Hello and welcome to the zero to finals podcast.

My name is Tom and in this episode I'm going to be talking to you about ovarian hyperstimulation

syndrome.

And you can find written notes on this topic at zero tofinals.com slash ovarian hyperstimulation

syndrome or in the fertility section of the 0-2-finals

obstetrics and gynecology book. So let's get straight into it. Ovarian hypostimulation

syndrome abbreviated to OHSS is a complication of ovarian stimulation during in vitro fertilization infertility treatment.

It's a complication of IVF.

OHSS is associated with the use of human corionic gonadotropin or HG to mature the follicles during the final steps of ovarian stimulation.

Let's talk about the pathophysiology. The primary mechanism for OHSS is an increase in

vascular endothelial growth factor, or VEGF, which is released by the granulosa cells of the follicles.

Veg F increases vascular permeability, causing fluid to leak from the capillaries.

Fluid moves from the intravascular space to the extravascular space, and this results in

edema, ascites and hypovolemia.

The use of gonadotropins, LH and FSA during ovarian stimulation

results in the development of multiple follicles.

OHSS is provoked by the trigger injection of HCG that comes 36 hours before egg collection.

HCG stimulates the release of Veg-F from the multiple follicles in the ovaries.

The features of the condition begin to develop after the HCG trigger injection.

There's also activation of the renin angiotensin system.

A notable finding in patients with OHSS is a raised renin level, and the renin level correlates with the severity of the condition.

Next let's talk about the risk factors.

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