Individuals with chronic constipation or functional constipation have two or more of the following more than 25% of the time for at least 6 months: straining, lumpy or hard stools, feeling of incompletely evacuating after a bowel movement, feeling that a bowel movement is blocked, having to press around the anal opening to help a bowel movement pass, and fewer than three bowel movements per week. Chronic constipation may be caused by the slow movement of food through the colon, known as slow transit constipation, and/or problems with the passing of stool once it reaches the rectum, known as outlet dysfunction or pelvic floor dysfunction (dyssynergic defecation). An x-ray may be helpful to evaluate the amount of stool within the colon. A sitzmark study can evaluate for slow transit constipation by measuring the time it takes for stool to travel through the colon. Also, anorectal manometry can help in diagnosing pelvic floor dysfunction. Finally, with increased use of opioids the entity of opioid induced constipation needs to be considered diagnostically and in terms of treatment.