Chapter 7 FIG. 6. Pain from balloon distention of the pelvic colon in normal subjects and those with irritable colon syndrome (IBS). As illustrated, 55% of 67 patients with irritable colon syndrome reported pain with balloon distention -60 mL, whereas only 6% of 16 normal and constipated subjects (one subject) reported pain at a distending volume of 60 mL. At a distending volume of 100 to 150 mL, nine of 16 normals (56%) complained of pain, whereas approximately 90% of IBS patients reported pain. (Adapted from ref. 42.) Click here to see the graphic at a different resolution