[Ultrasound screening for chromosomal anomalies by assessment of the fetal nasal bone during 11-14 weeks of gestation--a pilot study]

Abstract

Aim: To assess the feasibility of ultrasound screening for chromosomal anomalies by verification of the fetal nasal bone at 11-14 weeks gestation.

Methods: A prospective longitudinal pilot study was performed in State University Hospital "Maichin dom" from September 2006 till September 2007. Thirty-six high-risk singleton pregnancies were examined between 11+0 and 14+0 weeks gestation with high-resolution ultrasound equipment. The first trimester scan included assessment of fetal number, viability and biometry, nuchal translucency measurement and fetal anatomy survey In each case the presence or absence of the fetal nasal bone was documented. The exam was performed in the mid-sagittal plane according to standardized published protocols. Increased NT > or = 95th centile and/or absence of the fetal nasal bone was considered as indication for invasive prenatal diagnosis. Pregnancy outcome was ascertained from hospital records, referring physicians or the patients themselves.

Results: Absence of the fetal nasal bone was verified in 11.1% (4/36) of cases. In all four cases an invasive prenatal procedure was performed. Chromosomal anomalies were found in three cases with absent fetal nasal bone (1--trisomy 21, 1--trisomy 18, 1--triplody), while the fourth case had normal fetal karyotype. In all three cases with chromosomal fetal anomalies termination of pregnancy was performed. The remaining 33 pregnancies had normal perinatal outcome.

Conclusion: Absence of the nasal bone at 11-14 weeks gestation is a new potential marker for chromosomal fetal anomalies in the first trimester of pregnancy.