Ovarian Hyperstimulation Syndrome (OHSS)

Ovarian hyperstimulation syndrome (OHSS), is a possible complication of in vitro fertilization (IVF). In this condition, your ovaries swell and fluid leaks into your abdomen. OHSS is more common in people with PCOS who are going through fertility treatments.


What is ovarian hyperstimulation syndrome (OHSS)?

Ovarian hyperstimulation syndrome (OHSS) happens when your ovaries swell and leak fluid into your abdomen. OHSS is a complication that typically occurs in people who receive fertility treatments that stimulate their ovaries to produce a large number of eggs.

Typically, a person releases one egg per menstrual cycle. People who have trouble getting pregnant may use hormonal medications to help them produce multiple eggs, especially if they’re planning an egg retrieval procedure and in vitro fertilization (IVF). Sometimes your ovaries overrespond or overreact to these drugs, leading to OHSS. This is more common with injectable medications that stimulate the ovaries.

In the past, OHSS was a relatively common complication of IVF. New protocols and strategies have made this less common, although mild cases still occur from time to time.

OHSS is more common in people receiving fertility treatments who have polycystic ovary syndrome (PCOS). PCOS is a reproductive disorder involving a hormonal imbalance. It’s also more common in people with a high egg supply.

Types of OHSS

Ovarian hyperstimulation syndrome can be mild, moderate or severe. Your healthcare provider classifies the type based on the severity of your symptoms. Most cases of OHSS are mild and cause temporary discomfort. Severe cases of OHSS are rare but can be life-threatening.

How common is ovarian hyperstimulation syndrome (OHSS)?

OHSS used to occur in about 10% of people undergoing controlled ovarian stimulation for IVF, but today the number is less than 5%. Severe cases of OHSS happen in less than 1% of people receiving ovarian stimulation for fertility treatment.


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Symptoms and Causes

What are the symptoms of ovarian hyperstimulation syndrome (OHSS)?

The signs and symptoms of OHSS vary depending on the severity of the condition. Symptoms often begin within a week after using medication to stimulate ovulation, though it can take two weeks for symptoms to develop.

Symptoms of mild to moderate OHSS include:

  • Abdominal pain.
  • Bloating.
  • Slight weight gain (more than 2 pounds per day).
  • Nausea.

In more severe cases of OHSS, symptoms may include:

  • Excessive weight gain.
  • Severe nausea and vomiting.
  • Severe abdominal swelling.
  • Difficulty breathing.
  • Blood clots.
  • Decreased urination.
  • Severe abdominal pain.

Contact your healthcare provider if you’re receiving fertility medication to get pregnant and have any symptoms of OHSS. Your team is likely closely monitoring you and would tell you if you’re at risk for developing OHSS based on your estrogen levels and number of follicles on your ultrasound. Most cases are mild and resolve on their own, but it’s best to discuss your symptoms with your provider.

What causes ovarian hyperstimulation syndrome (OHSS)?

In most cases, OHSS develops because of the hormone HCG (human chorionic gonadotropin) stimulating your ovaries. Your ovaries typically produce just one egg at a time, but hormone treatments stimulate your ovaries to grow a lot of eggs at one time. People undergoing fertility treatments often receive a “trigger shot” of HCG to help the eggs mature before the egg retrieval process of IVF. When people develop a lot of potential eggs, the ovaries can respond excessively to this medication, and they can develop OHSS.

In people with OHSS, drugs used in fertility treatments cause the blood vessels surrounding their ovaries to leak fluid. Sometimes this fluid moves into your belly and causes symptoms like swelling and pain.

What are the risk factors for this condition?

People assigned female at birth (AFAB) at a higher risk for OHSS include those who:

  • Have PCOS.
  • Have previously had OHSS.
  • Have a large number of follicles or high levels of estrogen during IVF stimulation.
  • Received high doses of HCG during an IVF cycle.
  • Have undergone a “fresh” rather than “frozen” embryo transfer (when people get pregnant while their ovaries are still stimulated, the pregnancy can prolong OHSS).

In addition, while there isn’t clear evidence, there may be a higher risk for OHSS in those who:

  • Are younger than 30 years old.
  • Weigh less than average.


What are the complications of OHSS?

People with OHSS are at risk for developing a thrombosis (blood clot) in the lungs or legs. Medicines can help decrease your risk for this complication. There’s also an increased risk of stroke. Tell your healthcare provider if you experience a painful, swollen leg or chest pain.

