ConditionDigestive system
Ischemic Colitis
Ischemic colitis is inflammation and injury of the large intestine (colon) caused by a temporary drop in blood flow. It is the most common form of intestinal ischemia, mostly affecting adults over 60. It typically causes sudden, crampy pain on the left side of the belly followed within 24 hours by an urge to pass stool and bloody diarrhea. Most cases are mild and heal within days with fluids and rest, but severe cases with gangrene of the bowel need surgery.
Also called: Colonic ischemia, ischemic bowel disease of the colon, colon ischemia
At a glance
- What it is
- Colon injury from a temporary reduction in blood supply.
- Who gets it
- Mainly adults over 60, more often women, and people with vascular risk factors.
- Symptoms
- Sudden crampy left-sided belly pain, urgency, then bloody diarrhea or maroon stool.
- Diagnosis
- CT scan and colonoscopy with biopsies. Stool tests to exclude infection.
- Treatment
- Bowel rest, IV fluids, stopping contributing medicines, antibiotics in moderate to severe cases, surgery for gangrene.
When to get help
Call 911 or go to the ER
- Severe abdominal pain out of proportion to tenderness, especially with atrial fibrillation (possible acute mesenteric ischemia involving the small bowel)
- Belly pain with a rigid abdomen, fever, vomiting, fainting or confusion
- Heavy rectal bleeding with dizziness or a racing heart
See a doctor within a day or two
- Sudden cramping belly pain followed by bloody diarrhea
- Bloody diarrhea after major surgery, a long run, or starting a new medicine
- Ongoing bloody stool for more than a day
Book a routine appointment
- Recurring episodes of crampy pain and bloody stool
- Follow-up colonoscopy after an episode, as advised
How ischemic colitis happens
The colon gets blood from branches of the superior and inferior mesenteric arteries. Some areas, such as the splenic flexure (where the colon turns near the spleen) and the junction of the sigmoid colon and rectum, are "watershed" areas at the edges of two blood supplies and are most vulnerable.
Most ischemic colitis is non-occlusive: blood flow falls temporarily, not because an artery is completely blocked. The inner lining, which needs the most oxygen, is injured first, causing bleeding and inflammation. With prompt restoration of flow, the lining heals.
It differs from acute mesenteric ischemia, which usually involves the small intestine, often comes from a blood clot, causes severe pain with surprisingly little tenderness, and is a surgical emergency.
Causes and risk factors
- low blood pressure: dehydration, heart failure, shock, sepsis, blood loss, dialysis
- atherosclerosis and vascular disease
- heart rhythm problems such as atrial fibrillation
- major surgery, especially aortic or heart surgery
- medicines: constipating drugs (opioids, anticholinergics), alosetron, vasopressors, some migraine medicines, decongestants, hormonal therapy, some chemotherapy, and laxatives in some cases
- cocaine and methamphetamine
- endurance exercise such as marathon running
- constipation and irritable bowel syndrome
- blood clotting disorders, especially in younger patients
- colon blockage from cancer or volvulus
Symptoms
- sudden, crampy, mild to moderate abdominal pain, usually on the left side
- an urgent need to pass stool
- bloody diarrhea, or passing bright red or maroon blood, usually within 24 hours of the pain
- nausea and sometimes vomiting
- tenderness over the affected area
Signs of severe disease include fever, rapid heart rate, peritonitis (rigid, very tender belly) and low blood pressure.
Ischemic colitis vs other causes of bloody diarrhea
| Condition | Clues |
|---|---|
| Ischemic colitis | Older age, sudden onset, left-sided pain, vascular risk factors |
| Infectious colitis | Fever, food exposure, other people sick, positive stool tests |
| Ulcerative colitis | Younger onset, longer history, starts in the rectum |
| C. difficile colitis | Recent antibiotics or hospital stay |
| Diverticular bleeding | Painless large-volume bleeding |
| Colorectal cancer | Gradual change in bowel habit, weight loss, anemia |
Diagnosis
- blood tests: blood count, inflammatory markers, lactate, kidney function, electrolytes
- stool tests: infection and C. difficile
- CT scan with contrast: shows thickened bowel wall in a typical segment and excludes other conditions and small bowel ischemia
- colonoscopy within 48 hours (if no peritonitis), with biopsies: shows patchy redness, ulcers and a characteristic pattern, and excludes other causes
- CT angiography: if acute mesenteric ischemia is suspected or the right colon is involved, which carries higher risk
- heart evaluation in selected patients (ECG, echocardiogram)
Treatment
Mild cases
- bowel rest or a clear liquid diet, advancing as tolerated
- IV fluids
- stopping medicines that reduce blood flow or cause constipation
- treating causes of low blood pressure
- monitoring
Moderate to severe cases
- hospital care
- antibiotics, as recommended by ACG guidance for moderate or severe disease
- close monitoring with repeat examinations and blood tests
Surgery
Needed for:
- peritonitis, perforation or gangrene
- massive bleeding
- worsening despite treatment
- chronic narrowing (stricture) causing obstruction
Surgery removes the damaged segment of colon.
Outlook
Most people recover fully within days to 2 weeks without long-term problems. Right-sided ischemic colitis and gangrenous forms carry higher risk. A small number develop chronic colitis or a stricture. Recurrence occurs in some, so controlling risk factors and reviewing medicines matters.
Frequently asked questions
What are the symptoms of ischemic colitis?
Typical symptoms are sudden crampy pain on the left side of the belly, an urgent need to pass stool, and bloody diarrhea or bright red to maroon blood in the stool, usually within 24 hours of the pain starting.
What causes ischemic colitis?
It is caused by a temporary drop in blood flow to the colon, often from low blood pressure, dehydration, heart rhythm problems, atherosclerosis, major surgery, certain medicines, cocaine or intense endurance exercise. Often no single cause is found.
Is ischemic colitis serious?
Most cases are mild and heal on their own within days with supportive care. Severe cases, especially with gangrene of the bowel or involvement of the right colon, can be life-threatening and need surgery.
How is ischemic colitis diagnosed?
Doctors use a CT scan to show the affected bowel and rule out other problems, stool tests to exclude infection, and colonoscopy with biopsies to confirm the diagnosis.
Can ischemic colitis come back?
Yes, it can recur, especially if the underlying cause persists. Managing dehydration, heart disease, constipation and medicines that reduce blood flow lowers the chance of another episode.
Sources
This guide was written from current patient and clinical guidance, including:
- American College of Gastroenterology (ACG): Clinical guideline: Epidemiology, risk factors, patterns of presentation, diagnosis and management of colon ischemia
- American Gastroenterological Association: Intestinal ischemia
- MedlinePlus: Ischemic colitis
- Merck Manual: Ischemic colitis
- NIDDK: Ischemic colitis