Effective & Trusted Medications Guide

Anoscopy

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 As the anoscope is withdrawn, the area where internal hemorrhoids and anal fissures are found is well seen.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

Flexible sigmoidoscopy utilizes a flexible sigmoidoscope, a flexible, fiberoptic viewing tube with a light at its tip. 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 a shorter version of a colonoscope. It can be 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. For more information, please see the Flexible Sigmoidoscopy article.

Colonoscopy

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. For more information, please see the Colonoscopy article.

Radionuclide scans

There are two types of radionuclide scans that are used for determining the site of gastrointestinal bleeding; Meckel’s scan, and tagged red blood cell (RBC) scan.

The Meckel’s scan is a scan for detecting a Meckel’s diverticulum. A radioactive chemical is injected into the patient’s vein, and a nuclear camera (like a Geiger counter) is used to scan the patient’s abdomen. The radioactive chemical will be picked up and concentrated by the acid-secreting tissue in the Meckel’s diverticulum and will appear as a “hot” area in the right lower abdomen on the scan.

Tagged RBC scans are used to determine the location of the gastrointestinal bleeding. After drawing blood from the bleeding patient, a radioactive chemical is attached to the patient’s red blood cells and the “tagged” red blood cells then are injected back into the patient’s vein. If there is active gastrointestinal bleeding, the radioactive red blood cells leak into the intestine where the bleeding is occurring and will appear as a hot area on the scan. A weakness of the tagged RBC scan is that it will not show a hot area if there is no active bleeding at the time of the scan. Thus, it can fail to diagnose the site of bleeding if bleeding is intermittent and the scan is done between bleeding episodes. A second weakness of the scan is that it requires a minimum amount of bleeding to form a hot area. Thus, it can fail to diagnose the site of bleeding if bleeding is too slow. The tagged RBC scan is safe, and can be done quickly and without discomfort.

Unfortunately, the tagged RBC scans are not very accurate in defining the exact location of the bleeding; there is often a poor correlation between where the tagged RBC scan shows the bleeding to be and the actual site of bleeding found at the time of surgery. Therefore, tagged RBC scans cannot be relied upon to help surgeons decide what area of the gastrointestinal tract to remove in the event bleeding is severe or persistent and requires surgery. However, if the scan shows a hot area, it usually means there is active bleeding, and the patient may be a candidate for a visceral angiogram to more accurately locate the site of bleeding.