Ovarian hyperstimulation syndrome: a review of recent practices

Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic adverse event that occurs as a result of ovarian stimulation, particularly in susceptible women. It is caused by an unusually high ovarian response to stimulation and results in enlarged ovaries and fluid shift from intravascular compartment to the third space. Clinical features include abdominal distension, discomfort, ascites, and pleural effusion. There is a risk of thromboembolism and hepatic and renal dysfunction. Ovarian reserve tests can identify patients at high risk of OHSS, allowing targeted preventative measures. High-quality evidence supports the use of GnRH antagonist regimes in women with a high ovarian reserve. GnRH agonist trigger and elective cryopreservation of all embryos further reduce the risk of OHSS. All women at risk of OHSS should have adequate information and access to 24-hour care. Women presenting with possible OHSS should be assessed and investigated to confirm the diagnosis and classify severity. Mild and moderate OHSS can be managed on an out-patient basis, while severe OHSS often needs in-patient care. Principles of management are maintaining intravascular hydration by encouraging fluid intake guided by thirst, close monitoring of fluid balance, prevention of thromboembolic complications, drainage of ascites in selected cases and symptom relief. If conception occurs in the treatment, the course of OHSS is likely to be more severe and protracted.