title: Is there evidence for preferential delivery of ovarian estradiol to the endometrium?
abstract: OBJECTIVE
  To determine the direction of delivery of E(2) in the female pelvis by assessing the ratio of endometrial to serum E(2) in women whose ovaries were stimulated to produce E(2) with women who received exogenous E(2).
  
  
  METHODS
  Prospective comparative study.
  
  
  METHODS
  University-based ART program.
  
  
  METHODS
  Oocyte donors and recipients of donor oocytes.
  
  
  METHODS
  Micronized E(2) administered by the oral or vaginal route and oocyte donation.
  
  
  METHODS
  Serum and endometrial levels of E(2).
  
  
  RESULTS
  Serum E(2) levels were significantly higher in women who underwent controlled ovarian hyperstimulation (COH) and women receiving exogenous E(2) by the vaginal route than in those who received oral E(2). Levels of E(2) in endometrial tissue were similar in women who underwent COH and those receiving oral E(2). Endometrial E(2) levels in women who underwent vaginal administration were significantly higher than those in the oral E(2) or COH groups. The ratio of endometrial to serum E(2) was highest in women who underwent vaginal E(2) and lowest in those undergoing COH.
  
  
  CONCLUSIONS
  Vaginal administration of micronized E(2) results in preferential absorption of E(2) into the endometrium, consistent with a "uterine first pass" effect. Since endogenous E(2) produced the smallest ratio of E(2) between the endometrium and serum, E(2) produced by the ovaries is not preferentially delivered to the uterus.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Southern California Keck School of Medicine, Los Angeles, California 90033, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Tourgeman
authors.forename: R
authors.initials: R
authors.lastname: Boostanfar
authors.forename: L
authors.initials: L
authors.lastname: Chang
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.forename: F Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: R J
authors.initials: RJ
authors.lastname: Paulson
mesh_terms: D000284:Administration, Oral; D004717:Endometrium / Q000378:metabolism*; D004958:Estradiol / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D006801:Humans; D010053:Ovary / Q000378:metabolism*; D011208:Powders; D011446:Prospective Studies; D014621:Vagina / Q000502:physiology
chemical_list: D011208:Powders; D004958:Estradiol