Sigmoidoscopy is a procedure by which a doctor inserts either a short and rigid or slightly longer and flexible fiber-optic tube into the rectum to examine the lower portion of the large intestine (or bowel).
Description
Most sigmoidoscopy is done with a flexible fiber-optic tube. The tube contains a light source and a camera lens. The doctor moves the sigmoidoscope up beyond the rectum (the first 1 ft/30 cm of the colon), examining the interior walls of the rectum. If a 2 ft/60 cm scope is used, the next portion of the colon can also be examined for any irregularities.
The procedure takes 20 to 30 minutes, during which time the patient will remain awake. Light sedation may be given to some patients. There is some discomfort (usually bloating and cramping) because air is injected into the bowel to widen the passage for the sigmoidoscope. Pain is rare except in individuals with active inflammatory bowel disease.
In a colorectal cancer screening, the doctor is looking for polyps or tumors. Studies have shown that over time, many polyps develop into cancerous lesions and tumors. Using instruments threaded through the fiber-optic tube,
cancerous or precancerous polyps can either be removed or biopsied during the sigmoidoscopy. People who have cancerous polyps removed can be referred for full colonoscopy, or more frequent sigmoidoscopy, as necessary.
The doctor may also look for signs of ulcerative colitis, which include a loss of blood flow to the lining of the bowel, a thickening of the lining, and sometimes a discharge of blood and pus mixed with stool. The doctor can also look for Crohn's disease, which often appears as shallow or deep ulcerations, or erosions and fissures in the lining of the colon. In many cases, these signs appear in the first few centimeters of the colon above the rectum, and it is not necessary to do a full colonoscopic exam.
Private insurance plans often cover the cost of sigmoidoscopy for screening in healthy individuals over 50, or for diagnostic purposes. Medicare covers the cost for diagnostic exams, and may cover the costs for screening exams.
Who Performs the Procedure and Where Is It Performed?
A colonoscopy procedure is usually performed by a gastroenterologist, a physician with specialized training in diseases of the colon. Alternatively, general surgeons or experienced family physicians perform sigmoidoscopic examinations. In the United States, the procedure is usually performed in an outpatient facility of a hospital or in a physician's professional office.
Persons with rectal bleeding may need a full colonoscopy in a hospital setting. Individuals whose blood does not clot well (possibly as a result of blood-thinning medications) may require the procedure to be performed in a hospital setting.
Questions to Ask the Doctor
Is the supervising physician appropriately certified to conduct a sigmoidoscopy?
How many sigmoidoscopy procedures has the doctor performed?
What other steps will be taken as a result of my test findings?
Definition
Sigmoidoscopy is a diagnostic and screening procedure in which a rigid or flexible tube with a camera on the end (a sigmoidoscope) is inserted into the anus to examine the rectum and lower colon (bowel) for bowel disease, cancer, precancerous conditions, or causes of bleeding or pain.
Cancer of the rectum and colon is the second most common cancer in the United States. About 155,000 cases are diagnosed annually. Between 55,000 and 60,000 Americans die each year of cancer in the colon or rectum.
After reviewing a number of studies, experts recommend that people over 50 be screened for colorectal cancer using sigmoidoscopy every three to five years. Individuals with such inflammatory bowel conditions as Crohn's disease or ulcerative colitis, and thus are at increased risk for colorectal cancer, may begin their screenings at a younger age, depending on when their disease was diagnosed. Many physicians screen such persons more often than every three to five years. Screening should also be performed in people who have a family history of colon or rectal cancer, or small growths in the colon (polyps).
Some physicians do this screening with a colonoscope, which allows them to see the entire colon. However, most physicians prefer sigmoidoscopy, which is less time-consuming, less uncomfortable, and less costly.
Studies have shown that one-quarter to one-third of all precancerous or small cancerous growths can be seen with a sigmoidoscope. About one-half are found with a 1 ft (30 cm) scope, and two-thirds to three-quarters can be seen using a 2 ft (60 cm) scope.
In some cases, the sigmoidoscope can be used therapeutically in conjunction with such other equipment as electrosurgical devices to remove polyps and other lesions found during the sigmoidoscopy.
Demographics
Experts estimate that in excess of 500,000 sigmoidoscopy procedures are performed each year. This number includes most of the persons who are diagnosed with colon cancer each year, a greater number who are screened and receive negative results, persons who have been treated for colon conditions and receive a sigmoidoscopy as a follow-up procedure, and individuals who are diagnosed with other diseases of the large colon.
