Diagnosing Irritable Bowel Syndrome: What's Too Much, What's Enough?

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http://www.medscape.com/viewarticle/465760?mpid=26286

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. ... 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.

.... Some physicians who see patients with IBS are concerned about the risk

of malpractice. Feld[21] recently described sources of risk under which

physicians may be sued, including negligence, duty to provide care to a

patient, and medical practice below standard of care, among others. But

the idea that more testing is better in IBS may not always be the case. For

example, colonoscopy leads to a change in diagnosis about 1% to 2% of the

time and may represent performance of substandard care based on testing

guidelines for IBS diagnosis recommended by gastroenterological associations

in the United States. Therefore, any complication resulting from

" unnecessary " testing may expose a physician to a malpractice suit.

Alternatively, if a physician explains to a patient why only limited testing

is necessary, this allows a patient to participate in the process and

understand inherent uncertainties and thus share in the responsibility when

a reasonable decision results in an adverse outcome.[21] ...

.... Table 6. Differential Diagnosis of IBS[15]

IBS with diarrhea

Dietary - lactose, sorbitol, fructose, caffeine, alcohol, fatty foods, fat

substitutes, gas-producing foods

Infections ­ Giardia spp, Amoeba spp, HIV-related, bacterial overgrowth

IBD ­ Crohn's disease, ulcerative colitis, microscopic colitis

Drug toxicity ­ antibiotics, proton pump inhibitors, nonsteroidal

anti-inflammatory drugs, ACE inhibitors, beta-blockers, chemotherapy

Malabsorption ­ celiac disease, bile acid-related

Other ­ ovarian cancer, endometriosis, colorectal cancer, hyperthyroidism,

carcinoid, VIPoma, ischemic colitis

IBS with constipation

Dietary/mode of life ­ inadequate fiber, immobility

Neurologic ­ Parkinson's disease, multiple sclerosis, spinal cord injuries

Endocrine ­ diabetes, hypothyroidism, hypercalcemia

Drug toxicity ­ opiate analgesics, calcium-channel blockers,

antidepressants, clonidine

Other ­ colorectal cancer, ovarian cancer, bowel obstruction, diverticular

disease, endometriosis

ACE, angiotensin-converting enzyme; HIV, human immunodeficiency virus; IBD,

inflammatory bowel disease; VIPoma, vasoactive intestinal polypeptide