Ovarian hyperstimulation syndrome: Focus on neurovascular complications

Ovarian hyperstimulation syndrome (OHSS) is a severe iatrogenic complication of ovulation induction which has a very serious impact on the patient's health and may cause morbidity and even mortality. Indeed, patients classified as having severe OHSS have rapid weight gain, tense ascites, hemodynamic instability, respiratory difficulty, progressive oliguria, and laboratory abnormalities. The underlying feature of OHSS is increased capillary permeability leading to a fluid shift from the intravascular space to third space compartments. Indeed, cardiovascular system findings include decreased intravascular volume, decreased blood pressure, decreased central venous perfusion, and compensatory increased heart rate and cardiac output with arterial vasodilation. Although venous thromboembolic phenomena are a possible complication in advanced phases of OHSS, arterial ischemia involving the cerebral circulation has not been frequently reported. The pathogenesis of thromboembolism in OHSS is not fully understood, though hemoconcentration and blood hyperviscosity seem to play a role in developing thrombotic changes into both venous and arterial system. Interestingly, the presence of cardiac abnormalities in combination with inherited or acquired hypercoagulable state seems to increase the risk of cerebral infarct in these subjects, as recently shown by our group. This chapter is aimed at investigating the pathomechanism and the management of neurovascular complications related to OHSS.