Hospital Medicine

Irritable Bowel Syndrome

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Irritable Bowel Syndrome

I. What every physician needs to know.

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder. It is a disorder that may cause abdominal bloating, gassiness, crampy abdominal pain, diarrhea (IBS-D), constipation (IBS-C), alternating constipation and diarrhea, mucousy stools, and fecal urgency. Individuals feel the need to defecate immediately following a bowel movement. Although many patients experience a great deal of pain and distress from their symptoms IBS is considered a functional disorder because there are no specific signs of physical disease when the colon is examined. IBS is also referred to as functional bowel syndrome, irritable colon, spastic bowel, and spastic colon.

IBS is believed to at least partially be a disorder of colon motility. The dysmotility results in an aberration in the digestion and propulsion of solids and fluids within the colon. Patients with IBS have colonic over-sensitivity and over-reactivity to the neuromuscular stimuli and events that occur within the GI tract. When propulsion of the intestinal contents is impaired it can lead to abdominal pain and spasms.

There are many triggers that cause IBS symptoms including eating, abdominal distension from gas or colon contents, certain medications, certain foods (typically spicy, processed, or fatty foods), and menses (for females). Rapid transit and/or decreased proteolytic degradation of fecal serine proteases (FSPs) may contribute to visceral hypersensitivity in patients with IBS-D. Emotional stress is also felt to play a role in IBS. It is hypothesized that stress stimulates colonic spasm which results in the various IBS symptoms.

In general, women are more commonly affected with IBS than males. The overall symptom profiles are characterized by an approximately equal occurrence of isolated diarrhea and isolated constipation (each ~25% of the time) and alternating diarrhea and constipation ~45% of the time. Over half of all patients consult their primary care provider for their symptoms (often multiple times) and ~15% of patients are referred to a specialist.

II. Diagnostic Confirmation: Are you sure your patient has Irritable Bowel Syndrome?

IBS is a diagnosis of exclusion. The key to establishing the diagnosis is to perform a thorough history and physical exam as well as to obtain both screening laboratory and radiological studies. The absence of hard findings for infection, inflammation, and structural abnormalities combined with the patient's history and physical exam will aid in the diagnosis.

According to the Rome III diagnostic* criteria IBS is characterized by recurrent abdominal pain or discomfort at least 3 days per month in the last 3 months associated with 2 or more of the following: 1) Improvement with defecation, 2) Onset associated with a change in frequency of stool, 3) Onset associated with a change in form (appearance) of stool.

* The Rome criteria is a system developed to classify the functional gastrointestinal disorders in which symptoms cannot be explained by the presence of structural or tissue abnormalities.

A. History Part I: Pattern Recognition:

Patients with IBS typically present with abdominal pain and cramping. The pain can be located in the upper quadrants (right and/or left) of the abdomen or it can be diffuse in nature. Patients often have a difficult time describing the pain quality. The timing of the pain is often telling in that it frequently occurs after eating. Some individuals often have fecal urgency within 20 minutes of eating especially if the meal consumed was high in fat and/or highly processed. Fecal content may include undigested food in this scenario.

Patients may also present with a history of constipation, diarrhea, or alternating constipation and diarrhea. The stools may be mixed with mucous. If the patient has diarrhea it is not accompanied by bloody stools, fever, weight loss, or persistent abdominal pain. The patient is not awakened from their sleep to have a bowel movement. This pearl will help distinguish organic diarrhea (e.g., Inflammatory bowel disease (IBD) or infectious diarrhea) from secretory diarrhea.

IBS may cause abdominal bloating and gassiness. These symptoms may occur after eating and may be confused with gallbladder disease if the patient complains about right upper quadrant abdominal pain as well. Eliciting the quality of the pain may distinguish between these two entities as cholestatic pain is typically more sharp and intense. Many IBS patients will describe their abdominal pain as a pressure or band reaching across the right and left upper abdominal quadrants. Patients with IBS typically don't have accompanying nausea.

Red flag considerations should include weight loss, gastrointestinal bleeding, anemia, and nocturnal symptoms.

B. History Part 2: Prevalence:

The prevalence of IBS is estimated to be ~ 10-15% in Western countries. Females are between 2- 3.2 times more likely to be affected than males, and whites 5.3 times more than black individuals. Patients between the ages of 45-64 years were most affected. The typical patient tends to be white, female, educated, approximately 44 years of age, married, employed, and has had symptoms for greater than 1 year.

