Ductus venosus pulsatility index measurement reduces the false-positive rate in first-trimester screening.
OBJECTIVE
To investigate if ductus venosus (DV) pulsatility index for veins (PIV) and a-wave measurements can increase the accuracy of first-trimester Down syndrome screening in a high-risk population.


METHODS
The database of our fetal medicine unit was searched for all cases at increased first-trimester Down syndrome risk. Multivariable logistic regression was used to construct a prediction rule for chromosomal anomalies at any given maternal age, nuchal translucency multiples of the median (NT-MoM) and DV-PIV MoM. The discriminative ability of the model was assessed by using receiver-operating characteristics (ROC) analysis.


RESULTS
The study population included 445 fetuses. DV-PIV was increased (≥ 95(th) percentile) in 239 (54%) and DV a-wave was abnormal in 187 fetuses (42%). In this cohort, 80% of all chromosomal anomalies were identified by an increased DV-PIV and 68% by an abnormal a-wave. The odds of chromosomal anomalies increased by a factor of 4.2 per MoM increase in DV-PIV, adjusted for NT and maternal age. The area under the ROC curve for the prediction of chromosomal anomalies was 0.79. After correction for DV-PIV, DV a-wave did not significantly add to the prediction of chromosomal anomalies.


CONCLUSIONS
In a population of fetuses at increased first-trimester risk for Down syndrome, the combination in a logistic regression model of NT, DV-PIV and maternal age can improve the accuracy of screening for trisomy 21 and other chromosomal anomalies. This is the first study that models the additional value of DV-PIV as a continuous variable to NT measurement alone in a high-risk first-trimester population.
Department of Obstetrics and Gynecology, Academic Medical Centre, Amsterdam, The Netherlands. e.timmerman@amc.nl
E
E
Timmerman
K
K
Oude Rengerink
E
E
Pajkrt
B C
BC
Opmeer
J A M
JA
van der Post
C M
CM
Bilardo
D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D004314:Down Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal; D014471:Umbilical Veins / Q000098:blood supply / Q000000981:diagnostic imaging*; D055815:Young Adult