Ischemic colitis results from a temporary blockage of blood flow through arteries that supply the large intestine. Often doctors cannot find a cause for the reduced blood flow, but it is more common among people with heart and blood vessel disease, people who have had surgery on their aorta, or people who have problems with increased blood clotting.
Ischemic colitis affects primarily people who are 60 or older.
Blockage of blood flow damages the inside lining and inner layers of the wall of the large intestine, causing ulcers (sores) in the lining of the large intestine, which can bleed.
Symptoms and Diagnosis
Usually, the person experiences abdominal pain. The pain is felt more often on the left side, but it can occur anywhere in the abdomen.
The person frequently passes loose stools that are often accompanied by dark red clots. Sometimes bright red blood is passed without stool. Low-grade fevers (usually below 100° F [37.7° C]) are common.
A doctor may suspect ischemic colitis on the basis of the symptoms of pain and bleeding, especially in a person older than 60.
It is important for doctors to distinguish ischemic colitis from acute mesenteric ischemia, a more dangerous condition in which blood flow to part of the intestine is completely and irreversibly blocked (see see Acute Mesenteric Ischemia).
Doctors usually do computed tomography and sometimes also colonoscopy (examination of the large intestine with a flexible viewing tube) to distinguish ischemic colitis from other forms of inflammation, such as infection or inflammatory bowel disease.
When should I contact my doctor about colitis?
Diarrhea is a common symptom of colitis. It, is usually self-limited, and resolves on its own with supportive care, including rest and a short course of a clear fluid diet.
However, if the diarrhea persists for more than three weeks, if there is blood in the stool, or the person has signs of dehydration, medical care should be obtained.
Blood in the stool is never normal and should always be evaluated. Common causes of blood in the stool include hemorrhoids; however, other serious causes of bleeding need to be investigated.
Colitis is not the only cause of rectal bleeding. Others causes include diverticular disease of the colon (diverticulitis), colon polyps, anal fissures, and cancer.
Chronic diarrhea can lead to dehydration, and if severe enough, dehydration may require treatment with fluids. The symptoms of dehydration may include:
- lightheadedness (dizziness) especially when changing from a sitting or lying position to standing position (orthostatic hypertension)
- dry mouth, dry eyes, and
- decreased output of urine.
High fever associated with diarrhea may be a warning sign that a significant infection may be present.
Abdominal pain is not normal, and while diarrhea may be associated with mild cramps, the presence of increasing abdominal pain, requires need to seek prompt medical attention.
Prognosis and Treatment
People with ischemic colitis are hospitalized. Initially, the person is given neither fluids nor food by mouth so that the intestine can rest.
Instead, fluids, electrolytes, and nutrients are given by vein (intravenously). Antibiotics are often given to prevent infection that might follow the inflammation.
Within a few days, antibiotics are usually stopped and eating is resumed. Nearly all people with ischemic colitis improve and recover over a period of 1 to 2 weeks.
However, when the interruption to the blood supply is more severe or more prolonged, the affected portion of the large intestine may have to be surgically removed.
Rarely, people get better but later on develop a scar in the affected area, causing a partial obstruction requiring surgical repair.
What is the prognosis for a patient with colitis?
Patients with infectious diarrhea tend to get better relatively quickly with supportive care. Most infections will resolve with or without specific treatment and often do not require antibiotics.
Those decisions depend on the patient’s diagnosis.
Patients with inflammatory bowel disease probably will require lifelong treatment to help control their symptoms. The goal, as with any long term illness, is to allow the patient to live a normal life with minimal symptoms from the disease.
Patients with ischemic colitis need to minimize their risk factors for progressive narrowing of the arteries.
These are the same risks as for heart disease, including controlling high blood pressure, diabetes, and high cholesterol; and stopping smoking.
Patients with severe ischemia that leads to a dead (gangrenous) colon require surgery to remove the gangrenous segment.