title: Doppler reference values of the fetal vertebral and middle cerebral arteries, at 19-41 weeks gestation.
abstract: OBJECTIVE
  Blood flow to the fetal brain is supplied by two vascular systems: the vertebral artery (VA) and the internal carotid artery with its anatomical continuation, the middle cerebral artery (ICA/MCA). In this work, our aim was to establish consistent reference values for the comparative study of both arterial systems.
  
  
  METHODS
  The study group consisted of 2323 Doppler examinations of the VA, MCA and UA performed on 2323 single pregnancies between 19 and 41 weeks. These values were afterwards used to calculate the pulsatility index (PI), peak systolic velocity (PSV) and cerebro-placental ratio (CPR) percentiles.
  
  
  RESULTS
  The VA and MCA PI reached maximum values at the end of the second trimester and decreased afterwards due to an increase in the diastolic flow. Conversely, the VA and MCA PSV increased progressively until the end of pregnancy. Regarding the VA and MCA CPR values, they were higher in the middle of the third trimester and decreased afterwards.
  
  
  CONCLUSIONS
  In both arterial systems, Doppler reference values have been calculated for the PI, PSV and CPR, being available for future comparative studies.
authors.affiliation: Servicio de Obstetricia, Hospital Universitario y Politécnico La Fe , Valencia , Spain .
authors.forename: José
authors.initials: J
authors.lastname: Morales-Roselló
authors.forename: Asma
authors.initials: A
authors.lastname: Khalil
authors.forename: Maddalena
authors.initials: M
authors.lastname: Morlando
authors.forename: David
authors.initials: D
authors.lastname: Hervás-Marín
authors.forename: Alfredo
authors.initials: A
authors.lastname: Perales-Marín
mesh_terms: D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply*; D005260:Female; D005865:Gestational Age; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012016:Reference Values; D018608:Ultrasonography, Doppler / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014711:Vertebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*
keywords: Fetal brain; fetal middle cerebral artery Doppler; fetal vertebral artery Doppler