Gastroenterology Book

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Irritable Bowel Syndrome

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  1. Epidemiology
    1. Lifetime Prevalence: 10-22%
    2. Slightly more common in women
    3. Prevalence for elderly same as for young
    4. Most common condition seen by Gastroenterologists
  2. Pathophysiology
    1. Organic gastrointestinal hypersensitivity
    2. Provoked by psychosocial risk factors
    3. Severe Gastroenteritis episode may be associated
  3. Associated Conditions
    1. Gastroesophageal Reflux Disease
    2. Dysphagia
    3. Globus Hystericus
    4. Fatigue
    5. Non-cardiac Chest Pain
    6. Urologic dysfunction
    7. Gynecologic disease (e.g. Chronic Pelvic Pain)
    8. Fibromyalgia
    9. Chronic Fatigue Syndrome
    10. Temperomandibular joint syndrome
    11. Food Allergy
    12. Low-fiber diet
  4. Risk Factors: Psychosocial
    1. Anxiety
    2. Major Depression
    3. Somatization Disorder
    4. Sexual abuse or physical abuse
    5. Stressful life events
    6. Substance Abuse
  5. Types
    1. Alternating Diarrhea and Constipation
    2. Nervous Diarrhea
    3. Predominant Constipation
    4. Upper abdominal bloating and discomfort
  6. Symptoms
    1. Altered bowel habits
      1. Diarrhea
      2. Constipation
      3. Scybalous stools
    2. Recurrent and Chronic Abdominal Pain
      1. Upper abdominal discomfort after eating
      2. Left Lower Quadrant Abdominal Pain
      3. Right Lower Quadrant Abdominal Pain
      4. Abdominal Pain relieved with Defecation
    3. Gaseousness
      1. Excessive Flatulence or Eructation
      2. Normal patients experience about 13 farts per day
    4. Nausea or Vomiting
  7. Diagnosis: Rome Criteria
    1. Abdominal symptoms persistent or recurrent for 3 months
      1. Abdominal Pain or discomfort
      2. Symptoms relieved with Defecation
      3. Irregular pattern of Defecation (>25% of time)
        1. Change in stool frequency
        2. Change in stool consistency
    2. Two or more below (one quarter of days)
      1. Altered stool frequency
      2. Altered stool consistency
        1. Constipation
        2. Diarrhea
      3. Altered stool passage
        1. Straining for normal consistency stool
        2. Urgency of Defecation
        3. Incomplete evacuation
      4. Mucus in stools
      5. Abdominal bloating or distention
  8. Diagnosis: Manning Criteria
    1. Abdominal Pain
    2. Loose stools
    3. Increased stool frequency
    4. Abdominal Pain relieved with Defecation
    5. Abdominal distention
    6. Mucus in stools
    7. Sensation of incomplete evacuation
  9. Red Flags: Symptoms and signs suggestive of other diagnosis
    1. Nighttime Diarrhea
    2. Nocturnal stool Incontinence
    3. Nocturnal awakening due to abdominal discomfort
    4. Abdominal Pain that interferes with normal sleep
    5. Visible or occult blood in stool
    6. Weight loss
    7. Recurrent Fever
    8. Family History of Colon Cancer
    9. Family History of Inflammatory Bowel Disease
    10. Elderly
    11. Laboratory abnormality
      1. Leukocytosis
      2. Anemia
      3. Increased Erythrocyte Sedimentation Rate (ESR)
  10. Differential Diagnosis
    1. Colonic Adenocarcinoma
    2. Inflammatory Bowel Disease
      1. Ulcerative Colitis
      2. Crohn's Disease
    3. Abdominal Angina (Ischemic colitis)
    4. Pseudo-obstruction (Diabetes Mellitus, Scleroderma)
    5. Intermittent sigmoid volvulus
    6. Toxic Megacolon or bacterial overgrowth syndrome
    7. Endocrine causes
