What is OHSS?

Ovarian hyper stimulation syndrome – OHSS is a serious condition where women over-respond to the use of FSH injections. They develop multiple follicles within their ovaries, and exhibit raised estrogen hormone blood levels.

It exclusively occurs as a side effect of Ovulation Induction treatment and IVF treatments, and is seen only after the administration of the hormone HCG injection (Human chorionic gonadotrophin).

The exact mechanism of how ovarian hyper stimulation OHSS occurs is still not fully  understood but a cascade of events leads to the leaking of fluids from your blood volume across the very small blood vessels (called capillaries) into areas in the body called the third space – cavities like the abdomen and chest. As the fluid flows to the third space the blood volume becomes less and dehydration occurs with electrolyte imbalances, thicker blood and the risk of clotting within the blood vessel increases.

The risk of developing this with ovulation induction treatment or IVF treatment is low at about 1% so don’t be alarmed and put off by the fertility treatment This is why you have careful and regular monitoring of your ovaries with ultrasound scans and hormone blood tests during fertility treatments. Fertility clinics are well trained in this area, and this is another good reason for having treatment through reputable clinics that do this fertility treatment all the time. If you are worried ask your doctor what their rate of OHSS is.

The symptoms and signs of ovarian hyper stimulation syndrome are: Enlargement of the ovaries as well as abdominal pain, nausea and vomiting, accumulation of fluid in the abdomen and/or chest with abdominal enlargement, weight gain, shortness of breath, urinating less than normal, and due to dehydration… the possible risk of blood clots in the legs or lung. See figure 1 and 2 below of enlarged ovaries after being stimulated.

Becoming pregnant with the FSH treatment can stimulate the symptoms of ovarian hyper stimulation syndrome further. This is due to the pregnancy hormone HCG secreted by the pregnancy acting on the enlarged ovaries.

If any of the above start to occur or you are not sure, then it is best to contact your fertility doctor and clinic.

Treatment is hospitalization and rehydration with IV fluids with close monitoring of your blood electrolyte levels. Hospitalization is usually between 2 to 7 days on average. Women are monitored in hospital until there is improvement in their symptoms and signs.