In rare cases, an ovarian cyst associated with OHSS can burst, causing dangerous bleeding. People with this complication may need surgery to stop the bleeding.

Diagnosis and Tests

How is ovarian hyperstimulation syndrome (OHSS) diagnosed?

Healthcare providers diagnose OHSS with several tests. These tests can include:

  • Physical exam: A provider checks your weight and measures the size of your waist to look for signs of swelling. A pelvic exam isn’t recommended because your ovaries are swollen and may burst under direct pressure.
  • Ultrasound: Detects free fluid in your belly (abdomen) the abdomen and the size of your ovaries.
  • Chest X-ray: Looks for fluid in your chest.
  • Blood test: Measures your hormone levels for signs of OHSS.


Management and Treatment

How is ovarian hyperstimulation syndrome (OHSS) treated?

The treatment for OHSS varies depending on how severe the condition is. Treatment aims to manage symptoms and avoid complications. Mild cases tend to go away within a week or two. However, if you get pregnant that cycle, your symptoms could last much longer.

For mild to moderate cases of OHSS, treatment usually involves:

  • Avoiding vigorous physical activity.
  • Drinking electrolyte-rich fluid like Gatorade® or Propel®.
  • Using acetaminophen to relieve symptoms.
  • Weighing yourself daily.
  • Monitoring yourself for any severe symptoms.

Severe cases of OHSS often require hospitalization. Treatment of severe OHSS may include:

  • Receiving intravenous (directly into the vein) fluids.
  • Undergoing paracentesis (a procedure to remove fluid from your belly).
  • Taking medicines to ease symptoms or reduce activity in your ovaries.
  • A blood thinner to help decrease the risk of a blood clot.

Sometimes hospitalization is required for supportive care and close monitoring until symptoms improve.

How long does it take to recover from OHSS?

Healing times for OHSS vary depending on the severity of the condition and if you become pregnant that cycle. Your healthcare provider will tell you when you can return to your usual activities and what you can expect.

How do you get rid of OHSS fast?

There isn’t a way to get rid of OHSS fast. Your treatment depends on the severity of your symptoms. Your healthcare provider is the best person to discuss treatment options with. They can let you know what you can expect and how long your symptoms may persist.

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How do you prevent ovarian hyperstimulation syndrome (OHHS)?

Some cases of OHSS can’t be prevented. However, your healthcare provider will know if you’re at risk based on your health history and bloodwork. During fertility treatments, your healthcare provider may monitor your ovaries regularly using blood tests (to check hormone levels) and ultrasounds (to look at how many follicles are developing) to reduce your risk of OHSS.

Ways your team can help prevent OHSS (or minimize symptoms) include:

  • Reducing or adjusting your fertility medication dosage.
  • Avoiding a “trigger shot” of HCG during treatment.
  • Changing the type of fertility medication.
  • Freezing your embryos and delaying their embryo transfer until the ovaries return to normal.

Outlook / Prognosis

What can I expect if I have this condition?

OHSS is temporary. The condition typically goes away within two weeks. Even severe cases have a positive outlook when you receive prompt treatment. If the fertility treatment is successful and you become pregnant, having OHSS doesn’t pose any risk to the pregnancy.

Can you still have a healthy pregnancy with OHSS?

Yes, having OHSS doesn’t impact your pregnancy. Your symptoms will eventually go away and your pregnancy is unaffected.

Living With

When should I see my healthcare provider?

Contact your healthcare provider if you’re receiving fertility treatments and experience symptoms of OHSS.

What questions should I ask my healthcare provider?

If you have OHSS, you may want to ask your provider:

  • How severe is my condition?
  • What are my treatment options?
  • What signs of complications should I look out for?
  • Will OHSS harm my chances of becoming pregnant or affect the fetus?

Additional Common Questions

Is it normal to feel sick after egg collection?

Yes, feeling sick after egg collection is a normal side effect of IVF. Common symptoms include bloating, spotting and feeling full.

A note from Cleveland Clinic

Ovarian hyperstimulation syndrome (OHSS) is a rare complication of IVF treatment. Most cases are mild and resolve within one to two weeks. Talk to your healthcare provider about your risk for OHSS. They can answer any questions you have. If, at any point during IVF treatment, you feel symptoms of OHSS, contact your healthcare provider as soon as possible.

Medically Reviewed

Last reviewed on 12/05/2023.

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