title: Prolongation of follicular phase by delaying hCG administration results in a higher incidence of endometrial advancement on the day of oocyte retrieval in GnRH antagonist cycles.
abstract: BACKGROUND
  Prolongation of follicular phase by delaying hCG administration has been reported to result in a significantly lower ongoing pregnancy rate that did not seem to be due to an embryonic factor. The aim of this prospective randomized study was to assess the effect of delaying hCG administration on endometrial histology.
  
  
  METHODS
  Ten oocyte donors underwent endometrial biopsy on the day of oocyte retrieval and endometrial histology was assessed by Noyes' criteria. Ovarian stimulation was performed with recombinant (r)FSH and daily GnRH antagonist starting on day 6 of stimulation. Patients were randomized by a computer-generated list to receive 10 000 IU of hCG either as soon as > or =3 follicles > or =17 mm were present on ultrasound (early-hCG group, n = 5) or 2 days after this criterion was met (late-hCG group, n = 5).
  
  
  RESULTS
  When hCG was delayed, endometrial advancement was present in all samples examined (median advancement 3 days, range 2-3 days). On the contrary, no secretory changes were observed when the follicular phase was not prolonged (difference in the proportion of patients with advancement between the early-hCG and the late-hCG group: 100%, 95% CI: 38-100).
  
  
  CONCLUSIONS
  Prolongation of follicular phase by delaying hCG administration results in a higher incidence of endometrial advancement on the day of oocyte retrieval in GnRH antagonist cycles.
authors.affiliation: Centre for Reproductive Medicine, Dutch-speaking Brussels Free University, Belgium. stratis.kolibianakis@otenet.gr
authors.forename: Efstratios M
authors.initials: EM
authors.lastname: Kolibianakis
authors.forename: Claire
authors.initials: C
authors.lastname: Bourgain
authors.forename: Evangelos G
authors.initials: EG
authors.lastname: Papanikolaou
authors.forename: Michel
authors.initials: M
authors.lastname: Camus
authors.forename: Herman
authors.initials: H
authors.lastname: Tournaye
authors.forename: André C
authors.initials: AC
authors.lastname: Van Steirteghem
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
mesh_terms: D000328:Adult; D001706:Biopsy; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D004717:Endometrium / Q000166:cytology / Q000187:drug effects*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage; D005498:Follicular Phase / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors*; D006801:Humans; D015994:Incidence; D009865:Oocytes / Q000166:cytology*; D010062:Ovulation Induction / Q000379:methods / Q000706:statistics & numerical data; D011994:Recombinant Proteins / Q000008:administration & dosage; D027724:Reproductive Techniques, Assisted / Q000706:statistics & numerical data
chemical_list: D006063:Chorionic Gonadotropin; D011994:Recombinant Proteins; D007987:Gonadotropin-Releasing Hormone; D005640:Follicle Stimulating Hormone