对妊娠中晚期孕妇行超声检测胎儿鼻骨发育状况以筛查唐氏综合征

摘要

目的 探讨超声检测胎儿鼻骨发育状况对产前筛查唐氏综合征的临床应用价值.方法 2004年10月至2007年3月,应用二维超声对中山大学附属第一医院1863例中晚期孕妇(正常组)和25例妊娠唐氏综合征胎儿的孕妇(研究组)检测其胎儿鼻骨,观察两组中正常胎儿和唐氏综合征胎儿的鼻骨缺失、鼻骨短小的发生率.鼻骨缺失为胎儿面部矢状切面、横切面和冠状切面均未能显示鼻骨声像;鼻骨短小为鼻骨超声测值小于同孕周正常值的第2.5百分位数.计算鼻骨发育异常值筛查唐氏综合征的诊断试验结果.结果 (1)正常组孕妇中成功检测胎儿鼻骨1761例,102例受胎位等因素影响未能得到清晰图像,检测成功率为94.5%(1761/1863);(2)正常组中1761例胎儿鼻骨长度与孕周呈正相关关系(r=0.605,P＜0.05),其中鼻骨缺失3例(0.2%,3/1761),鼻骨短小44例(2.5%,44/1761);(3)研究组唐氏综合征胎儿中,鼻骨缺失7例(28.0%,7/25),鼻骨短小15例(60.0%,15/25);(4)以鼻骨缺失为截断值筛查唐氏综合征的敏感度为28.O%,特异度为99.8%,阳性似然比164.45(95%可信区间为45.11～599.60),阴性似然比0.72(95%可信区间为0.57～0.92);以鼻骨短小为截断值筛查唐氏综合征的敏感度为60.0%,特异度为97.5%,阳性似然比24.03(95%可信区间为7.15～80.71),阴性似然比0.41(95%可信区间为0.29～0.59).结论 胎儿鼻骨发育异常尤其是鼻骨缺失,与唐氏综合征关系密切,可作为产前超声筛查唐氏综合征的指标应用于临床.%Objective To investigate the clinic value of ultrasonographic fetal nasal bone examination as a screening marker for Down syndrome(DS).Methods The study was conducted in the First Affiliated Hospital of Sun Yat-sen University from Oct 2004 to Mar 2007.Two-dimensional ultrasound was used to assess the fetal nasal bone of 1863 normal pregnancies(normal group)and 25 cases with DS fetus (study group)during their second and third trimesters.The incidence of nasal bone absence or short nasal bone in two groups was determined.The fetal nasal bone absence should be confirmed in three orthogonal planes of the fetal face.and the short nasal bone included the cases that the fetal nasal bone was shorter than the 2.5th percentile of normal according to the gestational week.The diagnostic test index was used for assessing the value of fetal nasal bone abnormality as a marker in prenatal screening for DS.Results (1)1761 fetuses of normal group were successfully examined for the nasal bone and the detection rate was 94.5%(1761/1863).102 fetuses failed examination because of inconvenient intra-uterine position.(2)The nasal bone length grew in a linear fashion throughout pregnancy and the growth pattern correlated well with gestational age(r=0.605,P＜0.05)in normal group.The nasal bone was absent in 3 normal fetuses (0.2%,3/1761)and short nasal bone was found in 44 normal fetuses(2.5%,44/1761).(3)The nasal bone was absent in 7 DS fetuses(28.0%.7/25)and short nasal bone was found in 15 DS fetuses (60.0%.15/25).(4)When the absence of nasal bone was used as a cut-off,the sensitivity for DS was 28.0%.the specificity was 99.8%,the positive likelihood ratio was 164.45(95%CI:45.11-599.60),and the negative likelihood ratio was 0.72(95%CI:0.57-O.92).When short nasal bone was used as a cut-off.the sensitivity was 60.O%,specificity was 97.5%.the positive likelihood ratio was 24.03(95%CI:7.15-80.71),and the negative likelihood ratio was 0.41(95%CI:0.29-0.59).Conclusion Fetal nasal bone hypoplasia at the second and third trimester scan is associated with a high risk for Down syndrome and it can be used as a screen marker for this chromosomal abnormality.