Rectal bleeding: why is there blood in my stool?

Written by: Professor Richard Cohen
Published: | Updated: 18/09/2019
Edited by: Cameron Gibson-Watt

Noticing blood in your stool can be both surprising and quite scary, but fortunately, most of the cases aren’t life-threatening and no need for concern. It’s surprisingly common and the treatment for it is usually quite simple. Professor Richard Cohen, a leading colorectal surgeon based in London, tells us the causes, risks and what to do if you have this symptom.




What can cause blood in the stool?

Finding blood in your stool can be a sign that there is bleeding along the digestive tract. It can appear as light red to maroon and sometimes even black and tarry. If it appears black, this usually means there is bleeding happening higher up in the digestive tract.

Most of the time, finding blood in your stool is caused by very innocent benign conditions and isn’t anything to worry about. These benign conditions include hemorrhoids, proctitis (inflammation) and anal fissures (tears).


Is blood in the stool dangerous?

It’s very unusual for blood in the stool to indicate something dangerous. For most people, it’s a benign phenomenon, but occasionally, more serious causes of blood in the stool can include:

  • Colon or rectal cancer - these are two types of cancer that can cause bleeding.
  • Colitis – a chronic digestive disease.
  • Crohn’s disease – inflammation of the digestive tract lining. Symptoms can also include abdominal pain and diarrhoea.
  • Ulcerative colitis – a chronic condition where the rectum and colon become inflamed.

It can also indicate that colon polyps are present, which are normally harmless wart-like lesions in the lining of the bowel but can be pre-malignant, meaning they can develop into cancer at a later stage.


What kind of diagnostic tests are available?

Normally, the patient would be seen and have a clinical discussion about the problem. After the discussion, the patient might undergo an internal examination depending on the cause.

This can take place in the consultation room, where the doctor will feel inside the rectum and anal canal with their finger and may insert a sigmoidoscopy and a proctoscope. These are lubricated instruments with a light on the end and are used by a physician to examine the anus and lower rectum.

It is not uncommon for patients to be sent to have a more thorough examination with a colonoscopy or a flexible sigmoidoscopy. These can be used to examine the lining of the colon or large intestine to see if there are any abnormal growths of tissue.

A virtual colonoscopy can also be suggested which is an alternative to actual colonoscopy and is carried out using a CT scan.


Management of blood in the stool

Treatment depends on the underlying diagnosis. For benign conditions this may involve local treatment of haemorrhoids or fissures (tears) with a variety of available procedures and treatments.


It can even be a case of simply changing your diet by eating more fibre or avoiding food that triggers symptoms.


For malignant conditions, the management will involve a multidisciplinary process (MDT) involving a surgeon, oncologist, radiologist and pathologist who work together as a team to get the best outcome for you.


Rectal cancer often requires very careful assessment and treatment options, which can include radiation and chemotherapy prior to surgery. The MDT will assess every case to make sure the best treatment plan is chosen for the particular situation of each individual patient.


If you’re experiencing blood in your stool and would like an appointment to see a consultant, visit Professor Richard Cohen’s profile and book through the website.

By Professor Richard Cohen
Colorectal surgery

Professor Richard Cohen is a leading colorectal and general surgeon based in London, practising at the Cleveland Clinic Colorectal Unit. He is an expert on open and minimally-invasive laparoscopic colorectal surgery, colorectal cancer, and irritable bowel disease (IBD). Currently, Professor Cohen serves as a clinical professor of surgery, consultant surgeon, and honorary senior lecturer at University College London (UCL). He is renowned as a pioneer of introducing new techniques in the United Kingdom. 

After receiving his medical qualification from Cambridge with distinction in 1987, Professor Cohen continued his training as a surgery registrar in Northwest England, and later as a senior registrar at Guy's and St Thomas' Hospital surgical training programme. Whilst undergoing his training, Professor Cohen also accomplished to carry out research at Yale University, USA, for his Master's thesis.

Professor Cohen joined UCL in 2005, where he has since helped to develop the colorectal service. Here and within his private practices, Professor Cohen maintains his expertise in open and minimally invasive colorectal surgery. Beyond his advanced surgery techniques, he focuses on colorectal cancer, benign colorectal disease, and management of ulcerative colitis, Crohn's disease, and IBD. He is a leading example for his practice fellows and other surgeons in his field.

Following his expertise in such subject, Professor Cohen continues to do research on topics of interest. These include pelvic floor disorders (incontinence and constipation), Crohn's disease, and colorectal cancer in Ashkenasi Jews. Research has persisted to be a passion of his, and subsequently he has had many papers published in peer-reviewed journals. Professor Cohen extends his involvement in colorectal surgery by also training young surgeons and lecturing nationally and internationally.

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