This is a condition where ovaries over respond to the hormone injections used to stimulate the growth of the follicles that contain the eggs. This is characterized by:

  1. Ovarian enlargement with more than the average number of follicles
  2. Fluid accumulation – most commonly in abdomen and rarely around the lungs and heart
  3.  Thrombo-embolism:
    1. Thrombosis: This means development of blood clots in large blood vessels. This is due to leakage of fluid from with in your blood vessels into the tissues (see point 2 above).
    2. Embolism: There is the risk of the blood clot dislodging and travelling to another part of your body.
  4. Both thrombosis and embolism can have their own complications.

How common is OHSS?

This can occur in 1% – 10% of patients undergoing IVF treatment. Approximately 1 in 100 to 1 in 200 patients will need short stay in the hospital because of hyperstimulation.

Who is at risk?

  1. Anyone undergoing treatment with fertility drugs is  ‘at risk’
  2. This complication occurs most commonly:
    1. In those patients who have had IVF or ICSI treatment.
    2. Patients with polycystic ovaries (PCO)
    3. Very young patients (less than 30 years).
  3. Occurrence is related to the total number of follicles present in the treatment cycle.
  4. Risk is increased in patients with increased number of follicles who subsequently become pregnant.