Abstract:

Abstract: With the development of the application of assisted reproductive technologies and the increasing of maternal age, the frequency of twin gestations has increased severely. The risk of fetal structural anomalies and placental abnormalities in twins is much higher compared with singleton. Some of the nonspecific placental abnormalities can be found in twin gestations which can also be seen in singleton gestations， such as placenta previa, placental abruption, etc. However, other anomalies are unique to twin gestations, and are mainly associated with monochorionic twins, which include intraplacental anastomosis. Most of abnormalities can be diagnosed with ultrasound, including determination of chorionicity and amnionicity, and the identification of placental anomalies. Pathologic placental examination after delivery is useful in assessing the presence of placental abnormalities, as well as providing information about chorionicity and understanding the potential mechanisms of disease affecting twin gestations.

Key words: twin gestation, placenta, chorionicity;fetal placental ratio, twin-to-twin transfusion syndrome;vascular anatomosis

摘要：

双胎妊娠较单胎妊娠更容易发生胎儿异常及胎盘异常。双胎妊娠中的一些胎盘异常在单胎妊娠中也可发生，如前置胎盘、胎盘早剥等。然而，有些胎盘异常是双胎妊娠所特有的，且主要与单绒毛膜双胎有关，如胎盘内血管异常融合等。这些情况大多数可以用超声诊断，包括测定绒毛膜性、羊膜性以及胎盘异常的识别。分娩后胎盘病理检查可以帮助评估胎盘异常的存在,提供关于绒毛膜性的信息，了解双胎妊娠疾病的胎盘相关发病机制。

关键词: 双胎妊娠, 胎盘, 绒毛膜性, 胎儿胎盘比例, 双胎输血综合征, 血管吻合