Description
Sigmoidoscopy may be performed using either a rigid or flexible sigmoidoscope. A sigmoidoscope is a thin tube with fiberoptics, electronics, a light source, and camera. A physician inserts the sigmoidoscope into the anus to examine the rectum (the first 1 ft [30 cm] of the colon) and its interior walls. If a 2 ft (60 cm) scope is used, the next portion of the colon can also be examined for any irregularities. The camera of the sigmoidoscope is connected to a viewing monitor, allowing the interior of the rectum and colon to be enlarged and viewed on the monitor. Images can then be recorded as still pictures or the entire procedure can be videotaped. The still pictures are useful for comparison purposes with the results of future sigmoidoscopic examinations.
If polyps, lesions, or other suspicious areas are found, the physician biopsies them for analysis. During the sigmoidoscopy, the physician may also use forceps, graspers, snares, or electrosurgical devices to remove polyps, lesions, or tumors.
The sigmoidoscopy procedure requires five to 20 minutes to perform. Preparation begins one day before the procedure. There is some discomfort when the scope is inserted and throughout the procedure, similar to that experienced when a physician performs a rectal exam using a finger to test for occult blood in the stool (another important screening test for colorectal cancer). Individuals may also feel some minor cramping pain. There is rarely severe pain, except for persons with active inflammatory bowel disease.
Private insurance plans almost always cover the cost of sigmoidoscopy examinations for screening in healthy individuals over 50, or for diagnostic purposes. Medicare covers the cost for diagnostic exams, and may cover the costs for screening exams. Medicaid benefits vary by state, but sigmoidoscopy is not a covered procedure in many states. Some community health clinics offer the procedure at reduced cost, but this can only be done if a local gastroenterologist (a physician who specializes in treating stomach and intestinal disorders) is willing to donate personal time to perform the procedure.
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.
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.
Bland, K. I., W. G. Cioffi, and M. G. Sarr. Practice of GeneralSurgery. Philadelphia: Saunders, 2001.
Grace, P. A., A. Cuschieri, D. Rowley, N. Borley, and A. Darzi. Clinical Surgery, 2nd Edition. London: Blackwell Publishers, 2003.
Miller, B. E. Atlas of Sigmoidoscopy and Cytoscopy.Boca Raton, FL: CRC Press, 2001.
Schwartz, S. I., J. E. Fischer, F. C. Spencer, G. T. Shires, and J. M. Daly. Principles of Surgery, 7th Edition. New York: McGraw Hill, 1998.
Townsend, C., K. L. Mattox, R. D. Beauchamp, B. M. Evers, and D. C. Sabiston. Sabiston's Review of Surgery, 3rd Edition. Philadelphia: Saunders, 2001.
Wigton, R. S. Flexible Sigmoidoscopy and Other Gastrointestinal Procedures. St. Louis: Mosby-Year Book, 2000.
Periodicals
Mandel, J. S. "Sigmoidoscopy Screening Probably Works, But How Well Is Still Unknown." Journal of the National Cancer Institute 95, no.8 (2003): 571–573.
Nelson, D. E., J. Bolen, S. Marcus, H. E. Wells, and H. Meissner. "Cancer Screening Estimates for U.S. Metropolitan Areas." American Journal of Preventive Medicine 24, no.4 (2003): 301–309.
Newcomb, P. A., B. E. Storer, L. M. Morimoto, A. Templeton, and J. D. Potter. "Long-term Efficacy of Sigmoidoscopy in the Reduction of Colorectal Cancer Incidence." Journal of the National Cancer Institute 95, no.8 (2003): 622–625.
Walsh, J. M., and J. P. Terdiman. "Colorectal Cancer Screening: Clinical Applications." Journal of the American Medical Association 289, no.10 (2003): 1297–1302.
Walsh, J. M., and J. P. Terdiman. "Colorectal Cancer Screening: Scientific Review." Journal of the American Medical Association 289, no.10 (2003): 1288–1296.
Organizations
American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 906-6000. E-mail: fp@aafp.org. http://www.aafp.org.
American College of Surgeons. 633 North St. Clair Street, Chicago, IL 60611-32311. (312) 202-5000, Fax: (312) 202-5001. E-mail: postmaster@facs.org. http://www.facs.org.
American Society for Gastrointestinal Endoscopy. 1520 Kensington Road, Suite 202, Oak Brook, IL 60523. (630) 573-0600, Fax: (630) 573-0691. E-mail: info@asgeoffice.org. http://www.asge.org.
Society of American Gastrointestinal Endoscopic Surgeons. 2716 Ocean Park Blvd., Suite 3000, Santa Monica, CA 90405. (310) 314-2404, Fax: (310) 314-2585. E-Mail: sagesweb@sages.org. http://www.sages.org.
