Gastroenterology Expert Column
Diagnosing Irritable Bowel Syndrome: What's Too Much, What's Enough?
Posted 03/12/2004
Susan Lucak, MD
Introduction
Irritable bowel syndrome (IBS) is the most common gastrointestinal disorder diagnosed in clinical practice in the United States. Because there is no biological marker to confirm the diagnosis of IBS, it is a diagnosis that has challenged clinicians for decades. In the past, IBS was a "waste-basket" diagnosis given to patients with unexplained gastrointestinal symptoms. It was considered to be "the diagnosis of exclusion" when extensive work-up for organic disease yielded no diagnosis.
In recent decades, it was recognized that patients with IBS experienced a constellation of specific gastrointestinal symptoms. Manning criteria were described in 1978,[1] followed by Rome I in 1989[2] and Rome II criteria in 1999.[3] Rome I and Rome II criteria were initially developed by multinational working groups to provide a framework for the selection of patients in diagnostic and therapeutic trials. These criteria are being continuously modified as we gain new knowledge about functional bowel disorders.
Recently published diagnostic guidelines[4,5] recommend using symptom-based criteria in making the diagnosis of IBS in clinical practice. Using these criteria in conjunction with "alarm features" allows a physician to minimize the extent of diagnostic testing needed to make the diagnosis of IBS. Furthermore, recent systematic review of the literature indicates that performing a number of diagnostic tests did not result in a significant increase in the diagnosis of organic gastrointestinal disease.[6]
This column discusses novel approaches to the diagnosis of IBS."
""Alarm Features"
An important aspect of making the diagnosis of IBS is the absence of "red flag" or "alarm features" ( Table 2 ).[4,11,12] Unexplained weight loss may reflect disorders such as malignancy, inflammatory bowel disease (IBD), or celiac disease. Persistent diarrhea or severe constipation may be associated with an organic disease.
IBS is generally an intermittent and recurrent disorder. Symptoms of IBS tend to disappear at night when the patient is asleep. Thus, nocturnal gastrointestinal symptoms warrant search for a diagnosis other than IBS. The onset of new gastrointestinal symptoms after the age of 50 should prompt the physician to look for organic disease, particularly colorectal cancer. Blood in stool may reflect IBD or an infectious process or colon cancer. Family history of IBD, celiac disease, or gastrointestinal malignancy requires evaluation for these diseases. Fever suggests the possibility of an infectious or inflammatory disorder. Anemia should alert the physician to look for IBD or colorectal cancer. Signs of bowel obstruction, malabsorption, extraintestinal signs of IBD, or thyroid dysfunction should all prompt organic disease work-up. Any laboratory test abnormalities should be pursued appropriately. Absence of these "alarm features" serves to support, not establish, the diagnosis of IBS."
Summary and Conclusions
What's too much when we think about diagnosing IBS is to do exhaustive and duplicate testing. In a retrospective, community-based study in Olmsted County, Minnesota, two thirds of patients who consulted for gastrointestinal symptoms had to wait at least 2 years to have their IBS diagnosed, despite averaging nearly 5 healthcare visits per year.[20] Such an approach is not only costly and inefficient, but it delays treatment and fosters frustration on the part of the patient and the physician.
What's enough is to use symptom-based criteria, "alarm features," and guidelines proposed by the ACG IBS Task Force and the AGA Technical Review on IBS in making a more timely diagnosis of IBS. Although additional studies are necessary to validate Rome II criteria and to assess diagnostic testing in prospective studies, the expert guidelines allow the diagnosis of IBS to be made with greater efficiency, certainty, and confidence. Furthermore, once a diagnosis of IBS is made, it is retained in more than 93% of cases with a long-term follow-up. Considering legal aspects of IBS diagnosis, symptom-based criteria and guidelines set forth by the ACG and AGA are becoming key elements in establishing standard of care. It has become clear that the diagnosis of IBS can and should be made quickly so that treatment can be initiated as soon as possible. This promotes greater patient confidence in the physician."
Introduction
Epidemiology
Symptom-based Criteria
"Alarm Features"
Physical Examination
Diagnostic Testing
Differential Diagnosis and Durability of Diagnosis
Legal Risks in Diagnosing IBS
Summary and Conclusions
http://www.medscape.com/viewarticle/465760_1
Diagnosis, Pathophysiology, and Treatment of Irritable Bowel Syndrome
Diagnosis of IBS
Symptoms of IBS can be common to any number of gastrointestinal disorders. Abdominal pain, bloating, and diarrhea or constipation can easily generate an extensive list of potential diagnostic possibilities. To adopt an open-ended approach to diagnosis and to value all diagnostic possibilities equally has never been an effective approach in the diagnosis of IBS. However, with the development and validation of the Rome II criteria for the diagnosis of IBS, our approach to the diagnosis of this traditionally perplexing disorder is rapidly changing.
Diagnosing the patient with IBS should include 3 steps. First, determine whether the patient at first encounter meets the Rome diagnostic criteria for IBS. Second, conduct a history and physical examination looking for so-called "alarm factors." Third, perform diagnostic testing.
