A potentially life-threatening complication that may occur in women receiving drugs to stimulate ovulation. The acute onset occurs within the first week ovulation is induced and is characterized by marked cystic ovarian enlargement, ascites, hydrothorax, arterial hypotension, tachycardia, hemoconcentration, oliguria, sodium retention, hypernatremia, and in severe cases renal failure. The condition is usually mild if the diameter of the ovary is less than 8 cm; moderate if 8 to 12 cm; and severe if greater than 12 cm.