Key Overview
- Blood in stool can appear as bright red blood (usually from the lower GI tract — rectum, anus, sigmoid colon) or as black, tarry stools — called melena — which indicate bleeding higher up in the digestive system.
- Common causes include piles (haemorrhoids), anal fissures, anal fistulas, bowel infections, inflammatory bowel disease (IBD), polyps, and colorectal cancer.
- Emergency signs that require immediate medical attention include large amounts of blood, blood accompanied by severe abdominal pain, rapid heartbeat, dizziness, or fainting.
- Investigations your doctor may order include stool tests, blood tests, sigmoidoscopy, and colonoscopy — which can both find and treat the source of bleeding.
- Ignoring blood in stool is risky. Colorectal cancer, for example, is highly treatable when caught early. Dismissing this symptom as “just piles” without a proper check is a common and dangerous mistake.
Understanding Blood in Stool: What Does It Mean?
Finding blood in or on your stool can be alarming — and it should prompt you to see a doctor. However, the nature of the blood — its colour, amount, and where it appears — provides important clues about its source.
Bright Red Blood in Stool (Rectal Bleeding)
Painless bright red blood in stool — on the toilet paper, on the surface of the stool, or dripping into the toilet bowl — usually originates from the lower GI tract: the rectum, anus, or sigmoid colon. Common causes include:
- Piles (haemorrhoids)
- Anal fissures (small tears in the anal skin)
- Rectal polyps or cancer
Bright red blood means the source is close to the outside — the blood has not had time to be digested.
Black or Tarry Stool (Melena)
Black, sticky, foul-smelling stools — called melena — indicate that blood has come from the upper GI tract (stomach, oesophagus, or small intestine) and has been digested as it travels through the gut. This is more serious and is linked to causes like stomach ulcers or bleeding in the oesophagus. Read more about black stool (melena) vs red blood in stool to understand the difference clearly.
Dark Maroon or Mixed Blood
Blood that is dark red or maroon-coloured and mixed throughout the stool usually comes from the middle GI tract — the right colon or small intestine.
Occult Blood in Stool
Occult blood (hidden blood) is blood that is invisible to the naked eye but detected by a chemical test (Faecal Occult Blood Test / FOBT). It may be the only early sign of colon polyps or colorectal cancer and is why routine screening is important in people over 45 years of age.
Is Blood in Stool Always Related to Piles?
One of the most common misconceptions is that blood in stool is “always piles.” While piles are the most frequent cause, blood in stool can have many causes — some of them serious. Self-diagnosing as piles and delaying investigation has caused many patients to miss early-stage colorectal cancer.
The rule is simple: any blood in stool must be evaluated by a doctor, regardless of whether you think it is piles.
Common Causes of Blood in Stool
1. Piles (Haemorrhoids)
Piles are the most common cause of blood in stool. They are swollen veins in the rectum or around the anus. Internal haemorrhoids bleed without pain (classically — painless bright red blood while passing stool). External haemorrhoids can be painful.
Learn more about piles problem – causes, symptoms and treatment to understand this condition in detail. There are different types — understand types of piles and how they cause bleeding before assuming all blood is from the same source. Women often experience piles differently — read about piles symptoms in women for gender-specific information.
If you have piles and want to know your options before considering surgery, our guide on non-surgical treatment options for piles-related bleeding covers medications, dietary changes, rubber band ligation, and other procedures.
2. Anal Fissure
An anal fissure is a small tear or crack in the skin lining the anal canal. It typically causes bright red blood in stool along with sharp pain during and after passing stools — a key feature that helps distinguish it from piles. Constipation and hard stools are common triggers. Read more about anal fissure symptoms and treatment and how it differs from piles.
3. Anal Fistula
An anal fistula is an abnormal tunnel-like channel that develops between the anal canal and the skin near the anus, usually as a consequence of an anal abscess. It can cause blood-stained discharge, pain, and swelling. Read a detailed explanation of anal fistula details including causes, symptoms, and treatment options.
4. Does Constipation Cause Blood in Stool?
Yes, constipation can cause blood in stool — through two mechanisms. First, straining to pass very hard stools can rupture small blood vessels in piles, causing bleeding. Second, hard stools can tear the anal skin, causing a fissure. While constipation itself is not a “serious” cause of rectal bleeding, it is important to investigate to rule out other causes.
