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 femoral vein runs parallel to the artery, like in first picture, on the side closest to your genitals. (So, if you're feeling on your left side, the vein is to the right of the artery; if feeling on the right side, the vein is to the left of the artery-- The first picture shows your left side only.)