Snijders R J, Sebire N J, Souka A, Santiago C, Nicolaides K H
Harris Birthright Research Centre for Fetal Medicine, King's College Hospital Medical School, London, UK.
Ultrasound Obstet Gynecol. 1995 Oct;6(4):250-5. doi: 10.1046/j.1469-0705.1995.06040250.x.
In an ultrasound screening study involving 15,726 viable, singleton pregnancies at 11-14 weeks of gestation, exomphalos was diagnosed in 0.11% of the cases and, in those with exomphalos, the frequency of trisomy 18, trisomy 13 or triploidy was 61%. The corresponding frequencies of exomphalos of fetuses with these chromosomal defects were 22.5%, 9.1% and 12.5%, respectively. The median maternal age of the screened population was 33 (range 15-48) years, which is higher than in all pregnancies in England and Wales. Expected prevalences of trisomy 18, trisomy 13 and triploidy in the total population were derived on the basis of the age distribution of all deliveries in England and Wales and maternal and gestational age-specific risks for these chromosomal defects. From these numbers and the observed frequencies of exomphalos in association with the various chromosomal defects, it was estimated that the prevalence of exomphalos in a population with the maternal age distribution of all deliveries in England and Wales was 7.4 per 10,000 at 12 weeks of gestation, and this decreased to 3.5 at 20 weeks and 2.9 in live births. The estimated frequency of chromosomal defects in fetuses with exomphalos decreased from 39.4% at 12 weeks of gestation to 27.5% at 20 weeks and 14.4% in live births. The prevalence of chromosomal defects in 153 fetuses with exomphalos referred to our center at 16-26 (median 20) weeks of gestation was not significantly different from that predicted in an unselected population. However, the reported frequency of chromosomal defects in a total of 299 neonates with exomphalos (9.3%) was significantly lower than expected in an unselected population. This study demonstrates that the prevalence of a fetal abnormality and the frequency of associated chromosomal defects depends on the maternal age and gestational age distributions of the populations examined.
在一项针对15726例妊娠11至14周的存活单胎妊娠的超声筛查研究中，腹裂的诊断率为0.11%，在腹裂病例中，18三体、13三体或三倍体的发生率为61%。这些染色体缺陷胎儿的腹裂相应发生率分别为22.5%、9.1%和12.5%。筛查人群的母亲年龄中位数为33岁（范围15至48岁），高于英格兰和威尔士所有妊娠的母亲年龄。根据英格兰和威尔士所有分娩的年龄分布以及这些染色体缺陷的母亲年龄和孕周特异性风险，得出了总体人群中18三体、13三体和三倍体的预期患病率。根据这些数据以及观察到的与各种染色体缺陷相关的腹裂发生率，估计在具有英格兰和威尔士所有分娩母亲年龄分布的人群中，妊娠12周时腹裂的患病率为每10000例中有7.4例，到20周时降至3.5例，活产时为2.9例。估计腹裂胎儿中染色体缺陷的发生率从妊娠12周时的39.4%降至20周时的27.5%，活产时为14.4%。在妊娠16至26周（中位数20周）转诊至我们中心的153例腹裂胎儿中，染色体缺陷的患病率与未选择人群中预测的患病率无显著差异。然而，在总共299例腹裂新生儿中报告的染色体缺陷发生率（9.3%）显著低于未选择人群中的预期发生率。这项研究表明，胎儿异常的患病率和相关染色体缺陷的发生率取决于所检查人群的母亲年龄和孕周分布。