5. Colorectal Cancer (Bowel Cancer)
Colorectal cancer is one of the most serious causes of blood in stool and must always be ruled out, especially in adults over 40 with new or changed rectal bleeding, combined with:
- Unexplained weight loss
- Change in bowel habits (alternating constipation and diarrhoea)
- Feeling of incomplete evacuation
- Abdominal pain or lump
Early-stage colorectal cancer is very treatable — survival rates are excellent when caught before it spreads. For patients requiring surgical management, learn about colorectal surgery in Nagpur for serious rectal bleeding and what it involves.
6. Colonic Polyps
Polyps are small growths on the inner lining of the colon or rectum. Most are benign but some can turn cancerous over time. They often bleed without causing pain. Colonoscopy can both detect and remove polyps in a single procedure.
7. Inflammatory Bowel Disease (IBD — Crohn’s Disease and Ulcerative Colitis)
IBD causes chronic inflammation of the bowel lining. Ulcerative colitis, in particular, causes bloody diarrhoea — often with mucus — along with abdominal cramping and urgency. Blood in stool from IBD tends to be mixed into the stool rather than just on its surface.
8. Intestinal Infections (Infectious Colitis)
Bacterial infections — from pathogens like Salmonella, Shigella, E. coli O157:H7, and Campylobacter — can cause bloody diarrhoea (blood while pooping) along with fever and abdominal cramps. In India, amoebic colitis from Entamoeba histolytica is also common.
9. Diverticular Disease
Diverticulosis refers to small pouches (diverticula) that form in the colon wall. These pouches can bleed — sometimes heavily and suddenly — particularly in older adults. The bleeding is usually painless.
10. Angiodysplasia
Abnormal blood vessels in the colon wall can bleed intermittently. This is more common in elderly patients and can be difficult to find without careful endoscopic examination.
Upper GI Bleeding Presenting as Blood in Stool
It is important to recognise that sometimes blood originating from the upper GI tract — from the stomach or oesophagus — can present as dark or black stool rather than vomiting blood. Learn about GI bleeding signs you must not ignore and understand the full spectrum of GI bleeding. For completeness, also read about vomiting blood (hematemesis) causes to understand how upper GI bleeding can present.
When Is Blood in Stool an Emergency?
Go to hospital immediately if you have:
- Heavy rectal bleeding that does not stop
- Large amounts of blood — clots or continuous flow
- Blood combined with severe abdominal pain, cramping, or rigidity
- Symptoms of shock: dizziness, fainting, rapid heartbeat, pale skin, cold sweat
- High fever combined with bloody diarrhoea
- You are on blood thinners and notice any rectal bleeding
When Should You See a Doctor (Not an Emergency, but Urgent)?
Even without emergency symptoms, see a doctor soon if:
- You have noticed blood in stool more than once
- You are over 45 years of age with new-onset rectal bleeding
- You have unexplained weight loss, fatigue, or loss of appetite
- Your stool colour or consistency has changed over weeks
- You have a family history of colorectal cancer or polyps
- You notice blood in stool during or after pregnancy
- Occult blood has been detected in a routine stool test
Diagnosis: Tests for Blood in Stool
Stool Tests
Your doctor will likely start with stool tests — including stool tests like occult blood, culture and parasites — to check for infection, parasites, and hidden blood. Alongside stool tests, a complete pathology test list for digestive health including blood counts, liver function, and inflammatory markers helps build a complete picture of your health.
Blood Tests
- Complete Blood Count (CBC): To check for anaemia from chronic blood loss
- Inflammatory markers (ESR, CRP): To check for IBD or infection
- Coagulation profile: To assess clotting ability
- Liver function tests: Relevant if portal hypertension or liver disease is suspected
Digital Rectal Examination (DRE)
A simple physical examination where the doctor uses a gloved finger to check the inside of the rectum for piles, fissures, masses, or tenderness. It takes less than a minute and provides valuable information.
Proctoscopy / Sigmoidoscopy
A short, rigid or flexible scope is used to examine the lower rectum and sigmoid colon — sufficient for identifying most piles, fissures, and low rectal tumours.
