الفهرس 
OVERVIEW OF OVULATION INDUCTIONOnly 14 pages are availabe for public view
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Abstract
Ovarian hyper stimulation syndrome (OHSS) is an iatrogenic and potentially life-threatening complication of ovarian stimulation in assisted reproduction technology (ART) and is characterized by cystic enlargement of the ovaries and rapid fluid shifts from the intravascular compartment to the third space.
Two main clinical forms of OHSS are defined, early-onset OHSS and late-onset OHSS. Early-onset OHSS usually occurring within 9 days after oocyte retrieval is correlated to ovarian response to stimulation. Late-onset OHSS occurs after the initial 10-days period and is correlated to the endogenous human chorionic gonadotropin (hCG) produced by an implanting embryo or to the administration of hCG for luteal phase support.
The pathophysiology of OHSS is characterized by increased capillary permeability, leading to leakage of fluid from the vascular compartment, with third-space fluid accumulation and intravascular dehydration.
Although the exact cause of OHSS has not been completely elucidated, it seems likely that the release of vasoactive substances secreted by the ovaries under human chorionic gonadotrophin (hCG) stimulation may play a key role in triggering this syndrome.
Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, has emerged as one of the factors most likely involved in the pathophysiology of OHSS.
The clinical manifestations of ovarian hyper stimulation syndrome originate from the combination of decreased intravascular space and the accumulation of protein-rich fluid into body cavities and interstitial space.