title: Evaluation of ductus venosus and inferior vena cava by using multiple Doppler ultrasound parameters in healthy fetuses.
abstract: OBJECTIVE
  The objective of this study was to describe multiple Doppler ultrasound parameters of ductus venosus and inferior vena cava in fetuses at gestational ages ranging from 22 to 38 weeks.
  
  
  METHODS
  In this prospective observational study, Doppler ultrasound exams were performed in 45 healthy fetuses at 22, 26, 34, and 38 weeks. Maximum venous velocity, minimum venous velocity, venous pulsatility index, and venous acceleration time (VAT) (defined as the time between minimum and maximum venous velocity) were evaluated at those gestational periods.
  
  
  RESULTS
  Increase in the velocities and decrease in the pulsatility index were observed in these vessels throughout gestational age. The VAT increased with gestational age.
  
  
  CONCLUSIONS
  The VAT, a Doppler parameter still not described elsewhere, increased during pregnancy could be related to a longer period of time needed to fill the atrium in bigger hearts. In this study, we provide reference values for VAT in healthy fetuses.
authors.affiliation: Departamento de Ginecologia e Obstetrícia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 8º andar, HCRP, Campus Universitário, Ribeirão Preto, São Paulo 14049-900, Brazil.
authors.forename: Francisco M P
authors.initials: FM
authors.lastname: Gallarreta
authors.forename: Wellington P
authors.initials: WP
authors.lastname: Martins
authors.forename: Carolina O
authors.initials: CO
authors.lastname: Nastri
authors.forename: Francisco
authors.initials: F
authors.lastname: Mauad Filho
authors.forename: Luis Guilherme C
authors.initials: LG
authors.lastname: Nicolau
authors.forename: Daniela A
authors.initials: DA
authors.lastname: Barra
authors.forename: Edson N
authors.initials: EN
authors.lastname: Morais
authors.forename: Gerson C
authors.initials: GC
authors.lastname: Crott
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005333:Fetus / Q000098:blood supply* / Q000502:physiology; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012016:Reference Values; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging* / Q000502:physiology; D055815:Young Adult