The ileum represents the final and longest segment of the small intestine, playing a significant role in digestive processes. Measuring approximately 11.5 feet (3.5 meters) in length, it connects the jejunum, the middle section of the small intestine, to the large intestine via the ileocecal valve. A primary function of the ileum involves absorbing vitamin B12, bile salts, and any remaining nutrients that were not absorbed in previous sections of the digestive tract. Ileal disease is a general term encompassing various conditions that lead to inflammation or damage within this specific intestinal region.
Common Conditions Affecting the Ileum
Crohn’s disease, an inflammatory bowel disease (IBD), is a significant cause of ileal inflammation, known as ileitis. Crohn’s disease can affect any part of the gastrointestinal tract, though it most commonly targets the terminal ileum. About one-third of individuals with Crohn’s disease experience inflammation exclusively in the ileum. This condition often involves patchy areas of inflammation, with sections of healthy gut tissue in between.
Other conditions can also cause ileitis, including various infections such as those caused by Yersinia bacteria or Mycobacterium tuberculosis. Ulcerative colitis, another form of IBD, can sometimes lead to inflammation in the ileum, a phenomenon referred to as backwash ileitis. Certain medications, like nonsteroidal anti-inflammatory drugs (NSAIDs), can induce ileal inflammation. Less common causes include ischemia (reduced blood flow), eosinophilic enteritis, lymphoma, or complications from radiation therapy.
Recognizing the Symptoms
Impaired ileal function often manifests through a range of gastrointestinal and systemic symptoms. Persistent diarrhea is a common complaint, often accompanied by abdominal pain and cramping, typically localized in the lower right abdomen. This pain can sometimes be severe and may worsen after eating. Bleeding can also occur, sometimes appearing as black stools or not visible.
Systemic symptoms frequently arise from the ileum’s inability to properly absorb nutrients. Unintentional weight loss is a common outcome due to malabsorption of fats, carbohydrates, and proteins. Fatigue is another frequent symptom, often linked to the body’s inflammatory state and potential nutritional deficiencies. Anemia can develop from poor vitamin B12 absorption, as the ileum is its primary absorption site. When the ileum is inflamed, its capacity to reabsorb bile salts is compromised, leading to excess bile acids entering the large intestine. This irritation can cause a specific type of watery diarrhea known as bile acid diarrhea.
Diagnostic Process
Diagnosing ileal disease involves a multi-faceted approach to identify the underlying cause. Initial steps often include a detailed medical history and a physical examination to assess symptoms like abdominal tenderness, swelling, or other abnormal findings. Laboratory tests, such as blood work, are performed to check for markers of inflammation, anemia, or specific nutritional deficiencies. Stool tests are also routinely used to detect infections or other potential contributing factors.
Imaging studies provide detailed views of the small intestine. Techniques like CT or MRI enterography (MRE) can reveal inflammation, thickening of the bowel wall, strictures, or other structural changes in the ileum. Endoscopic procedures, particularly a colonoscopy with ileoscopy, allow direct visualization of the terminal ileum. During this procedure, a doctor can observe the inner lining for irritation, ulcers, or erosions. Tissue samples (biopsies) are collected for microscopic examination to confirm inflammation and help determine its cause.
Management and Treatment Approaches
Treatment for ileal disease depends significantly on the underlying cause and the severity of the condition. For inflammatory conditions like Crohn’s disease affecting the ileum, medication is often the first line of approach to reduce inflammation and prevent further damage. Anti-inflammatory drugs, such as 5-aminosalicylates or corticosteroids like budesonide, are used to manage mild to moderate inflammation. Immunosuppressants, including azathioprine, work by altering the body’s immune response.
Biologic therapies represent a more targeted approach, aiming to block specific proteins in the immune system that contribute to inflammation. These are often reserved for more severe cases or when other medications are not effective. Nutritional therapy also plays a role in managing symptoms and correcting deficiencies caused by malabsorption, such as those related to vitamin B12 or iron. In cases of severe disease, such as those with strictures, fistulas, or abscesses that do not respond to medication, surgery may be necessary. An ileal resection involves removing the diseased section of the ileum, and in some instances, this may include the beginning of the large intestine (ileocecal resection).