中晚孕期胎儿鼻骨缺失及染色体异常的超声诊断分析

目的：探讨孕16-34周超声筛查胎儿鼻骨缺失在染色体异常诊断中的应用价值。方法2008至2013年中晚孕期在北京协和医院超声筛查发现鼻骨缺失的20例胎儿均行染色体检查并随访至引产或出生后，总结胎儿鼻骨缺失超声声像图特征。结果20例胎儿产前超声显示：（1）双侧鼻骨缺失17例，面部正中矢状切面及横切面扫查均不能显示鼻梁皮肤下方的鼻骨强回声。其中5例胎儿合并多发畸形：4例胎儿心脏畸形（房室间隔缺损3例，房室间隔缺损合并大血管异常1例），1例胎儿十二指肠梗阻。其他微小结构异常包括：股骨及肱骨短，肠管回声增强，迷走右锁骨下动脉，单侧侧脑室临界增宽，双肾盂轻度增宽，吐舌征，双手姿势形态异常。（2）单侧鼻骨缺失3例，面部横切面扫查仅能显示胎儿一侧鼻骨强回声。其中2例合并心脏畸形（房室间隔缺损1例，室间隔缺损1例）；合并其他微小结构异常包括：股骨及肱骨短，肠管回声增强，颈背部皮肤增厚。（3）染色体检查：17例双侧鼻骨缺失胎儿中9例为21-三体，1例为4p-（Wolf-Hirschhorn综合征），7例为正常核型；3例单侧鼻骨缺失胎儿中2例为21-三体，1例为正常核型。（4）产后检查及随访：20例胎儿超声及染色体检查后引产12例（尸检1例），出生8例，5例随访无明显异常，3例失访；12例胎儿产前超声与产后检查结果均符合。结论中晚孕期鼻骨缺失胎儿超声图像特征为双侧或单侧鼻骨强回声缺失，且多伴微小结构异常，超声检出胎儿鼻骨缺失应行染色体核型分析，减少21-三体等染色体异常胎儿的出生。

The evaluation of fetal nasal bone absence at second and third trimester and its relationship with chromosomal abnormalities

Objective To evaluate the ultrasonic characteristics of nasal bone absence at 16-34 weeks of pregnancy referring to fetal chromosomal anomalies. Methods The ultrasonic findings of the 20 fetuses with nasal bone absence at second or third trimester in Peking Union Medical College Hospital were reviewed referring to chromosomal karyotyping and labor induction or birth outcomes. Results The ultrasound features of the 20 fetuses including：（1） There were 17 fetuses showed bilateral nasal bones absence. The sonographic features were absence of hyper echo of nasal bone underneath the skin on either sagittal or transverse section. There were 5 fetuses showed multiple abnormalities：Four fetuses showed cardiac abnormalities （three showed atrioventricular septal defect, one showed ventricular septal defect, one showed ventricular septal defect with abnormal great vessels）. One fetus showed duodenal obstruction′double bulbs′. The other minor abnormalities including short femur and humerus, increasing echogenetic bowels, aberrant right subclavian artery, mild unilateral ventriculomegaly, mild renal pelvic ectasia, outreached tongue, abnormal gestures of hands. （2） There were 3 fetuses showed unilateral nasal bone absence. The sonographic features were absence of hyper echo of either nasal bone on transverse section but with hyper echo on sagittal section. Two fetuses showed cardiac abnormalities （one fetus showed atrioventricular septal defect, one showed ventricular septal defect）. The other minor abnormalities including short femur and humerus, hyper echogenetic bowels, increasing thickness of nuchal translucency or nuchal fold. Twelve fetuses were induced labor but only one had biopsy showed accordant result with ultrasound. （3） Karyotyping results：there were 9 of trisomy 21, 1 of 4p-and 7 of normal karyotype fetuses showed bilateral nasal bone absence. There were 2 of trisomy 21 and 1 of normal karyotype fetuses showed unilateral nasal bone absence. （4） Birth outcomes and follow-up：twelve fetuses induced labor but only one fetus had biopsy. Eight fetuses were born until term and 5 fetuses showed normal in follow-up. The results of twelve fetuses showed concordant with ultrasonic ifndings. Conclusions Characteristics of the nasal bone absence are absence of bilateral or unilateral nasal bones. If we ifnd nasal bone absence in prenatally ultrasound screening, the karyotyping should be recommended in order to detect chromosomal abnormalities especially trisomy 21.