American Gastroenterological Association medical position statement: Guidelines on constipation☆
Article Outline
- Abstract
- Definitions
- Clinical subgroups
- Clinical evaluation
- Diagnostic tests
- Medical management
- Place of surgery and pelvic floor retraining program
- References
- Copyright
Abstract
This document presents the official recommendations of the American Gastroenterological Association (AGA) on constipation. It was approved by the Clinical Practice and Practice Economics Committee on March 4, 2000, and by the AGA Governing Board on May 21, 2000.
GASTROENTEROLOGY 2000;119:1761-1766
Symptoms of constipation are extremely common; the prevalence has been reported to be as high as 20%. Many people seek medical care for constipation, but fortunately, most do not have a life-threatening or disabling disorder, and the primary need is for control of symptoms. The impressive number of people affected and the cost of most diagnostic tests dictate that, in the next century, we manage this symptom in a cost-effective manner. Therefore, internists and gastroenterologists must be efficient in excluding life-threatening or treatable conditions, in identifying persons who may benefit from specialized testing, and in developing effective therapy that will relieve symptoms as much as possible. We suggest the following practice guidelines for the symptom of constipation; our rationale for these guidelines is supported by the accompanying technical review.1
Constipation is a symptom that can be associated with life-threatening diseases, although these are in this review primarily for exclusion. Thus, recommendations will relate to (1) more rational and, where possible, less invasive diagnostic approaches, and (2) more rational and efficacious therapies that will improve the quality of life, both of which should have (3) beneficial fiscal and logistic impacts on the health care system.
Definitions
Although physicians often focus mainly on the infrequency of bowel movements in the definition of constipation, patients have a broader set of complaints. The lower limit of normal stool frequency usually quoted is 3 per week, and 2 or fewer stools weekly has been included as one of the Rome consensus criteria for the symptom. In this Rome definition, frequency was only 1 of 6 prime features (including straining, hard stools, and a feeling of incomplete evacuation). It has been estimated that the symptoms encompassed by the patients' definitions are (in decreasing importance) straining, stools that are excessively hard, unproductive urges, infrequency, and a feeling of incomplete evacuation. In practice, it is not unusual for patients to describe constipation while having their bowels move often on a daily, and even more frequent, basis!
Clinical subgroups
The symptom of constipation may arise secondary to another condition. These include primary diseases of the colon (stricture, cancer, anal fissure, proctitis), metabolic disturbances (hypercalcemia, hypothyroidism, diabetes mellitus), and neurologic disorders (parkinsonism, spinal cord lesions). Some of these will be amenable to specific therapies, but when they are not, the challenge remains one of symptomatic treatment of constipation.
On the other hand, constipation is the major feature of 2 disorders of colorectal motility.
Slow-transit constipation
Slow-transit constipation (“colonic inertia”) is thought to have as a primary defect slower than normal movement of contents from the proximal to the distal colon and rectum. In some individuals, the basis for slow transit may be dietary or even cultural. In others, slow colonic transit probably has a true pathophysiologic basis, although little is known about these mechanisms. Indeed, it has been suggested that there are 2 subtypes of slow-transit constipation: (1) colonic inertia, possibly related to decreased numbers of high-amplitude propagated contractions. These peristaltic sequences are thought to be the mechanism for the mass movement of colonic contents. Thus, their absence is expressed as prolonged residence times of fecal residues in the right colon and (2) increased, uncoordinated motor activity in the distal colon that offers a functional barrier or resistance to normal transit. This distinction requires colonic manometry for its definition, although this technique is not generally available and is not appropriate for most patients, except in research settings.
Pelvic floor dysfunction
Pelvic floor dysfunction is the other major pathophysiologic condition. It features normal or slightly slowed colonic transit overall, but a preferential storage of residue for prolonged periods in the rectum. In this instance, the primary failure is an inability to evacuate adequately contents from the rectum. This functional defect in coordinated evacuation has received numerous names (“outlet obstruction,” “obstructed defecation,” “dyschezia,” “anismus,” “pelvic floor dyssynergia”). The plethora of pseudonyms expresses our incomplete understanding of the mechanisms and has complicated, and perhaps confused, what otherwise is an important concept.
Combination syndromes
Combination syndromes are often observed clinically, in which elements of slow transit and disorders of evacuation coexist, often in conjunction with other features of the irritable bowel syndrome (IBS). The presence of pain as a major component should evoke this possibility.
Clinical evaluation
Historical features are key, and the questioning of the patient must be specific. What feature does the patient rate as most distressing? Is it infrequency per se, straining, hard stools, unsatisfied defecation, or symptoms that occur between infrequent bowel movements (bloating, pain, malaise)? Presence of these last characteristics suggests underlying IBS.
Pelvic floor dysfunction should be suspected strongly on the basis of a careful history and physical examination. Prolonged and excessive straining before elimination are suggestive; when evacuatory defects are pronounced, soft stools and even enema fluid may be difficult to pass. The need for perineal or vaginal pressure to allow stools to be passed or direct digital evacuation of stools is an even stronger clue. It is important to raise these questions early because evacuatory disorders do not respond well to standard laxative programs, and failure to recognize this component is a frequent reason for therapeutic failure.
