Crohn disease

Clinical Manifestations

• Diarrhea frequency, consistency, bloody, steatorrhea
• Ileitis and Colitis: diarrhea, abdominal pain, weight loss, fever
• Crampy abdominal pain
• Bleeding less common than UC
• Fistulae: enteroenteric, enterovesicular, fistulae to psoas abscess
• Associated symptoms: aphthous ulcers, dysphagia, odynophagia, gastric outlet obstruction, fat malabsorption and steatorrhea, perianal disease

History

• Consider other causes
  • Food poisoning: restaurant, foods
  • Infectious: travel history, contacts, HIV risk factors, Yersinia, TB
  • Ischemic: CAD and cardiac risk factors
  • Drug induced: recent antibiotics
• Complications of IBD
  • General: fever/chills/weight loss
  • HEENT: eye for uveitis, episcleritis
  • Chest: pulmonary fibrosis
  • GI: PSC with elevated ALP, steatorrhea causing malnutrition, Vit D deficiency
    • Massive hemorrhage, acute perforation, fistula, abscess, toxic megacolon
  • Renal: oxalate stones due to increased oxalate absorption (Ca bound to free fatty acids)
  • MSK: arthritis (large joints, ank spondylitis), osteoporosis
  • Skin: erythema nodosum, pyoderma gangrenosum
  • Heme: venous thromboembolism, vit B12 deficiency (ileal disease)
• PMH, Meds, Allergies, Smoking, Alcohol
• Family history of IBD

Physical

• Vitals: may be volume depleted or febrile
• H&N: uveitis, episcleritis, oral ulcers, lymphadenopathy
• Resp: pulmonary fibrosis
• GI: abdo pain, liver, jaundice, spleen, masses, acute abdomen
• MSK: arthritis, osteoporosis
• Skin: erythema nodosum, pyoderma gangrenosum

Differential Diagnosis

• For ileitis specifically, see 1
• Irritable bowel syndrome
• Lactose intolerance
• Infectious colitis
  • Bacteria
    • Shigella, Salmonella, Campylobacter, Escherichia coli O157:H7, Yersinia
    • Clostridium difficile
    • Ileocecal tuberculosis
    • Chlamydia (more common), syphilis, and gonorrhea
  • Protozoa
    • Parasites, including Giardia
    • Ileocecal amebiasis
  • Viruses
    • CMV (in immunocompromised)
  • Common variable immunodeficiency
• Ulcerative colitis: from rectum extending proximally
• Others: appendicitis, diverticulitis, ischemic colitis, carcinoma with obstruction, lymphoma, chronic mesenteric ischemia, endometriosis, and carcinoid

Comparison to Ulcerative Colitis

Feature	Crohn	UC
Symptoms	Abdo pain/cramping, diarrhea +/- blood	Tenesmus, bloody stool, mucous
Distribution	Discontinuous with skip lesions; 80% TI, 50% ileocolonic, 30% isolated ileal, 20% isolated colonic	Continuous; 30% pancolitis, 50% proctosigmoiditis
Muscosa	Transmural inflammation	Mucosal inflammation
Extraintestinal manifestations	More skin (pyoderma, EN), arthritis, osteopenia, fistulas, strictures	More PSC, more ophtho, arthritis, osteopenia

Management

• Mild
  • Colonic: sulfasalazine
  • Ileocolic: controlled-release budesonide
  • Azathioprine or methotrexate for maintenance
• Fistulas
  • Infliximab or other anti-TNF-alpha biologic
    • Add antibiotics for perianal fistulas
  • May be able to use antibiotics alone for simple fistulas
• Active
  • Oral corticosteroids for remission followed by azathioprine for maintenance
    • Can also consider methotrexate for maintenance
  • If refractory, use infliximab

Further Reading

• ACG Guidelines for the Management of Crohn’s Disease in Adults. Am J Gastroenterol. 2018 Apr;113(4):481-517.
• AGA Guideline on the Management of Crohn’s Disease After Surgical Resection. Gastroenterology. 2017 Jan;152(1):271-275.
• CAG Clinical Practice Guidelines: The use of tumour necrosis factor-alpha antagonist therapy in Crohn’s disease. Can J Gastroenterol. 2009 Mar;23(3):185-202.