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Ovarian hyperstimulation syndrome

Key sources
The following summarized guidelines for the evaluation and management of ovarian hyperstimulation syndrome are prepared by our editorial team based on guidelines from the Society of Obstetricians and Gynaecologists of Canada (SOGC 2023), the American Society for Reproductive Medicine (ASRM 2016), and the Royal College of Obstetricians and Gynaecologists (RCOG 2016).


1.Classification and risk stratification

Prediction of ovarian hyperstimulation syndrome: recognize that PCOS, elevated anti-Müllerian hormone values (> 3.4 ng/mL), peak estradiol levels (> 3,500 pg/mL), multifollicular development (antral follicle count > 24, development of ≥ 25 follicles), and a high number of oocytes retrieved (≥ 24) increase the risk of OHSS.
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  • Classification

2.Diagnostic investigations

Initial evaluation: assess patients presenting with symptoms suggestive of OHSS face-to-face by a clinician if there is any doubt about the diagnosis or if the severity is likely to be greater than mild.
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3.Medical management

Setting of care: as per SOGC 2023 guidelines, manage patients with mild or moderate OHSS in an outpatient setting. Ensure that the patient is capable of adhering to clinical instructions and there is a system in place to assess her status every 1-2 days when offering outpatient management for more severe OHSS.
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  • Fluid resuscitation

  • Diuretics

  • Thromboprophylaxis

  • Pain management

  • Antiemetics

  • GnRH antagonists

  • Dopamine agonists

  • Plasma expanders

4.Therapeutic procedures

Paracentesis: as per SOGC 2023 guidelines, perform paracentesis in hospitalized patients with tense ascites to alleviate the condition.

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  • Culdocentesis

5.Surgical interventions

Indications for surgery: perform surgery by an experienced surgeon only in patients with a coincident condition, such as adnexal torsion, ovarian rupture, or ectopic pregnancy.

6.Patient education

General counseling
As per SOGC 2023 guidelines:
Counsel each female of her personal risk for OHSS when prescribing gonadotropins.
Counsel females to contact a physician or a member of the team within the hospital with relevant experience, if needed, when prescribing gonadotropins in areas where patients do not have ready access to physicians familiar with the diagnosis and management of OHSS.

7.Preventative measures

Ovarian stimulation protocols: as per SOGC 2023 guidelines, use GnRH antagonist stimulation protocols in patients at high risk for OHSS. Consider administering a GnRH agonist as a substitute for hCG to trigger final oocyte maturation in order to reduce the risk of severe OHSS in patients on GnRH antagonist protocols with a very robust ovarian stimulation response.
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  • Luteal phase support

  • Embryo transfer

  • Embryo cryopreservation

  • Metformin

  • Aspirin

  • Dopamine agonists

  • Plasma expanders

  • Calcium

8.Follow-up and surveillance

Serial clinical assessment: assess patients admitted with OHSS at least once daily. Obtain more frequent assessments in patients with critical OHSS and in patients with complications.

9.Quality improvement

Hospital regulations
Establish local protocols for the assessment and management of OHSS in all acute units where patients with suspected OHSS are likely to present and ensure access to appropriately skilled clinicians with experience in the management of this condition.
Ensure close liaison and coordination between centers providing fertility treatment and acute units where patients with OHSS may present.