Campbell K H, Copel J A, Ozan Bahtiyar M
Section of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Yale University School of Medicine, 333 Cedar Street, P.O. Box 208063, New Haven, CT, 06520-8063, USA.
Minerva Ginecol. 2009 Jun;61(3):239-44.
As ultrasound technology advances, diagnosis of fetal malformations, particularly congenital heart defects (CHD) is becoming standard practice. Currently, a key element of obstetrical care is the use of ultrasound to diagnose chorionicity in multiple gestations. Given the difference in incidence and types of complications between dichorionic and monochorionic pregnancies, early diagnosis of chorionicity is critical to determine the type of care and counseling a patient receives throughout the pregnancy. Early diagnosis of chorionicity allows investigators to more accurately determine the risk of CHD in monochorionic pregnancies. It has been long known that twin gestations incur a higher risk of congenital malformations, including CHD. However, it was not until recently that the incidence could be determined according to chorionicity. Previous studies looking at risk of malformations including CHD used the like-sex technique as a proxy for chorionicity, thereby overestimating the prevalence of monochorionic twins because roughly two-thirds of all twin gestations (including dichorionic) are the same sex. The rate of multiple gestations is increasing in the developed world. Assisted reproductive technology (ART) is partly responsible for the increased incidence of multiples. While many of the ART conceived pregnancies are dichorionic multiples, there is evidence that ART increases the risk of monochorionic multiple gestations. Presently, it is not technically feasible, nor practical, to screen all pregnancies with fetal echocardiography. Thus, many perinatal ultrasound centers screen women for risk factors that place them at higher risk for having a fetus with CHD. This higher risk' group then receives a fetal echocardiogram. The available literature regarding risk of CHD in monochorionic multiple gestations strongly points to a significant increase over the general population risk of 0.5-0.8%. Fetal echocardiography is technically feasible in twin pregnancies and increasingly available. Monochorionic multiple gestations should be screened with fetal echocardiography.
随着超声技术的进步，胎儿畸形的诊断，尤其是先天性心脏病（CHD）的诊断正成为标准做法。目前，产科护理的一个关键要素是使用超声诊断多胎妊娠的绒毛膜性。鉴于双绒毛膜妊娠和单绒毛膜妊娠在并发症发生率和类型上的差异，绒毛膜性的早期诊断对于确定患者在整个孕期接受的护理和咨询类型至关重要。绒毛膜性的早期诊断使研究人员能够更准确地确定单绒毛膜妊娠中患先天性心脏病的风险。长期以来人们都知道双胎妊娠患先天性畸形（包括先天性心脏病）的风险更高。然而，直到最近才能够根据绒毛膜性确定发病率。以往研究先天性心脏病等畸形风险时，使用同性技术作为绒毛膜性的替代指标，从而高估了单绒毛膜双胎的患病率，因为所有双胎妊娠（包括双绒毛膜妊娠）中约三分之二是同性别的。在发达国家，多胎妊娠的发生率正在上升。辅助生殖技术（ART）是多胎妊娠发生率增加的部分原因。虽然许多通过辅助生殖技术受孕的妊娠是双绒毛膜多胎妊娠，但有证据表明辅助生殖技术会增加单绒毛膜多胎妊娠的风险。目前，用胎儿超声心动图对所有妊娠进行筛查在技术上既不可行也不实际。因此，许多围产期超声中心会对有较高风险因素的女性进行筛查，这些因素使她们怀有患先天性心脏病胎儿的风险更高。然后这个“高风险”组会接受胎儿超声心动图检查。关于单绒毛膜多胎妊娠患先天性心脏病风险的现有文献有力地表明，其风险比一般人群0.5 - 0.8%的风险显著增加。胎儿超声心动图在双胎妊娠中技术上是可行的，并且越来越容易获得。单绒毛膜多胎妊娠应该接受胎儿超声心动图筛查。
