WHAT IS SIGMOIDOSCOPY TEST?
Sigmoidoscopy is the endoscopic visualization of the interior space and walls of the sigmoid colon, using a sigmoidoscope. A sigmoidoscope is a 50-cm fiberoptic tube with a lighted mirror lens system that illuminates the sigmoid colon for visualization. A rigid sigmoidoscope is rarely used because of the degree of discomfort it causes. The most common method for this procedure is a flexible sigmoidoscopy, in which a short, flexible tube with a light source is inserted through the rectum and advanced to the sigmoid colon. Because flexible sigmoidoscopy examines only the lower one–third of the colon, it cannot completely rule out colon cancer. However, it has been shown to identify 50%-70% of advanced colorectal neoplasms and thus is considered a cost-effective test for screening. The American Cancer Society recommends screening sigmoidoscopy every 5 years for all adults >50 years, followed by colonoscopy in those with positive results.