Awwad J T, Azar G B, Karam K S, Nicolaides K H
Department of Obstetrics and Gynecology, American University of Beirut Medical Center, Lebanon.
Int J Gynaecol Obstet. 1994 Mar;44(3):233-8. doi: 10.1016/0020-7292(94)90172-4.
The purpose of this study was to determine if antenatal sonographic determination of fetal ear length is a useful screening method for identification of fetuses with Down syndrome.
Ear length measurements were recorded in 418 fetuses undergoing ultrasound scanning between 20 and 28 weeks of gestation. Four trisomy 21 and six trisomy 18 fetuses were identified by karyotyping. The relationship between ear length and gestational age in the normal population was determined by linear regression analysis: expected ear length = -6.000 + 1.075 gestational age. The ability of measured-to-expected ear length cut-off ratios to discriminate between affected and non-affected fetuses was assessed.
The mean ear length and measured-to-expected ear length ratios were significantly lower in the affected group as compared to the normal one. A measured-to-expected ear length ratio of less than 0.8 was 75.0% sensitive and 98.8% specific in detecting Down syndrome fetuses, and resulted in an 8.5% positive predictive value in the general population.
This preliminary study suggests that antenatal ear length measurements might be a promising sonographic screening method for the detection of Down syndrome in the second trimester of pregnancy.
本研究旨在确定产前超声测定胎儿耳长是否为一种用于识别唐氏综合征胎儿的有效筛查方法。
记录了418例妊娠20至28周接受超声扫描的胎儿的耳长测量值。通过核型分析确定了4例21三体胎儿和6例18三体胎儿。通过线性回归分析确定正常人群中耳长与孕周之间的关系：预期耳长 = -6.000 + 1.075×孕周。评估了实测耳长与预期耳长的截断比值区分患病胎儿和未患病胎儿的能力。
与正常组相比，患病组的平均耳长和实测耳长与预期耳长的比值显著更低。实测耳长与预期耳长的比值小于0.8时，检测唐氏综合征胎儿的敏感度为75.0%，特异度为98.8%，在普通人群中的阳性预测值为8.5%。
这项初步研究表明，产前耳长测量可能是孕中期检测唐氏综合征的一种有前景的超声筛查方法。