Sigmoidoscopy is a procedure by which a doctor inserts either a short and rigid or slightly longer and flexible fiber-optic tube into the rectum to examine the lower portion of the large intestine (or bowel).
Cancer of the rectum and colon is the second most common cancer in the United States, claiming the lives of about 56,000 people annually. As a result, The American Cancer Society recommends that people age 50 and over be screened for colorectal cancer every five years. The screening includes a flexible sigmoidoscopy. Screening at an earlier age should be done on patients who have a family history of colon or rectal cancer, or small growths in the colon (polyps).
Individuals with inflammatory bowel disease (Crohn's colitis or ulcerative colitis) are at increased risk for colorectal cancer and should begin their screenings at a younger age, and be screened more frequently. Many doctors screen such patients more often than every three to five years. Those with ulcerative colitis should be screened beginning 10 years after the onset of disease; those with Crohn's colitis beginning 15 years after the onset of disease.
Some doctors prefer to do this screening with a colonoscope, which allows them to see the entire colon (certain patients, such as those with Crohn's colitis or ulcerative colitis, must be screened with a colonoscope). However, compared with sigmoidoscopy, colonoscopy is a longer process, causes more discomfort, and is more costly.
Studies have indicated that about one-fourth of all precancerous or small cancerous growths in the colorectal region can be seen with a rigid sigmoidoscope. The longer, flexible version, which is the primary type of sigmoidoscope used in the screening process, can detect more than one-half of all growths in this region. This examination is usually performed in combination with a fecal occult blood test, in an effort to increase detection of polyps and cancers that lie beyond the scope's reach.
Precautions
The exam is not always adequate. A 2004 study reported that among older patients and women, sigmoidoscopy is not always effective, particularly because insertion depth is not adequate. For unknown reasons, this is almost twice as true for women as for men.
Sigmoidoscopy can usually be conducted in a doctor's office or a health clinic. However, some individuals should have the procedure done in a hospital day surgery facility. These include patients with rectal bleeding, and patients whose blood does not clot well (possibly as a result of blood-thinning medications).
Description
Most sigmoidoscopy is done with a flexible fiber-optic tube. The tube contains a light source and a camera lens. The doctor moves the sigmoidoscope up beyond the rectum (the first 1 ft/30 cm of the colon), examining the interior walls of the rectum. If a 2 ft/60 cm scope is used, the next portion of the colon can also be examined for any irregularities.
The procedure takes 20 to 30 minutes, during which time the patient will remain awake. Light sedation may be given to some patients. There is some discomfort (usually bloating and cramping) because air is injected into the bowel to widen the passage for the sigmoido-scope. Pain is rare except in individuals with active inflammatory bowel disease.
In a colorectal cancer screening, the doctor is looking for polyps or tumors. Studies have shown that over time, many polyps develop into cancerous lesions and tumors. Using instruments threaded through the fiber-optic tube, cancerous or precancerous polyps can either be removed or biopsied during the sigmoidoscopy. People who have cancerous polyps removed can be referred for full colonoscopy, or more frequent sigmoidoscopy, as necessary.
The doctor may also look for signs of ulcerative colitis, which include a loss of blood flow to the lining of the bowel, a thickening of the lining, and sometimes a discharge of blood and pus mixed with stool. The doctor can also look for Crohn's disease, which often appears as shallow or deep ulcerations, or erosions and fissures in the lining of the colon. In many cases, these signs appear in the first few centimeters of the colon above the rectum, and it is not necessary to do a full colonoscopic exam.
Private insurance plans often cover the cost of sigmoidoscopy for screening in healthy individuals over 50, or for diagnostic purposes. Medicare covers the cost for diagnostic exams, and may cover the costs for screening exams.
Preparation
The purpose of preparation for sigmoidoscopy is to clean the lower bowel of stool so that the doctor can see the lining. Many patients are required to consume only clear liquids on the day before the test, and to take two enemas on the morning of the procedure. The bowel is cleaner, however, if patients also take an oral laxative preparation of 1.5 oz phospho-soda the evening before the sigmoidoscopy.
Certain medications should be avoided for a week before having a sigmoidoscopy. These include:
iron or vitamins containing iron Although most prescription medication can be taken as usual, patients should check with their doctor in advance.
Aftercare
Patients may feel mild cramping after the procedure that will improve after passing gas. Patients can resume their normal activities almost immediately.
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. The most serious complication of sigmoidoscopy is bowel perforation (tear). This complication is very rare, however, occurring only about once in every 7,500 procedures.
Normal Results
A normal exam shows a smooth bowel wall with no evidence of inflammation, polyps or tumors.
