Ovarian Hyperstimulation Syndrome (OHSS) – Symptoms and Causes

Overview

In vitro fertilization (IVF) is a reproductive technology where eggs and sperm are combined outside the body. This process involves several key steps:

1. Ovarian Stimulation: Fertility medications stimulate the ovaries to produce multiple eggs rather than the single egg typically released during a menstrual cycle.

2. Egg Retrieval: Once the follicles are mature, eggs are collected from the ovaries using a needle guided by ultrasound imaging.

3. Fertilization: The retrieved eggs are combined with sperm in a laboratory dish. This can happen in two ways:
   • Traditional method: Eggs and sperm are mixed together.
   • Intracytoplasmic Sperm Injection (ICSI): A single sperm is directly injected into each egg.

4. Embryo Development: Successfully fertilized eggs develop into embryos over 3-5 days.

5. Embryo Transfer: The embryo is placed into the uterus using a thin tube inserted through the cervix.

During IVF treatment, some women may develop ovarian hyperstimulation syndrome (OHSS) as a reaction to the fertility medications. This condition causes ovarian swelling and pain. Risk factors include young age, low body weight, and polycystic ovary syndrome.

Signs and Symptoms

Mild to Moderate Ovarian Swelling

Patients with mild to moderate ovarian swelling may experience:

• Mild to moderate pain in the abdomen
• Bloating or increased waist size
• Feeling sick to the stomach (nausea)
• Throwing up (vomiting)
• Loose bowel movements
• Tender feeling near the ovaries

These symptoms often start within a week after receiving fertility shots. For many women, mild symptoms go away after about a week on their own.

However, if pregnancy occurs during this time, symptoms might get worse and last for several days or even weeks.

Severe Ovarian Swelling

Signs of severe ovarian swelling include:

• Quick weight gain (more than 2.2 pounds in 24 hours)
• Strong abdominal pain
• Severe, ongoing nausea and vomiting
• Blood clots
• Reduced urine output
• Trouble breathing
• Tight or swollen abdomen

When to See a Doctor

Tell your healthcare provider right away if you notice any symptoms of ovarian hyperstimulation syndrome during fertility treatments. Even with mild symptoms, your doctor should monitor you for sudden weight gain or worsening signs.

Seek immediate medical attention if you experience:

• Breathing Difficulties
• Leg pain

These symptoms may indicate a serious condition requiring prompt medical care. Your doctor needs to know about any changes in your health during fertility treatments to ensure your safety.

Causes

OHSS happens when ovaries respond strongly to hormones. The main trigger is high levels of human chorionic gonadotropin (HCG) in the body.

When HCG enters the system, blood vessels in the ovaries start to leak fluid abnormally. This leaked fluid makes the ovaries swell and can collect in the abdomen.

In fertility treatments, doctors give HCG injections to help eggs release from follicles. Most OHSS cases develop within a week after receiving this injection.

If pregnancy occurs during treatment, the condition may worsen because the body begins making its own HCG.

Injectable fertility drugs create a higher risk for OHSS than oral medications like clomiphene. Some people might experience OHSS without any fertility treatments, though this happens rarely.

Scientists still don’t completely understand why OHSS occurs. Research continues to learn how HCG affects ovarian blood vessels and why some women are more sensitive to these hormonal changes than others.

Risk Factors

Several factors may increase the chance of developing OHSS:

• Polycystic Ovary Syndrome (PCOS): This common reproductive condition causes irregular periods, excess hair growth, and unusual ovary appearance on ultrasound.
• High Follicle Count: Having many follicles during treatment.
• Younger Age: Being under 35 years old.
• Low Body Weight: Having a lower than average body mass.
• Hormone Levels: High or rapidly increasing estradiol (estrogen) before HCG trigger shot.
• Previous OHSS: Having experienced OHSS in the past.

Some women develop OHSS without any known risk factors. Your doctor can help assess your personal risk.

Possible Health Issues

Severe ovarian hyperstimulation syndrome rarely occurs, but can threaten a person’s life when it does. This condition may lead to fluid buildup in the abdomen and chest areas.

Blood chemistry problems involving sodium, potassium, and other essential elements can develop. Blood clots might form in major blood vessels, particularly in the legs.

Other serious complications include:

• Kidney failure
• Ovarian torsion (twisting of the ovary)
• Bleeding from ruptured ovarian cysts
• Respiratory difficulties
• Pregnancy complications including miscarriage
• Death (in extremely rare cases)

These complications require immediate medical attention to prevent long-term health problems.

Prevention

Reducing the risk of ovarian hyperstimulation syndrome requires a personalized approach to fertility treatments. Regular monitoring through ultrasounds and blood tests helps track follicle development and hormone levels during each treatment cycle.

Effective prevention strategies include:

• Medication Dosage Optimization: Using the lowest effective dose of gonadotropins to stimulate ovulation.
• Supplementary Medications: Adding treatments like low-dose aspirin, dopamine agonists (carbergoline or quinagolide), or calcium infusions.
• Metformin Use: For women with polycystic ovary syndrome, taking metformin during ovarian stimulation may help prevent complications.

The “coasting” technique can be valuable when estrogen levels rise too high or too many follicles develop. This approach involves temporarily stopping injectable medications for a few days before administering the hormone that triggers ovulation.

Alternative trigger methods can reduce risks.

Instead of using human chorionic gonadotropin (HCG) shots, which often contribute to OHSS development, medications called gonadotropin-releasing hormone agonists like leuprolide may be used.

For patients undergoing in vitro fertilization (IVF), doctors might recommend removing all follicles from the ovaries.

The mature follicles can be fertilized and frozen while the ovaries rest. This allows the IVF process to continue later when the body has recovered.

Each prevention strategy requires careful consideration and monitoring by healthcare professionals. The right approach depends on individual risk factors and response to treatment.