Toi A, Simpson G F, Filly R A
Am J Obstet Gynecol. 1987 Jan;156(1):150-3. doi: 10.1016/0002-9378(87)90227-4.
Fetal nuchal thickening in the second trimester is suggested as an ultrasonographic sign strongly suggesting the presence of Down syndrome. To better understand this potentially valuable observation, we explored aspects of the finding not considered in previous reports. The published data were reanalyzed to estimate statistically the presence of the sign in a low-risk obstetric population. Second, films of chromosomally normal fetuses were reviewed to confirm the normal range of measurement. Finally, autopsy reports of aborted Down syndrome fetuses were reviewed. Our results confirm that true nuchal thickening is present in some second-trimester Down syndrome fetuses. Unfortunately, a positive sign occurs in a significant proportion of chromosomally normal fetuses. Also our calculations predict a high incidence of false positive results in a low-risk obstetric population. Consequently we urge caution in the interpretation of these findings until prospective characterization of these observations is available.
孕中期胎儿颈部增厚被认为是一种强烈提示唐氏综合征存在的超声征象。为了更好地理解这一潜在有价值的观察结果，我们探讨了先前报告中未考虑的该发现的一些方面。重新分析已发表的数据以统计估计低风险产科人群中该征象的存在情况。其次，复查染色体正常胎儿的影像以确认测量的正常范围。最后，复查唐氏综合征流产胎儿的尸检报告。我们的结果证实，部分孕中期唐氏综合征胎儿确实存在颈部增厚。不幸的是，相当一部分染色体正常的胎儿也出现了阳性征象。此外，我们的计算预测在低风险产科人群中假阳性结果的发生率很高。因此，在获得这些观察结果的前瞻性特征描述之前，我们敦促在解释这些发现时要谨慎。
