The diagnostic criteria for chronic constipation in the Rome III criteria: In the past 12 months, persistent or cumulative for at least 12 weeks with 2 or more of the following symptoms: 1. at least one of the 4 bowel movements is excessive straining 2. at least one of the 4 bowel movements feels poorly evacuated 3. at least one of the 4 bowel movements is hard or granular 4. at least one of the 4 bowel movements has a feeling of anorectal obstruction or blockage 5. at least one of the 4 bowel movements requires manual assistance 6. less than 3 bowel movements per week and a daily bowel movement of less than 35 grams 7. no dilute stool and does not meet the diagnostic criteria for IBS.