[Ovarian hyperstimulation syndrome (OHS): borderlines between physiology and pathology]

The use of gonadotropins in therapy has led to the appearance of a complication due to hyperstimulation, referred to as "syndrome due to ovarian hypertension" (SOH). There are three clinical stages of SOH: slight, moderate and severe, caused by a pathogenetic mechanism which is thought to involve the action of prostaglandins and the renin-angiotensin system leading to an alteration in capillary permeability with increased ovarian diameter. SOH can be prevented using a protocol to evaluate clinical conditions during therapy mainly based on hormone assays and echographic monitoring. SOH can be predicted but not prevented, thus making it important to commence immediate treatment for in-patients so as to restore the volume of blood and the blood protein load in the most severe cases.