The evaluation of fetal nasal bone absence at second and third trimester and its relationship with chromosomal abnormalities / 中华医学超声杂志（电子版）

ABSTRACT

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 abnormalitiesFour 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-uptwelve 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.