THE EFFECT OF NUCHAL CORD ON NUCHAL TRANSLUCENCY MEASUREMENT AT 10-14WEEKS

The aim of this study was to determine the incidence of nuchal cord an d its possible effect on nuchal translucency thickness at 10-14 weeks' gestation. Out of 316 consecutive pregnancies in which nuchal translu cency thickness was measured transabdominally, 26 (8.23%) fetuses were shown to have the umbilical cord around the neck. The umbilical cord can be measured together with the nuchal translucency thickness when i t passes around the fetal neck and this adds a mean of 0.8 mm to the a ctual translucency measurement. After the thickness of the cord was su btracted, the measurements of nuchal translucency thickness did not di ffer from those in the overall population studied. Of the 22 fetuses a vailable for follow-up, a nuchal cord was found in only one at 20 week s and in none at delivery. Our findings indicate that the presence of a nuchal cord may bias the results of fetal nuchal translucency measur ement and that the use of color Doppler might decrease the false-posit ive rate in screening for fetal aneuploidy by nuchal translucency meas urement at 10-24 weeks' gestation.