Gastroenterology Consultants,SC: Diseases of the GI tract IRRITABLE BOWEL SYDNROME [<<back | list all>>] Irritable Bowl Syndrome (IBS), also known as spastic colon, spastic colitis, mucous colitis, and nervous or functional bowel, is mostly due to abnormal physiology. Typically, through rhythmic contractions, the colon quietly propels the stool from the right side of the colon to the rectum, where it is stored until it can be evacuated. However, when IBS occurs, the colon does not contract normally. The contractions may be disorganized, exaggerated, and last for prolonged periods of time. These abnormal contractions may result in a change of bowel habits, with constipation being the most common. They also cause abdominal pain and discomfort, which will usually move around rather than remain localized in one area. Diarrhea can occur, especially after meals. Air can also accumulate behind localized contractions causing the bowl to swell. These causes bloating and abdominal distress. Although mucous is a normal secretion of the bowel, gobs of mucous in the stool may be seen. This is not, however, a serious problem.