Finding blood when you wipe or seeing it in the toilet bowl can be an alarming experience. While it is often a symptom of a treatable, non-life-threatening condition, it is a sign from your body that should never be ignored.
Below is a comprehensive guide to the most common causes of rectal bleeding and the crucial signs that indicate you need medical attention.
Rectal bleeding (hematochezia) refers to any blood that passes from your anus. The appearance of the blood can often provide a clue about where it is coming from:
Bright Red Blood: Usually indicates bleeding in the lower colon or rectum.
Dark Red/Maroon Blood: May suggest bleeding higher up in the colon or the small intestine.
Black, Tarry Stools (Melena): Often indicates bleeding in the stomach (e.g. a peptic ulcer).
1. Haemorrhoids (Piles)
Hemorrhoids are swollen veins in the rectum or anus. They are the most common cause of rectal bleeding. You might notice bright red blood on the toilet paper or dripping into the bowl after a bowel movement.
2. Anal Fissure
An anal fissure is a small tear in the lining of the anus, often caused by passing hard stools. This usually causes sharp, stinging pain during and after a bowel movement, accompanied by small amounts of bright red blood.
3. Diverticulitis/Diverticulosis
Diverticula are small pouches that bulge outward through the colon wall. If these pouches become inflammed (diverticulitis) or the small blood vessels within them burst, it can lead to sudden, heavy painless bleeding. It is a common cause in older people.
4. Inflammatory Bowel Disease (IBD)
Conditions like Crohn’s disease and Ulcerative Colitis cause chronic inflammation of the digestive tract. Symptoms often include bloody diarrhoea, fatigue, and abdominal cramping. This is a common cause in younger people.
5. Colonic Polyp
Colonic polyps are small growths on the lining of the colon. While most are benign (non-cancerous), some can develop into cancer over time. They can bleed as stool passes over them.
6. Colorectal Cancer
This is the most important and serious cause of rectal bleeding. Whilst it often affects older adults, rates are rising in younger populations. Early detection through screening is vital for successful treatment.
7. Proctitis
Proctitis is inflammation of the lining of the rectum. It can be caused by IBD, infections (including STIs), or as a side effect of radiation therapy for cancer.
8. Angiodysplasia
This occurs when enlarged, fragile blood vessels develop in the colon. It is more common in older adults and typically causes painless, bright red bleeding.
9. Peptic Ulcer
While ulcers are in the stomach or duodenum (upper intestine), a “brisk” or heavy bleed can result in dark, tarry stools or, in rare cases, bright red blood if the transit time through the gut is very fast.
10. Gastroenteritis/Food Poisoning
Bacterial infections like Salmonella, E. coli, or Campylobacter can cause “hemorrhagic colitis,” leading to diarrhea mixed with blood and mucus.
You should always get rectal bleeding assessed by your GP. However, the urgency depends on your symptoms.
Seek Emergency Care (Call 999 in UK, 911 in USA) If:
The bleeding is heavy or continuous.
You feel dizzy, lightheaded, or faint.
The bleeding is accompanied by severe abdominal pain.
You are vomiting blood or material that looks like coffee grounds.
Schedule an Appointment Soon If:
The bleeding lasts more than a day or two.
Your bowel habits have changed (e.g., persistent diarrhea or constipation).
Your stools look black, tarry, or maroon.
You have a family history of colorectal cancer.
To find the cause, a doctor may perform:
Digital Rectal Exam (DRE): A physical check of the rectum.
Anoscopy/Sigmoidoscopy: Using a small scope to look at the lower part of the colon.
Colonoscopy: A full examination of the colon under sedation.
The Bottom Line: Most causes of rectal bleeding are minor and easily treated, but because it is a primary symptom of colon cancer, a professional diagnosis is the only way to have peace of mind.
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