What Causes Ovarian Hyperstimulation Syndrome (OHSS) and How to Prevent It

Ovarian Hyperstimulation Syndrome (OHSS) is one of the potential complications that some women may experience during their IVF or ICSI journey — especially when using hormonal medications to stimulate the ovaries.

Although OHSS is rare in modern fertility clinics, early understanding and awareness are crucial steps in prevention and ensuring a woman’s safety throughout treatment.

In this article, we will explain what OHSS is, its causes and symptoms, and how to reduce the risk of developing it — with a focus on medical support during care stages.

What Is Ovarian Hyperstimulation Syndrome (OHSS)?

OHSS is a condition that occurs when the ovaries respond excessively to fertility drugs, leading to swelling, enlargement, and sometimes fluid accumulation in the abdomen or pelvic cavity.

OHSS is classified into three categories:

• Mild: Symptoms include mild bloating, abdominal discomfort, or light cramping.
• Moderate: Includes enlarged ovaries and noticeable weight gain.
• Severe: May cause difficulty breathing, reduced urination, or serious complications requiring immediate medical attention.

What Causes OHSS?

OHSS is primarily triggered by high levels of human chorionic gonadotropin (hCG), the hormone used to trigger final egg maturation.

Risk factors for OHSS include:

• Young age (under 35 years)
• Polycystic Ovary Syndrome (PCOS)
• High number of developing follicles
• Use of the hCG "trigger shot"
• Pregnancy in the same treatment cycle

What Are the Symptoms of OHSS?

Symptoms vary depending on severity:

Mild Cases:

• Abdominal bloating
• Feeling of fullness or mild cramping
• Slight weight gain

Moderate to Severe Cases:

• Significant abdominal swelling
• Severe pelvic pain
• Shortness of breath
• Decreased urine output
• Persistent nausea or vomiting
• Headache or dizziness

If any of these symptoms appear, immediate medical consultation is essential.

How Can OHSS Be Prevented?

Fortunately, treatment protocols have evolved significantly, greatly reducing the incidence of OHSS.

Effective preventive strategies include:

• Personalized medication dosing based on individual ovarian response.
• Using alternatives to hCG trigger, such as a "dual trigger" (a combination of hCG and a GnRH agonist).
• Freezing all embryos and delaying transfer (Freeze-All) in high-risk cases.
• Close monitoring via ultrasound and hormone level testing.

Can OHSS Be Treated?

In most mild cases, symptoms resolve on their own within a few days. Supportive care includes:

• Drinking plenty of fluids
• Avoiding intense physical activity
• Regular follow-up with the medical team

In severe cases, hospitalization may be required for:

• Drainage of excess fluid
• Intravenous fluids and electrolyte balance
• Monitoring vital organ function

Thanks to close monitoring and modern protocols, severe OHSS is now very rare.

Conclusion

Ovarian Hyperstimulation Syndrome (OHSS) is a rare but predictable complication that can be effectively prevented in most cases — especially with personalized care and advanced treatment protocols.

At Fertiliv Clinic, we believe a woman’s safety is our top priority. We conduct a thorough assessment for every patient and design a personalized treatment plan to minimize risks, with continuous monitoring throughout every stage of your fertility journey.

You can contact us today to find out if you’re at risk for OHSS, or visit our clinic directly for a free consultation.