title: [Doppler ultrasound examination of fetal umbilical arteries of the intra-abdominal segment in normal singleton pregnancies].
abstract: BACKGROUND
  In the management of high risk pregnancies, blood flow measurements in the umbilical arteries (Aa. umb) have reduced perinatal morbidity and mortality. No consensus has been reached about the optimal location of measurements along the umbilical cord. The present study analyses the blood flow in both umbilical arteries where they pass by the fetal bladder.
  
  
  METHODS
  In 48 normal pregnancies, Doppler examinations were used to measure the pulsatility indices (PI). From the 20th week of pregnancy onward, the PI were measured once every four weeks in the intraabdominal segments of the right and the left Aa. umb. lateral to the fetal bladder. Measurements were also done in a free loop and at the placental insertion.
  
  
  RESULTS
  For all locations, normal ranges were calculated. The PI at all four sites decreased as the pregnancies were approaching term. In the III. trimester, the standard deviations of PI were smaller than in the II. trimester. The PI at the intraabdominal segment of the right and the left umbilical arteries turned out to be similar to each other and exceeded the values measured at the free loop and at the placental insertion respectively.
  
  
  CONCLUSIONS
  The intraabdominal segments of the umbilical arteries were defined as a new location for PI measurements. When adopting a fixed place of measurement, it is likely that the reproducibility of PI measurements will be increased.
  
  
  CONCLUSIONS
  The higher PI at the intraabdominal segment of the umbilical arteries are caused by the more central location compared to the placental insertion.
authors.affiliation: Fetal Medicine Unit, St. George's Hospital Medical School, London.
authors.forename: M
authors.initials: M
authors.lastname: Schaefer
authors.forename: G
authors.initials: G
authors.lastname: Wittstock
authors.forename: Y
authors.initials: Y
authors.lastname: Ville
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011673:Pulsatile Flow / Q000502:physiology; D012016:Reference Values; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging*