Abstract & Commentary
Synopsis: This review article sums up the symptoms and treatment of chronic constipation.
Source: Lembo A, Camilleri M. N Engl J Med. 2003;349: 1360-1368.
Chronic constipation may affect up to 27% of the population, resulting in 2.5 million physician visits, 92,000 hospitalizations, and laxative sales in the hundreds of millions of dollars. This syndrome is most common in women, Caucasians, and the elderly. Risk factors include sedentary lifestyle, lower educational and socioeconomic status, history of sexual abuse, and depression.
Constipation is arbitrarily described as less than 3 stools/week associated with straining and inability to completely evacuate stools. This excellent review divides constipation by normal vs slow transit vs disorders of rectal evacuation.
Normal-transit constipation is most common and is often relieved with administration of supplementary fiber or administration of an osmotic laxative. Defecatory disorders include pelvic floor dyssynergia, anismus, and other less common pelvic neuromuscular defects. Slow-transit constipation seems most common in young women, often associated with bowel movements once a week or less frequently. Poor responses to diet changes and laxatives are common in this group, and there have been subtle-to-marked changes in enteric neural networks in these patients. Evaluation of constipation must include careful physical examination, including rectal examination (described nicely in the article).
Laboratory tests might include measures of calcium, glucose, blood count, and electrolytes. Any "alarm" symptoms mandate anatomic examination of the colon. Colonoscopy should always be done in patients older than 50 years. Physiological examinations such as anal-rectal manometry, defecography, and colon transit times are only needed in patients found to be refractory to simple therapeutic maneuvers. Contrary to the opinions held by some, there is no role of increased fluid intake in patients who are not dehydrated. Fiber supplements up to 25 g/d are appropriate in patients with normal or slow-transit constipation. If fiber therapy fails, options include osmotic laxatives such as milk of magnesia, polyethylene glycol, or Lactulose. Tegaserod has been useful in patients with constipation-predominant irritable bowel syndrome. Biofeedback can be very helpful in correction of defecatory disorders. Botulinum toxin injection into the puborectalis muscle has been suggested, but controlled trials are absent. Colectomy and ileorectostomy have been effective for some truly refractory cases of constipation, but complications may be severe after this procedure.
Comment by Malcolm Robinson MD, FACP, FACG
This article is a very helpful review of a common and often vexing problem for physicians and their patients. In my view, it should be read by all physicians likely to see such patients (and that includes almost all of us). There have been some very important advances in the differential diagnosis and management of chronic constipation since most of us were trained, and it would be wise to take this opportunity for a well-prepared and highly readable update.
Dr. Robinson, Medical Director, Oklahoma Foundation for Digestive Research; Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City, OK, is Associate Editor of Internal Medicine Alert.