Is bloody stools a sign of some disease?

Depends: Blood in the stool occurs from bleeding in the lower colonic tract and the rectum. It can result from blood vessel leakage, hemorrhoids, disease like ulcerative colitis, or anal fissures and trauma (from anal sex for instance). If persistent, it needs evaluation by your gastroenterologist.

It can be.: Possible causes of blood in stool include: fissures, fistulas, hemorrhoids, cancer, ulcers, infections, inflammation, Diverticular disease & Angiodysplasia . Get evaluated if more than a one time occurrence.