Blood in stool: Your questions answered

Written by: Dr Sarmed Sami
Edited by: Carlota Pano

Blood in stool, also known as rectal bleeding, is a medical symptom that can manifest as bright red blood, maroon-coloured stools, or black tarry stools. Blood in stool should never be ignored.


Here, Dr Sarmed Sami, renowned consultant gastroenterologist, explores the common causes, symptoms, and potential treatment options for blood in stool.



What can cause blood in stool?


Blood in stool may be caused by a range of conditions, some of which are harmless and others which are more serious.


These conditions include:

  • Haemorrhoids (Piles): One of the most common causes of rectal bleeding, haemorrhoids are swollen blood vessels in the rectum or anus. They can be internal or external, and are often triggered by straining during bowel movements, chronic constipation, hard stools, or pregnancy.
  • Anal fissures: These are small tears or cracks in the lining of the anus, usually caused by passing hard stools. The resulting pain and discomfort can lead to traces of bright red blood on the stool or on the toilet paper.
  • Diverticular disease: Diverticula are small pouches that can form in the colon (large bowel) wall, a condition called diverticulosis. If these pouches become inflamed or infected, it leads to diverticulitis, which can cause rectal bleeding.
  • Inflammatory bowel disease (IBD): Conditions such as ulcerative colitis and Crohn's disease can cause inflammation in the digestive tract, leading to ulcers that bleed and result in blood appearing in the stool.
  • Peptic ulcers: These are sores that develop on the lining of the stomach, small intestine, or oesophagus. When these sores bleed, the blood can pass through the digestive system and usually appear as black tarry stool.
  • Polyps and colon cancer: Colorectal polyps are abnormal growths that can bleed. While most polyps are benign, some can progress into colon cancer, which is a more serious condition that can also cause blood in the stool.
  • Gastrointestinal infections: Bacterial or viral infections in the gastrointestinal tract can irritate the intestines and lead to bleeding.
  • Anal cancer: Though rare, cancer of the anus can cause rectal bleeding.


What are the symptoms of blood in stool?


The primary symptom of blood in stool is, of course, the presence of blood itself. The colour and the amount of blood can vary depending on the underlying cause.


Other associated symptoms may include:


When should I seek medical attention?


If you notice blood in your stool, it's important to seek medical attention promptly. While it may be due to minor issues like haemorrhoids, it can also be a sign of a more serious condition, such as colon cancer, that requires immediate medical attention for successful treatment.


How is blood in stool diagnosed and treated?


To determine the cause of blood in stool, a doctor may perform several diagnostic tests, including:

  • A physical examination and medical history review
  • A stool analysis
  • A colonoscopy or sigmoidoscopy
  • A CT or MRI scans
  • Blood tests to check for anaemia or signs of infection


Treatment for blood in stool will depend on the underlying cause.


For less severe cases, lifestyle changes, dietary modifications, and over-the-counter medications may be sufficient.


In more serious cases, surgical procedures or prescription medications, may be necessary.


Can I prevent blood in stool?


While some causes of blood in stool cannot be prevented, certain lifestyle changes can reduce the risk of developing certain conditions.


These changes include:

  • Maintaining a high-fibre diet to prevent constipation and straining during bowel movements.
  • Staying hydrated to soften stools and ease bowel movements.
  • Practising regular exercise to help promote healthy digestion.
  • Avoiding prolonged sitting on the toilet, as it may aggravate haemorrhoids.


Blood in stool is a serious symptom that warrants immediate medical attention. While it may be caused by benign conditions, it can also indicate more severe underlying issues. Early diagnosis and appropriate treatment are essential for better outcomes.



If you notice blood in your stool or experience any related symptoms, don’t hesitate to book an appointment with Dr Sarmed Sami via his Top Doctors profile today.


Remember, timely action can make all the difference in managing and treating potential health concerns.

By Dr Sarmed Sami

Dr Sarmed Sami is an accomplished consultant gastroenterologist who specialises in acid reflux testing (BRAVO capsule), endoscopy, swallowing problems, stomach pain, diarrhoea, blood in stool, bowel cancer screening, polypectomies, as well as Barrett's oesophagus. He is currently practising at esteemed clinic Digestive Health UK as well as at the Mayo Clinic Healthcare

Dr Sami, who is also an honorary consultant gastroenterologist at University College London Hospital and an honorary associate professor at University College London, is also an expert when it comes to bloating, indigestion, heartburn, IBS, and oesophageal cancer, but to mention only a few. Notably, Dr Sami undertook his specialist training as well as his initial clinical practice at some of the world's most renowned hospitals, including the Mayo Clinic in the United States of America. 

He has been awarded a whole host of prestigious awards during his career so far, including the Fellows-in-Training Award, which was presented to him by the American College of Gastroenterology in recognition of his scientific paper. He has published extensively to-date, and currently offers the London International Upper GI Symposium to GPs.

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