Functional Constipation
Pathogenesis and Management
Constipation is a very common clinical problem, and a questionnaire-based study in Olmsted County, Minnesota, demonstrated that up to 20% of patients report symptoms consistent with functional constipation.[9] Approximately 40% of such patients have historic evidence of needing to strain excessively to evacuate the bowel. This suggests that these patients may also have a component of an evacuation disorder, although the questionnaire-based data do not allow sufficient distinction between an evacuation problem and slow-transit constipation. In a tertiary center study, 50% of patients (N=70) with severe, unresponsive constipation referred to a single gastroenterologist over a 3-year period had impaired evacuation; the remaining patients had either normal or slow-transit constipation.[10]
Physiologic characterization of constipated patients is important for several reasons. First, among patients with slow-transit constipation, drug-induced constipation, or evacuation disorders, supplementation of up to 30 grams of fiber per day does not result in any improvement in symptoms.[43] Second, it is important to identify evacuation disorders because a biofeedback treatment program with muscle relaxation of anal sphincters and the puborectalis can result in a 70% or greater cure rate for the constipation.[44] Also important to note is that surgical and other aggressive strategies previously employed in the treatment of evacuation disorders have been shown to be either unnecessary or damaging to patients, resulting in incontinence. Finally, characterization of pelvic floor function and transit profiles by radiopaque markers or scintigraphy[45,46] facilitates a more physiologic approach to relieving constipation. Thus, the appropriate characterization of these patients can guide the management strategy -- individuals with slow-transit constipation tend to benefit from fiber, osmotic laxatives, and stimulant laxatives (eg, bisacodyl), whereas patients with evacuation disorders usually do not need medication other than fiber supplementation following pelvic floor retraining.
Medscape General Medicine. 1999;1(3) © 1999
Cite this: Functional Gastrointestinal Disorders: Novel Insights and Treatments - Medscape - Nov 01, 1999.
