March 18, 2024
8 Minutes

What is OHSS and How to Prevent it?

What is OHSS and How to Prevent it?

In an eggshell...

  1. OHSS is a risk associated with egg freezing where the ovaries overproduce eggs and swell up
  2. There’s no exact reason behind it- but doctors monitor symptoms and vitals to check out for any warning signs
  3. Your medical history and genetics can play a part in whether you can be at risk of OHSS
  4. OHSS is preventable- and treatable.

Egg freezing, as every other procedure comes with a fair share of minor risks. 

Egg freezing involves medication that tells your ovaries “hey we need to grow more eggs this time, and we need to catch ‘em all” 👮

So your brain gets working to direct the ovaries to produce more eggs than usual.

But sometimes, the ovary can overreact (ovary-act😔). It gets into egg-producing mode, to the point where it gets a little risky for the body. 

That's OHSS or Ovarian Hyperstimulation Syndrome. 

We get it, as someone who’s thinking of an egg-freezing cycle you may be confused and scared, even. But we’re here to give you all the insider information on what it is, and how it's preventable. 

Read on!

What is OHSS?

OHSS is one such risk associated with egg freezing where the ovaries tend to swell up due to overproduction of eggs, along with fluid retention in the abdomen and pain. 

There are three types- mild, moderate, and the least common one, severe.

Mild to moderate cases have lesser symptoms and are often managed with outpatient treatment. This could mean repeated visits to the doctor after your egg retrieval, to check on your vitals, and intake medication until your period comes in.

But in severe cases, you may be redirected to a doctor specialised in managing severe OHSS. 

So how often does it occur?

Let's take a realistic view of it. As per studies, the incidence of OHSS is anywhere between 3.1 and 8%, but can be up to 20% in high-risk women (that is, women who are at risk or have a previous history of OHSS)

What causes OHSS?

Well, this is a puzzle for scientists too🧩

There’s no single cause behind OHSS. For instance, the HcG trigger given to mature the eggs before egg retrieval is known to be a cause. 

On the other hand, it can also happen with the usage of gonadotropins, which is usually given during the stimulation phase of your egg-freezing cycle.

So the cause of OHSS may be different, depending on the case. But it’s almost, always detectable.

Does OHSS occur during egg freezing?

Yes, OHSS can occur during egg freezing. OHSS typically peaks around 5-10 days after an egg retrieval. 

This is because your egg-freezing cycle involves “stimulating” the ovaries to produce more eggs. Stimulation involves medications and hormonal triggers. 

These medications and triggers are known to be a major cause of OHSS. And since they hang around in your system for quite a while, even after the egg retrieval, they can put you at risk for OHSS.

Does OHSS affect egg quality?

NNo ideally, OHSS does not affect egg quality. 

However, as per this study, if you have an underlying condition such as PCOS and go through OHSS, there may be an effect on the egg quality. This is due to pre-existing conditions such as PCOS, and not OHSS. 

But what it could affect is the quantity. OHSS could lead to more number of eggs being retrieved than usual.

But it’s not on a positive note either. These eggs may be immature, and your body would still have to deal with the effects of OHSS.

What are the symptoms of OHSS after egg retrieval?

So, how exactly do you know if you have OHSS?

Given that there are hormonal tests done right before your egg retrieval, there are some telltale signs of OHSS that healthcare providers can look out for (more on that below).

However, the symptoms of OHSS depend on the severity of the condition. Here are some symptoms to look out for:

Mild OHSS symptoms can look like:

  1. Mild abdominal swelling
  2. Vomiting
  3. Discomfort
  4. Nausea

Moderate OHSS symptoms can look like:

  1. Symptoms of mild OHSS
  2. Leakage of fluid from follicles, and fluid build-up in abdomen leading to swelling and pain

Severe OHSS symptoms can look like:

  1. Symptoms of moderate OHSS
  2. Extreme thirst and dehydration
  3. Hypotension
  4. Passing small amounts of urine
  5. Difficulty breathing due to fluid buildup in the abdomen

But here’s the thing: Severe OHSS is as rare as it comes. Only about 1 in 100 women may develop moderate or severe OHSS.

When should I seek medical attention with OHSS?

Ideally, it's best to reach out to your healthcare provider if you feel that your mild OHSS symptoms aren’t receding. If you feel dehydrated, vomiting, have discomfort or are having difficulty passing urine, it’s better to get some additional care at the hospital. 

This can ensure that your symptoms subside faster, and you’re back on the road to recovery. 

How do I know if I'm at risk of OHSS?

