title: Empty follicle syndrome: the reality of a controversial syndrome, a systematic review.
abstract: OBJECTIVE
  To examine all case reports and studies of empty follicle syndrome (EFS) that have been published since the condition was first reported, in an attempt to identify trends or common features that may expose possible risk or causative factors.
  
  
  METHODS
  Systematic review of all available literature obtained from PubMed, Ovid, and Embase.
  
  
  METHODS
  Academic unit.
  
  
  METHODS
  Review of all published case reports and case studies.
  
  
  METHODS
  All original work was assessed and labeled as "genuine" or "false" EFS according to set definitions.
  
  
  METHODS
  Genuine and false EFS. We defined genuine EFS as a failure to retrieve oocytes from mature ovarian follicles after ovarian stimulation for IVF after apparently normal follicular development and steroidogenesis in the presence of optimal beta-hCG levels on the day of oocyte retrieval. False EFS included all cases in which this definition cannot apply and often in which human error or a pharmaceutical inaccuracy has occurred.
  
  
  RESULTS
  By classifying all cases of EFS as "genuine" or "false" according to stated definitions, it was evident that a much greater proportion of cases of reported EFS, 67%, occurred as a result of human error and that "genuine empty follicle syndrome" is an even rarer event than previously presumed.
  
  
  CONCLUSIONS
  Our report highlights the value of classifying cases of EFS as "genuine" or "false" and shows that more epidemiological data are required of "genuine" EFS cases to develop a clearer picture of the possible etiology.
authors.affiliation: Medical School, University of Sheffield, Jessop Wing, Sheffield, United Kingdom.
authors.forename: Tania Luisa
authors.initials: TL
authors.lastname: Stevenson
authors.forename: Hany
authors.initials: H
authors.lastname: Lashen
mesh_terms: D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D019317:Evidence-Based Medicine / Q000706:statistics & numerical data*; D005260:Female; D005307:Fertilization in Vitro / Q000706:statistics & numerical data*; D006801:Humans; D007247:Infertility, Female / Q000453:epidemiology*; D038622:Internationality; D010049:Ovarian Diseases / Q000453:epidemiology*; D006080:Ovarian Follicle / Q000473:pathology*; D015995:Prevalence; D013577:Syndrome; D020858:Tissue and Organ Harvesting / Q000706:statistics & numerical data*