أسئلة السابعة GIT الدلتا

• Crohn's Disease is a chronic inflammatory condition affecting any part of the gastrointestinal tract, most frequently the terminal ileum.
• Slightly more common in females.

Epidemiology

• Peak onset occurs between ages 20-40, with a smaller peak in older adults.

Etiology & Pathogenesis

• Tissue inflammation results from an abnormal immune response to bacterial antigens in the gut lumen.
• It has a strong genetic component, with high concordance among monozygotic twins, along with diet and smoking playing a role.

Pathology

• In 40% of cases, it affects the terminal ileum and cecum
• 20% affects the colon only
• 30% affects the ileum and colon
• 10% affects any part of the GIT, perianal disease, mouth, esophagus, and stomach.
• The hallmark is focal intestinal inflammation and discontinuous disease, leading to 'skip lesions'.

Early Lesions

• Include aphthous ulcers.
• Non-caseating granulomas are present in up to 70% of cases.
• Inflammation is transmural, leading to large ulcers, sinus tracks, fissures, and fistulae.
• Healing leads to extensive fibrosis

Clinical Features

• Symptoms are abdominal pain, diarrhea, weight loss, anorexia, and fever
  • Growth retardation is common in children.
  • Anemia occurs in 30%, often due to iron, B12, or folate deficiency
  • Small bowel obstruction may occur due to strictures
  • Colonic Crohn's disease may present with bloody diarrhea.
  • Gastroduodenal Crohn's can present as Helicobacter-negative peptic ulcer disease.
  • Intestinal affection may be inflammatory, stricturing, or penetrating.

Extra-Intestinal Manifestations

• Arthropathy (including sacroiliitis), with large joints predominantly affected
  • Association with ankylosing spondylitis in HLA-B27 patients
  • Metabolic bone disease: osteopenia
  • Venous and arterial thromboembolic disease
  • Skin manifestations: pyoderma gangrenosum and erythema nodosum
  • Ocular manifestations: Scleritis, episcleritis, and anterior uveitis
  • Gallstones
  • Fatty liver, autoimmune hepatitis and primary sclerosing cholangitis
  • Renal oxalate stones

Laboratory Investigations

• CBC indicates anemia, increased WBC, and increased platelets.
• Decreased serum iron, B12, and folate levels.
• LFTs show low serum albumin and high CRP.
• Low calcium, magnesium, and zinc levels.
• Stool tests are performed, including stool culture and sensitivity as well as testing for Clostridioides difficile toxin, to exclude infectious colitis.

Differentiation Between IBD and IBS

• Elevated fecal calprotectin or lactoferrin can differentiate between IBD and IBS.
• Immunological markers: ASCA found in up to 50% of Crohn's but less often in Ulcerative Colitis
• p-ANCA is found in 70% of UC but only 15% of Crohn's

Imaging

• Colonoscopy is the gold standard for diagnosing colonic and terminal ileal disease, allowing for mucosal biopsy
• Video capsule endoscopy visualizes all parts of the GIT to detect lesions not visible in other imaging
• Barium follow-through: Standard method for evaluating the small bowel, largely replaced by US, CT, and MRI. A "string sign" can be observed when using this method.
• Small bowel US detects thickened terminal ileum wall, abscesses, and fistulae
• CT enterography is useful in evaluating small bowel disease
• MRI enterography is better than CT for detecting strictures

Treatment

• Corticosteroids are used for rapidly inducing remission, but not as long-term therapy.
  • Budesonide is nearly as effective as prednisolone, with fewer side effects.
• Azathioprine or methotrexate are widely used in patients with active CD who fail to taper steroids and require several weeks for action.
• Aminosalicylates like mesalazine are used in treating colonic disease.
• Anti-TNF α antibodies: Infliximab IV infusions and Adalimumab SC.
• Anti-integrin therapy: Vedolizumab.
• Anti-IL-12/IL-23 therapy: Ustekinumab.

Other Novel Oral Therapies

• Tofacitinib selective JAK inhibitors are given orally.
• Metronidazole heals perianal fistulae
• Ciprofloxacin is used in treating complications with good effect

Nutritional Therapy

• Corrects nutritional deficiency
• Elemental diets induce disease remission

Surgery Indications

• Intra-abdominal masses
• Fistulae
• Fibrotic strictures with obstruction
• Toxic megacolon
• Hemorrhage
• Cancer
• Surgical treatment is for complications such as stricture and is not a cure.

Ulcerative Colitis vs Crohn's Disease

• Site of Origin: Terminal ileum in Crohn's, rectum in Ulcerative Colitis
• Pattern of Progression: Skip lesions/irregular in Crohn's, proximally contiguous in Ulcerative Colitis
• Thickness of Inflammation: Transmural in Crohn's, submucosa or mucosa in Ulcerative Colitis
• Symptoms: Crampy abdominal pain in Crohn's, bloody diarrhea in Ulcerative Colitis
• Complications: Fistulas, abscess, obstruction in Crohn's, hemorrhage, toxic megacolon in Ulcerative Colitis
• Radiographic Findings: String sign on barium X-ray in Crohn's, lead pipe colon on barium X-ray in Ulcerative Colitis
• Risk of Colon Cancer: Slightly increased in Crohn's, markedly increased in Ulcerative Colitis
• Surgery: For complications such as stricture in Crohn's, curative in Ulcerative Colitis