The incidence of IBS is higher in individuals who have chronic fatigue syndrome, depression, fibromyalgia, and those individual who are under significant stress in their lives. IBS accounts for approximately 12% of primary care visits and 28% of referrals to gastroenterologists.

C. History Part 3: Competing diagnoses that can mimic Irritable Bowel Syndrome.

A variety of diseases and symptom complexes can mimic IBS. For example, patients who have lactose intolerance, celiac sprue disease, IBD, thyroid disorders (hypo and hyper), and infections of the colon (Giardia, bacterial, viral) can all feature abnormal defecation and abdominal pain. Colon cancer should be considered in those patients who fit the demographic profile and/or have a family history of colon cancer. Other diagnosis that can mimic IBS include abdominal angina, chronic mesenteric ischemia, biliary disease, food allergies, anxiety disorders, carcinoid syndrome, lead toxicity, endometriosis, collagenous and lymphocytic colitis, and bacterial overgrowth.

IBS is quite common and therefore, it is not cost effective to routinely test suspected (IBS) patients for all of the above diseases. It is prudent to rule out only the more common diseases when testing is necessary to establish the diagnosis. Furthermore, if a patient has one of the more serious diagnoses the symptom complex and physical exam should eliminate IBS from the differential.

D. Physical Examination Findings.

Patients with IBS will have a normal abdominal and pelvic exam (females). Vital signs are stable. The bowel sounds may vary depending on whether the patient has constipation (bowel sounds may be hypoactive) or diarrhea (bowel sounds may be hyperactive). The rectal exam may reveal rectal irritation, hemorrhoids, and/or heme-positive stools as a result of either constipation (when the stools are hard) and/or diarrhea.

E. What diagnostic tests should be performed?

Laboratory studies should include a CBC and ESR to assess for inflammation, infection, and anemia. A thyroid test and comprehensive metabolic profile are also useful to rule out metabolic problems, dehydration, elevated liver enzymes, and electrolyte abnormalities. Testing for celiac sprue disease should be considered as presentations may be quite similar. It is recommended to start with tissue transglutaminase Ab IGA. If positive, biopsy should be pursued. If negative, and there is a high clinical suspicion, further serologic testing with a total IgA level, a tissue transglutaminase IgG serum, IgA anti-gliadin, IgG anti-gliadin, and endomysial antibodies may be pursued.

Hemoccult testing should be obtained to rule out a GI bleed. If additional colon testing is required, then a colonoscopy may be obtained to rule out IBD and other abnormalities such as lymphocytic or collagenous colitis and/or colon cancer (especially if the patient is over 50 years of age or has a first degree relative with a history of colon cancer).

If a patient has significant diarrhea, microbiologic studies can be obtained to rule out infectious etiologies. In this case stool specimens should be obtained for ova and parasites (to rule out Giardiasis), culture and sensitivity (to rule out enteric pathogens), leukocytes (which will suggest an inflammatory and/or infectious process), and Clostridium difficile toxin.

1. What laboratory studies (if any) should be ordered to help establish the diagnosis? How should the results be interpreted?

Laboratory studies should include a CBC and ESR to assess for inflammation, infection, and anemia. A thyroid test, magnesium level, and comprehensive metabolic profile are also useful to rule out metabolic problems, dehydration, elevated liver enzymes, and electrolyte abnormalities. As stated above a tissue transglutaminase IgA antibody can be checked to evaluate for celiac sprue. If negative, and depending on clinical suspicion, Serum IgA anti-gliadin, IgG anti-gliadin, and endomysial antibodies (EMA) can also be obtained for those patients presenting with significant diarrhea in whom there is a high concern for celiac disease. These studies will not establish a diagnosis of IBS but rather rule out other causes of the patient’s symptoms. The blood work will also assess for sequelae resulting from diarrhea (such as dehydration or electrolyte abnormalities).

2. What imaging studies (if any) should be ordered to help establish the diagnosis? How should the results be interpreted?

