P63The effect of fetal neck position on nuchal translucency measurement

Abstract

BackgroundThe aim of this study was to determine whether the position of the fetal neck has a significant effect on nuchal translucency measurement (NT).MethodA prospective cross‐sectional study was carried out. One hundred and ninety‐six women from an unselected population underwent transabdominal sonography. The nuchal translucency was measured in the mid‐sagittal plane, with the fetal neck in the flexed, neutral and extended positions. Measurement was taken to the nearest 0.1 mm. Statistical analysis using a paired t‐test for the differences in the extended and neutral position nuchal translucency [delta extended NT] and in the flexed and neutral position nuchal translucency [delta flexed NT] was performed.ResultsOn average the extended NT was 0.62 mm greater than the neutral NT value [95% confidence interval 0.53–0.70, T = 14.33, P = < 0.00001]. The flexed NT was on average 0.40 mm less than the neutral NT value [95% confidence interval 0.34–0.47, T = 11.99, P = < 0.00001]. The repeatability coefficient was lower in the case of neutral NT measurement [0.48] and was higher in the other groups [extended = 1.04, flexed = 0.70].ConclusionThe effect of fetal neck position can make a significant difference on nuchal translucency measurement. Repeatability of measurements are more accurate with the fetal neck in the neutral position. These findings have important implications for clinicians using nuchal translucency to screen the general obstetric population.