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Ovarian hyperstimulation syndrome

Definition

Ovarian hyperstimulation syndrome (OHSS) is a problem that is sometimes seen in women who take fertility medicines that stimulate egg production.

Alternative Names

OHSS

Causes

Normally, a woman produces one egg per month. Some women who have trouble getting pregnant may be given medicines to help them produce and release eggs.

If these medicines stimulate the ovaries too much, the ovaries can become very swollen. Fluid can leak into the belly and chest area. This is called OHSS. This occurs only after the eggs are released from the ovary (ovulation).

You may be more likely to get OHSS if:

  • You receive a shot of human chorionic gonadotropin (hCG).
  • You get more than one dose of hCG after ovulation.
  • You become pregnant during this cycle.

OHSS rarely occurs in women who only take fertility drugs by mouth.

OHSS affects 3% to 6% of women who go through in vitro fertilization (IVF).

Other risk factors for OHSS include:

  • Being younger than age 35
  • Having a very high estrogen level during fertility treatments
  • Developing an unusually large number of ovarian follicles with your fertility treatment
  • Having polycystic ovarian syndrome
  • Low body weight

Symptoms

The symptoms of OHSS can range from mild to severe. Most women with the condition have mild symptoms such as:

  • Abdominal bloating
  • Mild pain in the abdomen
  • Weight gain

In rare cases, women can have more serious symptoms, including:

  • Rapid weight gain (more than 10 pounds or 4.5 kilograms in 3 to 5 days)
  • Severe pain or swelling in the belly area
  • Decreased urination
  • Shortness of breath
  • Nausea, vomiting, or diarrhea
  • Blood clots

Exams and Tests

If you have a severe case of OHSS, your health care provider will need to monitor your symptoms carefully. You may be admitted to the hospital.

Your weight and the size of your belly area (abdomen) will be measured. Tests that may be done include:

Treatment

Mild cases of OHSS usually don't need to be treated. The condition may actually be associated with a greater chance of becoming pregnant.

The following steps can help you ease your discomfort:

  • Get plenty of rest with your legs raised. This helps your body release the fluid. However, light activity every now and then is better than complete bed rest, unless your provider tells you otherwise.
  • Drink at least 10 to 12 glasses (about 1.5 to 2 liters) of fluid a day (especially drinks that contain electrolytes).
  • Avoid alcohol or caffeinated beverages (such as colas or coffee).
  • Avoid intense exercise and sexual intercourse. These activities can cause ovarian discomfort and may cause ovarian cysts to rupture or leak, or cause the ovaries to twist and cut off blood flow (ovarian torsion).
  • Take an over-the-counter pain reliever such as acetaminophen (Tylenol).

You should weigh yourself each day to make sure you are not putting on too much weight (2 or more pounds or about 1 kilogram or more a day).

If your provider diagnoses severe OHSS before transferring embryos in an IVF, they may decide to cancel the embryo transfer. The embryos are frozen and they wait for OHSS to resolve before scheduling a frozen embryo transfer cycle.

In the rare case that you develop severe OHSS, you will probably need to go to a hospital. Your provider will give you fluids through a vein (intravenous fluids). They will also remove fluids that have collected in your body, and monitor your condition.

Outlook (Prognosis)

Most mild cases of OHSS will go away on their own after menstruation starts. If you have a more severe case, it can take several days for symptoms to improve.

If you become pregnant during OHSS, the symptoms may get worse and can take weeks to go away.

Possible Complications

In rare cases, OHSS can lead to fatal complications. These can include:

  • Blood clots
  • Kidney failure
  • Severe electrolyte imbalance
  • Severe fluid buildup in the abdomen or chest

When to Contact a Medical Professional

Contact your provider if you experience any of the following symptoms:

  • Less urine output
  • Dizziness
  • Excessive weight gain, more than 2 pounds (1 kg) a day
  • Very bad nausea (you cannot keep food or liquids down)
  • Severe abdominal pain
  • Shortness of breath

Prevention

If you are getting injections of fertility medicines, you will need to have regular blood tests and pelvic ultrasounds to make sure that your ovaries aren't over-responding.

References

Catherino WH. Reproductive endocrinology and infertility. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 218.

Legro RS, Fauser BCJM. Medical approaches to ovarian stimulation for infertility. In: Strauss JF, Barbieri RL, Dokras A, Williams CJ, Williams Z, eds. Yen & Jaffe's Reproductive Endocrinology. 9th ed. Philadelphia, PA: Elsevier; 2024:chap 34.

Lobo RA. Infertility: etiology, diagnostic evaluation, management, prognosis. In: Gershenson DM, Lentz GM, Valea FA, Lobo RA, eds. Comprehensive Gynecology. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 40.

Last reviewed August 23, 2023 by LaQuita Martinez, MD, Department of Obstetrics and Gynecology, Emory Johns Creek Hospital, Alpharetta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..

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