sigmoidoscopy

sigmoidoscopy is a common endoscopic procedure used to examine the lower portion of the large intestine, specifically the sigmoid colon and the rectum. It is a vital tool in the diagnosis and management of various gastrointestinal tract disorders. The procedure is often performed by a gastroenterologist or a colorectal surgeon and can be either diagnostic or therapeutic in nature. Its role in colorectal cancer screening programs, such as those recommended by the American Cancer Society, is well-established.

Procedure

The examination is typically conducted using a flexible endoscope known as a sigmoidoscope, which is inserted through the anus. The device transmits images to a monitor, allowing the physician to visually inspect the mucosal lining for abnormalities like polyps, inflammation, or tumors. During the procedure, the physician may insufflate air to distend the colon for better visualization. Instruments can be passed through the scope's channel to perform biopsies or remove polyps, a process known as polypectomy. The entire process usually takes between 10 to 20 minutes and is often performed without sedation in an outpatient setting like a clinic or hospital endoscopy unit. Advancements in technology, such as high-definition television imaging, have improved the diagnostic yield of the examination.

Indications

Common reasons for performing this procedure include investigating symptoms such as rectal bleeding, unexplained diarrhea, abdominal pain, or changes in bowel habits. It is a cornerstone for screening and surveillance in individuals at average or increased risk for colorectal cancer, as endorsed by organizations like the United States Preventive Services Task Force. The procedure is also indicated for monitoring patients with a history of inflammatory bowel disease, such as ulcerative colitis, or for assessing the response to treatments for conditions like diverticulitis. Furthermore, it can be used to evaluate abnormal findings from other tests, such as a positive fecal occult blood test or an abnormal barium enema.

Preparation

Adequate bowel preparation is essential for a successful and clear examination. This typically involves a restricted diet, often clear liquids, for 12 to 24 hours prior. Patients are usually instructed to use one or more enemas shortly before the procedure to cleanse the distal colon. Instructions may vary depending on the protocol of the institution, such as those at the Cleveland Clinic or Mayo Clinic. Patients are generally advised to inform their doctor of all medications, especially anticoagulants like warfarin or clopidogrel, which may need to be temporarily adjusted. Unlike preparation for a full colonoscopy, a rigorous oral lavage solution is usually not required.

Risks and complications

While generally safe, the procedure carries a small risk of complications. The most serious, though rare, risk is perforation of the colon wall, which may require surgical repair. Other potential complications include significant bleeding, particularly after a biopsy or polypectomy, and reactions to the enema preparation. There is a very low risk of infection, and complications related to sedation are uncommon when it is used. Patients should report severe abdominal pain, fever, or heavy rectal bleeding to their physician immediately. The overall safety profile is supported by data from large studies like the PLCO cancer screening trial.

Results and follow-up

Findings can range from normal to the identification of hemorrhoids, diverticula, polyps, colitis, or cancer. If adenomatous polyps are found, they are usually removed, and the patient may be referred for a full colonoscopy to examine the entire colon. A normal result in a screening context typically suggests a repeat examination in 5 to 10 years, per guidelines from the American College of Gastroenterology. If cancer is diagnosed, further staging with imaging like a CT scan is arranged. The results directly inform management plans, which may involve referral to an oncologist or scheduling surveillance intervals as recommended by the National Comprehensive Cancer Network.

Category:Endoscopy Category:Medical procedures Category:Gastroenterology