Irritable bowel syndrome (IBS) is a functional intestinal disorder without any organic substrate. IBS Diagnosis is established when all other possible diseases, infections, tumors, etc… of the gastro-intestinal tract (GIT) that have similar symptoms have been excluded. IBS manifests with constipation, diarrhea, bloating, reflux, indigestion, abdominal pain, gases etc. These symptoms and signs are also observed during many other disorders of the GIT. Blood in the stools is not a sign of IBS. Blood in the stool is always a sign of some organic disorder of the GIT. You can request an occult blood test to confirm or exclude the presence of blood in the stool. After that procedure, you can request a colonoscopy to visualize the bowels from the inside and to identify the source of the bleeding. Mucous stools lined with blood are typical for some large intestine inflammations such as colitis but, again, that diagnosis can be confirmed or excluded only by a colonoscopy. Colon cancer is also diagnosed only via colonoscopies. You can consult a gastroenterohepatologist for expert opinion and follow up on your condition.