Ovarian Hyperstimulation Syndrome (OHSS): Pathogenesis and Prevention

Abstract

Ovarian hyperstimulation syndrome (OHSS) is a serious and potentially fatal complication affecting ovulation induction. Its severest manifestation takes the form of massive ovarian enlargement and multiple cysts, hemoconcentration, and third-space accumulation of fluid. The full-blown clinical syndrome may be complicated by renal failure and oliguria, hypovolemic shock, thromboembolic episodes, adult respiratory distress syndrome (ARDS), and death. Although the pathophysiology of this syndrome has not been completely elucidated, it seems likely that the increased capillary permeability triggered by the release of vasoactive substance secreted by the ovaries under hCG stimulation plays a key role in this syndrome. Several factors such as histamine, serotonin, prostaglandins, prolactin, and variety of other substances were implicated in this process in the past. At present factors belonging to the renin-angiotensin system, cytokines like the interleukins, tumor necrosis factor alpha, endothelin-1, and vascular endothelial growth factor (VEGF) are thought as being involved in triggering increased vascular permeability after ovulation induction treatment.

This manuscript summarizes the current knowledge of the pathophysiology of ovarian hyperstimulation syndrome with emphasis on the correlation of the various factors to the clinical phenomena of this iatrogenic syndrome.