American Gastroenterological Association Medical Position Statement: Guidelines on Constipation

AMERICAN GASTROENTEROLOGICAL ASSOCIATION
American Gastroenterological Association Medical Position
Statement: Guidelines on Constipation
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浙江中医药大学附属第二医院消化内科刘福
May 21, 2000.
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 highamplitude
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.
GASTROENTEROLOGY 2000;119:1761?1778
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-thecounter
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:
c In the left lateral position, with the buttocks separated,
observe the descent of the perineum during
simulated evacuation and the elevation during a
squeeze aimed at retention. The perianal skin can be
observed for evidence of fecal soiling and the anal
reflex tested by a light pinprick or scratch.
c During simulated defecation, the anal verge should
be observed for any patulous opening (suspect neurogenic
constipation with or without incontinence)
or prolapse of anorectal mucosa.
c The digital examination should evaluate resting
tone of the sphincter segment, and its augmentation
by a squeezing effort. The voluntary external anal
sphincter will be tightened by squeezing; the internal
sphincter will not. Above the internal sphincter
is the puborectalis muscle, which should also be
palpated during the squeeze and compressed between
the examining finger and the thumb. Acute
localized pain along the border of the muscle is a
feature of the puborectalis spasm syndrome. Finally,
the patient should be instructed to integrate the
expulsionary forces by requesting that she/he “expel
my finger.”
c An examination should then be made to look for a
rectocele, or consideration be given to gynecologic
consultation.
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 en-
1762 AMERICAN GASTROENTEROLOGICAL ASSOCIATION GASTROENTEROLOGY Vol. 119, No. 6
ema 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).
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. We suggest a gradual increase in fiber
intake, as both foods included in the diet and as supplements.
If more treatment is needed, the simplest program
should begin with an inexpensive saline agent,
such as milk of magnesia. Only later should stimulant
agents (Dulcolax; Novartis Consumer Health, Summit,
NJ) or more expensive agents such as lactulose and
polyethylene glycol be considered.
Algorithm 1. Diagnostic algorithm for refractory constipation. R/O, rule out.
December 2000 AMERICAN GASTROENTEROLOGICAL ASSOCIATION 1763
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.
Algorithm 2. Treatment algorithm for normal- and slow-transit constipation. MOM, milk of magnesia; PEG, polyethylene glycol; p.r.n., as needed.
1764 AMERICAN GASTROENTEROLOGICAL ASSOCIATION GASTROENTEROLOGY Vol. 119, No. 6
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.
Algorithm 3. Algorithm for pelvic floor dysfunction and slow-transit constipation. MOM, milk of magnesia; PEG, polyethylene glycol; p.r.n., as needed.
December 2000 AMERICAN GASTROENTEROLOGICAL ASSOCIATION 1765
This Medical Position Statement has been endorsed in principle
by the American Society for Gastrointestinal Endoscopy
and the American College of Gastroenterology.
G. RICHARD LOCKE III, M.D.
Division of Gastroenterology
JOHN H. PEMBERTON, M.D.
Division of Colon and Rectal Surgery
SIDNEY F. PHILLIPS, M.D.
Division of Gastroenterology
Mayo Clinic and Mayo Medical School
Rochester, Minnesota
References
1. Locke GR III, Pemberton JH, Phillips SF. AGA technical review on
constipation. Gastroenterology 2000;119:1766?1778.
Address requests for reprints to: Chair, Clinical Practice and Practice
Economics Committee, AGA National OfÞce, c/o Membership Department,
7910 Woodmont Avenue, 7th Floor, Bethesda, Maryland
20814. Fax: [phone].
© 2000 by the American Gastroenterological Association
0016-5085/00/$10.00
doi:10.1053/gast.2000.20390
1766 AMERICAN GASTROENTEROLOGICAL ASSOCIATION GASTROENTEROLOGY Vol. 119, No. 6