Ovarian hyperstimulation syndrome


Ovarian hyperstimulation syndrome (OHSS) primarily affects women undergoing fertility treatments involving hormone medications to stimulate egg development. It can also occur with oral medications like clomiphene, presenting with symptoms ranging from mild discomfort and bloating to severe complications. OHSS severity is categorized as mild, moderate, or severe, with severe cases being rare but potentially life-threatening.

Mild OHSS causes temporary discomfort and bloating, often resolving on its own. More severe cases can lead to symptoms like ovarian swelling, abdominal pain, nausea, vomiting, and breathing difficulties. Severe OHSS may result in serious complications, including blood clots and abdominal fluid buildup.

Treatment depends on OHSS severity, ranging from supportive care for mild cases to hospitalization for severe ones. Interventions may include fluid drainage, intravenous hydration, and symptom management. Close monitoring by healthcare providers is crucial during fertility treatments to detect and address OHSS promptly, tailoring treatment accordingly.


When injectable medications are employed to stimulate ovulation, the symptoms of ovarian hyperstimulation syndrome typically begin to manifest approximately one to two weeks later. The severity of these symptoms can range from mild to severe, and their progression may vary, either worsening or improving over time.

Mild to moderate OHSS

The following symptoms may be present in mild to moderate ovarian hyperstimulation syndrome:

  • Tenderness where the ovaries are located
  • Mild to moderate pain in the abdomen
  • Bloating of the abdomen
  • Enlarged abdomen
  • Diarrhea
  • Nausea
  • Vomiting

A modest type of OHSS is experienced by certain women who use injectable reproductive medications. Usually, this passes within a week or so. However, OHSS symptoms may intensify and persist for a few days to weeks if pregnancy develops.

Severe OHSS

In the event that you have severe OHSS, you may:

  • Low amount of urine output
  • Difficulty of breathing
  • Blood clots
  • Severe pain in the abdomen
  • Severe, continues nausea and vomiting
  • Excessive weight gain: gaining more than 2.2 pounds (1 kilogram) in a single day
  • Abdominal enlargement or tightness
  • Kidney failure

If you are undergoing fertility treatments and notice any symptoms of ovarian hyperstimulation syndrome, it is crucial to inform your healthcare provider, even if your case appears mild. Your provider will want to monitor you for sudden weight gain or worsening symptoms. Additionally, if you experience breathing difficulties or leg pain during fertility treatment, contact your healthcare provider immediately, as these symptoms could signify an urgent medical situation requiring prompt attention.


The exact cause of ovarian hyperstimulation syndrome (OHSS) remains not completely understood, but it is associated with the introduction of high levels of human chorionic gonadotropin (HCG), a hormone typically produced during pregnancy, into the system. In OHSS, ovarian blood vessels react abnormally to HCG, leading to fluid leakage. This fluid accumulation causes swelling of the ovaries, and sometimes significant amounts of fluid move into the abdomen. In fertility treatments, HCG is often administered as a “trigger” to induce the release of an egg from a mature follicle, with OHSS typically developing within a week of receiving an HCG injection. If pregnancy occurs during a treatment cycle, OHSS can worsen as the body starts producing its own HCG in response to pregnancy. Injectable fertility medications carry a higher risk of causing OHSS compared to clomiphene, an orally administered medication. In some rare cases, OHSS can also occur spontaneously, unrelated to fertility treatments.

Risk factors

Women who have no risk factors at all may experience OHSS occasionally. However, the following are known to raise your risk of OHSS:

  • History of OHSS
  • Below 35 years old
  • Huge amount of follicles
  • Being under weight
  • Elevated or sharply rising estradiol (estrogen) before to an HCG trigger shot

The common reproductive condition known as polycystic ovarian syndrome is characterized by irregular menstrual cycles, excessive hair growth, and an abnormal appearance of the ovaries during ultrasonography.