First-trimester screening for Down syndrome with ductus venosus Doppler studies in addition to nuchal translucency and serum markers.
OBJECTIVE
To estimate the improvement in screening efficiency when fetal ductus venosus Doppler studies are added to existing first-trimester Down syndrome screening protocols.


METHODS
Statistical modelling was used with parameters derived from prospective ductus venosus studies and from the published literature. The pulsatility index for veins (PIV), was determined in the fetal ductus venosus for 3706 unaffected and 25 Down syndrome pregnancies at 10-14 weeks' gestation. Concurrent nuchal translucency measurement and maternal serum pregnancy associated plasma protein A and free-beta human chorionic gonadotrophin were also measured.


RESULTS
The median PIV in Down syndrome was 1.70 times higher than in unaffected pregnancies (95% confidence interval 1.36-2.12). PIV levels followed an approximately log Gaussian distribution with log(10) standard deviations of 0.193 and 0.076 in Down syndrome and unaffected pregnancies. There were no statistically significant correlations between PIV and the other markers. Modelling predicts that for a fixed 5% false-positive rate, the addition of PIV to nuchal translucency alone will increase the detection rate from 76 to 85%, and combined with serum markers, from 88 to 92%. For a fixed 85% detection rate, the false-positive rate reduced from 15 to 4.8% and from 3.2 to 1.2% respectively.


CONCLUSIONS
Ductus venosus Doppler studies can substantially improve Down syndrome screening efficiency.
Borrell
Antoni
A
Prenatal Diagnosis Unit, Institute of Gynecology, Obstetrics and Neonatology, University of Barcelona Medical School, Catalonia, Spain. aborrell@medicinia.ub.es
Gonce
Anna
A
Martinez
Josep M
JM
Borobio
Virginia
V
Fortuny
Albert
A
Coll
Oriol
O
Cuckle
Howard
H
D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000097:blood* / Q000000981:diagnostic imaging*; D005260:Female; D005333:Fetus / Q000098:blood supply*; D005865:Gestational Age; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000196:embryology; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011673:Pulsatile Flow; D016216:Ultrasonography, Prenatal; D014471:Umbilical Veins; D014680:Veins / Q000196:embryology; D014682:Vena Cava, Inferior / Q000196:embryology
D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A