Although imaging studies aren’t necessary to establish a diagnosis of IBS they may be useful to eliminate other diagnostic considerations. For example, a flat plate abdominal XR will assess for a bowel obstruction as well as evaluate the amount of stool within the colon. An Upper GI with Small Bowel Follow Through will help to establish the diagnosis of Celiac Sprue, or IBD (Gastric and/or duodenal Crohn’s Disease). It will also assess for obstruction and inflammation. An abdominal computed tomography (CT) will screen for tumors, obstruction and pancreatic disease. A Gallbladder ultrasound will screen for cholestatic disease.

F. Over-utilized or “wasted” diagnostic tests associated with this diagnosis.

An abdominal CT is often ordered to assess patients for IBS although it is not warranted in the majority of cases. In addition, colonoscopy may be over-performed to establish the diagnosis.

III. Default Management.

Rule out acute life threatening etiologies for the patient’s presenting symptoms (e.g.. abdominal angina, mesenteric ischemia, etc.) by performing a thorough history and physical exam. Fluid resuscitation, electrolyte replacement, pain management, and diarrheal control are typically the mainstays of therapy (depending upon the patient’s presenting symptoms and signs).

A. Immediate management.

The primary focus of treatment should be based upon the patient’s presenting symptoms and physical findings. For example, fluid resuscitation should be initiated for dehydrated patients. If the patient has an electrolyte abnormality (e.g., hypokalemia, hypomagnesemia) then it must be treated accordingly to avoid such problems as a cardiac arrhythmia.

If the patient has significant abdominal pain and a surgical cause has been ruled out then anti-spasmodics (e.g., anticholinergics such as hyoscyamine or dicyclomine) may be prescribed. In some cases, antidiarrheals (e.g., loperamide, codeine, diphenoxylate) may be indicated. When patients are severely constipated serotonin (5-HT) agonists can be administered to stimulate gut motility. Lubiprostone can also be used for constipation predominant IBS. It is a prostaglandin E1 derivative that acts specifically by activating chloride channels which result in chloride-rich secretions within the bowel, softening the stool and increasing motility.

B. Physical Examination Tips to Guide Management.

The hospitalized patient’s hydration status should be monitored (vital signs, daily weight, urinary output, skin turgor, mucous membranes), as well as cardiac exam (e.g., for arrhythmia) and abdominal exam (e.g., assessing bowel sounds, tenderness, rigidity, etc.). Stool frequency should also be monitored.

C. Laboratory Tests to Monitor Response To, and Adjustments in, Management.

The patient’s electrolytes and renal functions should be monitored if the patient has an electrolyte abnormality or is dehydrated. These laboratories may be monitored until resolution depending on the severity.

D. Long-term management.

Long-term management of IBS is multifaceted. It involves prevention of the most common symptoms (constipation and diarrhea) by placing the patient on a high fiber diet, with copious amounts of water. If additional fiber is needed the patient should be guided to purchase over the counter soluble fiber supplements. Occasionally, a patient may require a laxative (not on a regular basis) or stool softener as well.

Utilization of probiotics may also be considered as they have beneficial effects on factors implicated in IBS pathophysiology such as dysmotility and visceral hypersensitivity. Global IBS, abdominal pain, bloating, and flatulence scores have improved with probiotic administration. However, if probiotics are utilized, particular caution is recommended for patients with immunodeficiency, acute pancreatitis, or central lines.

The patient should also avoid known triggers such as stressful situations or eating processed or fatty foods. Caffeine, chocolate, soda, and sugar-free sweeteners may also trigger symptoms. One controlled, cross-over study indicated symptom relief from bloating, abdominal pain, and flatus when a diet low in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) is utilized. If underlying stress is a significant trigger consideration should be given to both anxiolytic and antidepressant medications. A referral to a psychotherapist for behavioral therapy may also be indicated.

When patients have a flare a CBC and comprehensive metabolic profile may be beneficial. For constipated patients a flat plate of the abdomen may be useful to assess stool load in the colon.

Dietary consultation should be ordered during the hospitalization to both educate and guide the patient regarding food choices, eating frequency, and the avoidance of triggers.

E. Common Pitfalls and Side-Effects of Management.

Although IBS is the most common functional gastrointestinal disorder in the world it may be easily overlooked. Failure to diagnosis IBS can lead to unwarranted tests which are expensive (e.g., abdominal CT scan) and and/or unnecessary procedures which carry potential risk to the patient (e.g., colonoscopy). Furthermore, failure to identify IBS may result in unnecessary abdominal and/or extra-abdominal surgery such as cholecystectomy, appendectomy, and hysterectomy.

