title: 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.
authors.affiliation: Fetal Medicine Unit, Obstetrics and Gynecology Department, Cruces University Hospital, Biscay, Spain.
authors.forename: Nerea
authors.initials: N
authors.lastname: Maiz
authors.forename: David
authors.initials: D
authors.lastname: Wright
authors.forename: Ana Fatima A
authors.initials: AF
authors.lastname: Ferreira
authors.forename: Argyro
authors.initials: A
authors.lastname: Syngelaki
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D000328:Adult; D000782:Aneuploidy; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis; D005189:False Positive Reactions; D005260:Female; D005333:Fetus / Q000098:blood supply*; D005865:Gestational Age; D006801:Humans; D008423:Maternal Age; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D011673:Pulsatile Flow; D014314:Trisomy / Q000175:diagnosis
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human