Colonoscopy — The Gold Standard
Colonoscopy is the most comprehensive investigation for blood in stool. The entire large intestine (colon) is examined using a long, flexible camera. It can detect:
- Polyps (and remove them immediately)
- Colorectal cancer
- IBD
- Diverticular disease
- Angiodysplasia
At LGI Hospitals, colonoscopy and endoscopy tests at LGI Hospitals are performed by experienced gastroenterologists using advanced equipment, ensuring a thorough and comfortable examination.
CT Colonography (Virtual Colonoscopy)
A CT scan-based alternative to standard colonoscopy, used when traditional colonoscopy is not possible or the patient declines it. It can visualise the colon without a scope.
Capsule Endoscopy
A small camera in a capsule is swallowed and captures images as it travels through the digestive tract — useful for investigating the small intestine, which cannot be reached by standard endoscopy or colonoscopy.
Treatment for Blood in Stool
Treatment depends entirely on the cause:
Piles: Dietary changes (high-fibre diet, adequate water), sitz baths, topical medications, rubber band ligation, sclerotherapy, or surgery in severe cases.
Anal fissure: High-fibre diet, stool softeners, topical medications (GTN ointment, diltiazem), Botox injection, or surgery (lateral internal sphincterotomy).
Anal fistula: Surgical treatment (fistulotomy, seton placement, LIFT procedure) is usually required.
Colorectal cancer: Surgery (colectomy), followed by chemotherapy and/or radiotherapy depending on the stage.
IBD: Aminosalicylates (5-ASA), steroids, immunosuppressants, or biologics (anti-TNF agents).
Infections: Appropriate antibiotics or antiparasitic medications.
Polyps: Removed during colonoscopy (polypectomy).
For the right specialist care, visit our gastroenterology hospital in Nagpur for rectal bleeding and blood in stool, where the full range of diagnostic and therapeutic options is available under one roof.
Frequently Asked Questions (FAQs)
Q1. Why does blood come in stool (why blood comes in stool)?
Blood in stool comes from bleeding somewhere along the digestive tract — from the mouth to the anus. The location determines the colour: bright red for lower GI bleeding (piles, fissures, rectal tumours) and dark/black for upper GI bleeding (stomach ulcers, oesophageal varices).
Q2. Is painless bright red blood in stool always piles?
Painless bright red blood is the classic presentation of internal piles — but it can also come from polyps, low rectal tumours, or vascular malformations. “Painless” does not mean “safe to ignore.” All cases should be evaluated by a doctor, especially in adults over 40.
Q3. When should I worry about blood in stool?
Worry — and see a doctor — if: it is more than a one-off occurrence, you are over 40, there is unexplained weight loss or change in bowel habits, there is a family history of colon cancer, the blood is dark/black, or there is any associated pain, fever, or dizziness.
Q4. Does constipation cause blood in stool?
Constipation can cause blood in stool through straining (worsening piles) or by creating anal fissures. However, constipation combined with blood in stool should always be investigated to rule out more serious causes like polyps or cancer.
Q5. What is occult blood in stool, and why does it matter?
Occult blood is blood that cannot be seen with the naked eye but is detected chemically. It matters because it can be the only early sign of colorectal cancer or large polyps, allowing treatment before the disease advances. Routine occult blood testing is recommended for adults over 45.
See a Specialist — Do Not Delay
Blood in stool — whether it is (मल में खून आना), bright red, dark, or hidden — should never be dismissed. With the right investigation done promptly, most causes are entirely treatable, and the serious ones are best managed when found early.
Book an urgent appointment if you notice blood in stool at LGI Hospitals, Nagpur. Our gastroenterology team provides comprehensive diagnosis, from stool tests to colonoscopy, and complete treatment under one roof.
Medical Disclaimer: This article is intended for general educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Blood in stool (मल में खून आना) can range from a minor issue to a sign of serious disease. If you notice blood in or around your stool — whether bright red, dark, or black — please consult a qualified doctor promptly. Do not attempt self-diagnosis. In cases of heavy bleeding, dizziness, or pain, seek emergency care immediately.