Complications of ovarian stimulation.

We review three complications of ovarian stimulation, namely ovarian hyperstimulation syndrome, thromboembolic disease in relation to fertility treatment and multiple pregnancy. Current views on the ovarian hyperstimulation syndrome emphasize its association with the presence of polycystic ovaries. We review here the pathophysiological background of this association and focus on the central role of vascular endothelial growth factor (VEGF). Overexpression of VEGF in the polycystic ovary is thought to contribute to its characteristic multifollicular response to gonadotrophic stimulation. Release of large amounts of VEGF into the circulation is thought to account for the development of the clinical syndrome of ovarian hyperstimulation. The implications of this understanding are explored and the clinical features of the condition and its management are described. Thromboembolic disease is increasingly recognized as a serious if rare complication of infertility treatment. The subject is reviewed here with special reference to two recently published and important papers. The most concerning complication of infertility treatment is multiple pregnancy. Few doctors seem to be aware of the dire statistics: every index of obstetric outcome is adversely affected. The survival, health and family circumstances of children born as the result of multifetal gestation are all impaired. Infertility patients need a clear understanding of the risks involved so that they can appreciate the need for intensive monitoring of ovarian stimulation. In our opinion a knowledge of the rate of multiple pregnancy is quite as important as knowing the clinic's 'success' rate.