All about OHSS (Ovarian Hyperstimulation Syndrome)

Ovarian Hyperstimulation Syndrome

This article will let you know all about the OHSS (Ovarian Hyperstimulation Syndrome). So let us start with what it’s all about?

When the ovaries adversely react to an abundance of hormones, that condition is called ovarian Hyperstimulation syndrome. This problem is seen in the women who have to take injectable hormone medications to stimulate egg production.

Rarely, OHSS can result from taking other medications, such as clomiphene citrate or gonadotropin-releasing hormone.

Women with OHSS have a large number of growing follicles along with high estradiol levels. This leads to fluid leaking into the abdomen (belly), which can cause bloating, nausea, and swelling of the abdomen. Mostly, OHSS cases are mild but when OHSS is severe, symptoms like blood clots, shortness of breath, abdominal pain, dehydration, and vomiting are possible.

Symptoms of ovarian hyperstimulation syndrome:

Symptoms of ovarian hyperstimulation syndrome often start within a week of using injectable medications to stimulate ovulation, but sometimes it takes two weeks or more. Symptoms can be mild to severe and may worsen or improve over time. 

Mild to moderate OHSS:

In mild to moderate ovarian hyperstimulation syndrome, symptoms can be like:

  • Mild to moderate abdominal pain
  • Abdominal bloating or increased waist size
  • Vomiting
  • Nausea
  • Diarrhoea

Some women who use injectable fertility drugs may suffer a mild form of OHSS. In most cases, this goes away after a week. But, if pregnancy occurs, symptoms of OHSS may worsen and last more than several days to weeks.

Severe OHSS:

In severe OHSS syndrome, symptoms can be like:

  • Rapid weight gain — more than 1kilogram in 24 hours
  • Severe abdominal pain
  • Blood clots
  • Severe, persistent nausea and vomiting
  • Shortness of breath
  • Decreased urination
  • Tight or enlarged abdomen

It’s important to get immediate treatment if one experiences severe symptoms and has any risk factors of OHSS. Issues like blood clots, trouble breathing, and severe pain may lead to more serious complications, like an ovarian cyst rupture with excessive bleeding.

Causes of Ovarian Hyperstimulation Syndrome:

In most cases, OHSS develops because of high levels of the pregnancy hormone hCG following fertility treatments that stimulate the production of many eggs at one time, as is done with many IVF protocols. In some rare cases, patients have genetic mutations in certain hormone receptors that predispose them to develop OHSS even without hormonal treatments.

In women with OHSS, drugs used in fertility treatments cause the blood vessels surrounding the ovaries to leak fluid. This fluid causes the ovaries to swell. Sometimes this fluid moves into the belly and other areas, causing:

  • Swelling
  • Pain
  • Nausea
  • Vomiting
  • Increased thirst

Mild OHSS happens in up to a third of all IVF cycles while more moderate to severe OHSS happens only 3 per cent to 8 percent of the time.

There are some risk factors including things like having polycystic ovary syndrome (PCOS) or having a large number of follicles in any given cycle. Women who are younger than 35 years may also face such complications.

   Some other risk factors include:

  • Fresh versus frozen IVF cycle
  • High estrogen level during an IVF cycle
  • Low body mass index (BMI)

There’s nothing to worry about a lot about it. With proper medication and treatment, such problems can be dealt with. And with our advanced medical science, there is a solution for these types of problems.

Treatments for Ovarian Hyperstimulation Syndrome:

The type of treatment one receives in such cases depends on the severity of the case.

Mild OHSS:  Mild cases will generally be cured on their own in around two weeks. Any treatment for mild OHSS is focused on relieving discomfort and avoiding complications.

The following treatment options will help in curing the discomfort one experiences with OHSS:

  • Increase fluid intake (1.5 to 2 litres)
  • Take sufficient rest with light activity as recommended by the doctor.
  • Take over-the-counter pain relievers
  • Check the weight daily to monitor drastic changes in body weight.
  • Avoid caffeine and alcohol.

Unless the symptoms are very serious, major treatments or hospitalization usually aren’t needed.

Severe OHSS: Severe cases may require hospitalization and significant treatments. Treating OHSS in the initial stage can prevent major complications. Treatments for severe OHSS may include intravenous (IV) fluids, medication to relieve symptoms, and medication to reduce ovarian activity.

Preventing/reducing the risk of having OHSS:

There are several strategies that are used to lower the risk of OHSS. Reducing the dose of ovarian stimulation medications may reduce the risk of OHSS.

Pregnancy can make OHSS worse or last longer. If a woman develops OHSS, avoiding immediate pregnancy by freezing her eggs/embryos for transfer at a later time can help the OHSS resolve more quickly and keep it from progressing.

Some patients who are at risk for OHSS may be given extra IV fluids at the time of egg retrieval. Giving IV fluids early can help prevent the worsening of symptoms later on.

Important Points to remember:

  • OHSS is relatively common after ovulation induction or ovarian stimulation for IVF.
  • A standard pelvic exam is NOT generally recommended because the ovaries are enlarged and the cysts that are present may burst under pressure.
  • Women with symptoms of OHSS should see a doctor familiar with assisted reproduction as soon as they have symptoms.
  • Other symptoms such as facial numbness, weakness, lower extremity swelling, or redness may occur.
  • OHSS often can be managed with decreased activity, drinking electrolyte-rich fluids, draining fluid that accumulates in the abdomen, medication for nausea and pain, careful monitoring, and frequent doctor visits.
  • Severe OHSS (continued vomiting, severe swelling of the abdomen, shortness of breath, inability to drink fluids or abnormal laboratory results) may require hospitalization for intensive monitoring and treatment. But such cases are very low in number.


There are a variety of ways one can consult with a doctor to lower the odds of developing OHSS.

Every case is unique, and the doctor will likely monitor the patient closely to decide how to proceed. Monitoring usually involves a mix of blood tests (to check hormones) and ultrasounds. But there’s no need to worry more because treatments are there to cure these problems.

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