For patients properly diagnosed with IBS, common management pitfalls include not treating the patient’s symptom complex. Approaching the syndrome as psychosomatic, aggressively introducing fiber at the onset of therapy, and insufficient emphasis on water intake may result in continued symptoms.

The use of opioids is controversial due to the lack of evidence supporting their benefit and the potential risk of tolerance, physical dependence, and addiction.

IV. Management with Co-Morbidities.

Patients who experience depression and/or anxiety along with IBS (constipation predominant) can be effectively treated with SSRIs. If IBS patients suffer from lactose intolerance dairy products should be restricted or eliminated from the diet. For patients suffering from excessive flatulence or bloating it may be prudent to avoid gas-producing foods such as beans, cabbage, onions, brussels sprouts, cauliflower, and broccoli. In addition bread, apples, peaches, pears, prunes, corn, oats, potatoes, milk, ice cream, and soft cheese may also cause this problem.

In IBS patients with adult onset diabetes mellitus, metformin may be a good choice to control hyperglycemia for constipation-dominant symptoms but not for patients who suffer from diarrhea and/or bloating. In addition, medications that slow transit time should be avoided in diabetic patients suspected of having gastroparesis.

In constipation dominant IBS verapamil should be avoided for treatment of hypertension, angina, or arrhythmias.

In those patients with depression or other psychiatric diseases carefully select SSRIs, tricyclics, and antipsychotic based upon the presenting symptoms.

A. Renal Insufficiency.

No change in standard management.

B. Liver Insufficiency.

No change in standard management.

C. Systolic and Diastolic Heart Failure.

In dehydrated IBS patients watch the use of diuretics.

D. Coronary Artery Disease or Peripheral Vascular Disease.

In constipation dominant IBS verapamil should be avoided for treatment of hypertension, angina, or arrhythmias.

E. Diabetes or other Endocrine issues.

In IBS patients with adult onset diabetes mellitus metformin may be a good choice to control hyperglycemia for constipation-dominant symptoms but not for patients who suffer from diarrhea and/or bloating. In addition, medications that slow transit time should be avoided in diabetic patients suspected of having gastroparesis.

F. Malignancy.

No change in standard management.

G. Immunosuppression (HIV, chronic steroids, etc).

No change in standard management but particular vigilance is required for patients on probiotics.

H. Primary Lung Disease (COPD, Asthma, ILD).

No change in standard management.

I. Gastrointestinal or Nutrition Issues.

No change in standard management.

J. Hematologic or Coagulation Issues.

No change in standard management.

K. Dementia or Psychiatric Illness/Treatment.

In those patients with depression or other psychiatric diseases carefully select SSRIs, tricyclics, and antipsychotic based upon the presenting symptoms.

V. Transitions of Care.

A. Sign-out considerations While Hospitalized.

Follow hydration and electrolyte status and consider oral or IV replacement depending upon the patient’s symptoms. Continue to follow the patient’s stool chart and initiate medications (e.g., loperamide ) if the stool culture comes back negative.

Slowly progress diet as tolerated if the patient’s abdominal pain subsides and monitor stool pattern.

B. Anticipated Length of Stay.

24-48 hours.

C. When is the Patient Ready for Discharge.

The patient may be discharged after the correction of underlying problems (e.g., dehydration, electrolyte abnormalities, etc.,) and when tolerating p.o. fluids and solids.

D. Arranging for Clinic Follow-up.

1. When should clinic follow up be arranged and with whom.

Follow up with PCP within 2-4 weeks.

2. What tests should be conducted prior to discharge to enable best clinic first visit.


3. What tests should be ordered as an outpatient prior to, or on the day of, the clinic visit.

A basic metabolic profile (if an electrolyte abnormality exists).

E. Placement Considerations.


F. Prognosis and Patient Counseling.

The progress for IBS patients is very good as there are no known structural sequelae. The prognosis is improved for patients who are educated and counseled about their condition. Counseling should focus on proper diet, lifestyle modifications, avoidance of triggers, and stress management. Compliance with the treatment plan is the key to symptom control. This should be emphasized with the patient.

