Digestion Q&A by Dr. Marks
Yes, both computerized tomography (CT) and particularly magnetic resonance imaging (MRI) can be used to evaluate anorectal problems. A less costly method is ultrasonography in which the ultrasound probe is painlessly passed through the anus and into the rectum. Since the ultrasound probe is passed into the body, it is not really "noninvasive;" however, it is painless and is associated with virtually no risks. The problem with ultrasonography as compared with MRI is that its sound waves do not penetrate very deeply so that it can evaluate only the tissues very close to the anus and rectum. Nevertheless, ultrasonography is a good place to start an evaluation--depending on the nature of the problem. There are several other ways of evaluating the anorectal area that are comfortable and risk-free. These include defecography (in which defecation is evaluated with x-rays after the rectum has been filled with barium) and anorectal manometry (in which a thin catheter is passed into the rectum through the anus so that pressures inside the anus and rectum can be measured). Most of these methods for studying the anorectal area are performed only in specialized centers.
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Last Editorial Review: 1/2/2007