Colon narrowing, or colonic stricture, describes a segment of the large intestine that has become abnormally constricted. This constriction impedes the normal flow of digested waste, making passage difficult or impossible. This condition can develop gradually over time, affecting various parts of the large intestine.
Inflammatory Bowel Diseases and Other Inflammatory Conditions
Chronic inflammation commonly leads to colon narrowing, particularly in conditions like inflammatory bowel disease (IBD). Crohn’s disease, a type of IBD, frequently causes strictures due to its transmural inflammation, meaning it affects all layers of the intestinal wall. This widespread inflammation leads to fibrosis and scarring, which narrows the colon’s lumen. Ulcerative colitis, another IBD, primarily affects the colon’s innermost lining, but severe or long-standing cases can also result in stricture formation due to chronic inflammation.
Diverticulitis, inflammation of small pouches (diverticula) in the colon wall, is another inflammatory cause. Repeated bouts of diverticulitis can lead to scar tissue accumulation, which stiffens and constricts the affected segment. Ischemic colitis, resulting from reduced blood flow, can also cause inflammation and scarring. If blood supply is compromised, damaged tissue may heal with fibrosis, leading to a narrowed area.
Non-Inflammatory Causes
Beyond inflammatory processes, other factors can lead to colon narrowing. Colorectal cancer is a significant non-inflammatory cause, as a growing tumor can physically obstruct the colon’s lumen. The mass of the tumor directly reduces the space available for stool passage, leading to a mechanical blockage.
Certain infections can also induce severe inflammation and scarring, resulting in strictures. For instance, Clostridioides difficile infection can lead to post-infectious strictures. Tuberculosis of the bowel is another infectious agent capable of causing significant scarring and narrowing within the colon.
Radiation therapy directed at the pelvis, often used for cancers, can damage the colon’s lining and tissues. This damage can lead to radiation proctitis or colitis, characterized by inflammation and eventual fibrosis. Over time, this fibrotic process can cause the irradiated segment to become stiff and narrowed. Surgical procedures on the colon can also result in strictures, particularly at the site where two ends of the bowel are reconnected (anastomotic strictures). This scarring can occur as part of the healing process, sometimes impeding waste flow.
Recognizing the Symptoms
Symptoms of colon narrowing often arise from obstructed waste passage. Abdominal pain, often cramping, is common, particularly after eating, as the bowel attempts to push contents past the narrowed segment. Changes in bowel habits are typical, presenting as persistent constipation, chronic diarrhea, or alternating periods. This irregularity reflects the colon’s difficulty in maintaining normal function.
A noticeable change in stool caliber, such as consistently narrow or ribbon-like stools, can indicate a physical constriction within the colon. Unexplained weight loss may occur due to impaired nutrient absorption or chronic illness. Nausea and vomiting can develop if the obstruction causes a significant backup of intestinal contents. The presence of blood in the stool, visible or microscopic, might suggest inflammation, irritation, or a tumor.
Diagnosing Colon Narrowing
Diagnosing colon narrowing involves physical examination and specialized tests to identify the stricture and its underlying cause. Blood tests check for signs of inflammation, anemia, or other systemic issues that might point to conditions like IBD. Stool tests can detect occult blood, infections like C. difficile, or markers of inflammation. Imaging studies provide visual evidence of the colon’s structure and narrowing.
Computed tomography (CT) scans and magnetic resonance imaging (MRI) can reveal thickening of the colon wall or narrowing. Barium enema, an X-ray procedure using barium liquid, can highlight the narrowed segment. Endoscopic procedures, such as a colonoscopy or flexible sigmoidoscopy, are often the most definitive methods for direct visualization. During an endoscopy, a flexible tube with a camera is inserted into the colon, allowing direct observation of the stricture and tissue biopsies for microscopic examination. This helps determine the exact cause, such as inflammation, cancer, or infection.
Treatment Approaches
The management of colon narrowing is individualized, depending on the cause and severity of the stricture. For strictures caused by inflammatory conditions like IBD, medical management with anti-inflammatory drugs or immunosuppressants aims to reduce inflammation and prevent further scarring. These medications can help control the underlying disease process.
Endoscopic dilation is a minimally invasive procedure often employed for symptomatic, non-cancerous strictures. During this procedure, a balloon catheter is inserted through an endoscope and inflated within the narrowed segment to widen the passage. If medical and endoscopic approaches are insufficient, or if the stricture is severe, cancerous, or causing complete obstruction, surgical intervention may be necessary. Surgical options include resection, where the narrowed segment is removed and healthy ends are reconnected, or stricturoplasty, which widens the stricture without removing a section of the bowel.