Ovarian hyperstimulation syndrome (OHSS) is a syndrome caused by over stimulating the ovaries during fertility treatment. Either during the induction of ovulation for women who are not ovulating or during stimulation of ovulation for IVF, OHSS is caused by giving too large a dose of follicle stimulating hormone (FSH). It is a largely preventable and often foreseeable syndrome which should only rarely be encountered by experienced reproductive practitioners. Women at greatest risk of developing OHSS are young and lean and have polycystic ovaries and those who have had OHSS in a previous treatment cycle.
The signs and symptoms include, from mild to severe, enlargement of the ovaries causing abdominal bloating, nausea and vomiting, diarrhea, collection of fluid in the abdomen and lung linings causing shortage of breath, thickening of the blood due to internal dehydration, blood clots and shutting down of the kidneys. Fortunately, these latter symptoms are very rarely seen but deaths have occurred.
OHSS does not occur if the final trigger injection of hCG (human chorionic gonadotrophin) is not given. Withdrawal of this injection and abandonment of the cycle is the best prevention if the large number of follicles that have been produced by the FSH injections suggest that OHSS is a distinct possibility.
Alternatively, the hCG injection may be substituted by an injection of GnRH agonist or coasting employed by withholding further injections until the hormone levels decrease within 2-3 days. Whatever the method, prevention is better than cure and discretion is the better part of valour!
Mild enlargement of the ovaries and a little abdominal bloating is commonplace but symptoms beyond these demand hospitalization where the first line treatment is an intravenous infusion of fluid. Fortunately, these symptoms are self limiting but the presence of a pregnancy will prolong them.