[Constipation: Initial evaluation and diagnostic approach].

Constipation is a common gastrointestinal symptom and affects about 20% of the general population. This symptom can reflect a vast array of problems, from inadequate fiber intake to colonic dismotility function. Identifying chronic constipation subtypes on underlying physiology guides the therapeutic choices. Chronic constipation subtypes includes: slow-transit constipation, functional constipation, irritable bowel syndrome with constipation predominance and pelvic floor dysfunction. The most useful tests for the evaluation of those patients are the colonic transit time with radiopaque markers and anorrectal manometry with balloon expulsion test. Patients with both normal tests have either functional constipation or irritable bowel syndrome with constipation. Subjects with a delayed colonic transit and normal anorectal manometry maybe classified as colonic inertia. Pelvic floor dysfunction maybe suspected if the patient had an abnormal manometry with failure to expulse de balloon. Initial treatments of chronic constipation are dietary fiber and medicinal bulk. Subsequent treatments if fiber is not successful or tolerated would include saline osmotic laxatives such as lactulose and polyethylene glycol, or stimulants like senna or bisacodyl. For patients with pelvic floor dyssynergia biofeedback therapy is the first therapeutic option. In this article we present an overview of current diagnostic tools for patients with chronic constipation.