- 2. Subjects must report having constipation and fulfill Rome III criteria19 for chronic constipation: at least 3 months, in the last 6 months with two or more of the following: i. Less than 3 SBM's per week ii. Straining with defecation more than 25% of the time iii. Lumpy or hard stools with defecation more than 25% of the time iv. Sensation of incomplete evacuation with defecation more than 25% of the time v. Sensation of anorectal obstruction or blockage with defecation more than 25% of the time vi. Use of manual maneuvers to facilitate defecation more than 25% of the time