Blood in stool is commonly caused by anal fissure or piles. However, the blood can come from colon (large intestine). Common causes are ulcers, colorectal polyp & colon cancer. Blood coming from colonic sources usually is dark red in colour. It is called hematochezia in medical language.
Polyp usually does not have any known causes. Old age is one of the risk factor. There are certain medical conditions which increases the risk of polyps such as familial adenomatous polyposis, ulcerative colitis, crohn's disease or family history of polyp or cancer.
When small colon polyp usually does not cause symptoms. However, with increasing size the colon polyp symptoms may be mucus discharge in stool, diarrhoea, constipation or blood in stool. When symptomatic, such polyps should be removed & examined in the laboratory. Among the types of polyps - hyperplastic, tubular, villous or mixed, it's the villous type which has a higher risk of turning into malignancy.
Removal of small tumourfrom colon