[Ovarian hyperstimulation syndrome: pathophysiology, risk factors, prevention, diagnosis and treatment].

The ovarian hyperstimulation syndrome is a major complication of ovulation induction for in vitro fertilization, with severe morbidity and possible mortality. Whereas its pathophysiology remains ill-established, the VEGF may play a key role as well as coagulation disturbances. Risk factors for severe OHSS may be related to patients characteristics or to the management of the ovarian stimulation. Two types of OHSS are usually distinguished: the early OHSS, immediately following the ovulation triggering and a later and more severe one, occurring in case of pregnancy. As no etiologic treatment is available, the therapeutic management of OHSS should focus on its related-complications. Thrombotic complications that can occur in venous or arterial vessels represent the major risk of OHSS, possibly conducting to myocardial infarction and cerebrovascular accidents. Once the OHSS is diagnosed, prevention of thrombotic accidents remains the major issue.