Rectal bleeding, when should you see a specialist?

Rectal bleeding is one of the most common reasons patients are referred to a colorectal surgeon. It is also one of the symptoms that people are most likely to ignore or delay acting on, often because they assume it is simply haemorrhoids, or because they feel embarrassed to discuss it. Whilst haemorrhoids are indeed the most frequent cause of rectal bleeding, they are far from the only one. Understanding when bleeding is likely to be benign and when it warrants prompt investigation can make a significant difference to outcomes.

What causes rectal bleeding?

Rectal bleeding has a wide range of potential causes, from entirely benign to more serious. The most common include:

• Haemorrhoids: swollen blood vessels in the anal canal, typically causing bright red blood on the paper or in the pan after opening the bowels.
• Anal fissures: small tears in the anal lining causing bright red bleeding and pain.
• Diverticular disease: bleeding from small pouches in the colon wall, which can occasionally be significant.
• Colorectal polyps: small growths on the lining of the bowel that may bleed and, if left untreated, can develop into cancer over time.
• Colorectal cancer: bleeding is one of the key warning signs and should never be assumed to have a benign cause until properly investigated.
• Inflammatory bowel disease: conditions such as ulcerative colitis and Crohn's disease frequently cause rectal bleeding alongside other symptoms.

What does the colour and pattern of bleeding tell us?

Bright red blood that appears on the toilet paper or coats the surface of the stool typically originates from the lower bowel or anal canal. Darker red blood mixed within the stool suggests a source higher up in the colon. Very dark, tarry stools (known as melaena) indicate bleeding from the upper gastrointestinal tract and require urgent assessment. However, the colour of bleeding alone is not a reliable guide, assessment by a specialist is always the safest approach.

When should you act immediately?

You should seek urgent medical attention if the bleeding is heavy, if you feel faint or unwell, or if the blood appears very dark or tarry. These may indicate significant bleeding requiring prompt intervention.

When should you see a specialist?

Any new rectal bleeding should be assessed by a doctor. You should seek a specialist opinion promptly if you are over the age of 40 and experiencing rectal bleeding for the first time, if the bleeding is associated with a change in bowel habit, unexplained weight loss, or abdominal pain, if it persists beyond a few weeks, or if you have a family history of colorectal cancer or bowel polyps. A colonoscopy is the gold standard investigation for rectal bleeding and allows the entire lining of the large bowel to be examined directly. As an accredited endoscopist, I am able to perform this investigation and discuss the findings with you on the same day.