title: Unpredictable cases of complicated ovarian hyperstimulation in IVF.
abstract: OBJECTIVE
  To characterize a subpopulation of complicated cases of ovarian hyperstimulation syndrome (OHSS).
  
  
  METHODS
  Descriptive retrospective study.
  
  
  RESULTS
  0.75% of our IVF-ET population suffered from OHSS. Among this group, 33% did not exhibit any recognized risk criteria of OHSS in terms of infertility characteristics and ovarian response to exogenous gonadotrophins. Only severe (ascites) OHSS cases were considered (n = 5) in this study. Previous IVF-ET attempts had been uneventful and during the complicated trial, estradiol peak levels and numbers of oocytes retrieved remained below 2,500 pg/mL (conversion factor to SI unit, 3.671) and 10, respectively. In all cases, the luteal phase was supplemented by hCG and all patients became pregnant. A threshold level of exogenous and/or endogenous hCG seems to be responsible for the occurrence of OHSS.
  
  
  CONCLUSIONS
  One-third of the patients developing an ovarian hyperstimulation syndrome after IVF-ET had not previously shown risk criteria. A causal role of exogenous and/or endogenous hCG is suggested.
authors.affiliation: IVF Clinic, St. Pierre Hospital, Free University of Brussels, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Delvigne
authors.forename: J
authors.initials: J
authors.lastname: Vandromme
authors.forename: I
authors.initials: I
authors.lastname: Demeestere
authors.forename: F
authors.initials: F
authors.lastname: Leroy
mesh_terms: D000328:Adult; D006063:Chorionic Gonadotropin / Q000032:analysis; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D016471:Ovarian Hyperstimulation Syndrome / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D010053:Ovary / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D018873:Pregnancy Rate; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D006063:Chorionic Gonadotropin