Inflammatory Bowel Disease (IBD)


Definition:

  • Chronic inflammation of the bowel that could be due to abnormal immune system response to the enteric flora. There are generally 2 types: Chron’s disease (CD) and Ulcerative colitis (UC).
  • Diagnosis of exclusion, bimodal onset (15-25 and 50-80). Chron’s disease usually in 20s and UC in the 40s
  • Sub-classified as Ulcerative colitis or Crohn’s disease.

Etiology and Association:

  • Abnormal immune response to the flora
  • Associated with genetics (HLAB27), infection, abnormal host reactivity
  • Associated with dysregulated cytokines (IL-12/IL-23)

Clinical Presentations:

  • Common to both IBD: Fever, abdominal pain, tenderness, diarrhea, weight loss, bloody stool).
  • Recurrent bouts of bloody mucoid diarrhea (especially Ulcerative colitis), Chrons more watery.
  • Lower abdominal pain/cramps – location depends on site affected; Tenesmus (painful defecate)
  • Fever, weight loss if severe; anemia of chronic disease
  • Symptoms of malabsorption – depending if you talking about UC or CD (CD with steatorrhea due to ↓ bilesalt)
  • If small intestine Chrons: features of subacute intestinal obstruction, mass
  • Extra-intestinal manifestations (seen in both but more common in Chron’s Disease > UC)
    • Joint: Sacrolieitis, Migratory Polyarthritis, Ankylosing Spondylitis,
    • Skin: Pyoderma gangrenosum / Erythema nodosum (indicator of disease severity),
    • 1o Sclerosing cholangitis, Eyes: Anterior Uveitis iritis

Diagnostic test

  • Most accurate test – Endoscopy when can be reach by the scope (UC and Chron’s)
  • Barium studies also diagnostic – in both UC and Chron’s.
  • If still unclear can use serologic testing
  • Chrons disease: ANCA–ve ASCA+ve
  • Ulcerative colitis: ANCA+ve ASCA–ve
  • CD – mainly in small bowel (never rectum) but most common affect terminal ileum
  • UC – always rectum and proximal but never pass the colon.

Complications

  • Colorectal Cancer, Toxic megacolon, Cholangiocarcinoma, 1osclerosing cholangitis
  • All above both can cause but UC more prone.
  • Note that both chrons involving colon and UC can cause colon cancer.
  • More common in Chrons: Mass, Upper GIT, Perianal disease (Perianal Abscess and Fistula), hypocalcemia from fat malabsorption, obstruction, kidney stones (CaOx), gall stones (cholesterol), B12 malabsorption.
  • Post diagnosis of IBD for 8-10 years you need to screen with colonoscopy every 1-2 years.

Treatment and Management

  • Treatment for UC and Chrons depends on the severity of the disease. The severity can be objectively evaluated with the following:
  • Chrons disease: severity is objectively measure via CDAI interpretation.
    • Asymptomatic remission
    • Mild to Moderate active
    • Moderate to severely active
    • Severely active to fulminant disease.
  • Initial Therapy for UC and Chrons
    • Mesalamine (not Sulfasalazine) due to side effect: rash, Interstitial nephritis, hemolytic anemia.
  • Acute Exacerbation
    • Steroids (Prednisone/Budesonide) for both Chrons and UC
    • Azathioprine or 6MP to wean patient off steroid [both can cause pancreatitis] in severe cases dependent on steroid. All need vitamin D and Calcium.
  • Severe disease:
    • Recurrent symptoms when steroids are stopped start
    • Azathioprine, 6-mercaptopurine (6-MP), wean off steroid.
  • Chronic Maintenance of remission (5-ASA derivatives = mesalamine) different types used
    • Mesalamine
      • Asacol – UC ; Rowasa – UC (limited to rectum); Pentasa – CD
      • Sulfasalazine (obsolete version of mesalamine) can cause Rash, AIN,hemolysis, infertility in men (reversible) and Leukopenia.
    • Metronidazole + Ciprofloxacin (perianal disease in chrons)
    • Infliximab (Fistula of Chrons or Refractory severe disease of IBD) fistula = severe.
      • Need PPD/Quantiferon screen and has Joint pain side effect: TNF cause granuloma, hence inhibit can release TB from granuloma
      • If PPD positive (Isoniazid for 9 months) and CXR negative
      • No need to wait 9 months to begin therapy infliximab
    • Newer drugs active only in colon (Balsalazide, Olsalazine)
    • Vedolizumab: IV for moderate to severe IBD not controlled with other medications. Need for induction and maintenance therapy. Better than Natalizumab due to no documented PML.
    • Surgery – Curative for UC if refractory to medication. Chrons usually recur at anastomosis but still do due to obstruction/stricture.

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