THE PATHOPHYSIOLOGY OF OVARIAN HYPERSTIMULATION SYNDROME - VIEWS AND IDEAS

Ovarian hyperstimulation syndrome (OHSS) is a serious complication aff ecting ovulation induction, Its most severe manifestation takes the fo rm of massive ovarian enlargement and multiple cysts, haemoconcentrati on and third-space accumulation of fluid. The full-blown clinical synd rome may be complicated by renal failure and oliguria, hypovolaemic sh ock, thromboembolic episodes, adult respiratory distress syndrome (ARD S), and death, Although the pathophysiology of this syndrome has not b een completely elucidated, it seems likely that the increased capillar y permeability triggered by the release of vasoactive substance secret ed by the ovaries under human chorionic gonadotrophin (HCG) stimulatio n plays a key role in this syndrome. Several factors such as histamine , serotonin, prostaglandins, prolactin, and a variety of other substan ces have been implicated in this process in the past, At present, fact ors belonging to the renin-angiotensin system, cytokines including the interleukins, tumour necrosis factor alpha, endothelin-1 and vascular endothelial growth factor (VEGF) are thought to be involved in trigge ring increased vascular permeability after ovulation induction treatme nt. This manuscript summarizes the current knowledge of the pathophysi ology of ovarian hyperstimulation syndrome with emphasis on the correl ation of the various factors with the clinical phenomena of this iatro genic syndrome.