5 Common Causes of GI Bleeding: When to Worry and When to See a Doctor

5 Common Causes of GI Bleeding: When to Worry and When to See a Doctor

Gastrointestinal (GI) bleeding is a clinical sign, not a diagnosis in itself. It can be a frightening experience, but the color, consistency, and accompanying symptoms provide vital clues about the source.

Whether the cause is a minor irritation or a serious condition like Colon Cancer, early identification is the key to successful treatment.

1. Peptic Ulcers and Gastritis – Upper GI

These two conditions are the leading causes of bleeding in the upper digestive tract (stomach and duodenum).

• Gastritis: This is the inflammation or erosion of the stomach lining. It is often caused by excessive alcohol use, chronic stress, or long-term use of NSAIDs (like Ibuprofen or Aspirin).

• Peptic Ulcers: These are actual sores that form in the lining. They are frequently linked to a bacterial infection called H. pylori.

• The Sign: Bleeding here often results in Haematemesis (vomiting blood that looks like coffee grounds) or Melaena (black, tarry, foul-smelling stools).

2. Colorectal Cancer (Ca Colon) – Lower GI

One of the most serious causes of GI bleeding is Colorectal Cancer (Colon Cancer). In its early stages, a polyp (a small growth) may bleed intermittently. As a tumor grows, it can cause more consistent bleeding.

• The Sign: Blood may be bright red, but it is often occult (hidden), meaning you can’t see it with the naked eye. It may also appear as dark or maroon streaks mixed into the stool.

• Warning Signs: Persistent changes in bowel habits (diarrhea or constipation), unexplained weight loss, and iron-deficiency anaemia (feeling constantly tired).

3. Diverticular Disease – Lower GI

Diverticulosis occurs when small, marble-sized pouches develop in the wall of the colon. While usually harmless, these pouches can become inflamed (Diverticulitis) or a small artery within a pouch can burst.

• The Sign: This usually causes a sudden, painless, and significant amount of bright red or maroon blood to pass during a bowel movement.

4. Hemorrhoids and Anal Fissures – Lower GI

These are the most frequent causes of “visible” blood.

• Hemorrhoids: Swollen veins in the rectum or anus.

• Anal Fissures: Small, painful tears in the anal lining, usually from passing hard stools.

• The Sign: Bright red blood that appears on the toilet tissue or splashes in the bowl, rather than being mixed into the stool itself.

5. Inflammatory Bowel Disease (IBD) – Lower GI

Chronic autoimmune conditions like Crohn’s Disease and Ulcerative Colitis cause the immune system to attack the digestive tract, leading to sores and inflammation.

• The Sign: Recurring bloody diarrhea, often accompanied by mucus, abdominal pain, and urgency.

The ‘Colour Guide’ to GI Bleeding

The appearance of the blood is the most important information you can give your doctor.

When to Worry: The Emergency “Red Flags”

You should call emergency services or go to the Emergency Room (A&E) immediately if GI bleeding is accompanied by:

• Signs of Shock: Rapid pulse, low blood pressure, or feeling faint/dizzy.

• Confusion: Sudden disorientation or cold, clammy skin.

• Severe Pain: Intense, rigid abdominal cramping.

• Heavy Flow: Continuous, heavy bleeding that does not stop.

When to See a Doctor (Non-Emergency)

Even if the bleeding is painless and minor, you must schedule an appointment with a GP or Gastroenterologist if you notice:

1. Any blood in the stool that lasts more than 1–2 days.

2. Iron Deficiency: Feeling breathless, pale, or chronically fatigued.

3. Bowel Changes: A “pencil-thin” stool or a change in frequency lasting more than three weeks.

4. Family History: If you have a family history of Colon Cancer or IBD.

Next Steps in Diagnosis

Your doctor may recommend a Colonoscopy or a FIT (Fecal Immunochemical Test) to screen for Colon Cancer. These tests are the gold standard for catching issues before they become life-threatening.