Ovarian hyperstimulation syndrome (OHSS) is typically an iatrogenic complication of ovulation induction (OI) occurring during the luteal phase or early pregnancy. OHSS is characterised by a cystic enlargement of the ovaries and an acute fluid shift from the intravascular to the third space, which may result in ascites, pleural infusions, pericardial infusion, and even generalized edema. Majority of OHSS cases have been associated with the use of gonadotrophins for OI in anovulatory women or for ovarian stimulation (OS) in the context of assisted reproductive technology (ART). Recurrent cases and familial occurrence of OHSS have been described, and different mutations in the follicle-stimulating hormone receptor (FSHr) have been reported in these cases. Polycystic ovarian syndrome (PCOS) appears to be the major predisposing factor for OHSS in a large number of studies.
