OHSS

Ovarian hyperstimulation syndrome (OHSS) is a medical condition that can occur after fertility treatments that stimulate the ovaries, most commonly during in vitro fertilization (IVF). It results from an exaggerated response to gonadotropin medications and involves increased vascular permeability, leading to fluid shifting from the bloodstream into the abdomen and other tissues. This can cause abdominal distension, rapid weight gain, and other systemic symptoms.

The pathophysiology is related to hormonal stimulation and the release of vascular factors such as vascular endothelial growth factor (VEGF), which increases capillary permeability. Clinically important manifestations range from mild symptoms, such as bloating and nausea, to severe disease with significant ascites, pleural effusions, electrolyte disturbances, kidney function impact, and risk of dehydration or thromboembolism.

OHSS is typically categorized by severity into mild, moderate, and severe. Risk factors include polycystic ovarian syndrome, young age, high ovarian response to stimulation, and the use of certain triggering methods such as human chorionic gonadotropin (hCG). Prevention focuses on careful cycle monitoring, individualized stimulation protocols (eg, GnRH antagonist protocols), and using alternative triggers (such as a GnRH agonist) in high responders.

Diagnosis is based on clinical findings supported by ultrasound showing enlarged ovaries and laboratory tests (eg, hematocrit, electrolytes). Management depends on severity, ranging from outpatient care with observation, hydration, and symptom control to inpatient treatment with IV fluids, electrolyte correction, and procedures such as paracentesis or thoracentesis for severe fluid accumulation. Most cases resolve with appropriate treatment, though severe OHSS can require intensive care and has potential complications.