What is Ovarian Hyperstimulation Syndrome?
💡 Ovarian hyperstimulation syndrome is an iatrogenic complication of IVF stimulation caused by excessive follicular response to gonadotropins. VEGF-mediated fluid shifts cause ascites, haemoconcentration, and organ dysfunction. Graded mild to critical. Severe OHSS incidence: 0.5–2% of IVF cycles.
Ovarian hyperstimulation syndrome (OHSS) is the clinical name for the most serious acute complication of controlled ovarian stimulation. It results from excessive ovarian response to gonadotropins, triggering a VEGF-driven vascular permeability cascade that causes fluid to shift from blood vessels into the abdomen and chest.
🇮🇳 India Context: Ovarian Hyperstimulation Syndrome is widely assessed and treated across major Indian fertility centres including Chennai, Mumbai, Bangalore, Delhi, and Hyderabad.
What are the key characteristics of Ovarian Hyperstimulation Syndrome?
- Iatrogenic condition — caused by fertility medications (gonadotropins), not by underlying disease
- Key driver: VEGF (vascular endothelial growth factor) released by granulosa cells in response to hCG — increases vascular permeability
- Severity grades: mild (bloating), moderate (ascites + nausea), severe (haematocrit >45%, renal impairment, respiratory compromise), critical
- Severe OHSS incidence: 0.5–2% of stimulated IVF cycles — higher in PCOS, high responders, and donor cycles
- Early OHSS: Day 3–9 post-trigger (iatrogenic hCG); late OHSS: Day 9–17 (endogenous hCG from implantation)
- Diagnosis: clinical symptoms + transvaginal ultrasound (ascites, ovarian enlargement >10cm) + haematocrit >45%
- Complications of severe OHSS: DVT/PE, acute kidney injury, ARDS, electrolyte disturbance, ovarian torsion
- Prevention: GnRH agonist trigger, freeze-all, cabergoline (dopamine agonist), judicious stimulation dosing
How does Ovarian Hyperstimulation Syndrome work?
Why does Ovarian Hyperstimulation Syndrome matter in fertility?
Ovarian hyperstimulation syndrome is entirely preventable with risk stratification and protocol modification. The shift to GnRH agonist triggers and freeze-all has reduced severe OHSS rates at leading IVF centres globally. Severe OHSS requires hospital admission: IV albumin, anticoagulation, fluid balance monitoring — embryo transfer must await full recovery. Egg quality from the retrieval cycle is unaffected by OHSS. In India, OHSS remains underreported; patients should be counselled on warning symptoms (rapid weight gain, severe bloating, reduced urine output) before stimulation begins.
What are related terms to Ovarian Hyperstimulation Syndrome?
FAQs about Ovarian Hyperstimulation Syndrome
What causes ovarian hyperstimulation syndrome?
OHSS is caused by hCG (from the trigger injection or early pregnancy) stimulating VEGF release from granulosa cells of multiple stimulated follicles. VEGF increases capillary permeability — fluid leaks into the abdominal and pleural cavities, causing ascites and haemoconcentration.
How is ovarian hyperstimulation syndrome diagnosed?
Diagnosis: clinical symptoms (bloating, nausea, abdominal pain, weight gain) + transvaginal ultrasound (ascites, ovarian enlargement >10cm) + blood tests (haematocrit >45%, rising creatinine, electrolyte disturbance). Graded mild to critical based on clinical and laboratory findings.
What are the serious complications of ovarian hyperstimulation syndrome?
Serious complications of severe OHSS: deep vein thrombosis (DVT) and pulmonary embolism — most feared; acute kidney injury from dehydration and haemoconcentration; ARDS (respiratory failure) from pleural effusion; electrolyte disturbance; and rarely ovarian torsion from enlarged ovaries.
How long does ovarian hyperstimulation syndrome last?
Mild OHSS: resolves in 1–2 weeks. Moderate OHSS: 2–3 weeks. Severe OHSS: 3–6 weeks. Late OHSS (from pregnancy) may persist longer — sustained by ongoing hCG production. Recovery is faster if freeze-all is used, as endogenous hCG from pregnancy does not extend the syndrome.
Can you still get pregnant after ovarian hyperstimulation syndrome?
Yes. Egg and embryo quality are unaffected by OHSS. Embryos can be cryopreserved during the OHSS cycle and transferred in a subsequent frozen embryo transfer cycle after full recovery. Pregnancy rates after freeze-all following OHSS are equivalent to standard FET cycles.
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