What is the management of Ovarian Hyperstimulation Syndrome (OHSS)?

Management of Ovarian Hyperstimulation Syndrome (OHSS)

For women with severe OHSS, initiate thromboprophylaxis with low-molecular-weight heparin (enoxaparin 40 mg daily subcutaneously) immediately, provide supportive care with fluid management and monitoring, consider paracentesis for symptomatic ascites, and implement a freeze-all embryo strategy to prevent pregnancy-related worsening. 1, 2, 3

Risk Stratification and Prevention

High-Risk Patient Identification

• Identify patients at increased risk before stimulation: those with polycystic ovary syndrome, high antral follicle counts, elevated estradiol levels, or underlying thrombophilia 4, 1
• Patients with antiphospholipid antibodies require special consideration as thrombophilia increases severe OHSS risk 1

Prevention Strategies

• Use GnRH antagonist protocols with GnRH agonist trigger instead of hCG trigger in high-risk patients 5, 6
• Consider ovarian stimulation protocols yielding lower peak estrogen levels, such as those incorporating aromatase inhibitors 1
• Implement freeze-all strategy when OHSS risk is identified—cryopreserve all embryos and cancel fresh transfer 2, 6

Severity Assessment

Clinical Evaluation Markers

• Measure abdominal girth serially to track ascites progression 2
• Assess for tense ascites requiring drainage 2
• Evaluate respiratory status for pleural effusion and dyspnea 2, 7
• Monitor for signs of hemoconcentration (elevated hematocrit, hypoalbuminemia) 2, 7

Laboratory Monitoring

• Check complete blood count for hematocrit elevation and leukocytosis 7, 8
• Evaluate renal function (creatinine, BUN) to detect acute kidney injury from intravascular volume depletion 2, 7
• Assess electrolytes for imbalances secondary to third-space fluid shifts 7, 8
• Obtain coagulation studies to evaluate thrombotic risk in the hypercoagulable state 2, 8
• Monitor liver function as hepatic dysfunction can occur 7, 8

Acute Management

Thromboprophylaxis (Critical Priority)

• Initiate LMWH (enoxaparin 40 mg subcutaneously daily) immediately in moderate-to-severe OHSS due to high thrombotic risk from hemoconcentration, elevated estrogen, and immobility 1, 2, 6
• Start thromboprophylaxis at beginning of ovarian stimulation in patients with known thrombophilia or antiphospholipid syndrome 1
• Withhold LMWH 24-36 hours before oocyte retrieval, then resume afterward 1
• Continue prophylaxis for 3 months post-resolution of clinical OHSS symptoms 1
• In patients with established thrombotic antiphospholipid syndrome on therapeutic anticoagulation, transition to therapeutic-dose LMWH (enoxaparin 1 mg/kg subcutaneously every 12 hours) 1

Fluid Management

• Provide intravenous crystalloid resuscitation for hypovolemia and hemoconcentration 7, 5, 8
• Monitor strict fluid intake and output to maintain euvolemia while avoiding overhydration 3, 7
• Target urine output >30 mL/hour as marker of adequate perfusion 5
• Avoid aggressive diuresis which can worsen hemoconcentration 5, 8

Paracentesis

• Perform paracentesis for symptomatic ascites causing abdominal distension, pain, or respiratory compromise 3, 5, 8
• Paracentesis is effective treatment and can be performed as outpatient procedure in appropriate settings 3
• Drain pleural effusions if causing significant respiratory symptoms 7, 8

Pain Management

• Use NSAIDs (naproxen 550 mg or ibuprofen 600-800 mg) for mild-to-moderate pain 2
• Avoid aspirin before oocyte retrieval due to bleeding risk, though it may be considered post-retrieval 1

Cycle Management

• Freeze all embryos if not already done—pregnancy will prolong and worsen OHSS significantly 2, 6
• Consider GnRH antagonist administration for early severe OHSS, though evidence is limited 3

Setting of Care

Outpatient Management Criteria

• Mild-to-moderate OHSS can be managed as outpatient with appropriate protocols and close monitoring 3, 5, 6
• Outpatient management requires established protocols, patient education, and ability for rapid reassessment 3
• Outpatient paracentesis is safe and cost-effective compared to hospitalization in selected patients 3

Hospitalization Indications

• Severe OHSS with hemoconcentration (hematocrit >45%), severe ascites, oliguria, or respiratory compromise requires hospitalization 7, 5
• Critical OHSS with acute kidney injury, thromboembolic events, ARDS, or multi-organ dysfunction mandates ICU admission 7, 5
• Inability to maintain oral intake or manage symptoms as outpatient 5, 8

Complications to Monitor

Thromboembolic Events

• OHSS creates hypercoagulable state with risk of deep vein thrombosis, pulmonary embolism, and arterial thrombosis 2, 7, 6
• Most thrombotic events occur days to weeks (range 2 days to 11 weeks) after OHSS resolution 1
• Maintain high index of suspicion for thromboembolism throughout disease course 6, 8

Other Serious Complications

• Acute respiratory distress syndrome from pleural effusions and pulmonary edema 7
• Hepatorenal failure from severe hemoconcentration 7, 8
• Ovarian torsion from enlarged ovaries 8
• Electrolyte disturbances requiring correction 7, 8
• Multi-organ dysfunction syndrome in critical cases 7

Duration of Monitoring

• Continue monitoring until clinical resolution of symptoms and normalization of laboratory parameters 5, 8
• If pregnancy occurs, OHSS may persist or worsen throughout first trimester 5, 8
• Maintain thromboprophylaxis for 3 months post-resolution of clinical symptoms 1