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Irritable Bowel Syndrome         ibs2008.pdf  

 DX  |  RX             

See Johns Hopkins IBS Resource Site  | IBS2011.pdf      

IBS is a very common, chronic, recurring GI disorder without cure and without dire consequences.  It is a benign disease.  The cause of IBS is only incompletely understood. Currently, IBS is believed to represent a complex of abnormal gastrointestinal motility, altered visceral sensation, and psychologic factors.  Emotional stress may alter small and large bowel function in normal people, and it does so to a much greater extent in people with IBS.

SX:  chronic recurrent crampy abdominal pain, bloating, excessive flatulence, diarrhea, constipation, or alternating diarrhea and constipation.

DX:  
Although IBS is ultimately a diagnosis of exclusion, certain features, including stable weight, chronic GI symptoms, and an unrevealing physical examination, often allow a presumptive diagnosis and initiation of treatment without extensive diagnostic testing.

(The Rome Criteria for Irritable Bowel Syndrome  -  Gastroent Int 1992; 5:75  Thompson WG, Creed F)
At least 3 months of continuous or recurrent symptoms of

1. Abdominal pain or discomfort that is
   • relieved with defecation
   • and/or associated with a change in frequency of stool
   • and/or associated with a change in consistency of stool and
2. Two or more of the following at least one-quarter of occasions or days:
   • altered stool frequency (> 3 times/day or < 3 times/week)
   • altered stool form (lumpy/hard or loose/watery stool)
   • altered stool passage (straining, urgency), or feeling of incomplete evacuation
   • passage of mucus
   • bloating or feeling of abdominal distention         

The Manning Criteria for Irritable Bowel Syndrome:

1. • Pain relieved by defecation 
2. • Looser stools at onset of pain    
3. • More frequent bowel movements at onset of pain  
4. • Abdominal distension (visible)    
5. • Mucus per rectum    
6. • Feeling of incomplete rectal emptying    

Approach to IBS

H & P to rule out organic cause of the symptoms as drugs, dietary habits, lactose intolerance, weight loss, bleeding, anemia, fever, colon inflammation, infection, or malignancy, biliary disease, previous GI surgery, etc.  History should also include emotional stress profile.

Diff-Diagnosis of IBS:

• Inflammatory Bowel Disease, Microscopic colitis 
• Colorectal carcinoma
• Colon diverticulosis
• Lactose intolerance
• Malabsorption syndrome; chronic pancreatitis; endometriosis; postsurgical syndromes 
• Chronic intestinal idiopathic pseudo-obstruction
• Endocrine disorders (diabetes, thyroid disease, gastrinoma, VIPoma )
• GI  bacterial or parasitic infections (Bacterial Overgrowth, Giardia, Entamoeba histolytica, Yersinia, Strongyloides)
• Medications (laxatives, Mg-containing antacids)

Lab:  CBC, glucose, BUN, Creat, liver enzymes, amylase, protein, calcium, stool exam, etc.  Sigmoidoscopy & Barium enema, UGI with Small Bowell Follow Through if not done before;  other diagnostic tests per clinical suspicion.

Management of IBS       

Educate & reassure the patient about the benign nature of the IBS, once the disgnosis is firm.  Stress management, anxiety & depression therapy if needed.
Repeated reassurance that the test results are normal often have considerable therapeutic benefit. Another important aspect in the management of the patient with IBS is the instillation of realistic expectations for long-term symptomatic improvement. This process of patient education and repeated reassurance may, in the long run, be the single most effective intervention the physician makes.

High fiber diet 30 g/day with adequate fluid intake.

Drug symptomatic therapy:

• For dominant diarrhea & incontinence:  Imodium (Loperamide) 2 mg 1-2 tab ac & prn; Lomotil (diphenoxylate 2.5 mg + atropine 0.025 mg) 1-2 tab qid prn;  Cholestyramine 1 scoop hs
  
• For dominant postprandial pain:  Anticholinergic, antispasmodic as
  Bentyl (dicyclomine) 10-20 mg 10-15 min ac;
  Pro-Banthine (Propantheline bromide) 7.5-15 mg.  Usual dose: 15 mg ac & 30 mg hs 
  Donnatal (phenobarbital 16.2 mg + hyoscyamine sulfate 0.10 mg + atropine sulfate 0.019 mg + scopolamine 0.0065 mg) tid; or Donnatal Extendtab = 3 Donnatal tabs
  Librax (chlordiazepoxide 5 mg + clidinium bromide 2.5 mg) 1 cap tid ac.
  Levsin ( Hyoscyamine sulfate)  or Levsin/SL 0.125 mg tab 1-2 tb q4h prn
  Levbid ( Hyoscyamine sulfate) 1 capsule (0.375 mg) q 8-12 h (each is equivalent to 3 Levsin tablets)
  Levsinex Timecaps (Hyoscyamine sulfate) 1 tablet (0.375 mg) q 8-12 h (each is equivalent to 3 Levsin tablets)
  
• For dominant chronic pain:  
  Tricyclic as Elavil (amitriptyline) 25-50 mg hs or Sinequan (Doxepin) 10-50 mg hs
  
• For dominant constipation:  
  bran, psyllium 1 tbsp tid with meals & prn; MOM 1-2 tbsp prn, Lactulose 1-2 tsp hs; Cisapride, 5 mg orally three times per day, increasing as necessary, may significantly improve the number and consistency of bowel movements and reduce complaints of abdominal pain and bloating [J Clin Gastroenterol 13:49-57, 1991 - Van Outryve M] 
  Zelnorm (Tegaserod) for women with IBS whose primary bowel Sx is constipation.   (Norvatis Pharmaceuticals)
  
• For gas (flatus):  Simethicone, Beano (beta-galactosidase)

* Among patients who had IBS without constipation, treatment with rifaximin at a dose of 550 mg, three times daily for 2 weeks provided significant relief of IBS symptoms, bloating, abdominal pain, and loose or watery stools.  
Significantly more patients in the rifaximin group than in the placebo group had adequate relief of global IBS symptoms during the first 4 weeks after treatment (40.8% vs. 31.2%)   N Engl J Med 2011; 364:22-32 January 6, 2011

The Effect of a Nonabsorbed Oral Antibiotic (Rifaximin) on the Symptoms of the Irritable Bowel Syndrome
Mark Pimentel, MD; Sandy Park, BA; James Mirocha; Sunanda V. Kane, MD; and Yuthana Kong, MPH
Annals of Internal Med 17 October 2006 | Volume 145 Issue 8 | Pages 557-563
Conclusions:   Rifaximin 400 mg 3 times daily for 10 days improves IBS symptoms for up to 10 weeks after the discontinuation of therapy.

2011