-          inflammatory involvement of the rectum, most often in ulcerative colitis or rectal involvement in Crohn's disease, also in venereal diseases (lymphogranulomavenereum, lues, gonorrhoea, AIDS) and as post-radiation colitis

-          pathologically-anatomically red, bleeding mucosa with erosions to ulcers

-          clinically bloody thin stools, fever, sometimes transient incontinence from sphincter insufficiency, diagnosis by rectoscopy and biopsy, bacteriology

-          treatment depending on the underlying disease