Constipation (cont.)
How is constipation evaluated?
A careful history and physical examination is important in all patients with
constipation. There are many tests that can be used to evaluate constipation.
Most patients need only a few basic tests. The other tests are reserved for
individuals who have severe constipation or whose constipation does not respond easily
to treatment.
Medical History
A careful medical
history from a patient with constipation is critical
for many reasons, but particularly because it allows the physician to define the type of
constipation. This, in turn, directs the diagnosis and treatment. For
example, if defecation is painful, the physician knows to look for anal problems
such as a narrowed anal sphincter or an anal fissure. If small stools are the
problem, there is likely to be a lack of fiber in the diet. If the patient is
experiencing significant straining, then pelvic floor dysfunction is likely.
The history also uncovers medications and diseases that can cause
constipation. In these cases, the medications can be changed and the diseases
can be treated.
A careful dietary history-which may require keeping a food diary for a week
or two-can reveal a diet that is low in fiber and may direct the physician to
recommend a high-fiber diet. A food diary also allows the physician to evaluate
how well a patient increases his dietary fiber during treatment.
Physical examination
A physical examination may identify diseases (for
example,
scleroderma) that can cause constipation. A rectal examination with the finger
may uncover a tight anal sphincter that may be making defecation difficult. If a
stool-filled colon can be felt through the abdominal wall, it suggests that
constipation is severe. Stool in the rectum suggests a problem with the anal,
rectal, or pelvic floor muscles.
Blood tests
Blood tests may be appropriate in evaluating patients with
constipation. More specifically, blood tests for thyroid hormone (to detect
hypothyroidism) and for calcium (to uncover excess parathyroid hormone) may be
helpful.
Abdominal X-ray
Large amounts of stool in the colon usually can be
visualized on
simple X-ray films of the abdomen; the more stool that is visualized, the more severe
the constipation.
Barium enema
A barium enema (lower GI series) is an x-ray study in which
liquid barium is inserted through the anus to fill the rectum and colon. The
barium outlines the colon on the X-rays and defines the normal or abnormal
anatomy of the colon and rectum. Tumors and narrowings (strictures) are among
the abnormalities that can be detected with this test.
Colonic transit (marker) studies
Colonic transit studies are simple X-ray studies
that determine how long it takes for food to travel through the intestines.
For transit studies, individuals swallow capsules for one or more days. Inside the
capsules are many small pieces of plastic that can be seen on X-rays. The gelatin
capsules dissolve and release the plastic pieces into the small intestine. The
pieces of plastic then travel (as would digesting food) through the small
intestine and into the colon. After 5 or 7 days, an X-ray of the abdomen is
taken and the pieces of plastic in the different parts of the colon are counted.
From this count, it is possible to determine if and where there is a delay in
the colon.
In non-constipated individuals, all of the plastic pieces are
eliminated in the stool and none remain in the colon. When pieces are spread
throughout the colon, it suggests that the muscles and/or nerves throughout the
colon are not working, which is typical of colonic inertia. When pieces accumulate
in the rectum, it suggests pelvic floor dysfunction.
Defecography
Defecography is a modification of the barium enema examination.
For this procedure, a thick paste of barium is inserted into the rectum of a
patient through the anus. X-rays then are taken while the patient defecates the
barium. The barium clearly outlines the rectum and anus and demonstrates the
changes taking place in the muscles of the pelvic floor during defecation. Thus,
defecography examines the process of defecation and provides information about
anatomical abnormalities of the rectum and pelvic floor muscles during
defecation.
Ano-rectal motility studies
Ano-rectal motility studies, which complement
defecography tests, provide an assessment of the function of the muscles and
nerves of the anus and rectum. For ano-rectal motility studies, a flexible tube,
approximately an eighth of an inch in diameter, is inserted through the anus and
into the rectum. Sensors within the tube measure the pressures that are
generated by the muscles of the anus and rectum. With the tube in place, the
patient performs several simple maneuvers such as voluntarily tightening the
anal muscles. Ano-rectal motility studies can help determine if the muscles of
the anus and rectum are working normally. When the function of these muscles is
impaired, the flow of stool is obstructed, thereby causing a condition similar
to pelvic floor dysfunction.
Colonic motility studies
Colonic motility studies are similar to ano-rectal
motility studies in many aspects. A very long, narrow (one-eighth inch in
diameter), flexible tube is inserted through the anus and passed through part or
all of the colon during a procedure called
colonoscopy. Sensors within the tube
measure the pressures that are generated by the contractions of the colonic
muscles. These contractions are the result of coordinated activity of the
colonic nerves and muscles. If the activity of the nerves or muscles is
abnormal, the pattern of colonic pressures will be abnormal. Colonic motility
studies are most useful in defining colonic inertia. These studies are
considered research tools, but they can be helpful in making decisions regarding
treatment in patients with severe constipation.
Next: What treatments are available for constipation? »
- polyethylene glycol (peg) 3350-oral, Miralax - Consumer information about the medication POLYETHYLENE GLYCOL (PEG) 3350 - ORAL (Miralax), includes side effects, drug interactions, recommended dosages, and storage information. Read more about the prescription drug POLYETHYLENE GLYCOL (PEG) 3350 - ORAL.
- Colonoscopy - Learn about the colonscopy procedure, what it is, why it is performed, preparation, complications, alternatives and the after effects of the screening exam on MedicineNet.com
- Abdominal Pain - Learn about abdominal pain (pain in the stomach / abdomen) including causes, symptoms, how abdominal pain is diagnosed, and how abdominal pain is treated.
Latest Medical News
Digestion RSS