Abuhamad A Z, Kolm P, Mari G, Slotnick R N, Evans A T
Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, VA.
Am J Obstet Gynecol. 1994 Oct;171(4):1063-7. doi: 10.1016/0002-9378(94)90036-1.
Pelvic bone abnormalities are common in newborns with Down syndrome. The aim of this study was to evaluate the utility of ultrasonographic iliac bone length measurement in the identification of fetuses with Down syndrome in the second trimester of gestation.
Ultrasonographic iliac length measurement was obtained, in an axial view of the fetal pelvis, on 10 fetuses with Down syndrome and 180 karyotypically normal fetuses before genetic amniocentesis. Regression equations relating biparietal diameter to iliac length measurement were used to calculate ratios of observed-to-expected length, sensitivity, and specificity at various cutoff points.
Linear regression of iliac length measurement on biparietal diameter for normal fetuses resulted in the following equation: iliac length measurement (centimeters) = -0.2723 + 0.0333 biparietal diameter (millimeters). Iliac length measurement in Down syndrome fetuses was significantly longer than in normal controls (p < 0.0001). A ratio of 1.21 for observed-to-expected iliac length measurement yielded a sensitivity of 40%, a specificity of 98%, and positive predictive values of 50% and 2.60%, respectively, in populations at risk for Down syndrome of 1 in 20 and 1 in 750.
Iliac length measurement is increased in fetuses with Down syndrome. An observed-to-expected iliac length measurement of > or = 1.21 has a positive predictive value of 1/38 in a low-risk population with a false-positive rate of 2%. This preliminary study suggests that iliac length measurement may be useful as an ancillary screening variable in antenatal screening for Down syndrome.
骨盆骨异常在唐氏综合征新生儿中很常见。本研究的目的是评估超声测量髂骨长度在孕中期识别唐氏综合征胎儿中的作用。
在遗传羊膜穿刺术前，对10例唐氏综合征胎儿和180例核型正常胎儿的胎儿骨盆轴位视图进行超声髂骨长度测量。使用将双顶径与髂骨长度测量相关的回归方程来计算不同切点处观察到的与预期长度的比值、敏感性和特异性。
正常胎儿髂骨长度测量与双顶径的线性回归得出以下方程：髂骨长度测量（厘米）=-0.2723 + 0.0333双顶径（毫米）。唐氏综合征胎儿的髂骨长度测量明显长于正常对照组（p < 0.0001）。在唐氏综合征风险人群中，观察到的与预期髂骨长度测量的比值为1.21时，在20分之一和750分之一的人群中，敏感性分别为40%，特异性为98%，阳性预测值分别为50%和2.60%。
唐氏综合征胎儿的髂骨长度测量增加。在低风险人群中，观察到的与预期髂骨长度测量≥1.21时，阳性预测值为1/38，假阳性率为2%。这项初步研究表明，髂骨长度测量可能作为唐氏综合征产前筛查的辅助筛查变量有用。
