36. inflammatory bowel disease - ulcerative colitis and Crohn's disease
Covers inflammatory bowel disease, contrasting Crohn's disease, which is transmural and can affect any part of the gut, with ulcerative colitis, which is superficial and confined to the colon and rectum. It then takes aetiology, pathogenesis, clinical features by severity, physical signs, laboratory and instrumental diagnosis, complications, treatment including surgery, and extraintestinal manifestations. It closes with notes on smoking, recurrence after surgery and distinguishing the disease from irritable bowel syndrome.
Topic 34 of 58 in the MU Sofia syllabus for Internal Medicine (Theory) (Medicine, Year 3). The free AceMed note covers it in 10 sections, about 392 words (3 min of reading), with 13 flashcards.
In this note
Inflammatory Bowel Disease – Ulcerative Colitis and Crohn’s Disease
Definition:
Etiology:
Pathogenesis:
Clinical Features:
Physical Examination:
Diagnosis:
Complications:
Treatment:
Prognosis:
Definition:
Inflammatory Bowel Disease (IBD) is a group of chronic, relapsing inflammatory conditions of the gastrointestinal (GI) tract. The two main types are:
Crohn's Disease (CD): A transmural, granulomatous inflammation that can affect any part of the GI tract from mouth to anus, most often terminal ileum and colon
Ulcerative Colitis (UC): A superficial inflammation restricted to the mucosa and submucosa of the colon and rectum.
Etiology:
Genetic predisposition (e.g., NOD2 mutations in Crohn's)
Environmental triggers:
Diet
Smoking (protective in UC but worsens Crohn’s)
Hygiene hypothesis
Immune dysregulation:
Abnormal mucosal immune response to intestinal flora
Autoimmune mechanisms
Breastfeeding, early childhood exposures (protective)
Pathogenesis:
Defective epithelial barrier ("leaky gut") allows bacterial antigens to enter lamina propria.
Inappropriate activation of mucosal immune system:
Crohn’s: TH1 and TH17-mediated response → granulomatous inflammation
