A persistent change in bowel habit (including both diarrhoea and constipation) warrants further assessment. Diarrhoea has a whole range of possible causes including infection, inflammation (Inflammatory Bowel Disease) or sometimes colon cancer.
Taking a thorough history and looking for associated factors helps to narrow the likely list of potential causes. Blood tests, stool samples and colonoscopy are the usual investigations.
Rectal bleeding can occur independently or in association with a change in bowel habit. Fresh rectal bleeding is more suggestive of a cause towards the end of the bowel (e.g. anus, rectum or sigmoid colon.)
Most of the time rectal bleeding is related to haemorrhoids (piles) or a tear (anal fissure); other important causes include bowel cancer, diverticular disease and Inflammatory Bowel Disease. Hence, rectal bleeding should not be ignored and is usually investigated with colonoscopy.