When you see bright red blood in your stool, itâs scary. You might think itâs just hemorrhoids. But for many people over 60, it could be something more serious-like diverticula or angiodysplasia. These are two of the most common causes of lower GI bleeding, and knowing the difference can mean the difference between a quick fix and a long, frustrating journey.
What Exactly Is Lower GI Bleeding?
Lower gastrointestinal (GI) bleeding means blood is coming from somewhere in your colon or rectum-anything past the ligament of Treitz, which is deep in your small intestine. The most obvious sign? Bright red or maroon blood in your stool, called hematochezia. Sometimes itâs just a streak on the toilet paper. Other times, itâs a full gush, like youâve opened a faucet. This isnât the same as melena-that black, tarry stool that comes from upper GI bleeding. If youâre seeing red, itâs likely coming from below. About 20 to 33% of all GI bleeds happen in the lower tract. And most of them happen to people over 60. The good news? In about 80% of cases, the bleeding stops on its own. The bad news? It often comes back.Diverticula: The Silent Bleeder
Diverticula are tiny pouches that bulge out from the wall of your colon. Theyâre super common-half of all people over 60 have them. Most never cause problems. But sometimes, one of those pouches starts bleeding. Hereâs how it happens: Blood vessels run close to the surface of the colon to feed the lining. When a diverticulum forms, those vessels get stretched and pulled over the top of the pouch. They become fragile. A little pressure, a bowel movement, or even nothing at all can make one rupture. No pain. No warning. Just blood. This is why diverticular bleeding is called âpainless.â You might be sitting there watching TV, then suddenly feel dizzy and see blood everywhere. Itâs often massive-enough to send someone to the ER. About 30 to 50% of all hospitalizations for lower GI bleeding are due to diverticula. And while itâs scary, itâs also usually self-limiting. Eight out of ten times, it stops without any treatment. But if it doesnât? Doctors reach for the colonoscope. Under sedation, they look inside your colon and find the bleeding spot. Then they use epinephrine injections or heat to seal the vessel. Success rate? Around 85 to 90%. But hereâs the catch: 20 to 30% of people bleed again within a year. Thatâs why doctors watch you closely after discharge.Angiodysplasia: The Slow Leak
If diverticula are the sudden gusher, angiodysplasia is the slow drip. Also called vascular ectasia or AVMs (arteriovenous malformations), these are tangled, enlarged blood vessels in the colon wall-usually on the right side, near the cecum. Unlike diverticula, angiodysplasia doesnât cause sudden bleeding. It causes fatigue. Weakness. Pale skin. You might not even notice blood in your stool. Instead, you just feel tired all the time. Your doctor orders a blood test and finds your hemoglobin is 8.5 g/dL-way below normal. Iron deficiency anemia. Then they start looking for the source. These vessels grow over time. Every time your colon contracts, the blood flow pushes through these weak spots. Itâs like a garden hose thatâs been kinked for years-eventually, the wall thins out and leaks. Itâs more common in older adults, especially those over 70. About 3 to 6% of lower GI bleeds come from this, but in some studies, itâs as high as 40% in elderly patients with chronic anemia. Thereâs another twist: if you have aortic stenosis-a narrowed heart valve-the turbulent blood flow can break down a clotting protein called von Willebrand factor. That makes you more likely to bleed from these vessels. So if youâve got heart valve disease and unexplained anemia? Doctors will check your colon. Treatment? Argon plasma coagulation (APC) is the go-to. Itâs a non-contact heat probe that zaps the vessels during colonoscopy. It works well-80 to 90% stop bleeding right away. But the problem? Recurrence. Up to 40% bleed again within two years. Thatâs why some patients end up needing repeat procedures every few months. For those with frequent recurrences, doctors may turn to thalidomide. Yes, that thalidomide-the one once used for morning sickness. At low doses (100 mg daily), it reduces bleeding in about 70% of patients by helping blood vessels stabilize. Octreotide, a hormone injection, can also help cut down on bleeding episodes. But neither is a cure. Itâs management, not a fix.
