Constipation is the difficult or infrequent passage of stool, hardness of stool or a sense of incomplete rectal emptying.
Acute constipation refers to a change for the patient, i.e. a change from their normal bowel habits to less frequent/more difficult elimination. Acute constipation usually has an organic cause such as mechanical obstruction of the colon, adynamic ileus (paralysis of the intestines), bed rest or severely restricted activity, or medications. If acute constipation continues long-term or worsens, diagnostic studies should be performed to rule out colonic cancer.
Chronic constipation may be due to functional causes such as hypothyroidism, hypercalcemia, uremia, porphyria, irritable bowel syndrome, colonic inertia and megacolon. Neurogenic causes are also possible, such as Parkinson's disease, cerebral thrombosis, or spinal cord injury. Psychogenic constipation is usually caused by the patient's overtreatment of a perceived problem by excessive use of laxatives, cathartics and enemas, resulting in rebound constipation (i.e. the colon loses its ability to function without these stimulations).
Treatment of constipation includes increasing daily fiber intake, increased water intake and exercise. The only laxatives accepted for long-term use are the bulking agents such as bran, psyllium and methylcellulose. Wetting agents are also acceptable because they do not act on the colon itself, but simply emulsify the stool, making it softer and looser. All other laxatives should be avoided if possible, and taken in the smallest dose and for the shortest duration necessary to relieve the problem.