Constipation (also known as costiveness, dyschezia, and dyssynergic defaecation) refers to bowel movements that are infrequent and/or hard to pass. Constipation is a common cause of painful defecation. Severe constipation includes obstipation (failure to pass stools or gas) and fecal impaction. Constipation is common; in the general population incidence of constipation varies from 2 to 30%. Constipation is a symptom with many causes. These causes are of two types: obstructed defecation and colonic slow transit (or hypomobility). About 50% of patients evaluated for constipation at tertiary referral hospitals have obstructed defecation...