Fetal Nasal Bone Length in the Period of 11 and 15 Weeks of Pregnancy in the Filipino Population

In the recent years, sonographic images of fetal nose have gained popularity in detecting trisomy 21 and other aneuploidies. Reference values for nasal bone length have been reported in different countries and ethnic populations. However, there was no reference range for the fetal nasal bone length (NBL) in the Filipino population. This prospective, cross-sectional study was conducted to establish reference values for the nasal bone length (NBL) at 11 – 15 weeks of gestation in the Filipino population. Ultrasonographic visualization of 74 fetuses at 11th to 15th week gestation was carried out during the months of August 2010 to January 2011. Fetal nasal bone was measured through sagittal section of the fetal profile. Fetal nasal bone length measurement was successfully performed in all 74 cases. The mean nasal bone lengths were 1.97 mm, 2.37 mm, 2.90 mm, 3.49 mm, and 4.05 mm between 11th, 12th, 13th, 14th, and 15th gestational weeks respectively. Nasal bone length increased linearly with advancing gestational age (GA) and crown rump length (CRL). Despite of the limitations posed by this investigation, reference values for the nasal bone length (NBL) at 11 – 15 weeks of gestation in the Filipino population was identified.