- Evidence of structural abnormality of the gastrointestinal tract or diseases/conditions that affect bowel transit including gastric, small bowel or colonic resection (appendectomy, cholecystectomy, benign polypectomy are allowed); history of colon cancer, history of inflammatory bowel disease (Crohn's disease or ulcerative colitis); insulin-dependent diabetes mellitus, history of Hirschsprung's disease, progressive systemic sclerosis (scleroderma), anorexia nervosa; other diseases or conditions that in the opinion of the investigator significantly affect bowel transit. Subjects with constipation secondary to any other documented cause.