Ovarian hyperstimulation syndrome (OHSS) is a morbid, iatrogenic, and potentially lethal condition caused by the pharmacological induction of ovulation. In OHSS, the ovaries are the site of significant stromal edema with bilateral cystic ovarian enlargement. It has been suggested that ascitic fluid accumulation may be due to increased capillary permeability, which results in fluid shift from the intravascular to the extravascular compartment. While the exact etiology is not clear, several biochemical markers are considered to be possible mediators. There is an incidence of OHSS in about 3% to 8% of all therapy cycles. Severe OHSS is the rarest form, with an incidence characterized by a degree of variability ranging from 0.1% to 2.5% of women subjected to induced polyovulation.