When fiber is not enough: current thinking on constipation management.

Constipation is a common disorder and many patients fail to respond to the simple constipation remedies of increased fiber and fluid intake. When secondary to other conditions, medications, or disease processes, the focus of constipation management is correction of causative factors. However, primary constipation - ie, constipation with no identifiable causative factor - is very common. Patients generally present with one of three patterns: constipation-predominant irritable bowel syndrome, slow transit constipation, or pelvic floor dysfunction resulting in dyssynergic defecation. Baseline evaluation for patients with chronic constipation includes a careful history, focused physical examination, and limited laboratory studies. Patients with dyssynergic defecation usually respond best to biofeedback therapy and pelvic muscle re-education. Constipation-predominant irritable bowel syndrome is best managed with dietary monitoring and modifications, fiber therapy, and education regarding self-monitoring and self-care. Patients with slow transit constipation may benefit from fiber therapy and increased activity, but most also will require laxative therapy. Current guidelines for prescribing laxatives suggest bulk agents as first line and osmotic agents as second line therapy. Stimulant laxatives should generally be reserved for PRN use. Current understanding about the etiology, pathology, and classification of different types of constipation are summarized and a stepwise approach to evaluation and management is presented.