Irritable bowel syndrome
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Synopsis

IBS is a diagnosis of exclusion, as it has no histologic phenotype and no sensitive or specific laboratory tests. However, recent American College of Gastroenterology guidelines recommend a diagnostic testing strategy to expedite the time of diagnosis, decreasing delays in treatment (see References section).
Rome III diagnostic criteria require recurrent abdominal pain at least 1 day per week over 3 months, associated with 2 of the following:
- Pain related to defecation
- Change in frequency of stool (constipation or diarrhea)
- Change in appearance of stool
- Onset of pain linked to more frequent bowel movements
- Looser stools associated with the onset of pain
- Pain relieved by passage of stool
- Noticeable abdominal bloating
- Sensation of incomplete evacuation more than 25% of the time
- Diarrhea with mucus more than 25% of the time
- IBS with constipation – Hard / lumpy stools > 25% and loose / watery stools < 25%
- IBS with diarrhea – Loose / watery stools > 25% and hard / lumpy stools < 5%
- Mixed IBS – Hard / lumpy stools > 25% and loose / watery stools > 25%
- Un-subtyped IBS – No consistent pattern of stool abnormality
Codes
ICD10CM:K58.9 – Irritable bowel syndrome without diarrhea
SNOMEDCT:
10743008 – Irritable Bowel Syndrome
Look For
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Chronic pancreatitis
- Inflammatory bowel disease (ulcerative colitis, Crohn disease)
- Bile acid diarrhea
- Microscopic colitis
- Celiac disease
- Hypothyroidism
- Hyperthyroidism
- Viral or bacterial gastroenteritis
- Lactose or fructose intolerance
- Small intestinal bacterial overgrowth
- Whipple disease
- Tropical sprue
- Acute coronary syndrome
- Coronary artery disease
- Gastritis
- Mesenteric ischemia
- Ischemic colitis
- Malignancy (particularly gastric, small bowel, pancreatic, colonic, ovarian)
- Zollinger-Ellison syndrome
- Chronic hepatitis (eg, hepatitis B, hepatitis C, or autoimmune hepatitis)
- Nephrolithiasis
- Liver abscess (pyogenic, amebic)
- Drug side effects (NSAIDs, alcohol, caffeine, antibiotics, corticosteroids, opiates, digoxin; see drug-induced constipation and drug-induced diarrhea)
- Uterine fibroids (leiomyoma)
- Endometriosis / adenomyosis
- Hypercalcemia
Best Tests
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Management Pearls
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Therapy
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References
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Last Reviewed:10/31/2017
Last Updated:02/04/2021
Last Updated:02/04/2021