      1. Hypothyroidism or Hyperthyroidism
      2. Diabetes Mellitus
      3. Addison's Disease
    8. Malabsorption
      1. Celiac Sprue (strongly consider if Diarrhea with red flags)
      2. Lactose Intolerance
      3. Pancreatic insufficiency
    9. Giardiasis
    10. Endometriosis
    11. Psychiatric illness
      1. Depression
      2. Somatization
      3. Anxiety Disorder or Panic Disorder
    12. Medications
      1. Laxatives
      2. Constipating medications
  11. Evaluation
    1. General
      1. Avoid a piecemeal work-up
        1. Perform a complete evaluation the first time
        2. Avoid over-investigation
      2. Irritable bowel is no longer diagnosis of exclusion
        1. Diagnostic criteria above are sufficient to treat
      3. Indications for full evaluation and Gastroenterology
        1. Red flags present (see above) or
        2. Onset over age 50 years
    2. Careful History
      1. History of Gastrointestinal Symptoms
      2. Family History of gastrointestinal disease
      3. Marital History
      4. Sexual Abuse (strong correlation)
    3. Reasonable exam
      1. Thorough abdominal examination
      2. Also focus on possible endocrine causes
    4. Look for Food Intolerance
      1. Lactose Intolerance
      2. Sorbitol
      3. Wheat (Gluten Sensitive Enteropathy)
  12. Labs: Initial, based on predominant symptom
    1. Constipation dominant
      1. Complete Blood Count (CBC)
      2. Serum Electrolytes or Chemistry panel (chem8)
      3. Thyroid Stimulating Hormone (TSH)
      4. Flexible Sigmoidoscopy or Colonoscopy
    2. Diarrhea predominant
      1. Stool Ova and Parasites
      2. Fecal Leukocytes
      3. Complete Blood Count (CBC)
      4. Serum Electrolytes or chemistry panel
      5. Thyroid Stimulating Hormone (TSH)
      6. Erythrocyte Sedimentation Rate (ESR)
      7. Flexible Sigmoidoscopy or Colonoscopy
      8. Celiac Sprue (Transglutaminase, endomysial Antibody)
        1. Usually associated with red flag signs or symptoms
    3. Pain Dominant
      1. Complete Blood Count (CBC)
    4. Reference
      1. Fass (2001) Arch Intern Med 161:2081
  13. Diagnostic studies
    1. Flexible Sigmoidoscopy
      1. More uncomfortable in Irritable Bowel Syndrome
    2. Consider additional studies as indicated
      1. Upper GI Study
      2. Barium Enema
  14. Management: General Measure
    1. See the patient frequently
      1. Maintain a strong doctor-patient relationship
      2. Offer frequent reassurance
      3. Identify and treat emotional stressors
      4. Answer patients questions in unhurried environment
    2. Do not downplay symptoms as psychiatric
      1. Irritable Bowel is a real functional bowel problem
      2. Explain physiology and absence of serious illness
    3. Reduce stressors
      1. Teach relaxation techniques
      2. Teach coping mechanisms for chronic illness
    4. General Diet recommendations
      1. Get adequate fluid intake (>64 ounces/day)
      2. Bulk agents (gradually increase)
        1. Metamucil
        2. Citrucel
        3. High fiber-bran
      3. Consider avoiding provocative agents
        1. Consider Elimination Diet
        2. Avoid caffeine
        3. Avoid Alcohol
        4. Avoid Legumes and other gas producing foods
        5. Avoid Dairy products (lactose)
        6. Avoid carbonated beverages (Sorbitol)
        7. Avoid Artificial Sweeteners (fructose)
        8. Avoid Fatty meals
        9. Corn, wheat and citrus may also exacerbate IBS
    5. Avoid Provocative or addictive medications
      1. Stimulant Laxatives (except brief use)
