Ovarian Hyperstimulation Syndrome (OHSS) Prevention and Management

Introduction to OHSS Risk Factors

• Standard hCG doses (5000-10,000 IU) for triggering oocyte maturation increase OHSS risk in susceptible patients, according to the American Society for Reproductive Medicine 1
• Polycystic ovary syndrome, young age, low body weight, high estradiol levels during ovarian stimulation, previous OHSS, multiple follicle development, pregnancy (especially multiple), and the use of hCG for luteal support are risk factors for OHSS, as identified by the American College of Obstetricians and Gynecologists, with a strength of evidence level of high 2

OHSS Pathophysiology and Complications

• Ovarian hyperstimulation syndrome (OHSS) can cause serious and potentially life-threatening complications, including venous thromboembolism, renal failure, and severe fluid shifts, leading to significant morbidity and mortality in patients undergoing assisted reproduction, particularly those with risk factors such as polycystic ovary syndrome, young age, and high estradiol levels during ovarian stimulation 2
• Third-space fluid accumulation can lead to ascites, pleural effusion, intravascular dehydration, hemoconcentration, and electrolyte abnormalities, particularly hyponatremia, in patients with severe OHSS, highlighting the need for careful monitoring and management 2
• Oliguria or anuria can occur due to decreased renal perfusion, potentially leading to acute kidney injury and the need for dialysis in severe cases, emphasizing the importance of early recognition and intervention 2
• Venous thrombosis is more common than arterial events in OHSS, predominantly occurring in neck and upper extremity veins, with an increased risk in patients with underlying thrombophilia, as reported by the American College of Chest Physicians 3

Preventive Strategies for OHSS

• The American College of Obstetricians and Gynecologists recommends LMWH prophylaxis (enoxaparin 40 mg daily) in severe OHSS, starting at the beginning of ovarian stimulation, withholding 24-36 hours before oocyte retrieval, and resuming after retrieval, with a strength of evidence level of moderate 4
• LMWH prophylaxis should continue until estrogen levels return to near-physiologic levels if no pregnancy occurs, and therapeutic anticoagulation may be required for patients with antiphospholipid syndrome or a history of thrombosis, as recommended by the American College of Chest Physicians, with a strength of evidence level of high 2
• The following table summarizes the recommended LMWH regimens:

Management of OHSS

• Careful monitoring of fluid balance, intravenous crystalloids for intravascular volume replacement, and albumin administration may be considered in severe cases, with a strength of evidence level of low 2
• Paracentesis may be performed for severe ascites causing respiratory compromise or significant discomfort, which can be done transvaginally or transabdominally and may prevent the need for hospitalization in moderate-severe cases, as supported by the American College of Obstetricians and Gynecologists, with a strength of evidence level of moderate 2
• Daily monitoring of weight, abdominal circumference, urine output, vital signs, complete blood count, electrolytes, liver and renal function tests, and coagulation profile is recommended for patients with OHSS, with a strength of evidence level of high 2
• Patients with severe OHSS should be monitored closely for the development of complications, particularly thromboembolism, which can occur up to 11 weeks after the initial presentation, as reported by the American College of Chest Physicians, with a strength of evidence level of moderate 4
• Regular monitoring of platelet counts, hematocrit, and stool blood tests is recommended during treatment, with a strength of evidence level of low 3
• In cases of refractory or complicated ovarian thrombosis (such as pulmonary embolism), thrombolysis or surgical treatment (excision of the ovarian vein) may be considered, as supported by the American College of Chest Physicians, with a strength of evidence level of moderate 3