Ischemic colitis occurs when blood flow to part of the large intestine (colon) is temporarily reduced, usually due to constriction of the blood vessels supplying the colon or lower flow of blood through the vessels due to low pressures. The diminished blood flow doesn't provide enough oxygen for the cells in your digestive system, which can result in tissue damage to the affected area of intestine.

Any part of the colon can be affected, but ischemic colitis most commonly causes pain on the left side of the belly area (abdomen).

Ischemic colitis can be misdiagnosed because it can easily be confused with other digestive problems. You may need medication to treat ischemic colitis or prevent infection, or you may need surgery if your colon has been damaged. Most often, however, ischemic colitis heals on its own.

Signs and symptoms of ischemic colitis can include:

• Pain, tenderness or cramping in your belly, which can occur suddenly or gradually
• Bright red or maroon blood in your stool or, at times, passage of blood alone without stool
• A feeling of urgency to move your bowels
• Diarrhea
• Nausea

The risk of severe complications is higher when you have symptoms on the right side of your abdomen. This is less commonly seen compared with left-sided colitis. People with right-sided colitis tend to have more underlying medical problems, such as high blood pressure, atrial fibrillation and kidney disease. They more frequently have to undergo surgery and also have a higher mortality risk.

When to see a doctor

Seek immediate medical care if you have sudden, severe abdominal pain. Abdominal pain that makes you so uncomfortable that you can't sit still or find a comfortable position is a medical emergency.

Contact your doctor if you develop worrisome signs and symptoms, such as bloody diarrhea. Early diagnosis and treatment can help prevent serious complications.

The precise cause of diminished blood flow to the colon isn't always clear. But several factors can increase your risk of ischemic colitis:

• Buildup of fatty deposits on the walls of an artery (atherosclerosis)
• Low blood pressure (hypotension) associated with dehydration, heart failure, surgery, trauma or shock
• Bowel obstruction caused by a hernia, scar tissue or a tumor
• Surgery involving the heart or blood vessels, or the digestive or gynecological systems
• Other medical disorders that affect your blood, such as inflammation of the blood vessels (vasculitis), lupus or sickle cell anemia
• Cocaine or methamphetamine use
• Colon cancer (rare)

The role of medications

The use of certain medicines also can lead to ischemic colitis, though this is rare. These medications include:

• Some heart and migraine medications
• Hormone medications, such as estrogen
• Antibiotics
• Pseudoephedrine
• Opioids
• Certain medications for irritable bowel syndrome
• Chemotherapy medications

Risk factors for ischemic colitis include:

• Age. The condition occurs mostly frequently in adults older than age 60. Ischemic colitis that occurs in a young adult may be a sign of a blood-clotting abnormality or inflammation of the blood vessels (vasculitis).
• Sex. Ischemic colitis is more common in women.
• Clotting abnormalities. Conditions that affect the way the blood clots, such as factor V Leiden, may increase the risk of ischemic colitis.
• High cholesterol, which can lead to atherosclerosis.
• Reduced blood flow, due to heart failure, low blood pressure, shock or certain conditions, such as diabetes or rheumatoid arthritis.
• Previous abdominal surgery. Scar tissue that forms after surgery may cause reduced blood flow.
• Heavy exercise, such as marathon running, which can lead to reduced blood flow to the colon.
• Surgery involving the large artery (aorta) that pumps blood from your heart to the rest of your body.

Ischemic colitis usually gets better on its own within two to three days. In more-severe cases, complications can include:

• Tissue death (gangrene) resulting from diminished blood flow
• Hole formation (perforation) in your intestine or persistent bleeding
• Bowel obstruction (ischemic stricture)

Since the cause of ischemic colitis isn't always clear, there's no certain way to prevent the disorder. Most people who have ischemic colitis recover quickly and may never have another episode.

To prevent recurrent episodes of ischemic colitis, some doctors recommend eliminating any medication that might cause the condition. Making sure to stay adequately hydrated, especially when doing vigorous outdoor activities, is also important — especially for those living in warm climates. A test for clotting abnormalities may be recommended as well, especially if no other cause for ischemic colitis is apparent.

Ischemic colitis can often be confused with other disorders because their symptoms overlap, especially inflammatory bowel disease (IBD). Based on your signs and symptoms, your doctor may recommend these imaging tests:

• Abdominal CT scans, to provide images of your colon that can be helpful in ruling out other disorders, such as IBD.
• Colonoscopy. This test, which provides detailed images of your colon, can be helpful in diagnosing ischemic colitis. Colonoscopy can also be used to check for cancer, and to see how well a treatment worked.
• Stool analysis, to rule out infection as a cause of your symptoms.

Treatment for ischemic colitis depends on the severity of your condition.

Signs and symptoms often diminish in two to three days in mild cases. Your doctor may recommend:

• Antibiotics, to prevent infections
• Intravenous fluids, if you are dehydrated
• Treatment for any underlying medical condition, such as congestive heart failure or an irregular heartbeat
• Avoiding medications that constrict your blood vessels, such as migraine drugs, hormone medications and some heart drugs

Your doctor may also schedule follow-up colonoscopies to monitor healing and look for complications.

Surgery

If your symptoms are severe, or your colon has been damaged, you may need surgery to:

• Remove dead tissue
• Repair a hole in your colon
• Remove part of the colon that has narrowed because of scarring and is causing a blockage

The likelihood of surgery may be higher if you have an underlying condition, such as heart disease, atrial fibrillation or kidney failure.

Go to the emergency room if you have severe abdominal pain that makes you so uncomfortable that you can't sit still. You may be referred for immediate surgery to diagnose and treat your condition.

If your signs and symptoms are moderate and occasional, call your doctor for an appointment. After an initial evaluation, you may be referred to a doctor who specializes in digestive disorders (gastroenterologist) or blood vessel disorders (vascular surgeon).

Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Be aware of any pre-appointment restrictions, such as not eating after midnight on the night before your appointment.
• Write down your symptoms, including when they started and how they may have changed or worsened over time.
• Write down your key medical information, including other conditions with which you've been diagnosed.
• Make a list of all medications, vitamins and supplements that you're taking.
• Write down questions to ask your doctor.

Questions to ask your doctor

• What is the most likely cause of my condition?
• What kinds of tests do I need?
• I have other health problems. How can I best manage these conditions together?
• If I need surgery, what will my recovery be like?
• How will my diet and lifestyle change after I have surgery?
• What follow-up care will I need?

What to expect from your doctor

Your doctor is likely to ask you questions about your symptoms, such as:

• When did you begin experiencing symptoms?
• Have your symptoms been continuous or occasional?
• How severe are your symptoms?
• Where do you feel your symptoms the most?
• Does anything seem to make your symptoms better?
• What, if anything, seems to worsen your symptoms?