title: Ductus venosus blood flow velocity waveforms during the early second trimester of pregnancy in a Thai population.
abstract: OBJECTIVE
  To establish reference ranges for ductus venosus (DV) blood flow velocities and indices during the early second trimester.
  
  
  METHODS
  A cross-sectional DV Doppler study of fetuses at 15-22 weeks of gestation was conducted at Songklanagarind Hospital, Songkhla, Thailand, during 2013-2014. The peak forward velocities were recorded and the DV indices were calculated. Predicted reference ranges based on the 5th and 95th percentiles according to the week of gestation were constructed.
  
  
  RESULTS
  Among 371 fetuses, measurement of DV Doppler waveforms in the sagittal plane was achieved in 97.5% of cases. With advancing pregnancy (weeks 15 to 22), the DV velocities during ventricular systole, early diastole, and atrial contraction increased from 47.48 cm/s to 68.22 cm/s, 42.23 cm/s to 60.52 cm/s, and 15.94 cm/s to 34.84 cm/s, respectively. The time-averaged maximum value increased from 37.61 cm/s to 55.42 cm/s. The DV indices-pulsatility index for the vein, peak velocity index for the vein, preload index, and systolic/a-wave ratio-decreased from 0.79 to 0.59, 0.71 to 0.53, 0.63 to 0.47, and 2.72 to 1.90, respectively. The systolic/diastolic ratio remained relatively constant at 1.12.
  
  
  CONCLUSIONS
  Normal reference ranges for DV flow velocities and indices during the early second trimester were established.
authors: Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand. Electronic address: s.manaphat@gmail.com.
authors: Manaphat
authors: M
authors: Suksai
authors: Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
authors: Chitkasaem
authors: C
authors: Suwanrath
authors: Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
authors: Ounjai
authors: O
authors: Kor-anantakul
authors: Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
authors: Thitima
authors: T
authors: Suntharasaj
authors: Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
authors: Ninlapa
authors: N
authors: Pruksanusak
authors: Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
authors: Alan
authors: A
authors: Geater
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000502:physiology*; D011446:Prospective Studies; D012016:Reference Values; D013785:Thailand; D018608:Ultrasonography, Doppler / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D014471:Umbilical Veins / Q000000981:diagnostic imaging / Q000502:physiology*
keywords: Doppler ultrasonography; Ductus venosus; Pregnancy; Reference range; Second trimester