• The SHAPE method is most commonly used to measure colonic transit is that of radiopaque markers (SHAPE study).
• The test is reproducible and can be recommended for any patient in whom constipation is a major symptom.
• It should be remembered that rectal distention by retained stools can slow colonic transit, and severely constipated patients should have laxatives and/or enemas to empty the colon before a study of transit.
• Patient takes one SITZMARKS capsule (each capsule contains 24 markers) on day 0 by mouth with water. X-ray on day 5.
• For this examination to be successful, it is very important that laxatives or purgatives or prokinetic are not taken after taking the markers and until the abdominal X-ray has been taken.
• Patients who expel at least 80% (19 or more) markers have grossly normal colonic transit. If remaining markers are scattered about the colon, the condition is most likely hypomotility or colonic inertia.
• If more than 20% of the rings are counted on the x-ray, delayed colonic transit is present. In pelvic dyssnergia- the markers may concentrate on the left colon or rectosigmoid junction. However 2/3 of pts with pelvic dyssnergia will have markers retained throughout the colon. Also 1/3rd of pts with pelvic dyssergia may have normal SHAPE study.

Ref

1. http://www.ucl.ac.uk (archived copy at WebCite)