Constipation diagnosed

 How is constipation evaluated (diagnosed)?

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 forindividuals who have severe constipation or whose constipation does not respond easilyto treatment.Medical HistoryA careful medical history from a patient with constipation is criticalfor many reasons, but particularly because it allows the physician to define the type of constipation. This, in turn, directs the diagnosis and treatment. Forexample, if defecation is painful, the physician knows to look for anal problemssuch as a narrowed anal sphincter or an anal fissure. If small stools are theproblem, there is likely to be a lack of fiber in the diet. If the patient isexperiencing 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 diseasescan be treated.A careful dietary history-which may require keeping a food diary for a weekor two-can reveal a diet that is low in fiber and may direct the physician torecommend a high-fiber diet. A food diary also allows the physician to evaluatehow well a patient increases his dietary fiber during treatment.Physical examinationA physical examination may identify diseases (for example, scleroderma) that can cause constipation. A rectal examination with the fingermay uncover a tight anal sphincter that may be making defecation difficult. If astool-filled colon can be felt through the abdominal wall, it suggests thatconstipation is severe. Stool in the rectum suggests a problem with the anal,rectal, or pelvic floor muscles.Blood testsBlood tests may be appropriate in evaluating patients withconstipation. More specifically, blood tests for thyroid hormone (to detect hypothyroidism) and for calcium (to uncover excess parathyroid hormone) may behelpful.Abdominal X-rayLarge amounts of stool in the colon usually can be visualized onsimple X-ray films of the abdomen; the more stool that is visualized, the more severethe constipation.Barium enemaA barium enema (lower GI series) is an X-ray study in whichliquid barium is inserted through the anus to fill the rectum and colon. Thebarium outlines the colon on the X-rays and defines the normal or abnormalanatomy of the colon and rectum. Tumors and narrowings (strictures) are amongthe abnormalities that can be detected with this test.Colonic transit (marker) studiesColonic transit studies are simple X-ray studiesthat determine how long it takes for food to travel through the intestines.For transit studies, individuals swallow capsules for one or more days. Inside thecapsules are many small pieces of plastic that can be seen on X-rays. The gelatincapsules dissolve and release the plastic pieces into the small intestine. Thepieces of plastic then travel (as would digesting food) through the smallintestine and into the colon. After 5 or 7 days, an X-ray of the abdomen istaken 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 inthe colon. In non-constipated individuals, all of the plastic pieces areeliminated in the stool and none remain in the colon. When pieces are spreadthroughout the colon, it suggests that the muscles and/or nerves throughout thecolon are not working, which is typical of colonic inertia. When pieces accumulatein the rectum, it suggests pelvic floor dysfunction.DefecographyDefecography is a modification of the barium enema examination.For this procedure, a thick paste of barium is inserted into the rectum of apatient through the anus. X-rays then are taken while the patient defecates thebarium. The barium clearly outlines the rectum and anus and demonstrates thechanges taking place in the muscles of the pelvic floor during defecation. Thus,defecography examines the process of defecation and provides information aboutanatomical abnormalities of the rectum and pelvic floor muscles duringdefecation.Ano-rectal motility studiesAno-rectal motility studies, which complementdefecography tests, provide an assessment of the function of the muscles andnerves 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 andinto the rectum. Sensors within the tube measure the pressures that aregenerated by the muscles of the anus and rectum. With the tube in place, thepatient performs several simple maneuvers such as voluntarily tightening theanal muscles. Ano-rectal motility studies can help determine if the muscles ofthe anus and rectum are working normally. When the function of these muscles isimpaired, the flow of stool is obstructed, thereby causing a condition similarto pelvic floor dysfunction.Magnetic resonance imaging defecographyThe newest test for evaluating defecation and its disorders magnetic resonance imaging defecography and is similar to barium defecography. However, magnetic resonance imaging (MRI) is used instead of X-rays to provide images of the rectum during defecation. MRI defecography appears to be an excellent way to study defecation, but the procedure is expensive and somewhat cumbersome. As a result, it is used in only a few institutions that have a particular interest in constipation and abnormalities of defecation. Colonic motility studiesColonic motility studies are similar to ano-rectalmotility studies in many aspects. A very long, narrow (one-eighth inch indiameter), flexible tube is inserted through the anus and passed through part orall of the colon during a procedure called colonoscopy. Sensors within the tubemeasure the pressures that are generated by the contractions of the colonicmuscles. These contractions are the result of coordinated activity of thecolonic nerves and muscles. If the activity of the nerves or muscles isabnormal, the pattern of colonic pressures will be abnormal. Colonic motilitystudies are most useful in defining colonic inertia. These studies areconsidered research tools, but they can be helpful in making decisions regardingtreatment in patients with severe constipation.