Systematic review of data concerning etiopathology of ovarian hyperstimulation syndrome.

The ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of ovarian stimulation occurring during the luteal phase or early pregnancy. It has been observed over the last 60 years, since gonadotropins were first used to induce ovulation. The prevalence varies, according to study, from 0.5% to 5%. The pathogenesis of OHSS is, apparently, complex. It involves a vasoactive mediator, secreted by the ovaries (in overabundance) after artificial stimulation. Estradiol, which is a marker of ovarian response, is not the mediator. The candidate mediators reviewed are prolactin and prostaglandins; the ovarian prorenin-renin-angiotensin system; cytokines (including allergy-cytokines-histamine as a system); VEGF; angiogenin; the Kinin-Kallikrein system; VCAM and ICAM; selectins; von Willebrand factor; and endothelin. The main conclusion is that OHSS is the result of disturbance of the basically inflammation-like normal ovulation process, and has as its main feature capillary leakage and transmission of mediators to other compartments.