Sigmoidoscopy

Description
Sigmoidoscopy is a procedure used to examine the lower part of the large intestine and rectum (the end of the large intestine).

Anatomy
The small and large intestines form the bowel. The large intestine extends from the small intestine to the anus (the opening at the far end of the digestive tract through which waste leaves the body). The large intestine is divided into segments: the ascending (right) colon, the transverse colon, the descending (left) colon and the sigmoid colon, which is connected to the rectum. Together, the segments of the colon extract water from undigested food and temporarily store bodily waste, which eventually leaves the body through the anus.

Purpose
Sigmoidoscopy can help doctors detect, evaluate or treat various conditions in the lower colon, such as:
diverticulosis (the presence of diverticula -- small, protruding pouches that can develop in the gastrointestinal tract, usually in the colon)
polyps (abnormal tissue growth)
hemorrhoids (stretched and swollen veins in the lower rectum or anus)
ulcers (open sores)
colorectal cancer

Indications
Sigmoidoscopy is about 80 percent effective in identifying significant colon disease. The U.S. Preventive Services Task Force (USPSTF) and the American Cancer Society (ACS) have recommended sigmoidoscopy as one of the screening tests for colorectal cancer, one of the leading causes of cancer deaths in the United States. Screening for colorectal cancer with annual fecal occult blood testing, periodic sigmoidoscopy or a combination of both screening methods can decrease the rates of death from colon cancer. Sigmoidoscopy itself is being recommended about every three to five years starting at age 50 and ending at age 80. If you have a family history of colon cancer, chronic inflammatory bowel disease or other risk factors for colon cancer, you may need earlier or more frequent or extensive testing.
If your doctor suggests a sigmoidoscopy, it does not necessarily mean that cancer is suspected. Sigmoidoscopy may also be recommended if:

You have abdominal or rectal pain, unexplained rectal bleeding or occult (hidden) blood within your stool.
You have unexplained weight loss or your bowel habits change (you notice diarrhea, constipation or pencil-thin stools, for example).
You have an abnormal barium enema (an X-ray of the bowel after the doctor inserts barium, a contrast dye, into the rectum).
The doctor wants to biopsy suspicious areas, remove polyps, or monitor inflammatory bowel disease (a chronic disorder in which the intestine becomes inflamed).

Patient preparation
Before the procedure, discuss the risks and benefits of sigmoidscopy with your doctor. You'll be asked to sign an informed consent document.
Your rectum and lower colon will be emptied before the procedure. The day before the appointment, your diet may be restricted to clear liquids. It's especially important to avoid red or orange gelatin because these products can resemble blood as they pass through the colon. You may also need to take medications that will encourage bowel movements. The morning of the test, you may need an enema (a solution used to stimulate a bowel movement).


Procedure
Sigmoidoscopy can be done in an outpatient or clinic setting, a hospital room, a special lab or an operating room. Anesthesia or sedation is not typically necessary.
The sigmoidoscopy can be done while you're in a kneeling position or lying on your side. An adjustable chair is used for the kneeling position. If you're lying down, you'll lie on an exam table on your left side with your right knee drawn up toward your chest. Once you're comfortable, the doctor will lubricate an instrument called a sigmoidoscope (a slender, tube-like device equipped with a light). The scope will be gently inserted into your anus, through the rectum, and into your lower colon. The doctor may send puffs of air through the scope to better view the bowel lining. When the sigmoidoscope is removed at the end of the exam, the air will often be suctioned out to minimize bowel cramping and discomfort.

The procedure usually takes about 20 minutes. It may take a little longer, however, if the doctor does a biopsy (takes a tissue sample for microscopic examination) or remove polyps or hemorrhoids.


Postprocedure care
After the procedure, you may have abdominal gas pain. Walking can ease this symptom. You may also notice slight rectal bleeding, especially if a biopsy was done. Call your doctor if you have heavy bleeding, severe abdominal pain, abdominal bloating, fever with chills or other symptoms described by your doctor.

Benefits
Sigmoidoscopy allows a doctor to clearly see the lower colon and rectum, areas difficult to see with other procedures. This visual exam also helps the doctor accurately diagnose certain diseases, making earlier treatment possible. Routine sigmoidoscopy screening significantly decreases the risk of death from colorectal cancer.

Risks
The procedure will not be done if the doctor believes your bowel may be easily perforated (torn) or suspects that you already have a perforated colon. Possible complications of sigmoidoscopy may include:
perforation of the colon
bleeding from a biopsy site
infection
incomplete viewing of the lower colon (because of inadequate bowel preparation or for other reasons)

Considerations
The exam is limited to only the lower part of the colon. You may need a colonoscopy, a more extensive procedure, if your doctor needs to see the entire colon.