        1. Correctol
        2. Dulcolax
        3. Cascara
      2. Sedatives or Tranquilizers (Benzodiazepines)
      3. Narcotics
  15. Management: Symptom specific medications
    1. Diarrhea
      1. Consider eliminating lactose, caffeine from diet
      2. Cholestyramine 4 grams qhs to 6 times daily
      3. Loperamide (Imodium) 2-4 mg qid prn
        1. Before meals
        2. As needed in stressful social situations
      4. Ondansetron (Serotonin antagonist)
        1. Reduces rapid transit
      5. Alosetron (Lotronex)
        1. Risk of Constipation and ischemic colitis
          1. Iatrogenic deaths have occured
          2. Black box warning: Signed informed consent needed
        2. FDA approved only for women with IBS with Diarrhea
        3. Dose: 1 mg daily (may advance to bid)
      6. Peppermint
        1. Pittler (1998) Am J Gastroenterol 93:1131
    2. Comorbid Mood Disorders
      1. Major Depression
        1. SSRI Medications or other Antidepressants
      2. Anxiety
        1. Buspar
        2. Amitriptyline (Elavil)
    3. Pain dominant symptoms
      1. Chronic Pain
        1. Amitriptyline (Elavil) 25 mg qhs
        2. Desipramine (Norpramin) 50 mg tid
        3. Tegaserod (Zelnorm)
          1. Nyhlin (2004) Scand J Gastroenterol 39:119
        4. SSRI medications may be effective as adjunct
          1. Tabas (2004) Am J Gastroenterol 99:914
      2. Post-prandial pain: Anticholinergic
        1. Avoid chronic use
        2. Trial for 2 weeks and stop if no effect
        3. Dicyclomine (Bentyl) 10-20 mg, 15 min before meal
        4. Hyoscyamine (Levsin) 0.125 to 0.25 mg before meal
    4. Constipation
      1. Use gastro-colic response
        1. Wake-up, eat breakfast and anticipate stool in AM
      2. First line: Bulk agents (e.g. Fiber, Psyllium, bran)
        1. Titrate to 20-30 grams per day
        2. Risk of bloating initially
      3. Second line (use at bedtime for AM stool)
        1. Osmotic agents
          1. Lactulose 1-2 teaspoons at bedtime
          2. Polyethylene glycol solution 8 ounces at bedtime
          3. Milk of Magnesia 1-2 tablespoons at bedtime
          4. Miralax
        2. Consider Stimulant Laxatives if osmotic agents fail
          1. Senna or Cascara
          2. Bisacodyl
      4. Other agents potentially useful
        1. Guar-Gum
          1. Parisi (2002) Dig Dis Sci 47:1696
        2. Peppermint
          1. Pittler (1998) Am J Gastroenterol 93:1131
        3. Loxiglumide (cholecystokinin-A receptor antagonist)
        4. Tegaserod (Zelnorm): 5-HT4 agonist
          1. Dose: 6 mg bid 30 minutes before meals
    5. Excessive flatus (gas)
      1. Simethicone 40 to 125 mg up to qid
      2. Beta-galactosidase (Beano)
  16. Resources
    1. International Foundation for Functional GI Disorders
      1. http://www.iffgd.org
    2. American College of Gastroenterology
      1. http://www.ACG.GI.org
    3. Mind-Body Digestive Center
      1. http://www.mindbodydigestive.com
  17. References
    1. Camilleri (2000) Gastroenterology 120:652
    2. Camilleri (1999) Am J Med 107(5A):27F
    3. Drossman (1999) Am J Med 107(5A):41S
    4. Hammer (1999) Am J Med 107(5A):5S
    5. Heymann-Monnikes (2000) Am J Gastroenterol 95:981
    6. Holten (2003) Am Fam Physician 67(10):2157
    7. Jailwala (2000) Ann Intern Med 133:136
    8. Mertz (2003) N Engl J Med 349:2136
    9. Naliboff (1999) Curr Rev Pain 3:144
    10. Ringel (2001) Annu Rev Med 52:319
    11. Viera (2002) Am Fam Physician 66:1867

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