No abstract

The aim of this review was to summarize previously published classifications for ovarian hyperstimulation syndrome (OHSS), as well as to analyse the available methods for preventing OHSS. Withholding hCG and cycle cancellation--once the main methods of preventing OHSS--are now seldom used. There is a growing body of evidence to support the use of coasting to prevent OHSS, without cycle cancellation. However, most studies on coasting are retrospective, and well-designed prospective randomized studies are lacking. There is no current consensus as to how coasting should be carried out. A serum estradiol level of 3000 pg/ml is generally considered optimum for administration of hCG. It appears that intravenous albumin or hydroxyethyl starch at the time of oocyte retrieval is beneficial in preventing OHSS, but does not offer complete protection. There is insufficient evidence to support routine cryopreservation of all embryos for the later transfer of frozen-thawed embryos in high-risk patients. Several uncontrolled studies have reported the protective effect of GnRH agonist to trigger ovulation in preventing OHSS, though the method is applicable solely for gonadotrophin-only or GnRH antagonist cycles. A single dose of recombinant LH to trigger ovulation significantly reduced OHSS as compared with hCG. The possible role of GnRH antagonist protocols in reducing the incidence of OHSS is debatable. The above measures to prevent OHSS were successful in reducing the incidence of the syndrome, but complete prevention is not as yet possible.

No abstract

We concluded that the fixed GnRH antagonist protocol is a short and simple protocol with good clinical outcome, but the lower pregnancy rate compared with the GnRH agonist long protocol and the non-significant difference between both protocols regarding prevention of premature LH surge and prevention of severe ovarian hyperstimulation syndrome necessitates counselling subfertile couples before recommending change from GnRH agonist to antagonist. The clinical outcome may be further improved by developing more flexible antagonist regimens, taking into account individual patient characteristics.

Gonadotrophin-releasing hormone (GnRH) antagonists suppress gonadotrophin secretion resulting in dramatic reduction in treatment cycle duration. Assuming comparable clinical outcomes, these benefits may justify changing the standard long GnRH agonist protocol to GnRH antagonist regimens. To evaluate the evidence, databases (e.g. Cochrane Library, MEDLINE, EMBASE) were electronically searched, hand searches were performed, and manufacturers in the field were contacted. Twenty-seven randomized controlled trials (RCT) fulfilled inclusion criteria for comparison of GnRH antagonist with long GnRH agonist protocol. Clinical pregnancy rate and ongoing pregnancy/live-birth rate were significantly lower in the antagonist group (P = 0.009; OR = 0.83, 95% CI 0.72-0.95 and P = 0.02; OR = 0.82, 95% CI 0.68-0.97 respectively). Conversely, incidence of severe OHSS was significantly reduced with the antagonist protocol (P = 0.01; OR = 0.60, 95% CI 0.40-0.88), and interventions to prevent OHSS were administered more frequently in the agonist group (P = 0.03; OR = 0.43, 95% CI 0.20-0.92). Concluding, GnRH antagonist protocols are short, simple, with good clinical outcomes and significant reduction in severe OHSS incidence and gonadotrophin amount; however, the lower pregnancy rate compared with the GnRH agonist long protocol necessitates counselling subfertile couples before recommending change from GnRH agonist to antagonist.