The current regime and bowel pattern should be recorded. How often is a “call to stool” noted? Is the call always answered? What laxatives are being used, how often, and at what dosage? Are suppositories or enemas used in addition? How often are the bowels moved, and what is the consistency of the stools? Physicians and patients need to be aware that after a complete purge, it will take several days for residue to accumulate such that a normal fecal mass will be formed. Importantly, many commonly used medications have constipation as a notable side effect (e.g., anticholinergics, calcium channel blockers). A full record of prescription and over-the-counter medications must be obtained.
The physical examination and screening tests, if deemed appropriate, should also eliminate diseases to which constipation is secondary (see technical review). Physical findings of more direct importance are confined to the perineal/rectal examination, but the following may be key:
After the initial history and physical, a set of focused tests should be considered to exclude disorders that are either treatable (e.g., hypothyroidism) or important to diagnose early (e.g., colon cancer). However, data do not exist to strictly evaluate and define the tests that need to be done. Complete blood cell count and thyroid-stimulating hormone and serum glucose, creatinine, and calcium tests are inexpensive and serve a screening function. A structural evaluation of the colon is appropriate, especially if the patient is older than 50 years or has not had previous screenings for colorectal cancer and colitis. Colonoscopy or flexible sigmoidoscopy and barium enema should effectively exclude lesions that could cause constipation.
If this evaluation leads to a diagnosis, the appropriate treatment can be offered. The patient's medications can be adjusted when possible to avoid those with constipating effects. Advice regarding exercise and water intake should be provided and a trial of fiber instituted.
At the conclusion of this initial evaluation, the patient complaining of constipation can be tentatively diagnosed as having (1) IBS, when pain and the other features of IBS are present; (2) slow-transit constipation; (3) rectal outlet obstruction; (4) a combination of (2) and (3); (5) organic constipation (mechanical obstruction or drug side effect); or (6) constipation secondary to systemic disease.
Diagnostic tests
The initial management of constipation as outlined above should be performed by a primary care provider. Patients who do not respond to these measures can be considered refractory. Such patients may benefit from special testing and treatments; these can be presented most simply as an algorithm (Algorithm 1).
Algorithm 1. Diagnostic algorithm for refractory constipation. R/O, rule out.
Interpretation of any single test must be guarded, because it must be recognized that patient cooperation comprises an important voluntary component of most tests of anorectal function. The tests themselves must be in a setting as private as possible, to reduce embarrassment and facilitate cooperation, but ideal conditions are often not possible.
Medical management
Algorithms 2 and 3 show treatments for the clinical subgroups.
Algorithm 2. Treatment algorithm for normal- and slow-transit constipation. MOM, milk of magnesia; PEG, polyethylene glycol; p.r.n., as needed.
Algorithm 3. Algorithm for pelvic floor dysfunction and slow-transit constipation. MOM, milk of magnesia; PEG, polyethylene glycol; p.r.n., as needed.
However, before therapeutic regimens are initiated, major decisions need to be made relating to the contribution of pelvic floor dysfunction. Is the role of impaired evacuation sufficient to justify an intensive program of education and practice? Formal evaluations of biofeedback training in constipation are sparse, and important practical details of individual programs are often not stated. However, results from the best integrated programs are impressive. The motivation of the patient and therapist, together with the frequency and intensity of the retraining program, likely contributes importantly to the chances of success. The program offered at the Mayo Clinic, for example, features 3 daily outpatient sessions for 2 weeks. In addition to biofeedback therapists, dietitians and behavioral psychologists participate. Although the results of biofeedback in children have been disappointing, intensive programs in adults can have a better than 75% success rate.
Place of surgery and pelvic floor retraining program
Surgical treatment of slow-transit constipation
The treatment of colonic inertia—when well documented and assuming failure of an aggressive, prolonged trial of laxatives, fiber, and prokinetic agents—is total colectomy with ileorectal anastomosis. Patients need to be told that the procedure is designed to treat the symptom of constipation and that other symptoms (e.g., abdominal pain) may not necessarily be relieved, even though regular defecation may be achieved. Even in a tertiary center with a strong presence of surgical referrals, only 5% of this highly selected cohort justify surgical treatment.
Pelvic floor retraining
Biofeedback and relaxation training have been quite successful and, importantly, free of morbidity. Biofeedback can be used to train patients to relax their pelvic floor muscles during straining and to correlate relaxation and pushing to achieve defecation. By the relearning process, the nonrelaxing pelvic floor is gradually suppressed and normal coordination restored. It should be pointed out that biofeedback is also used in the treatment of fecal incontinence. There are, however, major differences between the approaches to fecal incontinence and constipation. The incontinent patient with intact neural pathways is able to appreciate a sensation of muscular contractile activity, whereas the constipated patient does not have a similar sensation of muscular relaxation. Nevertheless, biofeedback has been shown to reduce obstructive symptoms, with an increase in the frequency of bowel actions, the ability to develop a more obtuse anorectal angle at the time of defecation, and more dynamic pelvic floor movements when the anal sphincter is contracted.
This Medical Position Statement has been endorsed in principle by the American Society for Gastrointestinal Endoscopy and the American College of Gastroenterology.
References
☆ Address requests for reprints to: Chair, Clinical Practice and Practice Economics Committee, AGA National Office, c/o Membership Department, 7910 Woodmont Avenue, 7th Floor, Bethesda, Maryland 20814. Fax: (301) 654-5920.
PII: S0016-5085(00)70023-0
© 2000 American Gastroenterological Association. Published by Elsevier Inc. All rights reserved.
