Ischemic colitis (IC) is a medical condition characterized by inflammation and injury to the large intestine (colon). This damage occurs when the blood supply to a segment of the colon is temporarily reduced, a state called ischemia. The lack of sufficient blood flow starves the tissue of oxygen and nutrients, leading to cellular damage and subsequent inflammation. IC is the most frequent form of intestinal ischemia, typically involving the left side. Prolonged or severe restriction of blood flow can lead to tissue death.
Understanding the Causes and Risk Factors
Reduced blood flow to the colon results from two primary mechanisms: a systemic low-flow state or a localized vascular blockage. Systemic low-flow states occur during periods of reduced blood pressure or cardiac output, diverting blood away from the intestines to supply the brain and heart. Conditions like severe dehydration, shock, congestive heart failure, or major surgery (e.g., aortic repair) can trigger this non-occlusive ischemia.
Local factors involve the direct narrowing or blockage of the blood vessels supplying the colon, a form of occlusive ischemia. Atherosclerosis (hardening of arteries due to fatty plaque buildup) can restrict blood flow over time. A blood clot forming in or traveling to the mesenteric arteries, or inflammation of the blood vessels (vasculitis), can cause a sudden reduction in circulation. Previous abdominal surgery can also leave scar tissue that constricts blood vessels, increasing risk.
The risk for developing ischemic colitis increases significantly with advanced age, particularly over 60, as arteries become stiffer and more prone to disease. Chronic medical conditions like heart disease, diabetes, and blood clotting disorders also elevate the likelihood. Certain medications are implicated because they can constrict blood vessels or cause severe constipation, impairing colonic blood flow. These include:
- Medications for migraines
- Certain heart conditions
- Hormone therapies
- Illicit drugs like cocaine
Recognizing the Key Symptoms
The onset of symptoms is rapid, often beginning with abdominal pain. This cramping pain is frequently localized to the left side of the abdomen, corresponding to the most commonly affected segments of the colon. The severity can range from mild discomfort to intense distress.
A second symptom is the passage of blood from the rectum, known as hematochezia, which usually follows the abdominal pain within 24 hours. The bleeding is typically mild to moderate, often appearing mixed with stool or as bloody diarrhea. Patients may also experience an urgent need to have a bowel movement, nausea, and a low-grade fever.
The location of the pain offers clues about severity. Left-sided colitis is more common and generally has a better outcome. However, pain isolated to the right side of the abdomen is linked to a more serious disease progression because the blood supply to the right colon also feeds a portion of the small intestine. Right-sided ischemia is often associated with underlying systemic illnesses and requires prompt medical evaluation.
How Ischemic Colitis is Diagnosed
Diagnosis begins with a physical examination and review of the patient’s medical history, focusing on cardiovascular risk factors and recent low blood pressure episodes. Laboratory blood tests look for inflammation indicators, such as an elevated white blood cell count. An increased serum lactate level suggests a more severe case involving tissue necrosis. Stool samples are analyzed to rule out infectious causes of colitis.
Imaging studies support the diagnosis and rule out other conditions. A computed tomography (CT) scan of the abdomen is often the initial test, revealing characteristic signs like thickening of the colon wall. The CT scan is also used for detecting complications such as perforation or assessing the severity of inflammation.
The definitive method for confirming ischemic colitis is a colonoscopy or flexible sigmoidoscopy. This procedure allows a physician to directly visualize the inner lining of the colon, which may show distinctive features like segmental inflammation, ulcers, or hemorrhage. A biopsy can be taken during the procedure to confirm the diagnosis and distinguish it from inflammatory bowel disease. In acute, severe cases, flexible sigmoidoscopy is preferred over a full colonoscopy to minimize perforation risk.
Treatment and Management Strategies
Treatment depends on the severity of the condition, as most cases are mild. Management for mild or moderate cases is supportive care. This typically involves stopping oral intake (bowel rest) and administering intravenous fluids to ensure hydration and maintain blood pressure.
Pain management is addressed, but doctors are careful about using medications that could further constrict blood vessels. Broad-spectrum antibiotics may be administered to prevent infection across the damaged colon lining. A crucial step is identifying and discontinuing any medications, such as vasoconstrictive drugs, that may have contributed to the reduced blood flow.
Close monitoring is maintained; if symptoms do not improve within 24 to 48 hours, or if they worsen, a more severe course is suggested. Severe ischemic colitis (fulminant or gangrenous colitis) indicates dying tissue and requires immediate surgical intervention. Surgery involves removing the damaged segment of the colon to prevent complications like perforation or sepsis. After recovery, long-term management focuses on addressing underlying risk factors, such as controlling high blood pressure or heart disease, to prevent recurrence.