Ovarian Hyperstimulation Syndrome (OHSS)

Ovarian Hyperstimulation is a complication of fertility treatment, particularly that of in vitro fertilisation (IVF).

Depending on severity of your symptoms, OHSS is graded as mild, moderate or severe.

Mild OHSS: mild abdominal swelling/bloating, abdominal discomfort and feeling sick.

Moderate OHSS: The same symptoms as mild but worsening of abdominal discomfort, swelling/bloating due to a build up of fluid in the abdomen, minor weight gain, pain, nausea and loose stools may be present.

Severe OHSS: The same symptoms as moderate plus: weight gain, increased abdominal girth measurements, extreme thirst, dehydration, passing little amounts of urine, difficulty in breathing, redness and tenderness in legs or chest pain.

When having fertility treatment the drugs used to stimulate the ovaries produce many follicles (follicles are small sacs of fluid where the eggs develop). Sometimes there is an excessive response to these drugs causing OHSS.

Overstimulated ovaries become bigger and they release chemicals into your bloodstream that make blood vessels leak fluid around your body. This fluid concentrates into your abdomen. In severe cases this fluid can disperse into the space around your lungs, and very rarely your heart. This can cause pressure making it difficult to breathe which will require immediate hospital admission.

All women undergoing ovarian stimulation during fertility treatment are at risk of developing OHSS. Mild OHSS can occur in 33% of women having treatment: moderate / severe OHSS is 1/100 women (1%).

Women are deemed more at risk of developing OHSS if:

• they are known to have polycystic ovaries
• they are aged over 30 years
• they have suffered OHSS previously
• they have had successful IVF pregnancies, particularly those of a multiple pregnancy

There is no specific tests to diagnose OHSS but is based on the severity of symptoms experienced, the size of your ovaries, and if there is presence of fluid in your abdomen. An ultrasound scan will be carried out to measure these.

OHSS can therefore be managed as an outpatient meaning you will be allowed to go home with follow up appointments (the doctor you see will decide when these will be arranged) or you will be admitted as an inpatient (requiring you to stay in hospital).

Outpatient management (mild to moderate OHSS)

• Take pain killers regularly such as paracetamol and/or codeine. No Non-Steroidal Anti Inflammatory Drugs (Ibuprofen/Nurofen) should be prescribed or administered
• Drink fluids to aid thirst not to excess
• Monitor how often you are passing urine
• Strenuous exercise and sexual activity should be avoided until symptoms are resolved
• Continue progesterone support provided by the IVF clinic
• Continuous monitoring and assessment of symptoms should be between every 2-3 days by a clinician

Inpatient management (moderate to severe OHSS)

• Take pain killers regularly such as paracetamol and/or codeine. No Non-Steroidal Anti Inflammatory Drugs (NSAIDs) should be prescribed or administered
• Anti sickness medications will be prescribed and administered if required
• Intravenous drip for hydration
• Monitoring a strict urine output. This could result in being catheterised (a small tube inserted into the bladder draining urine)
• Support stockings and anti coagulation injections administered to prevent blood clots in the veins and lungs (thrombosis) developing
• Regular monitoring of vital signs (blood pressure, heart rate, breathing), weight, abdominal girth and blood tests
• A chest x-ray or ultrasound scan may be organised
• A low sodium diet should be maintained
• A procedure called paracentesis (a thin needle/tube is inserted into your abdomen) might be offered to release the build up of fluid.

Every person who has symptoms of OHSS suffers differently so the above is a list of the most common management options. They might not all be applicable to you, your doctor will discuss the treatment with you, and your specific conditions.