What are the latest treatment guidelines for Ovarian Hyperstimulation Syndrome (OHSS)?

Management of Ovarian Hyperstimulation Syndrome (OHSS)

Initiate low-molecular-weight heparin (LMWH) thromboprophylaxis immediately in all patients with moderate-to-severe OHSS, as thromboembolism represents the most serious life-threatening complication of this condition. 1

Risk Stratification Before Treatment

Identify high-risk patients before ovarian stimulation begins, specifically those with: 1

• Polycystic ovary syndrome (PCOS)
• High antral follicle counts
• Elevated estradiol levels during stimulation
• Known thrombophilia or antiphospholipid antibodies

For patients with known thrombophilia or antiphospholipid syndrome, start thromboprophylaxis at the beginning of ovarian stimulation rather than waiting for OHSS to develop. 1

Acute Management of Moderate-to-Severe OHSS

Thromboprophylaxis (Most Critical Intervention)

Begin enoxaparin 40 mg subcutaneously daily immediately upon diagnosis of moderate-to-severe OHSS. 1 This addresses the hypercoagulable state created by hemoconcentration, elevated estrogen, and immobility. 1

• Continue thromboprophylaxis for 3 months after complete resolution of clinical OHSS symptoms, as thrombotic events can occur 2 days to 11 weeks post-resolution 1
• For patients with established thrombotic antiphospholipid syndrome already on therapeutic anticoagulation, transition to therapeutic-dose LMWH (enoxaparin 1 mg/kg subcutaneously every 12 hours) 1

Fluid Management and Monitoring

Administer intravenous crystalloids (normal saline) and colloids (albumin or hydroxyethyl starch) to expand intravascular volume in severe cases requiring hospitalization. 2

• Monitor hematocrit, electrolytes, and kidney and liver function regularly 2
• Avoid diuretics as they further contract intravascular volume and worsen hemoconcentration 2
• Dopamine may be used to improve diuresis in hospitalized patients 2

Paracentesis for Symptomatic Relief

Perform abdominal or vaginal aspiration of ascitic fluid when present, as this results in marked symptom improvement, enhanced diuresis, and shortened hospital stay. 2 Early outpatient paracentesis may prevent progression to severe OHSS and avoid hospitalization, though this approach is still being evaluated in clinical trials. 3

Pain Management

• Use NSAIDs as first-line: naproxen 550 mg or ibuprofen 600-800 mg for mild-to-moderate pain 1
• Avoid aspirin before oocyte retrieval due to bleeding risk 1

Severity-Based Treatment Algorithm

Mild OHSS

• No specific treatment required 2
• Outpatient monitoring only 2

Moderate OHSS

• Outpatient follow-up with close monitoring 2
• Consider early paracentesis if ascites present 3
• Initiate LMWH thromboprophylaxis (enoxaparin 40 mg daily) 1

Severe OHSS

• Hospitalization for intensive monitoring and treatment 2
• Intravenous fluid resuscitation with crystalloids and colloids 2
• LMWH thromboprophylaxis mandatory 1
• Paracentesis for ascites 2
• Monitor for complications: respiratory distress, renal failure, thromboembolism 4, 5

Critical OHSS

• Intensive care unit admission for severe respiratory distress or major electrolyte imbalance with elevated creatinine 2
• All interventions as per severe OHSS 2

Prevention Strategies

Use ovarian stimulation protocols that yield lower peak estradiol levels, such as those incorporating aromatase inhibitors, in high-risk patients. 1 Despite optimal preventive strategies, severe OHSS can still occur in susceptible individuals, emphasizing the importance of early recognition and aggressive management. 5

Common Pitfalls to Avoid

• Never use diuretics in OHSS management - they worsen intravascular volume depletion 2
• Do not delay thromboprophylaxis until OHSS becomes severe - start immediately with moderate disease 1
• Do not discontinue anticoagulation prematurely - continue for 3 months after symptom resolution 1
• Avoid aspirin before oocyte retrieval 1