Ovarian Hyperstimulation Syndrome

Ovarian hyperstimulation syndrome (OHSS) happens when your ovaries swell and leak fluid into your abdomen. OHSS is a complication that typically occurs in people who receive fertility treatments that stimulate their ovaries to produce a large number of eggs.

Typically, a person releases one egg per menstrual cycle. People who have trouble getting pregnant may use hormonal medications to help them produce multiple eggs, especially if they’re planning an egg retrieval procedure and in vitro fertilization (IVF). Sometimes your ovaries overrespond or overreact to these drugs, leading to OHSS. This is more common with injectable medications that stimulate the ovaries.

In the past, OHSS was a relatively common complication of IVF. New protocols and strategies have made this less common, although mild cases still occur from time to time.

OHSS is more common in people receiving fertility treatments who have polycystic ovary syndrome (PCOS). PCOS is a reproductive disorder involving a hormonal imbalance. It’s also more common in people with a high egg supply.

Types of OHSS

Ovarian hyperstimulation syndrome can be mild, moderate or severe. Your healthcare provider classifies the type based on the severity of your symptoms. Most cases of OHSS are mild and cause temporary discomfort. Severe cases of OHSS are rare but can be life-threatening.

How common is ovarian hyperstimulation syndrome (OHSS)?

OHSS used to occur in about 10% of people undergoing controlled ovarian stimulation for IVF, but today the number is less than 5%. Severe cases of OHSS happen in less than 1% of people receiving ovarian stimulation for fertility treatment.