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Objectives: To evaluate trends of nasal bone length (NBL), prenasal thickness (PT), nuchal fold (NF), prenasal thickness to nasal bone length (PT-NBL) ratio, and prefrontal space ratio (PFSR), measured serially in second- and third-trimester Down syndrome (DS) fetuses. Methods: Prenatal databases were searched for cases of continuing DS pregnancies with serial measurements, taken at least two weeks apart. Trends were plotted on previously reported normal ranges. Results: Serial measurements were available in 25 Down syndrome fetuses. Median gestational age (GA) was 25 weeks; average number of visits per case was 2.44, with a median interval of 39 days between investigations. In DS fetuses, NBL and PT showed fairly stable trends with gestation. PFSR, but especially NF, had a more unpredictable trend. The PT-NBL ratio was the most stable marker, remaining unchanged in 95% of cases. NBL, PT, and NF showed more deviance from the normal range with advancing gestation, but MoM values remained stable. All but two fetuses had ultrasound markers or structural anomalies, especially heart defects. Conclusions: The PT-NBL ratio is the most constant DS marker throughout gestation, following a predictable trend. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The aim of this study was to present our preliminary data about nasal bone measurements at 11-14 weeks of pregnancy. This study was conducted in our prenatal unit between 2000 and 2003. A total of 642 pregnant women (single pregnancies) were enrolled into the study. During the first trimester of pregnancy, crown-rump length, nuchal translucency thickness, and fetal nasal bone length measurements and ductus venosus Doppler images were evaluated. The distribution of absent or small nasal bones in both normal fetuses and in those having some pathological conditions was compared by statistical analysis. p < 0.05 was considered significant. Nasal bone evaluation was successful in 600 of 642 (93.4%) ultrasound examinations. The linear regression line showed a significant positive slope with increasing crown-rump length (r = 0.54, p < 0.001). Absent or small nasal bones were more common in abnormal than in normal fetuses (p = 0.007). It is clear that the fetal nasal bone is becoming a powerful tool in prenatal screening for aneuploidy. Larger studies to be performed in a low-risk population are needed to assess whether the measurement of the nasal bone length provides additional benefits beyond the assessment of the presence or absence of the nasal bone. [ABSTRACT FROM AUTHOR]