A Mixture Model of Ductus Venosus Pulsatility Index in Screening for Aneuploidies at 11–13 Weeks’ Gestation

Abstract

Objective: To assess the value of ductus venosus pulsatility index for veins (DV PIV) in screening for aneuploidies at 11–13 weeks’ gestation. Methods: Fetal DV PIV was measured in singleton pregnancies undergoing first-trimester screening for aneuploidies. In euploid (n = 44,756) and aneuploid (202 cases of trisomy 21, 72 cases of trisomy 18 and 30 cases of trisomy 13) fetuses, DV PIV was best described by a mixture model of distributions. Performance of screening for aneuploidies by DV PIV alone and in combination with fetal nuchal translucency (NT) thickness and serum free β-hCG and PAPP-A was estimated. Results: In euploid pregnancies there was a bimodal distribution of DV PIV with a dominant crown-rump length (CRL)-dependent part, accounting for around 97% of cases in Caucasians and around 93% in Afro-Caribbeans, and a smaller CRL-independent distribution. In aneuploidies the dominant part was the CRL-independent distribution, which accounted for around 85% cases of trisomies 21 and 18 and 70% of cases of trisomy 13. In screening for trisomy 21 by maternal age, NT and biochemistry at a risk cutoff of 1 in 100, the detection rate was 89.7% and false positive rate was 2.74%; with addition of DV PIV, the values were 93.5 and 1.63%, respectively. Conclusions: Measurement of DV PIV improves the performance of first-trimester combined test for aneuploidies.

Screening for trisomy 21 based on maternal age, nuchal translucency measurement, first trimester biochemistry and quantitative and qualitative assessment of the flow in the DV — the assessment of efficacy

“…The main challenge in screening is achieving the highest possible DR and lowest FPR [3,9]. The addition of DV flow analysis, after obtaining trisomy 21 risk calculated based on NT + BC, allows for more precise separation of the group with a high trisomy 21 risk, as compared to the method based on NT + BC only [3,5]. Abnormal DV in trisomy 21 is assumed to be indicative of impaired diastolic www.…”

“…Maiz and Nicolaides reported that an abnormal flow in the DV was observed in 69.1% of trisomy 21 fetuses, and in 3.7% of chromosomally normal fetuses [5,17]. First reports of the use of the DV flow assessment in trisomy 21 screening have been published in 1990's [16].…”

“…Our results demonstrate that adding DVPI measurement increases DR from 87.5% to 93.75%, with decrease of FPR from 6.94% to 5.55%. Using the double-step screening model for trisomy 21 with DVPI analysis, Maiz et al achieved the DR of 93.5% and FPR of 1.63% [5].…”

“…Nuchal translucency (NT) is considered to be the strongest marker of chromosomal defects, but in order to increase sensitivity and specificity some additional ultrasound markers are also assessed, including the nasal bone (NB), flow through the tricuspid valve (Tricuspid Regurgitation, TR), and flow through the ductus venosus (DV) [3,4]. The use of the last marker is increasing in screening for chromosomal defects and cardiac defects [3,5,6]. There are two methods of the DV assessment: qualitative -the assessment of the shape of the A-wave (the atrial component of the waveform), and quantitative -DVPI based on the pulsatility index for veins (PIV) [5,7,8] The screening algorithm for trisomy 21 (Down's Syndrome) involving maternal age (MA), NT, and first trimester biochemistry (BC) -serum free beta subunit of chorionic gonadotropin (free β-hCG), and pregnancyassociated plasma protein A (PAPP-A) levels expressed in MoMs -shows detection rate (DR) of 91% and 3% false positive rate (FPR).…”

“…The use of the last marker is increasing in screening for chromosomal defects and cardiac defects [3,5,6]. There are two methods of the DV assessment: qualitative -the assessment of the shape of the A-wave (the atrial component of the waveform), and quantitative -DVPI based on the pulsatility index for veins (PIV) [5,7,8] The screening algorithm for trisomy 21 (Down's Syndrome) involving maternal age (MA), NT, and first trimester biochemistry (BC) -serum free beta subunit of chorionic gonadotropin (free β-hCG), and pregnancyassociated plasma protein A (PAPP-A) levels expressed in MoMs -shows detection rate (DR) of 91% and 3% false positive rate (FPR). According to previous studies, adding the assessment of the DV increases DR of the test to 96% whereas FPR remains at the level of 3% [5,8].…”