Prevention and treatment of moderate and severe ovarian hyperstimulation syndrome: a guideline

•There is fair evidence (level II-2) that PCOS, elevated AMH values, peak estradiol levels, multifollicular development, and a high number of oocytes retrieved increase the risk of OHSS. (Grade B)•While cut points require validation, AMH values >3.4 ng/mL, AFC >24, development of ≥25 follicles, estradiol values >3,500 pg/mL, or ≥24 oocytes retrieved are particularly associated with an increased risk of OHSS. (Grade B)•There is good evidence to support the use of ovarian stimulation protocols using GnRH antagonists in order to reduce the risk of OHSS. (Grade A)•There is insufficient evidence that clomiphene independently reduces OHSS risk. (Grade C)•There is fair evidence that aspirin reduces the incidence of OHSS based on a single, randomized trial comparing aspirin alone with no treatment and another study comparing combined acetylsalicylic acid and steroid treatment with no treatment. (Grade B)•There is good evidence that metformin decreases the risk of OHSS risk in PCOS patients. (Grade A)•There is insufficient evidence to recommend coasting for the prevention of OHSS. (Grade C)•There is insufficient evidence to recommend a lower dose of hCG to trigger oocyte maturation for reduction in OHSS risk based on one underpowered randomized trial. (Grade C)•There is good evidence to recommend the use of a GnRH agonist to trigger oocyte maturation prior to oocyte retrieval in order to reduce the risk of OHSS. (Grade A)•There is good evidence that live-birth rates are lower in fresh autologous cycles after GnRH trigger, but not donor-recipient cycles. (Grade A)•There is fair evidence that reproductive outcomes are improved when a low dose of hCG is co-administered at the time of GnRH agonist trigger for luteal support. (Grade B)•There is good evidence that dopamine agonist administration starting at the time of hCG trigger for several days reduces the incidence of OHSS. (Grade A)•There is insufficient evidence to conclusively state that albumin lowers OHSS risk. (Grade C)•There is fair evidence that calcium lowers OHSS risk. (Grade B)•There is fair evidence that cryopreservation prevents OHSS, based on the results of two small RCTs. (Grade B)•There is fair evidence to recommend paracentesis or culdocentesis for the management of OHSS in an outpatient setting. (Grade B)•There is insufficient evidence to support the use of volume expanders alone in treatment of OHSS. (Grade C)