title: Ductus venosus Doppler velocimetry in the first trimester: a new finding.
abstract: OBJECTIVE
  To establish reference curves for ductus venosus blood flow velocities during the first trimester and compare them with previously published curves.
  
  
  METHODS
  This was a cross-sectional and retrospective study performed between January 1998 and January 2003. The following inclusion criteria were used: singleton pregnancy, velocity measurements taken when the crown-rump length (CRL) was between 34 and 84 mm, absence of fetal anomalies, full-term pregnancy and newborn birth weight appropriate for gestational age. The following variables of the ductus venosus were measured: peak velocity during ventricular systole (S-wave) and diastole (D-wave), nadir during atrial contraction in late diastole (A-wave), time-averaged maximum velocity (TAMXV) and pulsatility index for veins (PIV).
  
  
  RESULTS
  A total of 843 fetuses were included. The mean CRL was 62 (range, 34-84) mm. The S-wave, D-wave, TAMXV and PIV were normally distributed, and logarithmic transformation was performed to achieve a normal distribution for the A-wave. S-wave, D-wave and A-wave and TAMXV increased with CRL. PIV increased up to a CRL of 63 mm and decreased thereafter. Regression analysis revealed a significant quadratic relationship between PIV and CRL.
  
  
  CONCLUSIONS
  S-wave, D-wave, A-wave velocities and TAMXV in the ductus venosus increase with CRL between 34 and 84 mm. The reference range for PIV has a biphasic pattern, with an initial non-significant increase up to a CRL of 63 mm and a fall thereafter.
authors.affiliation: Pós-Graduação em Saúde da Mulher, Faculdade de Medicina, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: L S
authors.initials: LS
authors.lastname: Teixeira
authors.forename: J
authors.initials: J
authors.lastname: Leite
authors.forename: M J B C
authors.initials: MJ
authors.lastname: Viegas
authors.forename: M M L
authors.initials: MM
authors.lastname: Faria
authors.forename: A S
authors.initials: AS
authors.lastname: Chaves
authors.forename: R C
authors.initials: RC
authors.lastname: Teixeira
authors.forename: M C
authors.initials: MC
authors.lastname: Pires
authors.forename: H
authors.initials: H
authors.lastname: Pettersen
mesh_terms: D003430:Cross-Sectional Studies; D018568:Crown-Rump Length; D003971:Diastole; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging*; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011673:Pulsatile Flow; D012016:Reference Values; D012039:Regional Blood Flow; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014680:Veins / Q000000981:diagnostic imaging