Inflammatory bowel diseases

• Inflammatory bowel diseases (IBD) is a term including two idiopathic diseases of the GI tract: ulcerative colitis and Crohn's disease
• Ulcerative colitis


  A mucosal disease that is limited to the large intestine and rectum
• Crohn's disease

  Involves the entire thickness of the bowel wall that may produce "patchy" ulcerations at any point along the alimentary canal from the mouth to the anus but most commonly involves the distal ileum and proximal colon
• The incidence and prevalence of IBD vary widely by race and geographic location
• Occurrence is much higher among whites than in blacks
• The peak age at onset is 20 to 40 years
• A second incidence peak for Crohn's disease has been noted in the seventh decade
• Children are known to develop IBD, and the incidence in this population is rising
• Crohn's disease and ulcerative colitis affect men and women equally
• A 10-fold increased risk of disease in first-degree relatives of patients strongly suggests that genetic factors are involved
• Environment factors also are contributory: breastfeeding appears to reduce the risk of IBD
• Numerous genetic susceptibility genes have been identified, mutations in these genes impair the immune response, thereby contributing to inefficient recognition and clearing of bacteria and cell degradation products by intestinal epithelium leading to inflammation and increased permeability of the intestinal wall
• Ulcerative colitis

  An inflammatory disease that targets the large intestine characterized by remissions and exacerbations. It starts in the colon and rectum region and may spread proximally to involve the entire large intestine
• Histopathologic findings in ulcerative colitis include epithelial necrosis, edema, vascular congestion, and monocellular infiltration
• The persistent disease causes epithelial erosions and hemorrhage, and submucosal fibrosis. Chronic deposition of fibrous tissue may lead to fibrotic shortening, thickening, and narrowing of the colon
• Ulcerative colitis usually is a lifelong disease, and progression to toxic dilatation (toxic megacolon) and dysplastic changes (carcinoma) of the intestine
• Toxic megacolon is the result of disease extension through deep muscular layers. The colon dilates because of weakening of the wall, and intestinal perforation then becomes likely. Associated fever, electrolyte imbalance, and volume depletion are reported
• Carcinoma of the colon is 10 times more likely in patients with ulcerative colitis than in the general population. The likelihood of malignant transformation increases with long-standing disease
• Crohn's disease

  A chronic, relapsing idiopathic disease that is characterized by a segmental distribution of intestinal mucosal ulcers interrupted by normal-appearing mucosa. Although the distal ileum and the proximal colon are affected most frequently, any portion of the bowel may be involved
• In gross specimens, the intestine displays sharply noncontinuous regions of thickened bowel wall, ulcerations and erosions
• The clinical course in Crohn's disease consists of remissions and relapses; relapses are more common in persons who smoke tobacco
• The unremitting disease is complicated by small bowel stenosis and fistula formation. Long-standing colonic Crohn's disease increases the risk for the colonic cancer
• Ulcerative colitis symptoms

  Attacks of diarrhea, rectal bleeding (or bloody diarrhea), abdominal cramps
• Dehydration, fatigue, weight loss, and fever caused by malabsorption of water and electrolytes frequently accompany ulcerative colitis. Extraintestinal manifestations may include arthritis and eye disorders such as iritis and uveitis
• Initial manifestations of Crohn's disease

  Recurrent or persistent diarrhea (often without blood), right lower quadrant abdominal pain or cramping, anorexia, and weight loss. Unexplained fever, malaise, arthritis, uveitis, and features related to malabsorption often emerge next
• Symptoms in Crohn's disease vary from patient to patient according to the site and extent of involved tissue, with three major patterns recognized: (1) Disease of the ileum and cecum, (2) Disease confined to the small intestine, (3) Disease confined to the colon
• Intestinal complications from chronic inflammatory damage in Crohn's disease include transmural fibrosis, intestinal fissuring, and the formation of fistulas or abscesses. These complications are common; 70% to 80% of patients require surgery within their lifetime
• Malabsorption is an additional complication in Crohn's disease that can result in a striking degree of weight loss, anemia, and clubbing of the fingers. Osteoporosis also results from malabsorption and chronic corticosteroid use
• Extraintestinal manifestations (e.g., peripheral arthritis, aphthous, uveitis, hepatic complications) occur in about 20% of patients with Crohn's disease
• Diagnosis of IBD

  Based primarily on clinical findings, results of endoscopy and biopsy, and observations on histopathologic examination of the intestinal mucosa. Abdominal radiographic imaging, including computed tomography and magnetic resonance enterography, and stool examinations also may provide supportive evidence
• Blood tests in IBD

  May show anemia (deficiencies of iron, folate, or vitamin B12) caused by malabsorption, decreased levels of serum total protein and albumin (as a result of malabsorption), inflammatory activity [evidenced as elevated erythrocyte sedimentation rate (ESR)]
• Ulcerative colitis and Crohn's disease management

  Can be managed by an array of drugs but not cured. Antidiarrheal and anti-inflammatory medications (e.g., Sulfasalazine, corticosteroids) generally are first-line drugs. Immunosuppressive agents and antibiotics are used as second-line drugs. Third-line approaches for the management of Crohn's disease in persons who are refractory to steroid treatment include biologic agents such as infliximab or surgical removal of the diseased portion of the colon
• Supportive therapy for IBD

  Includes bed rest, dietary manipulation, and nutritional supplementation. Dietary intervention with fish oil supplements may be beneficial to persons with Crohn's disease
• Sulfasalazine

  Remains the mainstay of treatment for ulcerative colitis and plays a small role in the management of Crohn's disease. Controlled-release oral formulations that dissolve in the distal ileum and colon are used; rectal suppositories or enemas also are used
• Corticosteroids

  Often are combined with sulfasalazine to induce remission in patients who are experiencing flare-ups. Steroids are not prescribed for maintenance therapy because several adverse effects are associated with long-term use
• Severe attacks management

  Patient should be hospitalized and parenteral corticosteroids administered. After about 2 weeks, or when a satisfactory response is achieved, oral steroids are substituted for parenteral steroids, and the dosage is gradually reduced until the drug is no longer needed
• Immunomodulators

  Used in patients who have an active disease that is unresponsive to corticosteroids and in corticosteroid dependent patients to reduce the amount of steroid needed and to limit dose-dependent adverse effects of steroids. Immunomodulators may be given for years; however, their use is limited by their toxicity (flulike symptoms, leukopenia, pancreatitis, hepatitis, and life-threatening infections); thus, white blood cell count and liver function tests must be monitored routinely
• Antibiotics

  Metronidazole or ciprofloxacin have been used for the treatment of active Crohn's disease (e.g., abscesses). They also are used after surgery when toxic colitis develops or when fever and leukocytosis are present
• Biologics

  Used to manage IBD, such as infliximab. Their use is generally reserved for severe disease that is refractory to other drugs and for maintenance of remission. These drugs are expensive and require either slow intravenous (IV) infusion generally performed at 8-week intervals or subcutaneous injections every 2 to 4 weeks
• Surgery for IBD

  Recommended for severe cases that do not respond to corticosteroids and to manage serious complications (e.g., massive hemorrhage, obstruction, perforation, toxic megacolon, carcinomatous transformation). Total proctocolectomy (the surgical removal of the colon and rectum) with ileostomy is the standard but infrequent treatment for intractable ulcerative colitis