Left: normal.
Right: Mild colitis produces redness and swelling of the mucosa, resulting in a loss of the normal vascular pattern, an overall granular appearance, and friability (fragility with ease of bleeding).


Mucosal granularity, exudate and superficial ulceration. There is often an abrupt transition to relatively normal-appearing mucosa (right).


With increasing severity, petechiae (points of bleeding), exudate (pus) and small, discrete ulcers appear.