The effect of nuchal cord on nuchal translucency measurement at 10–14 weeks

Abstract

The aim of this study was to determine the incidence of nuchal cord and its possible effect on nuchal translucency thickness at 10-14 weeks' gestation. Out of 316 consecutive pregnancies in which nuchal translucency 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 it passes around the fetal neck and this adds a mean of 0.8 mm to the actual translucency measurement. After the thickness of the cord was subtracted, the measurements of nuchal translucency thickness did not differ from those in the overall population studied. Of the 22 fetuses available for follow-up, a nuchal cord was found in only one at 20 weeks and in none at delivery. Our findings indicate that the presence of a nuchal cord may bias the results of fetal nuchal translucency measurement and that the use of color Doppler might decrease the false-positive rate in screening for fetal aneuploidy by nuchal translucency measurement at 10-14 weeks' gestation.

The prevalence of nuchal cords noted during nuchal translucency screens and subsequent perinatal outcomes

“…In a series of 316 patients by Schaefer et al [7] they found that there were 8.2% cases of nuchal cord at the time of NTS, with a NT measurement of 2.5mm in nuchal cords and 1.62mm in patients without nuchal cords. However, they subtracted the thickness of the nuchal cord (mean nuchal cord thickness of 0.8mm) from the NT measurement and concluded that the mean NT measurement was no different in nuchal cords cases and those without a nuchal cord.…”

“…The investigators suspected the prevalence of nuchal cords at the NTS would be 5% based on prior studies from Schaefer et al [7] and Scheier et al [8] A sample size of 456 would allow the study to detect the prevalence with 2% precision and 95% confidence. The two-year study time period included a sufficient number of eligible patients to reach this level of precision.…”

“…However, during the nuchal translucency screen (NTS) nuchal cords are searched for, as this alters the nuchal translucency (NT) measurement. There have been two studies [7,8] describing the prevalence of nuchal cords found during the first trimester NTS and the impact the presence of a nuchal cord has on the NT measurement. However, neither study followed their cohort through delivery and perinatal outcomes were not reported, which is the primary focus and aim of our study.…”

Variability of Nuchal Translucency Measurement

“…In contrast, there was no signifi cant difference when measured the fetus in the prone or supine position [19] . The nuchal cord also increased the value of NT 0.8 mm [20]. Then, color Doppler ultrasound is recommended to check whether there is a cord around the fetal neck in case of thick NT.…”

15 Haftalık Fetusun İntrauterin Fetal Ölümü ile Sonuçlanan Boynuna ve Sol Koluna Dolanmış Umblikal Kor

“…Schaefer ve ark. 10 ve 14. gebelik haftaları arasında nukal kord oranını (ve ense kalınlığı ölçümünde etkisini) belirlemede Doppler görüntülemeden yararlandılar (10). Transabdominal değerlen-dirilen 316 hastada, 26 (%8.23) fetüsta nukal kord varlığı izlendi.…”