Mayo Clinic doctors start with a thorough 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, to assess the functioning of your digestive system. It's important to find the source of your problem so that your symptoms can be managed.
The type of tests depends on whether your IBS involves constipation or diarrhea.
Tests for IBS with constipation
- Gastrointestinal transit study (scintigraphy)
- Anorectal testing
- Defecating proctogram (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 intolerance without celiac disease, lactose and sugar intolerance, and bile acid malabsorption
- Colonoscopy and sigmoidoscopy with tissue sample testing (biopsy) to screen for microscopic colitis and colon cancer
- Ultrasound to screen for weakness in the sphincter (anal muscle), which can cause incontinence
Read more about celiac disease diagnosis, constipation diagnosis and microscopic colitis diagnosis.