Diagnosis at Mayo Clinic

By Mayo Clinic Staff


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Mayo Clinic doctors start with a physical exam and medical history, and often colonoscopy to exclude colon cancer. After that, Mayo specialists use several tests, some of them developed at Mayo Clinic, to assess the functioning of your digestive system. The types of tests depend on whether your IBS involves constipation or diarrhea.

Doctors may want to rule out any of the following conditions, depending on your symptoms and your initial evaluation:

  • Slow transit constipation — severe constipation caused by abdominal muscles or nerves that don't work normally
  • Pelvic floor dysfunction — severe constipation caused by anal muscles that don't work normally
  • Microscopic colitis
  • Mechanical bowel obstruction
  • Systemic disease, including celiac disease, hypothyroidism, diabetes and hypercalcemia

Tests for IBS with constipation

  • Gastrointestinal transit study (scintigraphy)
  • Anorectal function testing
  • Defecating proctogram
  • Dynamic pelvic floor MRI
  • Colonic motility test, if constipation is difficult to control

Tests for IBS with diarrhea

  • Laboratory tests (blood, breath and stool) to screen for celiac disease, gluten sensitivity without celiac disease, bacterial overgrowth, lactose and sugar intolerance, and bile acid malabsorption
  • Colonoscopy and sigmoidoscopy with tissue sample testing (biopsy) to screen for microscopic colitis and colon cancer
July 31, 2014