Bajoria R, Kingdom J
Department of Obstetrics and Gynaecology, St Mary's Hospital, University of Manchester Medical School, U.K.
Prenat Diagn. 1997 Dec;17(13):1207-25.
Twin pregnancy has a disproportionate effect on perinatal mortality, being six times higher than for singleton gestations. The major threats to perinatal survival are from two very different pathological processes: spontaneous preterm delivery, and the interlacing clinical complications of monochorionicity. With the realization that perinatal loss/handicap is higher in monochorionic than dichorionic twins, attempts have been made in the last decade to assign chorionicity ultrasonographically, using single or composite parameters, such as number of placental masses, fetal sex, septal thickness and twin peak signs. Such knowledge will allow (a) risk stratification of twin gestations, (b) appropriate selection of prenatal screening and diagnostic methods, (c) vigilant monitoring for early diagnosis of twin-twin transfusion syndrome and growth restriction, and (d) management of preterm labour, congenital malformation, single intra-uterine death and polyhydramnios. By contrast, prospective knowledge of zygosity is unlikely to influence perinatal outcome, since approximately 25 per cent of monozygous conceptions have dichorionic placentation. Postnatal determination of zygosity in like sex twin pairs with dichorionic placenta is important for the future consideration of organ transplantation compatibility and to evaluate the genetic component of various diseases.
双胎妊娠对围产期死亡率有不成比例的影响，其围产期死亡率比单胎妊娠高六倍。围产期存活的主要威胁来自两个截然不同的病理过程：自发性早产和单绒毛膜性的一系列临床并发症。随着人们认识到单绒毛膜双胎的围产期丢失/残疾率高于双绒毛膜双胎，在过去十年中，人们尝试使用单一或综合参数，如胎盘块数量、胎儿性别、隔厚度和双峰征，通过超声检查来确定绒毛膜性。这些知识将有助于：（a）对双胎妊娠进行风险分层；（b）适当选择产前筛查和诊断方法；（c）密切监测以早期诊断双胎输血综合征和生长受限；（d）处理早产、先天性畸形、单胎宫内死亡和羊水过多。相比之下，合子性的前瞻性知识不太可能影响围产期结局，因为大约25%的单合子妊娠有双绒毛膜胎盘。对于有双绒毛膜胎盘的同性双胎，产后确定合子性对于未来考虑器官移植相容性和评估各种疾病的遗传成分很重要。