Diagnostic Criteria
The latest version of the Rome diagnostic criteria (Rome II) for IBS were first published in abbreviated form in 1999[7] and in full form in 2000.[8] See the Table below. The Rome criteria have been shown to be both sensitive and specific for the diagnosis of IBS[9] and can be used advantageously in clinical practice. If a patient presents with symptoms suggestive of IBS and epidemiologically fits the profile of a patient most likely to have IBS (ie, younger than 40 years of age and with typical symptoms), the Rome criteria can be used to validate the physician's initial impression. Starting with a "positive approach" to diagnosing IBS, as opposed to adopting a diagnosis of exclusion, sets the entire physician-patient encounter off in a positive and thoughtful direction. Providing the diagnostic framework presented by the Rome criteria gives the physician an intellectual basis for making an IBS diagnosis with confidence.[10]
History-Taking
The key to history-taking in a patient with suspected IBS is first and foremost to look for the presence of so-called "alarm factors." It is clear that the symptoms of IBS can be typical of many other structural disorders of the gastrointestinal tract. Diarrhea, abdominal bloating, and constipation can all represent an extraordinarily wide spectrum of gastrointestinal pathology. The challenge using the framework provided by the Rome II diagnostic criteria is to rapidly exclude the possibility of other disorders. The key is to look for symptoms in the history that are atypical of IBS and suggestive of other disorders. The list of so-called "alarm factors" can certainly be open to debate and discussion.
Physical Examination
After a patient history has been completed and the absence of "alarm factors" documented, a physical examination should always be performed. The physical examination should focus specifically on ruling out inflammatory bowel disease, colorectal or other gastrointestinal cancers, and malabsorption caused by luminal or pancreatic causes. Look for extraintestinal manifestations of inflammatory bowel disease, such as ophthalmic changes, Sicca syndrome, intraoral lesions (eg, aphthous ulcers), and skin or arthritic changes suggestive of inflammatory bowel disease. Likewise, signs of malabsorption, such as muscle wasting, nail or perioral changes, and weight loss should all be ruled out. Finally, the issue of colorectal cancer must be addressed. There is agreement in the functional bowel community that the best guide to help clarify this situation is to follow the colorectal cancer screening guidelines of the American Cancer Society. It is therefore recommended that patients 50 years of age or older who have never had a screening colonoscopy should have one performed as part of an IBS evaluation. Likewise, individuals 40 years of age or older who have a family history of colorectal cancer in a first-rank relative should also have a screening colonoscopy.[11] Finally, the use of sigmoidoscopy in individuals younger than 50 years old who have no family history is open to some discussion.[12]
Small bowel (to rule out Giardia or small bowel malabsorption) or colonic (to rule out microscopic colitis) biopsies may be indicated, particularly for patients with loose or watery stools.[13] These studies, although they include some diagnostic testing, may be considered part of the "physical examination" and initial evaluation of the patient with suspected IBS.
Diagnostic Testing
The use of diagnostic testing in IBS has become an increasingly controversial topic. Traditionally, the "diagnosis of exclusion" approach encouraged extensive diagnostic testing to evaluate patients with suspected IBS to rule out other possible causes of the disorder. Given the high prevalence of IBS , this approach has been subject to considerable scrutiny over the last 5 years.[10] Numerous studies have shown that the use of routine lactase hydrogen breath-testing for sugar malabsorption,[14] abdominal ultrasound,[15] routine computed tomography scanning, particularly in younger patients, and more esoteric tests, such as screening for acute intermittent porphyria[16] or thyroid testing for hyper- or hypothyroidism,[17] rarely yield data that change the diagnosis of IBS. Testing for bacterial overgrowth has been recently proposed by 1 group as a possible cause of IBS-like symptoms.[18] However, the article supporting the reasonableness of this approach studied a cohort of patients who were specifically referred by their treating physician to a tertiary center specializing in bacterial overgrowth. These patients were specifically referred to the tertiary center to rule out the possibility of bacterial overgrowth. However, given the selection bias in this study, the applicability of these data to the universe of IBS patients is open to some question. Based on the available literature, routine testing for bacterial overgrowth in patients with suspected IBS cannot be routinely recommended at this time.
One additional issue that is rapidly evolving in the area of IBS diagnosis is the issue of celiac disease. A number of studies have recently demonstrated a higher prevalence of celiac disease in the North American population than was previously thought, as well as a possible higher prevalence among patients with IBS-like symptoms.[19] This issue is yet to be completely resolved. It would therefore seem prudent for physicians who have patients with suspected IBS who have subtle signs or symptoms of celiac disease, such as osteoporosis in a premenopausal female or male, infertility, mild anemia, or weight loss, to evaluate the patient by obtaining celiac disease markers. Endoscopy with small bowel biopsy can confirm any equivocal serologic results.
Given these data, it would seem reasonable for the patient with IBS who presents absent alarm factors and who has a normal physical examination to have a complete blood count and chemistry panel and perhaps erythrocyte sedimentation rate measurement and thyroid function testing in the form of thyroid-stimulating hormone (TSH) levels. As noted above, in patients with diarrhea, additional initial investigation may be warranted, particularly investigation for the possibility of microscopic colitis and perhaps celiac disease.[17] For the majority of patients, this should end the initial evaluation. It is at this point that the physician should begin treatment and follow the patient prospectively. Failure to respond to reasonable treatment for IBS after a period of 2-4 weeks should certainly invite the physician to question the validity of IBS diagnosis and to consider additional evaluation as indicated. See the Figure below for a schematic that outlines this approach.
Of course recently they have published the rome lll criteria.
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My website on IBS is www.ibshealth.com
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