Skip to main contentLast updated: 12-Nov-2026
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Dr Harsh Shah
MS, MCh (Surgical Gastroenterology), DrNB (Surgical Gastroenterology)
Registered with Gujarat Medical Council, Reg. No. G-38738
Gastro & Cancer Surgeon
Dr. Jivraj Mehta Hospital, Vasna, Ahmedabad · 18 years of experience
In short
Blood from the lower gut has a short list of causes. Your age, your medicines and the way the blood looks point to the likely source before any test.
In older adults, bleeding pouches and fragile vessels top the list. In the young, piles, colitis, infection and Meckel pouch are more common.
When two scopes are normal, the small bowel is the next place to look. Piles should never be blamed until a growth is ruled out.
This post maps the causes. For tests and treatment in full, see our lower GI bleeding treatment page.
Think in two steps: where in the gut, and what kind of problem. Then add the patient: age, medicines, heart, kidney and travel history.
The gut has three zones for this purpose. The back passage and rectum give bright red blood on the stool. The colon gives red or maroon blood, mixed or in clots. The small bowel, in between, gives dark or hidden blood, often found only because of anaemia.
| Pattern | Likely source | Usual age |
|---|---|---|
| Sudden and large, with no pain | Bleeding pouch (diverticulum), or a vessel under the lining | Over 60 |
| Repeated or hidden, anaemia | Fragile vessels (angiodysplasia), pain-killer ulcers in the small bowel | Over 40 |
| Cramp pain, then blood | Poor blood supply to the colon (ischaemic colitis) | Elderly, or heart and vessel disease |
| Blood with loose motions, fever | Infection, amoeba, colitis, bowel tuberculosis | Any age |
| Bright red on wiping or dripping | Piles, fissure | Any age |
| Dark blood without pain in a young person | Meckel pouch, or a small bowel lump | Under 40 |
A bleeding pouch is the usual cause of a large bleed that does not hurt. Most such bleeds stop on their own.
A blood vessel runs over the dome of a diverticulum and can break. Pouches sit mostly on the left, yet the larger bleeds often come from the right colon. Fragile vessels (angiodysplasia) are the other big cause. They are often many, and they bleed again and again. A tight aortic valve, kidney failure and some clotting problems drive them.
Poor blood supply to the colon gives a different story. Cramping pain comes first, then bloody motions. It usually settles with rest and drips. Rarely a part of the colon dies and needs an operation.
Piles and fissure are the common answers. Colitis, infection and Meckel pouch come next. Each leaves a different clue.
If the upper scope and colonoscopy are normal and the bleeding goes on, the small bowel is the next suspect.
Over 40, pain-killer tablets and fragile vessels are the usual finds. Under 40, Meckel pouch and small bowel lumps are. A capsule camera or a long scope can look further. These tests are not available everywhere, so you may be sent to a bigger centre.
Blood thinners and pain-killer tablets such as diclofenac turn a small source into a big bleed. Never stop a heart tablet on your own.
Bring every tablet strip to the consultation. A safer pain plan can lower the risk of a repeat bleed.
Piles are common, so they get blamed too often. A colonoscopy rules out other causes, and it is advised over 40 or with any warning sign.
A heavy upper gut bleed can also look like red blood from below. So if you feel faint, the team checks the upper gut too.
Piles and fissures are common and mild. In older people, bleeding pouches (diverticula) and fragile blood vessels are common. Infection, inflammation, and bleeding after polyp removal also occur.
No. Piles are a common cause, but they should not be assumed. A colonoscopy is advised for anyone over 40, or with weight loss, anaemia, or blood mixed with the stool.
When both the upper scope and colonoscopy are normal, the small bowel is the next place to look. A capsule camera is the usual next test.
Yes. Diclofenac and similar tablets can cause small bowel ulcers. They also raise the risk of bleeding from other spots. Tell your doctor about every tablet.
Sometimes. A heavy bleed high in the gut can pass quickly and look like red blood from below. So an upper scope is considered if you feel faint.
In young people the usual causes are piles, fissure, colitis and infection. A small bowel pouch called Meckel diverticulum is another.
Yes. A narrowed aortic valve can cause repeated bleeding from tiny gut blood vessels. Treating the valve can reduce the bleeding.
See a doctor at once for heavy bleeding, faintness or a racing heart. See a surgeon for repeated bleeding, anaemia, or blood that no test has explained.
For the whole picture, start at the lower GI bleeding page. For questions before you travel, call +91-63555-64601.
Dr Harsh Shah — Dr. Jivraj Mehta Hospital, Vasna, Ahmedabad
Dr. Jivraj Mehta Hospital, Dr Jivraj Mehta Marg, Vasna, Ahmedabad 380007.
Consultations, review of reports and scans, operations and follow-up. OPD Monday to Saturday, 9 am to 5 pm.
Appointments: +91-63555-64601 · +91-63590-11009 · Hospital 079-2663 6363
Directions to the hospital · WhatsApp +91-63555-64601
Have you passed blood from the bowel, and nobody has told you why? Dr Harsh Shah, a surgeon, goes through your history, medicines and reports with you. He lists the likely sources for your age and tells you which test comes next. Bring your colonoscopy, scan and blood reports. You can also call, or message us on WhatsApp. Call For Appointment Book on WhatsApp Tapping Book on WhatsApp will likely open the WhatsApp app on your phone.
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