Unit
- Definition: Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract, primarily comprising Crohn's disease (CD) and ulcerative colitis (UC). Both involve immune-mediated inflammation but differ in location and depth of involvement.
- Crohn's disease: CD can affect any part of the GI tract from mouth to anus, with transmural inflammation leading to strictures, fistulas, and abscesses. It often presents with abdominal pain, diarrhea, and weight loss.
- Ulcerative colitis: UC is limited to the colon and rectum, with continuous mucosal inflammation starting at the rectum. Symptoms include bloody diarrhea, urgency, and tenesmus.
- Epidemiology: IBD incidence is highest in Western countries but rising globally. Peak age of onset is between 15-30 years, with a second peak in the 50s-70s. Both genetic and environmental factors contribute.
- Natural history: IBD follows a relapsing-remitting course, with periods of active inflammation and quiescent disease. Over time, complications such as strictures or colorectal cancer risk may develop.
- Impact on quality of life: Chronic symptoms, hospitalizations, and surgeries significantly affect physical, emotional, and social well-being. Many patients require lifelong medication and monitoring.
- Clinical presentation differences: CD often presents with right lower quadrant pain and non-bloody diarrhea, while UC presents with bloody diarrhea and lower abdominal cramps. Extraintestinal manifestations can occur in both.
- Diagnostic delay: Due to symptom overlap with other conditions, diagnosis may be delayed by months to years, leading to complications. Early recognition through proper history and testing is critical.
- Pathophysiology: IBD results from a dysregulated immune response to gut microbiota in genetically susceptible individuals. Key pathways involve tumor necrosis factor alpha, interleukins, and T cell subsets. Environmental triggers such as smoking, diet, and antibiotics may initiate or perpetuate inflammation.
- Treatment goals: Therapy aims to induce and maintain remission, prevent complications, improve quality of life, and avoid long-term corticosteroid use. A treat-to-target strategy with objective markers like endoscopic healing and fecal calprotectin normalization is increasingly adopted.
- Medical therapy options: Aminosalicylates are used mainly in UC for mild to moderate disease. Immunomodulators like thiopurines and methotrexate help maintain remission. Biologic agents targeting TNF, integrins, or interleukins, and small molecules like JAK inhibitors, are reserved for moderate to severe cases.
- Surgical indications: Surgery is indicated for medically refractory disease, strictures causing obstruction, fistulas not responding to medications, dysplasia or cancer, and acute complications like toxic megacolon or perforation. In UC, colectomy can be curative; in CD, surgery is not curative but provides symptom relief.
Terminology
- Transmural inflammation
- Inflammation extending through all layers of the intestinal wall, characteristic of Crohn's disease.
- Mucosal inflammation
- Inflammation limited to the innermost lining of the colon, typical of ulcerative colitis.
- Relapsing-remitting course
- Pattern of active disease flares alternating with periods of remission.
Quick Revision
- IBD includes Crohn's disease (transmural, anywhere in GI tract) and ulcerative colitis (mucosal, limited to colon).
- Both conditions have a relapsing-remitting course and significant impact on quality of life.
- Early diagnosis reduces complications and improves outcomes.