As oulined elsewhere, it is vital to exclude organic causes of ODS, so all patients need:

I. Flexible Sigmoidoscopy / colonoscopy [preferably Colonoscopy]
II. Pelvic US in ladies [preferably abdominal & pelvic US or even CT]

These are ordered during the initial consultation. Patients should be educated about the cause of their symptoms at the initial consultation as well and given advice regarding management. There is no need to order anorectal physiology testing in patients with seemingly mild symptoms, at least at this stage. On the other hand, it is wise to arrange these tests in patients with moderate to severe ODS, since full explanation of the factors contributing to their symptoms is essential and also because patients may become candidates for surgery.

• III. Proctography (Defaecography)
  • - Contrast proctography [preferably with simultaneous small bowel & bladder contrast]
    - MRI proctography
• IV. Anorectal physiology ± colonic transit

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Finally, one may consider laparoscopy combined with an examination under anaesthesia as a final diagnostic investigation in patients undergoing surgery, to make the final decision on the appropriate surgical treatment.

Imaging & physiology are discussed in a different web page