Chronic Constipation

Abstract

Constipation is a common symptom that may be primary (idiopathic or functional) or associated with a number of disorders or medications. Although most constipation is self-managed by patients, 22% seek health care, mostly to primary care physicians (>50%) and gastroenterologists (14%), resulting in large expenditures for diagnostic testing and treatments. There is strong evidence that stimulant and osmotic laxatives, intestinal secretagogues, and peripherally restricted μ-opiate antagonists are effective and safe; the lattermost drugs are a major advance for managing opioid-induced constipation. Constipation that is refractory to available laxatives should be evaluated for defecatory disorders and slow-transit constipation using studies of anorectal function and colonic transit. Defecatory disorders are often responsive to biofeedback therapies, whereas slow-transit constipation may require surgical intervention in selected patients. Both efficacy and cost should guide the choice of treatment for functional constipation and opiate-induced constipation. Currently, no studies have compared inexpensive laxatives with newer drugs that work by other mechanisms.

Figure 1.. Normal colonic contractile responses to a meal in a patient with isolated slow transit constipation.

Motor activity was recorded with manometry and a barostat balloon under fasting conditions (30 minutes), for 1 hour after a meal, and for 15 minutes after the cholinesterase inhibitor neostigmine. Before the meal, phasic pressure activity was greater in the distal than the proximal sigmoid colon. Phasic activity increased after the meal and more so after neostigmine. The volume of a balloon, located between the uppermost and second manometry sensors and inflated to a constant pressure of 12 mmHg, declined after a meal, and more so after neostigmine, reflecting increased colonic tone.

Figure 2.. Representative examples of normal and abnormal anorectal evacuation recorded with MRI (upper panel) and high resolution manometry (lower panel).

With MRI, observe increased puborectalis indentation during squeeze (arrow, panel B) and normal relaxation of the puborectalis, perineal descent, opening of the anal canal and evacuation of ultrasound gel during evacuation (panel C). During evacuation in constipated patients, observe paradoxical contraction of the puborectalis (panel D) and exaggerated perineal descent with an enterocele (panel E). High resolution manometry shows increased anal pressure during squeeze (G) compared to rest (F). The white rectangle demarcates the duration of squeeze (G) and evacuation (H-K). Observe increased rectal pressure with anal relaxation during evacuation (H) in a healthy person. By contrast, during evacuation in constipated patients, observe increased rectal pressure with paradoxical anal contraction (I), no change in rectal pressure versus rest (J), and no change in rectal pressure with paradoxical anal contraction (K).

Figure 3.

Suggested algorithm for treating patients with chronic constipation