title: Fetal pulmonary venous blood flow velocities in a normal population and new calculated reference values.
abstract: OBJECTIVE
  The aim of this study is to establish new Doppler reference values in a population with normal pulmonary veins during different phases of the fetal cardiac cycle for maximum blood flow velocities during ventricular systole (S), early ventricular diastole (D), atrial contraction (a), intensity-weighted mean velocity (Vmean) and the indices derived from these parameters [(S - a)/D] and [(S - a)/Vmean].
  
  
  METHODS
  The pulsed-wave color advanced dynamic flow Doppler technique was used in a prospective cross-sectional study of 365 low-risk pregnancies between 18 and 41 completed gestational weeks. Reference ranges were calculated for the individual measuring parameters based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square principle.
  
  
  RESULTS
  During the observation period of 18 to 41 gestational weeks, a continuous increase was evident in maximum flow velocities for ventricular systole (S), early ventricular diastole (D), atrial contraction (a) and intensity-weighted mean velocity (Vmean) of 14.7 to 431.1, 12.5 to 426.2, 5.4 to 411.9 and 8.7 to 421.6 cm/s, respectively. Venous indices, however, showed a decrease with increasing gestational age: (S - a)/D from 0.9 to 0.7 and (S - a)/Vmean from 1 to 0.9.
  
  
  CONCLUSIONS
  The newly established normal values for the fetal pulmonary vein can be used in standardized Doppler sonography measurement to assess the left atrial pressure in the fetal heart. © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Obstetrics and Gynecology, Bürgerhospital Frankfurt, Frankfurt, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Bahlmann
authors.affiliation: Department of Obstetrics and Gynecology, Bürgerhospital Frankfurt, Frankfurt, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Gallinat
authors.affiliation: Department of Obstetrics and Gynecology, Bürgerhospital Frankfurt, Frankfurt, Germany.
authors.forename: Monica
authors.initials: M
authors.lastname: Schmidt-Fittschen
authors.affiliation: Department of Obstetrics and Gynecology, Bürgerhospital Frankfurt, Frankfurt, Germany.
authors.forename: Ammar
authors.initials: A
authors.lastname: Al Naimi
authors.affiliation: Department of Biostatistics, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Heidelberg, Germany.
authors.forename: Iris
authors.initials: I
authors.lastname: Reinhard
authors.affiliation: Department of Obstetrics and Gynecology, University Bonn, Bonn, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Willruth
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011446:Prospective Studies; D011652:Pulmonary Circulation; D011667:Pulmonary Veins / Q000502:physiology*; D012016:Reference Values; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal; D055815:Young Adult