The Workup: How Doctors Find the Source
When you walk into the ER with GI bleeding, the first thing they do is stabilize you. Blood pressure? Heart rate? Hemoglobin? If youâre crashing, they give fluids and blood. Then they start looking for the cause. The gold standard? Colonoscopy. Done within 24 hours. Not 48. Not 72. Twenty-four. Studies show doing it this fast cuts death risk by 26%. You donât need a perfect prep. In emergencies, theyâll give you IV fluids and erythromycin to clear the bowel a bit. Enough to see. If the colonoscope finds nothing? Thatâs when things get tricky. About 10 to 20% of lower GI bleeds have no clear source on colonoscopy. Thatâs called âobscureâ bleeding. Now you need more tools. CT angiography is one. Itâs a special CT scan that looks for active bleeding-detects it if itâs leaking faster than half a milliliter per minute. Itâs fast, non-invasive, and works even if youâre too unstable for colonoscopy. If thatâs negative too? Capsule endoscopy. You swallow a pill-sized camera. It takes pictures as it travels through your small intestine. It finds the cause in 62% of cases. But thereâs a risk: if you have a hidden narrowing in your gut, the capsule can get stuck. Thatâs why some doctors only use it after colonoscopy. Another option? Device-assisted enteroscopy. Itâs like a colonoscope with a balloon that can reach deep into the small bowel. It finds bleeding in 71% of cases. But itâs complex. Only a few centers do it well. And hereâs a new twist: AI-assisted colonoscopy. New software flags tiny vascular lesions that human eyes might miss. One study showed it boosts detection of angiodysplasia by 35%. Thatâs huge for patients whoâve had multiple negative scopes.What Happens After the Bleed?
Survival rates for both diverticula and angiodysplasia are actually pretty good-78 to 82% five-year survival. But thatâs mostly because the bleeding itself isnât what kills you. Itâs the other stuff: heart disease, kidney failure, cancer. The bleed is often the red flag that something else is wrong. For diverticula, if youâve had one big bleed, youâll likely be advised to avoid NSAIDs (like ibuprofen), which can irritate the colon. Youâll also be told to eat more fiber. Not to prevent bleeding-because fiber doesnât stop it-but to prevent diverticulitis, which is a different problem. For angiodysplasia, the goal is to avoid repeated transfusions. Iron supplements help, but they donât stop the bleeding. You might need repeat APC sessions. Some patients get so frustrated theyâve had three, four, even five negative colonoscopies before their lesion was finally found. One patient group reported an average diagnostic delay of 18 months. And hereâs the reality: many elderly patients are told their anemia is âjust aging.â But if youâre losing blood slowly over months, itâs not normal. Itâs a signal.
When Surgery Becomes Necessary
Most people never need surgery. But if bleeding keeps coming back, and endoscopy fails, itâs time to think about cutting out the bad part. For diverticula, if the bleeding is coming from one specific segment-say, the sigmoid colon-you can have that piece removed. Itâs a clean fix. Recovery is usually good. For angiodysplasia, if itâs in the cecum or ascending colon, doctors often recommend a right hemicolectomy. That means removing the right side of your colon. Itâs major surgery, but for people with recurrent bleeding, itâs often the only way to stop it for good. One European trial tested a new endoscopic clip device for diverticular bleeding. It stopped bleeding in 92% of cases. Thatâs better than epinephrine and heat. Itâs not everywhere yet, but itâs coming.What You Can Do
If youâve had a lower GI bleed:- Follow up with a gastroenterologist-even if you feel fine.
- Ask if you need a repeat colonoscopy in 6 to 12 months.
- Get your iron checked regularly. Even if youâre not bleeding now, you might be losing blood slowly.
- Donât ignore fatigue. If youâre tired all the time, get blood work done.
- Ask about AI-assisted colonoscopy if your previous scopes were negative.
Is lower GI bleeding always serious?
Not always. About 80% of cases stop on their own without treatment. But even if it stops, you still need to find the cause. Recurrent bleeding can lead to chronic anemia, hospitalizations, or missed diagnoses like colon cancer. Never ignore it.
Can diverticula bleeding be prevented?
You canât prevent diverticula from forming-theyâre a normal part of aging. But you can reduce the risk of bleeding by avoiding NSAIDs, staying hydrated, and eating fiber. Fiber doesnât stop bleeding, but it helps prevent constipation, which can trigger it.
Why does angiodysplasia cause anemia instead of visible bleeding?
Because it bleeds slowly-just a few drops at a time. Your body canât replace the iron fast enough, so your hemoglobin drops over weeks or months. You feel tired before you see blood. Thatâs why itâs often discovered during routine blood tests, not when youâre bleeding.
Is capsule endoscopy safe for everyone?
No. If you have a history of bowel obstructions, strictures, or Crohnâs disease, thereâs a risk the capsule could get stuck. Doctors usually avoid it in those cases unless theyâve ruled out blockages with a CT scan or X-ray.
Can angiodysplasia come back after surgery?
Rarely, but yes. If the surgery removes the main bleeding area, like the cecum, recurrence is low. But if new vessels form elsewhere in the colon-which can happen with aging-you might need more treatment. Thatâs why lifelong follow-up matters.
Whatâs the latest treatment for recurrent angiodysplasia?
Thalidomide is showing strong results in clinical trials, cutting transfusion needs by 70%. A phase III trial is ongoing and results are expected in late 2024. For now, itâs used off-label for patients who donât respond to endoscopy. Itâs not a first-line treatment, but itâs changing outcomes for those with frequent bleeding.
