Pattern-match the story: infertility treatment + bilaterally enlarged ovaries + third-space fluid (ascites and pleural effusion causing dyspnea) = ovarian hyperstimulation syndrome until proven otherwise.
Mechanism in one line: gonadotropins drive multiple follicles, the ovaries release vasoactive mediators (VEGF), capillary leak follows, and fluid pours into the abdomen and chest while the blood concentrates, raising clot risk.
Knock out the rest: PCOS is a chronic anovulatory state, not an acute fluid-shift emergency. Theca lutein cysts come from very high hCG (hydatidiform mole, multiple gestation), not gonadotropin injections. A mucinous cystadenoma is a slow-growing benign tumour, a single huge cyst, not bilateral cystic ovaries with sudden ascites. Everything points to OHSS. Ref: DC Dutta's Textbook of Gynecology, 6th Edition.
