Angiodysplasia

Angiodysplasia refers to small, fragile, abnormal blood vessels that can develop in the lining of the colon, most often in older adults. It’s the most common vascular abnormality in the GI tract and a recognized cause of bleeding that can otherwise look similar to a hemorrhoid or diverticular bleed.

Key takeaways

Angiodysplasia is generally a condition of aging blood vessels, not related to colon cancer or diverticular disease.
Bleeding from angiodysplasia is typically painless and can range from occasional spotting to more significant blood loss.
It’s often found incidentally during a colonoscopy done for another reason, or specifically sought out after unexplained bleeding or anemia.

What it is

Angiodysplasia involves thin-walled, dilated blood vessels in the lining of the digestive tract, most often in the colon. It’s thought to relate to normal wear on blood vessel walls over time, which is why it’s seen much more often in older adults. Unlike diverticular bleeding or hemorrhoids, angiodysplasia isn’t caused by straining or constipation, and it isn’t linked to colon cancer.

How it presents

Often no symptoms at all — many cases are found incidentally during a colonoscopy done for another reason
When it does bleed, it’s typically painless, similar to internal hemorrhoid bleeding
Bleeding can range from minor, intermittent spotting to, less commonly, more significant blood loss
Because bleeding can be low-grade and recurrent rather than dramatic, it sometimes shows up first as unexplained anemia or fatigue rather than visible blood

How this differs from a hemorrhoid

The symptom pattern alone often can’t distinguish angiodysplasia from a hemorrhoid — both are painless and can cause intermittent bright red or occult (not visibly obvious) bleeding. What tends to raise suspicion for angiodysplasia specifically is bleeding in an older adult that doesn’t fit a clear hemorrhoid pattern, recurrent unexplained anemia, or bleeding found not to be coming from an identifiable hemorrhoid on exam.

How it’s diagnosed and treated

Colonoscopy is the primary way angiodysplasia is identified, and in many cases, treatment (such as cauterizing the abnormal vessel) can be done during the same procedure. Mild bleeding may resolve on its own without any treatment at all; more significant or recurrent bleeding usually prompts treatment to reduce the risk of ongoing blood loss.

When to see a doctor

Recurrent, unexplained rectal bleeding, especially in older adults, that doesn’t clearly match a known hemorrhoid pattern
Unexplained fatigue or anemia found on blood tests, even without obvious visible bleeding
Any bleeding alongside the broader red flags for this site

Want the fuller list of what rectal bleeding can mean? See Rectal bleeding: what it can mean.

This page is for general education. Angiodysplasia is generally diagnosed and treated during colonoscopy — it can’t be identified from symptoms alone.