Ovarian Hyper-stimulation Syndrome (OHSS)

What does the HFEA do about OHSS?

The HFEA does not tell clinics how they should medically treat patients.  As with all drug treatments used for fertility patients, clinical guidance and supervision is provided by professional bodies such as the Royal College of Obstetricians and Gynaecologists (see below) and the General Medical Council. 

The HFEA´s role is to make sure that clinics provide patients with proper information about all the steps of their treatment, including any possible risks and side effects.

What are clinics required to do?

The HFEA provides guidance to clinics in our Code of Practice. This says that clinics must:

  • have clear and understandable patient information about the risks of treatment, including OHSS
  • give patients the opportunity to discuss those risks before, during and after treatment
  • tell patients what they should do if they feel unwell during treatment and what they should tell any doctors or medical staff if taken ill
  • have an out-of-hours telephone number if patients need to contact them urgently
  • use the best practice clinical guidelines to manage OHSS
  • have systems in place to deal with any cases of OHSS, including guidance for neighbouring hospitals where a patient may be admitted in an emergency.

How is OHSS reported and identified?

As the HFEA does not tell clinics how they should medically treat patients there is no requirement for clinics to report mild or moderate cases of OHSS to the HFEA. However, clinics are asked to report treatment cycles to the HFEA if a treatment cycle has been stopped because the patient was at risk of developing OHSS.

Severe cases of OHSS are treated as incidents. The HFEA expects an incident report from a clinic whenever the clinic is made aware of a severe case of OHSS resulting in prolonged hospitalisation or death. The HFEA Code of Practice defines an incident as 'Any occurrence that is inconsistent with the routine care of the patient or the routine operation of the organisation, including adverse incidents and serious adverse events and reactions'. See Directions on Reporting Adverse Incidents.


For more information about how the HFEA regulates clinics see How We Regulate. 

What information does the HFEA hold about OHSS?

In 2005, Professor Adam Balen wrote a report on OHSS for the HFEA as part of the Authority´s SEED (Sperm, Egg and Embryo Donation) review.  The report found that severe OHSS occurs in approximately 1% of treatment cycles. The report was updated in 2008 and can be downloaded here.

The HFEA does not publish statistical information relating to the reporting of adverse or serious incidents in relation to specific clinics because there is a risk that patients may be identified.

Further information

Last updated: 22 October 2008