title: Longitudinal doppler sonographic measurements of vascular impedance in the central and peripheral spiral arteries throughout pregnancy.
abstract: OBJECTIVE
  We assessed vascular impedance in the spiral arteries in the central and peripheral placental bed throughout uncomplicated pregnancies.
  
  
  METHODS
  Transabdominal color Doppler sonography was used to measure the pulsatility index (PI), resistance index (RI), and peak systolic velocity in the central and peripheral spiral arteries in 94 women with uncomplicated singleton pregnancies. Sonographic examinations took place approximately every 5 weeks from 10 to 40 weeks' menstrual age.
  
  
  RESULTS
  PI, RI, and peak systolic velocity were not different in the central versus the peripheral segments of the spiral arteries. The PI and RI values of central spiral arteries after 25 weeks' menstrual age. The PI and RI values of peripheral arteries decreased after 20 weeks' menstrual age.
  
  
  CONCLUSIONS
  Additional subjects are needed to clarify changes in the impedance of central and peripheral spiral arteries over the course of normal and complicated pregnancies.
authors.affiliation: Department of Obstetrics and Gynecology, China Medical College Hospital, No. 2 Yuh-Der Road, Taichung, Taiwan.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Hsieh
authors.forename: C C
authors.initials: CC
authors.lastname: Chang
authors.forename: H D
authors.initials: HD
authors.lastname: Tsai
authors.forename: C C
authors.initials: CC
authors.lastname: Lee
authors.forename: C H
authors.initials: CH
authors.lastname: Tsai
mesh_terms: D000328:Adult; D001158:Arteries / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology; D021041:Placental Circulation; D011247:Pregnancy / Q000502:physiology*; D018608:Ultrasonography, Doppler / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D014655:Vascular Resistance