Why does an ic patient often experience the ic belly. The generalized swelling of the lower abdomen

Not always. But ibs (irritable bowel syndrome) is strongly associated with ic. The good news is that it responds well to the same diet as ic. Aerobic exercise may help as well.
IC belly swelling. Ic is often associated in (especially female) patients with ulcerative colitis/"irritable bowel syndrome"/regional enteritis/....) the complete pathophysiology of ic is still not known - theorized that up to 10% of people in the general populace has some form/degree of ic......