This depends on your medical history and genetics. Here are some risk factors for OHSS:

  1. Having PCOS (polycystic ovary syndrome)
  2. Under 30 years of age
  3. Lower BMI
  4. High antral follicle count (>24)
  5. Having a rapidly rising oestrogen level during stimulation
  6. Large number of developing follicles on the day of maturation trigger

Other risk factors include a history of allergies, high levels of AMH, high doses of gonadotropins during stimulation, usage of HcG as the maturation trigger, and high serum oestrogen levels. 

Especially if you have PCOS, it might act as a risk factor as people with PCOS have naturally higher AMH and AFC levels, along with serum oestrogen levels.

How can OHSS be prevented in egg-freezing cycles? 

While there’s no single signal that can predict OHSS, almost all prevention strategies involve attentive, personalised care and adjusting the dosage of medications accordingly. 

OHSS can be prevented in egg-freezing cycles by following a mix of monitoring and strategies, such as:

Identifying the “at risk” population

Being aware of the patients at risk can help clinicians modify protocols, such as reducing the dosage of gonadotropins, from the start, and avoid the occurrence of OHSS

Using AMH and AFC as a predictive tool

Studies mention that AMH levels >3.36ng/mL before an egg freezing cycle could indicate a risk of OHSS. For reference, AMH levels of 1-3 are considered normal, and not at risk. Similar to AMH, an AFC level of >24 can be a predictor of moderate to severe OHSS. This way, healthcare providers can be more vigilant of your response in the egg-freezing cycle. 

Using metformin therapy

Some studies suggest metformin to inhibit the secretion of VEGF (which is the villain 🦹 in a way, as these are the hormones that start OHSS).

Replacing the HcG trigger

In egg freezing cycles, 36 hours before your egg retrieval, a hCG trigger is given to mature the eggs. But the effects of hCG stay in the body for longer, increasing the risk of OHSS. Instead, replacing the hCG trigger with an alternative such as recombinant LH can reduce the risk of OHSS.

Choosing alternative procedures such as IVM

IVM or In vitro maturation is a method where immature eggs are retrieved from your ovaries and matured in the laboratory, before freezing. This requires little to no stimulation medication, thus reducing the risk of OHSS. 

So with all this in mind, clinics work on providing personalised protocols, if they detect any of these factors, during the monitoring and treatment stage. Tailored protocols help stimulate your eggs, but largely minimise the risk of OHSS. 

How is OHSS treated?

Mild to moderate OHSS symptoms usually resolve with medication, treatment, and lots of rest. You may have regular consultations, ultrasound, and blood tests to ensure that your symptoms don't worsen. Some of the treatments include:

Drinking plenty of fluids

As OHSS causes dehydration and a decrease in urine output, electrolyte-supplemented drinks, and water are recommended such that your urine becomes pale yellow. Refrain from sodas or any other caffeinated drinks while you recover.

Say no to strenuous activity

It’s best to rest and recover after an egg-freezing cycle. You will usually be recommended to not engage in heavy exercise or lift weights for about 48 hours until a week for good measure.

Eat nutritionally healthy food

It's advised to avoid oily, junk food and switch to leafy greens and a protein-rich diet, as recommended by your healthcare provider. 

Take prescribed medications

You may be prescribed pain relievers, anti-nausea medications, and diuretics to drain excess fluid from the abdominal region.

If you do happen to develop severe OHSS, you may require hospitalisation and treatment. This involves:

  1. A thorough investigation such as CBC, liver function test, serum oestrogen levels, etc 
  2. Heart rate, and blood pressure checkups 
  3. Daily assessment of BMI
  4. Intravenous fluids
  5. Electrolyte replacement

This can help prevent complications such as dehydration and blood clots. And even at this stage, bed rest and good fluid intake are at the top of the priority list! 

From Amilis: Personalised care and support for your egg-freezing cycles

Taking the decision to go for an egg-freezing cycle is daunting on its own, let alone learning about the risks that it tags along. 

But the good thing is: the chances of OHSS are rare, and most often preventable- by adjusting the dosage of fertility medications and monitoring your response to them. 

That is why, a huge part of the prevention of OHSS lies in personalised care from your healthcare provider and clinics, as well as the treatment protocols. 

Amilis is your one-stop solution for getting started with a personalised quiz or with an AMH test to help you decide, and even zero in on the right clinic for your egg-freezing journey. 

And if you ever feel stuck or confused at any point, our experts are just a chat away!

Remember, you’ve got this!







Written by
Navya Muralidhar
MSc Clinical Embryology & Embryologist

An embryologist by degree, and an educator by heart, Navya has completed her Bachelors in Genetics, and her Masters in Embryology and now strives to deconstruct the complex, into educational and informative articles surrounding her field of interest. She's specifically focused on time-lapse technology, IVM, and pre-implantation genetics. When not writing, you can find her at her favourite or newest coffee shop in town, sketching away, or listening to a podcast.