Peritonitis is defined as inflammation of the peritoneum. The inflammatory response involves vasodilation, exudation of protein-rich fluid, cellular infiltration, pain and, chronically, formation of fibrous adhesion. The disease can be classified into primary and secondary cases.
It begins in the venous plexus along the medial side of the foot, and it runs up the medial side of the leg and knee, alongside the saphenous nerve. In the thigh, the long saphenous vein continues up the medial surface, accompanying the medial femoral cutaneous nerve.
The Great Saphenous Vein (GSV) is the main truncal vein of the lower leg and, as such, drains blood from the inner part of the foot, the skin and fat of the front and inner aspect of the lower leg, and the skin and fat of the inner part of the thigh.