Ductus venosus blood flow assessment at 10–16 weeks' gestation and chromosomal abnormalities

Abstract

Background: Enlarged fetal nuchal translucency (NT) is a well established ultrasonographic marker for aneuploidy screening, especially during the first trimester of gestation. Nuchal translucency screening combined with maternal age at early mid‐trimester can identify about 75–80% of chromosomal abnormalities with a false–positive rate of 5%. Recently, Doppler parameters have been included in fetal aneuploidy screening, in order to improve the test performance. Changes in the ductus venosus (DV) blood flow velocity waveforms have been reported in a significant proportion of chromosomally abnormal fetuses at first and early mid‐trimester of pregnancy.Objective: The aim of our study was to evaluate the role of the DV blood flow assessment at 10–16 weeks' gestation in the screening for chromosomal abnormalities.Methods: From December 1998 to June 2001, DV blood flow was prospectively evaluated in 5067 consecutive pregnancies between 10 and 16 weeks of gestation. Pulsatility index for the DV (DVPI) was calculated. All cases were screened for chromosomal defects combining maternal age and fetal NT thickness.Results: The average maternal age was 32 years (range 22–47). Seventy‐four percent of the women were younger than 35. The incidence of chromosomal abnormalities was 1.06% (n = 54), including trisomy 21 (n = 25), trisomy 18 (n = 6), trisomy 13 (n = 2) and others (n = 21). The incidence of chromosomal abnormalities was 13.8% in those cases where DVPI was greater than the 95th centile, compared with an incidence of 0.3% in the remaining cases with a DVPI below this cut‐off. This fact gives and odds ratio (OR) of 48 (95% IC: 26–87). The overall detection rate (DR), specificity (S), positive predictive value (PPV) and negative predictive value (NPV) for chromosomal abnormalities were 70.4, 95.3, 13.8, and 99.7%, respectively, when using the 95th centile DVPI as a cut‐off. According to gestational age, all the statistical parameters were increased in early gestational age (10–13 weeks) when comparing with late gestational age (14–16 weeks), the corresponding DR and OR being 76.3% and 64 (95% CI: 30–138) compared with 56.3% and 26 (95% CI: 9–72), respectively. Moreover, when only autosomal trisomies were considered, a DR of 87.9% was reached with an S, PPV, NPV and OR of 95.3, 10.9, and 99.9% and 146 (95% CI: 51–418).Conclusions: Our results suggest that the evaluation of DVPI at 10–16 weeks' gestation is a useful tool in the screening for chromosomal defects, especially in detecting autosomal trisomies and when it is assessed in early gestational age.