了羊膜穿刺术和绒毛取样术在技术方面、对妊娠的风险和益处。虽然双胎妊娠进行羊膜穿刺术后流产的风险至少是单胎妊娠的两倍，但这种额外风险大多是双胎固有风险所致，而非与操作相关。在经验丰富的中心，绒毛取样同样安全有效，且能更早诊断，当发现不一致结果时可能有益。文中还概述了双胎妊娠血清筛查的独特之处。绒毛取样术和羊膜穿刺术进行的产前诊断在双胎妊娠及更高阶多胎妊娠中均可安全实施。血清筛查也有用，但似乎比单胎妊娠的敏感性和特异性更低。
