Ischemic Colitis

Overview

Ischemic colitis occurs when blood flow to part of the large intestine (colon) is temporarily reduced. The colon needs a steady blood supply to deliver oxygen to its tissues. When that flow drops, even briefly, the affected area can become inflamed and injured, leading to pain and changes in bowel function.

Ischemic colitis is the most common form of intestinal ischemia and most often affects older adults. In many cases it is mild and improves on its own or with supportive care within a few days. Less commonly, the reduction in blood flow is severe enough to cause lasting damage to the bowel wall, which can be a medical emergency requiring urgent treatment.

Symptoms

Symptoms usually come on fairly suddenly and may include:

• Abdominal pain or cramping, often on the left side, that may begin abruptly.
• An urgent need to have a bowel movement.
• Bloody stool or the passage of bright red or maroon blood, often mixed with or following the pain.
• Diarrhea.
• Nausea and abdominal tenderness.

In mild cases, symptoms ease over a few days as blood flow returns and the colon heals. Severe abdominal pain, especially pain that is out of proportion to the examination, fever, or signs of shock are warning features that may indicate more serious damage and require immediate medical attention.

Causes

Ischemic colitis results from a temporary reduction in blood flow to the colon. The exact trigger is not always identified, but contributing causes include:

• Narrowing or hardening of arteries (atherosclerosis) that supply the intestine.
• A drop in blood pressure, for example from dehydration, heart failure, major blood loss, or shock, which reduces flow to the colon.
• Blood clots in the vessels supplying the colon.
• Certain medications, including some that constrict blood vessels, and some heart, migraine, and hormone medicines.
• Strenuous activity, such as long-distance running, in some cases.
• Surgery on the aorta or other major vessels.

Risk Factors

Several factors increase the risk of ischemic colitis:

• Older age, as it is most common in people over 60.
• Heart and blood vessel disease, including atherosclerosis, heart failure, and irregular heart rhythms that can throw clots.
• Low blood pressure or conditions that cause it.
• Diabetes and other conditions affecting blood vessels.
• Clotting disorders that make blood more likely to clot.
• Previous abdominal or vascular surgery.

Diagnosis

Diagnosing ischemic colitis can be challenging because its symptoms overlap with other bowel conditions. Evaluation often includes:

• Medical history and physical examination, focusing on the pattern of pain and bleeding and on risk factors.
• Blood tests to look for signs of inflammation and infection.
• CT scan of the abdomen, which can show changes in the colon wall and help rule out other problems.
• Colonoscopy, which allows the doctor to view the lining of the colon directly, confirm the diagnosis, and take tissue samples while excluding other causes such as infection or inflammatory bowel disease.

Stool tests may be done to rule out infection as a cause of bloody diarrhea.

Treatment

Treatment depends on how severe the condition is. Most mild cases improve with supportive care:

• Resting the bowel, often with intravenous fluids and a temporary change in diet.
• Treating the underlying cause, such as correcting dehydration or low blood pressure and reviewing medications that may have contributed.
• Antibiotics in some cases to prevent infection.
• Monitoring to ensure the colon is healing and symptoms are improving.

Severe ischemic colitis, with signs of bowel tissue damage, a hole in the bowel, or ongoing deterioration, may require surgery to remove the damaged portion of the colon. Managing related conditions such as heart disease and atherosclerosis helps lower the chance of recurrence.

Prevention

While not every case can be prevented, steps that protect blood vessels and circulation may lower the risk:

• Manage conditions that affect blood vessels, such as high blood pressure, high cholesterol, and diabetes.
• Stay well hydrated, especially during illness, hot weather, or vigorous exercise.
• Avoid smoking, which damages blood vessels.
• Review medications with your doctor if you have had ischemic colitis, since some drugs can contribute.
• Treat heart rhythm problems and clotting disorders as advised.

When to See a Doctor

Seek immediate emergency care or call emergency services if you have:

• Severe, sudden abdominal pain, particularly pain that seems out of proportion to the exam.
• Significant rectal bleeding or repeated bloody stools.
• Fever, rapid heartbeat, confusion, or feeling faint, which can signal serious illness.

Contact a healthcare provider promptly for milder abdominal pain with diarrhea or blood in the stool, so the cause can be identified. Because severe ischemic colitis can damage the bowel and become life-threatening, do not delay seeking care for severe pain or heavy bleeding.

Related Topics

Frequently Asked Questions

References

1. Mayo Clinic. Ischemic colitis.
2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
3. MedlinePlus, U.S. National Library of Medicine.
4. American College of Gastroenterology.