This pressure results in transudation of inflammatory mediators into the subcutaneous tissues of the lower extremity and subsequent breakdown of the tissue including the skin.

It is thought to result from direct transmission of pressure to cerebral capillaries with transudation of fluid from the capillaries into the extravascular compartment.

It is possible that this leakage was caused by minute perforations of the gall bladder allowing transudation of bile, that healed by the time of cholecystoscopy.

The pressure differentials are directed to the center of the sinuses producing mucosal edema, transudation, and mucosal-or submucosal-hematoma, leading to further occlusion of the sinus ostium.

In females, erection of the clitoris (nocturnal clitoral tumescence or NCT) causes enlargement, with accompanying vaginal blood flow and transudation (i.e. lubrication).