Ileitis describes a condition where the ileum, the final segment of the small intestine, becomes inflamed. This inflammation can arise from various factors, ranging from short-term infections to chronic conditions. Because the ileum performs specialized functions in the digestive process, inflammation in this area directly impacts the body’s ability to process nutrients effectively. Understanding the origins and clinical presentations of ileitis allows for appropriate medical investigation and tailored treatment strategies.
What Ileitis Is and Where It Occurs
The ileum is the third and longest section of the small intestine, connecting the jejunum to the large intestine at the ileocecal valve. This segment completes the digestive process by absorbing water, remaining nutrients, and particular substances. Specialized functions include the absorption of vitamin B12, necessary for nerve function and red blood cell formation, and the reabsorption of bile salts used for fat digestion.
When inflammation occurs, the tissue lining becomes swollen, reddened, and often ulcerated. This disrupts the mucosal surface, severely impairing its ability to absorb bile salts and vitamin B12. Unabsorbed bile salts pass into the colon, leading to diarrhea, while the lack of B12 absorption can result in anemia and neurological issues. The presence of Peyer’s patches, which are clusters of lymphoid tissue, makes the terminal ileum a common site for inflammation, particularly in cases involving infection or immune system activity.
Common Triggers and Underlying Causes
The inflammation specific to the ileum is not a single disease but a response to a range of underlying factors, grouped into acute or chronic causes. Acute ileitis is typically short-term and caused by a bacterial or viral infection, such as those involving Salmonella, Yersinia, or viruses that cause gastroenteritis. These infections localize in the ileum, causing a self-limited episode of inflammation that resolves once the body clears the pathogen.
Chronic ileitis involves persistent or recurring inflammation and is most commonly associated with Crohn’s disease, a type of inflammatory bowel disease. In Crohn’s disease, the immune system attacks the digestive tract, and the ileum is the most frequently affected site, sometimes leading to transmural inflammation that penetrates the entire wall of the intestine. Other non-infectious causes include the prolonged use of medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), which can damage the intestinal lining. Radiation enteritis can also cause ileitis when radiation therapy damages the delicate cells of the ileum. Conditions like ischemia (reduced blood flow to the tissue) or certain systemic disorders can also lead to ileal inflammation.
How Ileitis Presents
Ileitis often manifests as abdominal pain and cramping, particularly in the lower right quadrant of the abdomen. This pain is a direct consequence of the inflamed terminal ileum, sometimes mimicking appendicitis in acute cases. The irritation and dysfunction of the ileum result in chronic diarrhea, which may be watery due to the malabsorption of bile acids.
Systemic symptoms accompany the localized intestinal issues, reflecting the body’s response to ongoing inflammation. Patients often experience a low-grade fever and fatigue, especially if the ileitis is chronic. Unintended weight loss is also common, stemming from reduced appetite and impaired absorption of nutrients across the inflamed intestinal wall. In severe instances, blood may appear in the stool due to ulcers or erosions on the ileal lining.
Steps for Diagnosis and Management
Diagnosing ileitis begins with a medical history and a physical examination to check for tenderness or swelling in the right lower abdomen. Blood tests are ordered to look for elevated inflammatory markers like C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), which indicate inflammation. Stool samples are collected to check for signs of infection, blood, or other factors that could point to an infectious cause.
Imaging and Endoscopy
To assess the extent of the inflammation, doctors use imaging studies and endoscopic procedures. Computed Tomography (CT) or Magnetic Resonance (MR) enterography provides detailed images of the small intestine, revealing wall thickening or structural complications. A colonoscopy is typically performed, allowing a flexible tube with a camera to pass into the terminal ileum to directly visualize the inflamed tissue and obtain biopsies for microscopic analysis.
Treatment Strategies
Treatment for ileitis is dependent on the identified cause, necessitating an accurate diagnosis. Acute infectious ileitis may be managed with antibiotics if a bacterial pathogen is found, often resolving spontaneously with supportive care and hydration. Management of chronic ileitis, particularly when due to Crohn’s disease, focuses on controlling the immune response and reducing inflammation. This often involves anti-inflammatory medications like corticosteroids, or advanced therapies such as immunosuppressants and biologics that target specific components of the inflammatory pathway. If the inflammation leads to complications like a bowel obstruction from a stricture or an abscess, surgical intervention to remove the damaged section of the ileum may be necessary.