Etiology

Functional

Sedentary lifestyle or prolonged immobilization

Low-fiber diet

Low fluid intake

Poor bowel habits, including ignoring the urge to defecate

Pregnancy

Medications

Anticholinergics

Antidepressants, particularly tricyclic antidepressants

Antipsychotics, particularly clozapine and olanzapine

Calcium channel blockers

Cholestyramine

Clonidine

Diuretics

Narcotics

Calcium

Iron

Sucralfate

Nonsteroidal anti-inflammatory drugs

Opiates

Systemic disease

Hypothyroidism

Diabetes

Hypercalcemia

Multiple sclerosis

Paraplegia

Uremia

Motility disturbance

Slow transit time

Outlet delay

Irritable bowel syndrome

Structural abnormalities, including pain due to defecation and obstruction

Anal stricture or fissure

Colonic mass/stricture

Hemorrhoids

Psychogenic conditions

Anxiety

Depression

Eating disorders

Somatization