A couple undergoes IVF. After oocyte retrieval, the embryologist reports that 4 oocytes are retrieved, 3 are MII (metaphase II) and fertilize normally. On day 3, two 8-cell embryos are transferred. The woman develops abdominal distension, nausea, and ovarian enlargement on day 8 post-retrieval. The pathophysiological key mediator responsible for ovarian hyperstimulation syndrome (OHSS) is:

• A Luteinizing hormone
• B Follicle-stimulating hormone
• C Vascular endothelial growth factor (VEGF) ✓
• D Prolactin

Explanation

OHSS is mediated primarily by VEGF (vascular endothelial growth factor, particularly VEGF-A), secreted by granulosa-lutein cells of hyperstimulated ovaries. VEGF increases vascular permeability, causing massive fluid shift from intravascular to third space (ascites, pleural effusion, hemoconcentration). This is triggered by hCG (exogenous trigger or endogenous from early pregnancy). GnRH agonist trigger instead of hCG, or dopamine agonists (cabergoline) that block VEGFR-2 phosphorylation, are used for OHSS prevention.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.