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29 Cards in this Set
- Front
- Back
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Irritable Bowel Syndrome
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IBS is a chronic functional GI disorder characterized by some combination of:
- Altered bowel habits - Lower abdominal symptoms It is a diagnosis of exclusion. |
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Epidemiology of IBS
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Commonly diagnosed GI disorder
Prevalence: 10-15% of adult population Females 2:1 Symptoms begin late teens-early 20s Most never seek medical attention |
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Pathophysiology of IBS
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Abnormal Motility
Visceral hypersensitivity Enteric infection Psychosocial abnormalities |
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How can abnormal motility cause IBS?
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Some myoelectrical and motor abnormalities
Temporally correlated with symptoms Unsure if it is primary or secondary to psychosocial stress |
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How can visceral hypersensitivity cause IBS?
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Patients often have lower visceral pain thresholds.
Complaints of bloating although intestinal gas is normal. Rectal urgency with little volume. |
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How can enteric infection contribute IBS?
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Some believe that bacterial overgrowth leads to immune system alterations which affect motility and visceral sensitivity and increase postprandial gas and bloating.
Increased incidence of IBS after an episode of bacterial gastroenteritis. |
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How can psychosocial abnormalities contribute to IBS?
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High rate of psychiatric comorbidity, as high as 50% of those seeking care.
Increased anxiety, depression, phobias and somatizations, may have history of abuse. Influencing perception and reaction to illness, alteration of intestinal motility and GI to CNS pathways. |
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Somatization
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Conversion of mental stress to physical symptoms.
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S/S of IBS
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Symptoms present for at least 3 months
- Usually intermittent Lower abdominal crampy pain - Onset associated with change in form and /or frequency Mucus common Does not usually interrupt sleep Sometimes visible bloating and distention |
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What is the most common cause of IBS?
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Idiopathic
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Rome Criteria for IBS
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Abnormal stool frequency
> 3 per day (with diarrhea) OR < 3 per week (with constipation) Change in form - IBS w/diarrhea - loose/watery, urgency, fecal soiling - IBS w/constipation - hard or lumpy, or straining Symptoms persist for 12 weeks within 12 months. Symptoms relieved with defecation. |
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Chief complaints of IBS
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Constipation predominant
Diarrhea predominant Alternating |
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Physical exam findings of IBS
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PE usually normal
Relieve patient anxiety Abdominal tenderness common, not severe |
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Diagnosis of IBS
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Generally it is a diagnosis by exclusion.
Alarm symptoms may alert you to a different diagnosis. If patient meets Rome criteria, no further testing is needed. |
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Alarm symptoms associated with IBS
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Abnormal blood studies
Anemia or anorexia Blood in stools, hematochezia (rectal bleeding) Family history of colon cancer, IBD, or Celiac Sprue Fever, malnutrition, involuntary weight loss >10 lbs Nocturnal symptoms Onset in patients > 40 yrs old Palpable abdominal or rectal mass Recent antibiotic use Persistent severe diarrhea or constipation |
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Diagnostic testing associated with IBS
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Good history and physical exam
Age appropriate testing Basic testing only: - CBC, CMP, serum albumin - FOBT (fecal occult blood test or Gauiac |
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Differential diagnosis of IBS
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Malabsorption
Celiac sprue Lactase deficiency Diverticulosis Bacterial overgrowth Infectious disease Inflammatory bowel disease Pancreatic insufficiency Colon cancer Depression/psychiatric disorders (consider abuse) Diabetes Mellitus Chronic Diarrhea Laxative use/abuse Endometriosis Thyroid dysfunction Parasites |
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Treatment of IBS
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Depends on:
- Nature and severity of the symptoms - Degree of functional impairment - Presence of psychosocial factors Most important interventions: - Reassurance - Education - Dietary |
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Dietary considerations of IBS
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Symptom diaries may be helpful, but usually no direct correlation with specific food.
- May rule out other problem Trial lactose-free diet Increased fiber intake, 20-25 g/day Avoid fatty foods and caffeine Foods may exacerbate bloating, flatulence, diarrhea: - coffee, alcohol, carbonated beverages, some fruits and vegetables (cabbage, beans), artificial sweetener |
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Pharmacotherapy for IBS
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Reserved for moderate to severe symptoms
Adjunct therapy, not curative Symptomatically based: - Antispasmodics (anti-cholerengics) - Antidiarrheals - Anticonstipation agents - Psychotropics (SSRIs - serotonin targeted) - Antibiotics - Probiotics |
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Characteristics of antispasmodic agents
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Anticholinergics used for acute pain or bloating
- Hyoscyamine (Levbid) - Methscopolamine (Pamine) - Dicyclomine (Bentyl) Contraindications - glaucoma, GI obstruction Common anticholinergic SEs - urinary retention, constipation, tachycardia, and dry mouth. |
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Characteristics of antidiarrheal agents
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Goal is to reduce frequency, liquidity, and urgency.
Prophylaxis in situations where diarrhea is anticipated or would be very inconvenient. - before stressful or important occasions, trips, social events |
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Characteristics of anticonstipation agents
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Goal to increase frequency, improve consistency, and reduce straining.
Osmotic laxatives - Milk of Magnesia - Polyethylene glycol Lactulose or sorbitol poorly tolerated with IBS - Increase flatus and distention |
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Characteristics of psychotrophic agents
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Patients with pain and bloating benefit from tricyclic antidepressants.
- Low doses - Anticholinergic effects – better for patients with diarrhea predominance. SSRIs may also lead to improvement – by promoting overall well-being. |
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Beneftit of psychotrophic drugs
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Not only do they help with depression symptoms, it is believed they target motility, visceral sensitivity, and central pain independently from psychotropic effects.
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Characteristics of serontonic antagonist
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Serotonin is important mediator of GI motility and sensation.
Alosetron (Lotronex) - Women with predominantly diarrhea - Reduces pain, urgency and diarrhea - Can have significant side effects – only severe IBS - Efficacy has not been demonstrated in men |
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How are antibiotics associated with IBS?
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Randomized controlled studies have shown significant improvement over controls with nonabsorbable antibiotic.
May be attributable to suppression of bacterial overgrowth. Remains controversial |
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Characteristics of probiotics
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Promising-safe, well tolerated, inexpensive
Bifidobacterium infantis Further study needed to define efficacy. Lactobacillus salivarius-may help resolve diarrhea following antibiotic use, not FDA approved. Activia yogurt-has Lactobacillus and bifidobacterium strains, lawsuits over claims, still worth eating. |
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Prognosis of IBS
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Patient education is very important
Complicated disorder or unknown origin can be frustrating for patient. Explanation of chronic nature and assurance that it is not life-threatening. Explanation of treatment-symptomatic, not a cure-all. Most patients learn to cope with continued intermittent symptoms. |
