Rectal Bleeding (cont.)
Bhupinder Anand, MD
In this Article
An anoscope is a three-inch long, tapering, metal or clear plastic, hollow tube approximately one inch in diameter at its wider end. The anoscope is lubricated, and the tapered end is inserted into the anus, through the anal canal, and into the rectum. As the anoscope is withdrawn, the area where internal hemorrhoids and anal fissures are found is well seen. Straining by the patient, as if they are having a bowel movement, may make hemorrhoids more prominent.
Whether or not hemorrhoids and anal fissures are found, if there has been rectal bleeding, the colon above the rectum needs to be examined to exclude other important causes of bleeding. Examination above the rectum can be accomplished by either flexible sigmoidoscopy or colonoscopy, procedures that allow the doctor to examine approximately one-third or the entire colon, respectively.
Flexible sigmoidoscopy utilizes a flexible sigmoidoscope, a fiberoptic viewing tube with a light at its tip. It is a shorter version of a colonoscope. It is inserted through the anus and is used by the doctor to examine the rectum, sigmoid colon and part or all of the descending colon. It is useful for detecting diverticula, colon polyps, and cancers located in the rectum, sigmoid colon, and descending colon. Flexible sigmoidoscopy also can be used to diagnose ulcerative colitis, ulcerative proctitis, and sometimes Crohn's colitis and ischemic colitis.
Despite its value, flexible sigmoidoscopy cannot detect cancers, polyps, or angiodysplasias in the transverse and right colon. Flexible sigmoidoscopy also cannot diagnose colitis that is beyond the reach of the flexible sigmoidoscope. Because of these limitations, colonoscopy may be necessary. The advantage of flexible sigmoidoscopy over colonoscopy is that it can be accomplished with no preparation of the colon or after only one or two enemas.
Colonoscopy is a procedure that enables an examiner (usually a gastroenterologist) to evaluate the inside of the entire colon. This is accomplished by inserting a flexible viewing tube (the colonoscope) into the anus and then advancing it slowly under direct vision through the rectum and the entire colon. The colonoscope frequently can reach the part of the small intestine that is adjacent to the right colon.
Colonoscopy is the most widely used procedure for evaluating rectal bleeding as well as occult bleeding. It can be used to detect polyps, cancers, diverticulosis, ulcerative colitis, ulcerative proctitis, Crohn's colitis, ischemic colitis, and angiodysplasias throughout the entire colon and rectum.
If there is any possibility that the bleeding is coming from a location above the colon, and esophagogasatroduodenal endoscopic examination (EGD) also should be done to identify or exclude an upper gastrointestinal source of bleeding.
Reviewed by Bhupinder Anand, MD on 4/25/2012
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