Abnormal Results
For a cancer screening sigmoidoscopy, an abnormal result involves one or more noncancerous or precancerous polyps or tumors. Patients showing polyps have an increased risk of developing colorectal cancer in the future.
Small polyps can be completely removed. Larger polyps or tumors usually require the doctor to remove a portion of the growth for diagnostic testing. Depending on the test results, the patient is then scheduled to have the growth removed surgically, either as an urgent matter if it is cancerous, or as an elective surgery within a few months if it is noncancerous.
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.
Questions to Ask the Doctor
Why do I need a sigmoidoscopy?
Should I undergo a colonoscopy instead?
If a biopsy is done, how long before I get the results?
Will I need to have this test again in the future? When?
Resources
Periodicals
Manoucheri, Manoucher, et al. "Bowel Preparations for Flexible Sigmoidoscopy: Which Method Yields the Best Results?" The Journal of Family Practice 48, no. 4 (April 1999): 272–4.
"Office Procedures—Flexible Sigmoidoscopy." American Family Physician 63, no. 7 (2001).
"Women are Twice as Likely as Men to Have an Inadequate Signoidoscopy Examination." Doctor February 5, 2004: 13.
Other
"Diagnostic Tests." The National Digestive Diseases Information Clearinghouse (National Institutes of Health). [cited July 5, 2001]. .
Doctor (many primary care physicians are qualified to perform sigmoidoscopy but do not usually do biopsies). Also gastroenterologists and gastrointestinal surgeons.
10-30 minutes.
Discomfort associated with having endoscope inserted into the rectum and having air instilled into the bowel.
Results Ready When
Special Equipment
Risks/Complications
Average Cost
As soon as the test is over; if biopsies are taken, they require 48-72 hours for analysis.
Sigmoidoscope and light source.
Perforation of the rectum or colon in 1 of about 5,000-7,000 people, bleeding, infection, and pain in the lower bowels.
As a screening test, to look for colorectal cancer or for polyps that may increase the risk of such cancer.
To look for fissures and hemorrhoids, to establish the cause of persistent bloody diarrhea, and to diagnose inflammatory bowel disease.
How it works
A flexible or rigid viewing instrument called a sigmoidoscope is inserted into the rectum and part of the colon, allowing the doctor to view the lining of these organs directly.
Preparation
You may be instructed to give yourself an enema and/or a laxative at home, or this may be done at the testing site.
If you are at a high risk of heart disease, you may be given antibiotics to prevent infection, since there is a small risk that infectious organisms from the bowels may penetrate the bloodstream as a result of this procedure and may travel to the heart.
You remove all clothing and don a hospital gown.
Sedatives or anesthetics are usually not required.
Test procedure
You lie on your side on the examination table, and the doctor inserts a gloved finger into your rectum to perform a digital exam.
A viewing tube called a sigmoidoscope is lubricated and inserted into the rectum. Flexible sigmoidoscopes may be advanced up to about 25 inches into the colon.
Air may be introduced to dilate the bowels, but in smaller quantities than during colonoscopy.
Tissue samples for a biopsy or stool samples may be collected if necessary during the procedure. They are removed with the help of special forceps and suction devices introduced through special channels in the sigmoidoscope.
After the test
You get dressed and are free to leave. You may pass a great deal of gas after the test.
Let your doctor know immediately if you experience abdominal pain or bleeding from the rectum. If a biopsy was performed, small amounts of blood in the stool can be expected but should not continue to appear for more than one to two hours.
Factors affecting results
Stool in the bowels.
Lack of patient cooperation.
Interpretation
The doctor studies the lining of your colon and rectum and looks for abnormalities, particularly polyps and bleeding sites. Any stool and tissue samples obtained are sent to a laboratory to be examined for the presence of infectious organisms, inflammation, or cancerous cells.
Advantages
The test provides a direct view of the bowels.
It makes it possible to perform a biopsy without surgery.
It can be readily performed in a doctor's office without major preparation.
Disadvantages
It's uncomfortable.
It's somewhat invasive, although less so than EGD, ERCP, or colonoscopy.
The next step
Colonoscopy if an abnormality is found; possible biopsy.
DID YOU KNOW?
Improvements in viewing instruments have made this test much more comfortable for patients. Most doctors use a soft, flexible tube that is less than half an inch in diameter. For sigmoidoscopy, which examines the lower third of the colon, the tube is about 2 feet long; for colonoscopy (see below), it is about twice that length. Rigid sigmoidoscopy is mainly used to examine hemorrhoids and abnormalities in the anus.
PATIENT TIP
If you are extremely anxious about this procedure, discuss it with your doctor ahead of time. You can be given a sedative, but you will have to arrange to have someone drive you home afterward.
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