This test is employed in some patients who are suffering from chronic constipation. It provides an assessment of how well the food is passing through the colon. The patient is given capsules which contain markers visible on x-ray. A high fibre diet is also provided during the course of this procedure. 3-4 days after consuming capsules (Day 0), the movement of food is monitored via the markers (checked by multiple x-rays). It helps in evaluating pathologies which affect colonic motility.