(a) An endoscopic image of the colonic mucosa, a Mayo endoscopic subscore of 0. The mucosal has a visible vascular pattern, and scattered white ulcer scars are evident. (b) An endoscopic image of the colonic mucosa, a Mayo endoscopic subscore of 1. The vascular pattern of the mucosa is decreased, with mild erythema. (c) An endoscopic image of the colonic mucosa, a Mayo endoscopic subscore of 2. The vascular pattern of the mucosa is decreased, with marked erythema and multiple erosions. (d) An endoscopic image of the colonic mucosa, a Mayo endoscopic subscore of 3. The mucosa shows marked erythema and ulcers.