Sigmoidoscopy Health Article

Diagnosis/Preparation

The purpose of preparation for sigmoidoscopy is to cleanse the lower bowel of fecal material or stool so the physician can see the lining. Preparation begins 24 hours before the procedure, when an individual must begin a clear liquid diet. Preparation kits are available in drug stores. In normal preparation, about 20 hours before the exam, a person begins taking a series of laxatives, which may be oral tablets or liquid. The individual must stop drinking any liquid four hours before the exam. An hour or two prior to the examination, the person uses an enema or laxative suppository to finish cleansing the lower bowel.

Individuals need to be careful about medications before having sigmoidoscopy. They should not take aspirin, products containing aspirin, or products containing ibuprofen for one week prior to the exam, because these medications can exacerbate bleeding during the procedure. They should not take any iron or vitamins with iron for one week prior to the exam, since iron can cause color changes in the bowel lining that interfere with the examination. They should take any routine prescription medications, but may need to stop certain medications. Prescribing physicians should be consulted regarding routine prescriptions and their possible effect(s) on sigmoidoscopy.

Individuals with renal insufficiency or congestive heart failure need to be prepared in an alternative way, and must be carefully monitored during the procedure.

Aftercare

There is no specific aftercare necessary following sigmoidoscopy. If a biopsy was taken, a small amount of blood may appear in the next stool. Persons should be encouraged to pass gas following the procedure to relieve any bloating or cramping that may occur after the procedure. In addition, an infection may develop following sigmoidoscopy. Persons should be instructed to call their physician if a fever or pain in the abdomen develops over the few days after the procedure.

Risks

There is a slight risk of bleeding from the procedure. This risk is heightened in individuals whose blood does not clot well, either due to disease or medication, and in those with active inflammatory bowel disease. Rarely, trauma to the bowel or other organs can occur, resulting in an injury (perforation) that must be repaired, or peritonitis, which must be treated with medication.

Sigmoidoscopy may be contraindicated in persons with severe active colitis or toxic megacolon (an extremely dilated colon). In general, people experiencing continuous ambulatory peritoneal dialysis are not candidates due to a high risk of developing intraperitoneal bleeding.

Normal results

The results of a normal examination reveal a smooth colon wall, with sufficient blood vessels for good blood flow.

Morbidity and mortality rates

For a cancer screening sigmoidoscopy, an abnormal result is one or more noncancerous or precancerous polyps, or clearly cancerous polyps. People with polyps have an increased risk of developing colorectal cancer in the future and may be required to undergo additional procedures such as colonoscopy or more frequent sigmoidoscopic examinations.

Small polyps can be completely removed. Larger polyps may require the physician to remove a portion of the growth for laboratory biopsy. Depending on the laboratory results, a person is then scheduled to have the polyp removed surgically, either as an urgent matter if it is cancerous, or as an elective procedure within a few months if it is non-cancerous.

In a diagnostic sigmoidoscopy, an abnormal result shows signs of active inflammatory bowel disease, either a thickening of the intestinal lining consistent with ulcerative colitis, or ulcerations or fissures consistent with Crohn's disease.

Mortality from a sigmoidoscopy examination is rare and is usually due to uncontrolled bleeding or perforation of the colon.

Alternatives

A screening examination for colorectal cancer is a test for fecal occult blood. A dab of fecal material from toilet tissue is smeared onto a card. The card is treated in a laboratory to reveal the presence of bleeding. This test is normally performed prior to a sigmoidoscopic examination.

A less invasive alternative to a sigmoidoscopic examination is an x ray of the colon and rectum. Barium is used to coat the inner walls of the colon. This lower GI (gastrointestinal) x ray may reveal the outlines of suspicious or abnormal structures. It has the disadvantage of not allowing direct visualization of the colon. It is less costly than a sigmoidoscopic examination.

A more invasive procedure is direct visualization of the colon during surgery. This procesdure is rarely performed in the United States.

See also Colonoscopy; Cystoscopy.