OVARIAN HYPERSTIMULATION SYNDROME (OHSS)

What is it?

This is a specific problem which occurs in about 1% - 2% of patients who undergo super-ovulation induction. It is impossible to predict which patients may suffer from it before Assisted Reproductive Technology treatments commence.

During the treatment it is more likely to occur in those producing large numbers of follicles and high hormone levels. It does NOT occur if the final HCG injection is not given.

Essentially, fluid from the blood stream leaks into the abdominal cavity causing it to swell noticeably and leaving the blood more concentrated and more viscous. Mild cases of OHSS may pass unnoticed.

The consequences of severe OHSS can be breathing difficulties, temporary kidney shut-down, and some arterial and venous thrombosis. Rarely extensive thrombosis could cause interference with blood supply to parts of the brain or to other organs. Death due to OHSS whilst very rare, is possible. Patients who suffer severe OHSS must be hospitalised and treated. This treatment would involve the infusion of intravenous fluids and the fluid in the abdomen may need draining off.

OHSS always disappears in a few days unless a pregnancy occurs. In early pregnancy the problem may last weeks and require prolonged hospitalisation.

PREVENTION OF OHSS

All patients using HMG or Gonal-F/Puregon will require close monitoring using blood tests and ultrasound scanning of the ovaries to ensure the ovaries do not over- respond to the drugs.

Patients are generally monitored daily and those who have oestradiol (E2) levels approaching 12,000pm/L are considered to be getting close to the risk level.

If this occurs, the options are as follows: To cancel the cycle, to collect and fertilise the oocytes and then freeze the embryos (ie. avoiding pregnancy in that cycle).