Prevention and treatment of ovarian hyperstimulation syndrome.

The ovarian hyperstimulation syndrome (OHSS) is a potentially fatal condition with a pathophysiology that is not clearly understood. A shift in fluid from the extravascular space occurs, thought to be induced by cytokines and/or vascular endothelial growth factor. Human chorionic gonadotrophin (hCG), exogenous or endogenous, seems to be the triggering mechanism, resulting in early and late development of the syndrome, respectively. The management of the syndrome is mainly symptomatic. Preventive strategies are being developed and constantly refined. Women at increased risk of OHSS need to be on the lowest possible dose of gonadotrophin with the aim of reducing the granulosa/luteal cell mass. Ultrasound and serum oestradiol (E2) measurements are, at present, the main methods used to identify and monitor those at risk during controlled ovarian hyperstimulation (COH). Withholding gonadotrophin stimulation (coasting), but continuing down-regulation, when a large number of follicles (greater than 20) and a rising serum oestradiol level are seen, is the most widely favoured and used preventive measure and the most cost effective. Management is symptomatic and aimed at achieving fluid balance, restoring plasma volume and improving renal function. This may be combined with an early resort to ascitic fluid aspiration, which will improve the feeling of wellbeing and may remove those agents responsible for the syndrome. Heparin, to prevent the risk of thromboembolism as a result of haemoconcentration, is important.