[超声检查胎儿鼻骨在唐氏综合征产前筛查中的应用]

Xie Hong-Ning, Zhu Yun-Xiao, Li Li-Juan, He Hua

Department of Obstetrics and Gynecology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.

Zhonghua Fu Chan Ke Za Zhi. 2008 Mar;43(3):171-4.

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: 0.57-0.92). When short nasal bone was used as a cut-off, the sensitivity was 60.0%, 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.

目的

探讨超声检查胎儿鼻骨作为唐氏综合征（DS）筛查标志物的临床价值。

方法

研究于2004年10月至2007年3月在中山大学附属第一医院进行。采用二维超声在孕中期和孕晚期对1863例正常妊娠（正常组）和25例DS胎儿（研究组）的胎儿鼻骨进行评估。确定两组中鼻骨缺失或鼻骨短小的发生率。胎儿鼻骨缺失需在胎儿面部的三个正交平面得到确认，鼻骨短小包括根据孕周胎儿鼻骨短于正常第2.5百分位数的情况。使用诊断试验指标评估胎儿鼻骨异常作为DS产前筛查标志物的价值。

结果

（1）正常组1761例胎儿成功进行了鼻骨检查，检出率为94.5%（1761/1863）。102例胎儿因宫内位置不便未能检查。（2）正常组中鼻骨长度在整个孕期呈线性增长，其生长模式与孕周相关性良好（r = 0.605，P < 0.05）。3例正常胎儿鼻骨缺失（0.2%，3/1761），44例正常胎儿鼻骨短小（2.5%，44/1761）。（3）25例DS胎儿中7例鼻骨缺失（28.0%，7/25），15例鼻骨短小（60.0%，15/25）。（4）以鼻骨缺失为截断值时，DS的敏感度为28.0%，特异度为９９.８%，阳性似然比为164.45（95%CI：45.11 - 599.60），阴性似然比为0.72（95%CI：0.57 - 0.92）。以鼻骨短小为截断值时，敏感度为60.0%，特异度为97.5%，阳性似然比为24.03（95%CI：7.15 - 80.71），阴性似然比为0.41（95%CI：0.29 - 0.59）。