Diagnostic approach to chronic constipation in adults.

Constipation is traditionally defined as three or fewer bowel movements per week. Risk factors for constipation include female sex, older age, inactivity, low caloric intake, low-fiber diet, low income, low educational level, and taking a large number of medications. Chronic constipation is classified as functional (primary) or secondary. Functional constipation can be divided into normal transit, slow transit, or outlet constipation. Possible causes of secondary chronic constipation include medication use, as well as medical conditions, such as hypothyroidism or irritable bowel syndrome. Frail older patients may present with nonspecific symptoms of constipation, such as delirium, anorexia, and functional decline. The evaluation of constipation includes a history and physical examination to rule out alarm signs and symptoms. These include evidence of bleeding, unintended weight loss, iron deficiency anemia, acute onset constipation in older patients, and rectal prolapse. Patients with one or more alarm signs or symptoms require prompt evaluation. Referral to a subspecialist for additional evaluation and diagnostic testing may be warranted.