title: Oocytes in the empty follicle: a controversial syndrome.
abstract: OBJECTIVE
  To assess the prevalence and etiology of the empty follicle syndrome (EFS).
  
  
  METHODS
  Observational longitudinal study.
  
  
  METHODS
  Tertiary fertility centers.
  
  
  METHODS
  All patients beginning in vitro fertilization (IVF) treatment from December 2002 to November 2004 were included. Couples undergoing IVF with donor oocytes or participating in an experimental IVF study were excluded from analysis.
  
  
  METHODS
  Identification of EFS cycles. Comparing ovarian hyperstimulation strategy, follicle count, and timing of human chorionic gonadotropin (hCG) for final oocyte maturation of the EFS cycles with normal IVF cycles.
  
  
  METHODS
  Number of follicles punctured, number of oocytes recovered, previous and future IVF attempts, and serum hormone levels.
  
  
  RESULTS
  Twenty-five of a total of 1,849 patients were identified with an EFS cycle. Reasons for occurrence of EFS cycles were mistiming of hCG for final oocyte maturation, premature ovulation, and poor ovarian response. None of the affected patients had experienced EFS cycles in earlier IVF attempts nor were there any recurrence in subsequent treatments.
  
  
  CONCLUSIONS
  Accurate timing of induction of final oocyte maturation, properly scheduled ovarian hyperstimulation, instruction of patients and doctors, and full workup for IVF are essential for the successful recovery of oocytes. Occurrence of EFS in IVF can normally be attributed to a failure of at least one of these factors and probably rarely or never occurs otherwise.
authors.affiliation: Department of Obstetrics and Gynecology, Erasmus MC/Daniel den Hoed, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Aktas
authors.forename: Nicole G
authors.initials: NG
authors.lastname: Beckers
authors.forename: Wouter G
authors.initials: WG
authors.lastname: van Inzen
authors.forename: Arie
authors.initials: A
authors.lastname: Verhoeff
authors.forename: Diederick
authors.initials: D
authors.lastname: de Jong
mesh_terms: D000328:Adult; D006063:Chorionic Gonadotropin / Q000627:therapeutic use; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D007247:Infertility, Female / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D008137:Longitudinal Studies; D009865:Oocytes / Q000166:cytology*; D010049:Ovarian Diseases / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D006080:Ovarian Follicle / Q000473:pathology*; D010060:Ovulation; D010062:Ovulation Induction / Q000379:methods; D015995:Prevalence; D013577:Syndrome
chemical_list: D006063:Chorionic Gonadotropin