OHSS: Causes, Symptom & Treatment

Advanced fertility treatments such as IVF have opened up new possibilities for parenthood for millions of couples across the world. But sometimes, these can come with unexpected challenges, and one such challenge that we will discuss in this article is OHSS. If you have not heard this term before, do not worry, we will understand this condition in detail so that you stay informed and have a smoother IVF journey.

What is OHSS?

The medical abbreviation OHSS stands for Ovarian Hyperstimulation Syndrome. As the name suggests, it is a condition that happens when the ovaries overreact to the fertility drugs that are given during IVF.

OHSS leads to swollen and painful ovaries because of too many eggs maturing at the same time. Mild cases of OHSS are common and can be managed easily; however, moderate to severe forms require timely management and closer medical supervision.

Note: Though there are risks involved, it does not mean that a successful pregnancy with OHSS is impossible. With timely intervention and careful monitoring, women with OHSS still have successful pregnancies.

Types of OHSS

OHSS is typically categorised into mild, moderate and severe depending upon its risk and severity.

Mild OHSS	Moderate OHSS	Severe OHSS
Ovaries are slightly enlarged, usually <5 cm. The body experiences minimal fluid shifts. Symptoms include: mild bloating, slight lower abdominal discomfort and minor weight gain. This type is easily manageable and rarely affects IVF results.	Ovaries are comparatively enlarged, 5–12 cm. Fluid accumulation may start to affect blood volume and kidney function. Symptoms include: noticeable abdominal swelling, nausea, vomiting, mild changes in urination and weight gain over a few days. Moderate OHSS requires closer monitoring by your fertility specialist.	Ovaries are significantly enlarged, >12 cm Fluid builds up in the abdomen or chest and can affect blood circulation, kidney function, and breathing. Symptoms include: rapid weight gain, severe abdominal pain, shortness of breath, reduced urination and significant bloating. Hospitalisation and medical intervention are often required.

Severe OHSS is less common but can be dangerous if not managed on time.

Symptoms of OHSS

Symptoms vary depending on severity.

Mild Symptoms Include: 

• Mild abdominal discomfort or bloating
• Mild nausea
• Slight weight gain

Severe Symptoms Include:

• Severe abdominal pain and swelling
• Persistent nausea and vomiting
• Shortness of breath
• Rapid weight gain
• Decreased urination
• Dizziness or fainting

Note: OHSS symptoms can appear anytime during the ovarian stimulation phase of IVF, after egg retrieval, or sometimes even after embryo transfer. Careful monitoring is crucial.

Causes of OHSS

There are multiple factors responsible for OHSS. These include:

• Excessive ovarian response to fertility drugs: Injectable fertility medicines like gonadotropins stimulate the development of multiple eggs. Sometimes, there is a too high ovarian response in some women that produces more eggs than expected, leading to OHSS.
• High estrogen levels: During the ovarian stimulation phase of an IVF cycle, estrogen levels will vary based on the ovarian response. Elevated estrogen levels cause the body to retain more fluid and can exacerbate OHSS.
• Polycystic ovary syndrome (PCOS): Ovarian follicles are naturally higher in women with PCOS. Fertility medicines make them more prone to OHSS due to the risk of over-response by the ovaries.
• Previous history of OHSS: If a woman has experienced OHSS in a prior IVF cycle, her risk is higher in subsequent treatments. Doctors often take special precautions in these cases to reduce the likelihood of recurrence.

Why Does OHSS Occur During IVF?

The process of IVF involves ovarian stimulation to produce multiple eggs. Sometimes, the ovaries respond more than required. This can lead to the release of certain hormones that increase vascular permeability, which causes fluid to shift from blood vessels into the abdomen and chest, leading to OHSS

How to Diagnose OHSS?

Your fertility specialist may combine a few diagnostic tools to assess your condition:

• Ultrasound: It helps detect enlarged ovaries and multiple fluid-filled follicles.
• Blood tests: These are required to monitor hormone levels, especially estradiol, and check kidney function.
• Physical examination: This checks for abdominal swelling, tenderness, and bloating.
• Monitoring weight and urine output: This is important to track fluid retention and early signs of complications.

Early diagnosis is critical to prevent progression from mild to severe OHSS.

Risk Factors Associated with OHSS

Certain factors increase the likelihood of developing OHSS:

• Young age (under 35)
• Low body weight
• PCOS or high antral follicle count
• High doses of injectable fertility medications
• Rapidly rising estrogen levels during stimulation
• Previous OHSS

How Can OHSS Be Treated?

OHSS treatment depends on the severity of the condition and focuses on managing symptoms, preventing complications, and supporting recovery.

Mild OHSS

Mild cases are usually manageable at home. Treatment focuses on comfort and monitoring:

• Rest and careful monitoring: Light activity is encouraged, but strenuous exercise should be avoided.
• Hydration: Drinking water and electrolyte-rich fluids helps maintain fluid balance.
• Diet: Light, balanced meals can reduce bloating and discomfort.
• Monitoring: Track weight, abdominal swelling, and any worsening symptoms.

Most women recover from mild OHSS within a few days after egg retrieval without affecting pregnancy outcomes.

Moderate to Severe OHSS

Moderate to severe OHSS may require hospitalisation for close monitoring and medical intervention:

• Intravenous (IV) fluids: These help maintain hydration and electrolyte balance.
• Pain management: Medications may be prescribed to relieve abdominal discomfort.
• Blood tests: These help keep a track of kidney function, electrolytes, and hormone levels.
• Fluid drainage: In some cases, excess fluid in the abdomen may be drained to relieve pressure and improve comfort.
• Adjusting IVF protocol: Doctors may freeze all embryos and delay embryo transfer to reduce the risk of worsening OHSS due to pregnancy hormones.

Note: Home care is only safe for mild OHSS. Moderate to severe cases require medical supervision to prevent serious complications such as kidney issues, blood clots, or fluid accumulation in the chest.

Prevention of OHSS

Prevention is always better than a cure. The following are some tips that can help and may reduce the risk of severe OHSS:

• Individualised ovarian stimulation protocols
• Using lower doses of gonadotropins
• Triggering final egg maturation with a GnRH agonist instead of hCG in high-risk patients
• Freezing all embryos and delaying embryo transfer to a later cycle
• Close monitoring with ultrasound and blood tests

Can OHSS Occur After Embryo Transfer?

Yes, OHSS can occur even after embryo transfer, especially if pregnancy occurs. The pregnancy hormone hCG can worsen symptoms by further stimulating the ovaries. This is why high-risk patients are often advised to freeze all embryos and transfer later when the ovaries have returned to their normal size.

The Closing Note

While OHSS can be a challenge for many women, it is important to understand that early intervention and expert guidance can help in effective OHSS management and prevent complications. There is no long-term impact of mild OHSS, and they are easy to manage at home. Moderate to severe cases require strict medical supervision, though severe cases are rare. With preventive strategies, monitoring symptoms, and seeking timely care, women can achieve a successful pregnancy with OHSS safely.

FAQs

What is the full form of OHSS?

OHSS stands for Ovarian Hyperstimulation Syndrome.

How Common is OHSS?

Mild OHSS is fairly common and occurs in up to 20% of women undergoing IVF. Moderate to severe OHSS is less common and affects nearly 1–5% of IVF cycles. Thanks to modern IVF protocols, the risk has decreased significantly.

What lifestyle factors can help prevent OHSS?

These include:

• Maintaining a healthy weight
• Keeping yourself hydrated
• Avoiding excessive caffeine or alcohol consumption
• Managing stress through yoga or meditation
• Following your doctor’s advice on diet and supplements