title: Ovarian hyperstimulation syndrome: pathophysiology, staging, prediction and prevention.
abstract: OBJECTIVE
  To identify, appraise and summarize the current evidence regarding the pathophysiology, staging, prediction and prevention of ovarian hyperstimulation syndrome (OHSS).
  
  
  METHODS
  Two comprehensive systematic reviews were carried out: one examined methods of predicting either high ovarian response or OHSS and the other examined interventions aimed at reducing the occurrence of OHSS. Additionally, we describe the related pathophysiology and staging criteria.
  
  
  RESULTS
  Seven studies examining methods of predicting OHSS and eight more examining methods of predicting high ovarian response to controlled ovarian stimulation were included. Current evidence shows that the best methods of predicting high response are antral follicle count and anti-Müllerian hormone levels, and that a high ovarian response (examined by the number of large follicles, estradiol concentration or the number of retrieved oocytes) is the best method of predicting the occurrence of OHSS. Ninety-seven randomized controlled trials examining the effect of several interventions for reducing the occurrence of OHSS were included. There was high-quality evidence that replacing human chorionic gonadotropin by gonadotropin-releasing hormone agonists or recombinant luteinizing hormone, and moderate-quality evidence that antagonist protocols, dopamine agonists and mild stimulation, reduce the occurrence of OHSS. The evidence for the effect of the other interventions was of low/very low quality. Additionally, we identified and described 12 different staging criteria.
  
  
  CONCLUSIONS
  There are useful predictive tools and several preventive interventions aimed at reducing the occurrence of OHSS. Acknowledging and understanding them are of crucial importance for planning the treatment of, and, ultimately, eliminating, OHSS while maintaining high pregnancy rates.
authors.affiliation: Department of Obstetrics and Gynecology, Ribeirao Preto Medical School, University of Sao Paulo (DGO-FMRP-USP), Ribeirao Preto, Brazil; School of Health Technology - Ultrasonography School of Ribeirao Preto (FATESA-EURP), Ribeirao Preto, Brazil.
authors.forename: C O
authors.initials: CO
authors.lastname: Nastri
authors.forename: D M
authors.initials: DM
authors.lastname: Teixeira
authors.forename: R M
authors.initials: RM
authors.lastname: Moroni
authors.forename: V M S
authors.initials: VM
authors.lastname: Leitão
authors.forename: W P
authors.initials: WP
authors.lastname: Martins
mesh_terms: D005260:Female; D006801:Humans; D016471:Ovarian Hyperstimulation Syndrome / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000517:prevention & control*; D011247:Pregnancy; D014463:Ultrasonography
keywords: ICSI; IVF; OHSS; assisted reproductive techniques; ovarian hyperstimulation syndrome; pathophysiology; prediction; prevention; prophylaxis