OHSS: Understanding, Preventing & Treating Ovarian Hyperstimulation

The good news? Modern protocols have made severe OHSS rare. Here's everything you need to know to stay safe and informed.

📖 11 min read ✅ Medically reviewed 📅 Updated January 2025

💚 The Reassuring Reality About OHSS

  • Severe OHSS affects less than 1% of IVF cycles with modern protocols
  • Your clinic can identify if you're high-risk before stimulation even starts
  • Prevention strategies (like Lupron trigger) are highly effective
  • When caught early, OHSS is very manageable
  • Most cases resolve completely within 1-2 weeks

If you're preparing for IVF, you've probably heard about OHSS (Ovarian Hyperstimulation Syndrome) and may be worried. That's understandable—it sounds scary! But here's what you need to know upfront: severe OHSS has become increasingly rare thanks to major advances in how fertility doctors manage stimulation.

This guide will help you understand what OHSS is, who's at risk, how it's prevented, what symptoms to watch for, and how it's treated if it does occur. Knowledge is power, and being informed will help you feel confident and prepared.

What Is OHSS?

OHSS occurs when your ovaries over-respond to fertility medications, becoming swollen and leaking fluid into your abdomen. It's triggered by hCG—either from the "trigger shot" that matures your eggs or from pregnancy itself (your body makes hCG when you're pregnant).

Here's what happens at a biological level:

<1%

Rate of severe OHSS with modern GnRH antagonist protocols and agonist trigger

Who's at Higher Risk?

Certain factors make OHSS more likely. The good news? Your doctor can identify most of these before your cycle even begins and adjust your protocol accordingly.

Risk Factor Why It Matters
PCOS 3.6x higher risk due to multiple small follicles and sensitivity to stimulation
High AMH (>3.4 ng/mL) Indicates high ovarian reserve = more follicles likely to develop
High AFC (>24 follicles) More follicles at baseline = higher response expected
Age under 35 Younger ovaries tend to respond more vigorously
Low BMI Less body mass to dilute fluid shifts
Previous OHSS History tends to repeat—your doctor will be extra cautious
Many eggs retrieved (>15-20) High response = higher risk
Pregnancy Endogenous hCG can trigger or worsen OHSS

💡 Important Note

Having risk factors doesn't mean you'll get OHSS! It means your doctor will use specific prevention strategies. Many high-risk patients go through IVF without any OHSS symptoms because their team plans carefully.

How Modern Clinics Prevent OHSS

This is where IVF has made tremendous progress. Clinics now have multiple effective strategies to virtually eliminate severe OHSS:

🛡️ GnRH Antagonist Protocol

This protocol (instead of the older "long agonist" protocol) allows for a special trigger option that dramatically reduces OHSS risk. It's now the preferred approach for most patients, especially those at higher risk.

💉 GnRH Agonist Trigger (Lupron)

Instead of hCG to trigger egg maturation, using Lupron (leuprolide) virtually eliminates OHSS. It causes a shorter, gentler LH surge. This is a game-changer for high-risk patients.

❄️ Freeze-All Strategy

By freezing all embryos instead of doing a fresh transfer, you avoid the "late OHSS" that can occur when pregnancy hCG kicks in. This is standard for high-risk patients.

📉 Lower Medication Doses

Starting with lower gonadotropin doses (especially for PCOS patients) reduces the chance of over-response. Your doctor calibrates based on your AMH and AFC.

💊 Cabergoline

This dopamine agonist medication, taken for 7-10 days after trigger, reduces VEGF and significantly lowers OHSS risk. Often prescribed for at-risk patients.

⏸️ Coasting

If estrogen levels get very high, your doctor may pause gonadotropin injections for 1-3 days before trigger, allowing levels to stabilize while follicles continue maturing.

🌟 The Prevention Success Story

In the early days of IVF, moderate-to-severe OHSS occurred in 3-8% of cycles. With modern protocols—especially GnRH antagonist cycles with agonist trigger and freeze-all—severe OHSS has dropped to less than 1%. That's a 90%+ reduction in risk!

Recognizing OHSS Symptoms

OHSS typically develops 3-7 days after trigger shot ("early OHSS") or 10-14 days after trigger if you become pregnant ("late OHSS"). Knowing the symptoms helps you catch it early:

🟢 Mild OHSS (Most Common)

  • Bloating and abdominal discomfort
  • Mild nausea
  • Slight weight gain (1-2 lbs)
  • Ovaries enlarged but <8 cm
  • Management: Rest, hydration, monitoring at home

🟡 Moderate OHSS

  • More pronounced bloating
  • Nausea and occasional vomiting
  • Weight gain of 2-5 lbs
  • Abdominal pain
  • Ultrasound shows fluid accumulation
  • Management: Close monitoring, possibly clinic visits

🔴 Severe OHSS (Rare)

  • Rapid weight gain (>2 lbs/day)
  • Severe abdominal pain/distension
  • Difficulty breathing
  • Decreased urination/dark urine
  • Persistent vomiting
  • Dizziness or fainting
  • Management: Medical intervention required

🚨 When to Contact Your Clinic Immediately

Call right away if you experience: rapid weight gain (>2 lbs in 24 hours), severe abdominal pain, difficulty breathing, inability to keep fluids down, very dark urine or significantly decreased urination, dizziness or fainting. These symptoms need prompt evaluation.

OHSS Treatment: What to Expect

Mild-to-Moderate OHSS: Home Management

Most OHSS cases are mild and resolve on their own within 1-2 weeks (or when your period starts if you're not pregnant). Your clinic will guide you through:

📊 Tracking Tips

Keep a simple log: morning weight, waist measurement, how much you're drinking, and rough urine output. If weight gain exceeds 2 lbs in 24 hours or your waist is growing rapidly, contact your clinic.

Severe OHSS: Hospital Care

Severe OHSS requires hospitalization, but it's highly treatable. Hospital care includes:

With proper care, even severe OHSS resolves completely. It may take longer if you're pregnant (because your body continues making hCG), but the outcome is still excellent.

OHSS and Pregnancy

Here's an important point: if you become pregnant, OHSS may last longer and potentially worsen initially as pregnancy hCG rises. This is called "late OHSS." However:

Many women who experience OHSS and become pregnant go on to have perfectly healthy pregnancies and babies. The discomfort is temporary; the baby is forever! 💛

The Freeze-All Advantage

If you're at high risk for OHSS, your clinic will likely recommend a "freeze-all" cycle. Here's why this is actually great news:

Think of it as a brief pause, not a setback. You're protecting yourself while still moving toward your goal.

Questions to Ask Your Doctor

Knowledge is empowering! Consider asking:

A good clinic will welcome these questions and explain their OHSS prevention approach clearly.

OHSS Prevention at Colombian Clinics

Top Colombian fertility clinics like InSer use the same evidence-based OHSS prevention protocols as leading US and European centers:

International patients are given detailed instructions on what to watch for after returning home, and clinics maintain close communication during the post-retrieval period.

Get Personalized Guidance

Wondering about your OHSS risk? Our partner clinics can review your AMH, AFC, and history to create a customized, safe stimulation plan. Your safety is always the priority.

Schedule a Free Consultation

The Bottom Line

OHSS is a known risk of IVF, but it's increasingly rare and highly manageable. Here's what to remember:

You're not helpless against OHSS—you're part of a team that's watching out for you. Trust the process, communicate openly with your clinic, and know that your safety is always the top priority. 💚