title: The temporal effect of progestogen on uterine artery pulsatility index in postmenopausal women receiving sequential hormone replacement therapy.
abstract: OBJECTIVE
  To determine the time relationship between the ingestion of progestogen during sequential hormone replacement therapy (HRT) and impedance to blood flow in the uterine arteries.
  
  
  METHODS
  Nine postmenopausal women who had already received HRT for at least 6 months were treated with either transdermal 17 beta-E2, 0.1 mg/d, or conjugated equine estrogens (Es), 1.25 mg/d, to which norethindrone, 0.7 mg/d, was added for 12 days in a single 28-day cycle of therapy. Transvaginal ultrasonography with color flow imaging was used to measure the pulsatility index (PI) in the uterine arteries every 3 to 5 days over one 28-day treatment cycle.
  
  
  RESULTS
  The ingestion of norethindrone increased the mean uterine artery PI by 30% (SE 16.4%). The PI fell significantly within 4 days of ceasing norethindrone.
  
  
  CONCLUSIONS
  Progestogen addition in sequential HRT causes changes in the uterine arterial tone, but the effect subsides within 4 days of progestogen withdrawal.
authors.affiliation: Academic Department of Obstetrics and Gynaecology, King's College School of Medicine and Dentistry, London, United Kingdom.
authors.forename: M S
authors.initials: MS
authors.lastname: Marsh
authors.forename: T H
authors.initials: TH
authors.lastname: Bourne
authors.forename: M I
authors.initials: MI
authors.lastname: Whitehead
authors.forename: W P
authors.initials: WP
authors.lastname: Collins
authors.forename: S
authors.initials: S
authors.lastname: Campbell
mesh_terms: D001158:Arteries / Q000000981:diagnostic imaging; D004717:Endometrium / Q000000981:diagnostic imaging; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D009640:Norethindrone / Q000494:pharmacology; D017698:Postmenopause; D011372:Progestins / Q000494:pharmacology*; D011673:Pulsatile Flow; D012039:Regional Blood Flow / Q000187:drug effects; D013997:Time Factors; D014463:Ultrasonography; D014599:Uterus / Q000098:blood supply*
chemical_list: D011372:Progestins; D009640:Norethindrone