VI. Patient Safety and Quality Measures.

A. Core Indicator Standards and Documentation.


B. Appropriate Prophylaxis and Other Measures to Prevent Readmission.

Adherence to the treatment plan should prevent readmission into the hospital. This includes following a high fiber diet, drinking copious amounts of water, avoiding known triggers, and exercising regularly to decrease underlying stress and stimulate bowel activity. Utilization of healthcare professionals such as a dietician and/or psychotherapist may be instrumental in avoiding recurrent hospitalization.

VII. What's the evidence?

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Gibson, PR, Varney, J, Malakar, S, Muir, JG.. "Food components and irritable bowel syndrome". Gastroenterology. vol. 148. 2015. pp. 1158-1174.

Shanahan, F, Quigley, EMM. "Manipulation of the microbiota for treatment of IBS and IBD - challenges and controversies". Gastroenterology. vol. 146. 2014. pp. 1554-1563.

Ford, AC. "Efficacy of prebiotics, probiotics, and synbiotics in irritable bowel syndrome and chronic idiopathic constipation: systematic review and meta-analysis". Am J Gastroenterol. vol. 109. 2014. pp. 1547-1561.

Roberts, LM, McCahon, D, Holder, R, Wilson, S, Hobbs, FD. "A randomised controlled trial of a probiotic 'functional food' in the management of irritable bowel syndrome". BMC Gastroenterol. vol. 13. 2013 Mar 7. pp. 45.

Halmos, EP, Power, VA, Shepherd, SJ, Gibson, PR, Muir, JG.. "A diet low in FODMAPs reduces symptoms of irritable bowel syndrome". Gastroenterology. vol. 146. 2014 Jan. pp. 67-75.e5.

Ford, AC, Bercik, P, Morgan, DG, Bolino, C. "Validation of the Rome III criteria for the diagnosis of irritable bowel syndrome in secondary care". Gastroenterology. vol. 145. 2013 Dec. pp. 1262-70.e1.

Quigley, EM, Abdel-Hamid, H, Barbara, G, Bhatia, SJ. "A global perspective on irritable bowel syndrome: a consensus statement of the World Gastroenterology Organisation Summit Task Force on irritable bowel syndrome". J Clin Gastroenterol. vol. 46. 2012 May-Jun. pp. 356-66.

Ahn, JY, Lee, KH, Choi, CH, Kim, JW. "Colonic mucosal immune activity in irritable bowel syndrome: comparison with healthy controls and patients with ulcerative colitis". Dig Dis Sci.. vol. 59. 2014 May. pp. 1001-11.

Tooth, D, Garsed, K, Singh, G, Marciani, L. "Characterisation of faecal protease activity in irritable bowel syndrome with diarrhoea: origin and effect of gut transit". Gut.. vol. 63. 2014 May. pp. 753-60.

Rubio-Tapia, A, Hill, ID, Kelly, CP, Calderwood, AH, Murray, JA.. "ACG clinical guidelines: diagnosis and management of celiac disease". Am J Gastroenterol. vol. 108. 2013 May. pp. 656-76.

Irritable Bowel Syndrome. New York Presbyterian Hospital.

Sanders, DS. "Association of adult coeliac disease with irritable bowel syndrome: a case-controlled study in patients fulfilling the ROME II criteria referred to secondary care". The Lancet. vol. 358. 3 November 2001. pp. 1504-1508.

Pace, F. "Inflammatory bowel disease versus irritable bowel syndrome: a hospital-based, case-control study of disease impact on quality of life". Scand J Gastroenterol.. vol. 38. 2003 October. pp. 1031-8.

ROME III Disorders and Criteria. ROME foundation.

Piche, T. "Low risk of irritable bowel syndrome after Clostridium difficile infection". Can J Gasroenterol.. vol. 21. 2007 November. pp. 727-731.

Lehrer, JK, Lichtenstein, GR.. "Irritable bowel syndrome: Differential diagnosis and workup". eMedicine Gastroenterology. 2009 August.

Hadley, SK, Gaarder, SM.. "treatment of irritable bowel syndrome". Am Fam Physician. vol. 72. 2005 December. pp. 2501-2506.

Schmulson, MW, Chang, L.. "Diagnostic approach to the patient with irritable bowel syndrome". Am. J. Med.. vol. 107. 1999 November. pp. 20S-26S.

Holten, KB, Wetherington, A, Bankston, L.. "Diagnosing the patient with abdominal pain and altered bowel habits: is it irritable bowel syndrome?". Am Fam Physician. vol. 67. 2003 May. pp. 2157-2162.

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