中晚孕胎儿单纯鼻骨缺如在唐氏综合征筛查中的临床意义

The role of isolated absent nasal bone in the screening of Down syndrome in the second and third trimester

目的评价中晚孕期胎儿单纯鼻骨缺如作为超声标记物在唐氏综合征筛查中的临床价值。方法回顾性分析2010至2013年中晚孕超声检查发现鼻骨缺如的胎儿,随访其产前诊断结果或新生儿检查结果。根据超声检查结果是否伴有其他结构异常分为单纯鼻骨缺如组(研究组)与伴有结构异常的鼻骨缺如组(对照组)。对比分析两组唐氏综合征的发病率。结果共发现36例鼻骨缺如的胎儿,其中唐氏综合征共7例(19.4%),其他染色体异常4例(11.1%),染色体正常25例(69.4%)。单纯鼻骨缺如的胎儿(研究组)中23例(95.8%)染色体正常,1例(4.2%)患有唐氏综合征;伴有结构异常鼻骨缺如的胎儿(对照组)中6例(50%)为唐氏综合征(P:0.003),4例(33.3%)为其他染色体异常,2例(16.7%)染色体正常。结论在中晚孕期超声检查中,伴有结构异常的鼻骨缺如与唐氏综合征关系密切,而不伴有结构异常的单纯鼻骨缺如与唐氏综合征的关系并不密切,单纯鼻骨缺如的胎儿是否需要进行有创性的产前诊断有待进一步研究。

Objective：To evaluate the significance of isolated absent nasal bone as an ultrasound marker for Down syndrome screening in the second and third trimester ultrasound scan. Methods：All cases of absent nasal bone during 2010-2013 were retrieved from database and all the ultrasound findings including structural abnormalities and fetal karyotype were reviewed. The cases were divided into a study group with isolated absent nasal bone and a comparison group with additional structural abnormalities. The incidence of Down syndrome confirmed by karyotyping or neonatal outcome was compared between the two groups. Results：Among 36 fetuses with absent nasal bone identified,7 cases（19.4%）had Down syndrome,4 cases had other chromosomal abnormalities（11.1%）and 25 cases（69.4%）were normal. In the study group,23 cases（95.8%）were normal and one case（4.2%）had Down syndrome. In the comparison group,6 cases（50%）had Down syndrome（P ：0.003）,4 cases（33.3%）had other chromosomal abnormalities and 2 cases（16.7%）had normal chromosomal type. Conclusions：In the second and third trimester ultrasound scan,absent nasal bone with structural abnormalities is strong marker for Down syndrome screening. However,isolated absent nasal bone may not be effective for Down syndrome screening. The necessity of taking the invasive prenatal diagnosis procedure for the isolated absent nasal bone needs further study.