Does rectal cancer cause blood in stool?

Rectal cancer can bleed when tissue in the rectum is irritated or damaged as stool passes. Blood may be bright red, darker, mixed with stool, or seen on toilet paper. A change in bowel habit, a feeling of incomplete emptying, unexplained tiredness, or abdominal discomfort can occur as well. Haemorrhoids, fissures, bowel inflammation, and other conditions can also cause rectal bleeding. Blood in stool does not on its own identify the cause, but it deserves medical review.

Book a medical appointment promptly for any new, recurring, or unexplained blood in stool. Note the colour and pattern of the blood, changes in bowel habit, weight change, pain, and medicines that can affect bleeding. Do not assume bleeding is due to piles without an assessment. A clinician may ask about your symptoms, examine the area, arrange blood tests, or recommend a bowel examination to find the source.

Seek emergency care for heavy bleeding, black tar-like stool, fainting, severe weakness, severe abdominal pain, or signs of shock such as cold clammy skin and confusion. Arrange urgent same-day assessment if bleeding is continuing or you feel increasingly unwell. Bring a list of medicines, particularly those that affect clotting, if you are able.

Ask what could be causing the bleeding, whether you need a rectal or bowel examination, and how quickly tests should be arranged. Ask which warning changes should prompt emergency care while you are waiting for assessment.