title: Distinction between early and late ovarian hyperstimulation syndrome.
abstract: OBJECTIVE
  To compare patient and cycle characteristics among three study groups: early ovarian hyperstimulation syndrome (OHSS), late OHSS, and non-OHSS.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  University assisted conception service.
  
  
  METHODS
  Women undergoing in vitro fertilization, intracytoplasmic sperm injection or gamete intrafallopian transfer treatment at Bristol University In Vitro Fertilization Service between January 1, 1995, and December 31, 1998.
  
  
  METHODS
  None.
  
  
  METHODS
  Patient age, prevalence of polycystic ovaries, gonadotropin requirement, peak serum estradiol (E(2)) concentration, number of oocytes retrieved, clinical pregnancy rate, number of gestation sacs, and severity of OHSS.
  
  
  RESULTS
  Women with early OHSS had significantly higher serum E(2) levels and lower gonadotropin requirements than did the other groups. Cycles with either early or late OHSS had significantly more oocytes collected than those without OHSS. Serum E(2) and oocyte numbers did not accurately predict the risk of developing late OHSS. Clinical pregnancies occurred in all cycles with late OHSS, and multiple pregnancies were significantly more frequent in the late OHSS group than in the other groups. Late OHSS was more likely than early OHSS to be severe.
  
  
  CONCLUSIONS
  Early OHSS relates to "excessive" preovulatory response to stimulation, whereas late OHSS depends on the occurrence of pregnancy, is likelier to be severe, and is only poorly related to preovulatory events.
authors.affiliation: Bristol University Center for Reproductive Medicine, Bristol, UK. rajmathur@repromed.co.uk
authors.forename: R S
authors.initials: RS
authors.lastname: Mathur
authors.forename: A V
authors.initials: AV
authors.lastname: Akande
authors.forename: S D
authors.initials: SD
authors.lastname: Keay
authors.forename: L P
authors.initials: LP
authors.lastname: Hunt
authors.forename: J M
authors.initials: JM
authors.lastname: Jenkins
mesh_terms: D000328:Adult; D000367:Age Factors; D004958:Estradiol / Q000097:blood; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D019370:Observation; D009865:Oocytes; D017063:Outcome Assessment, Health Care; D016471:Ovarian Hyperstimulation Syndrome / Q000097:blood / Q000150:complications / Q000473:pathology*; D011085:Polycystic Ovary Syndrome / Q000150:complications; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D020858:Tissue and Organ Harvesting
chemical_list: D004958:Estradiol