A proctosigmoidoscopy is a procedure for examination of the anus, rectum, and distal sigmoid colon. It may involve the use of a proctoscope, sigmoidoscope, or colonoscope. These instruments all provide visual examination of the intestine, as well as the ability to obtain tissue samples for biopsy.
The large intestine, or colon, is approximately 5 feet (1.5 m) long. It begins on the right side of the abdomen as the ascending colon. This portion of the colon extends from the cecum to the hepatic flexure. The transverse colon then proceeds across the abdomen from the hepatic flexure to the splenic flexure. At this point, the descending colon goes down the left side of the abdomen, to the S-shaped sigmoid colon, rectum, and anus.
The sigmoid colon is the portion of the colon where stool may be stored until it is passed into the rectum. The rectum is usually about 4.7 inches (12 cm) long, and ends at the anus. Stool may be temporarily stored in the rectum until defecation.
Proctosigmoidoscopy may be recommended if someone is experiencing changes in bowel habits, blood or mucus in stools, abdominal pain, or severe itching, known as pruritis. This type of examination may be suggested for those who have a family history of inflammatory bowel disease (IBD), cancer, or other digestive tract diseases. Other symptoms that may prompt a physician to perform a proctosigmoidoscopy include previous occurrences of polyps, unusual flatulence, or urinary tract issues.
In preparation for the procedure, a patient will be likely be given directions for a bowel cleansing. Individual physician’s preparation instructions will vary, but may include a laxative product and clear liquid diet for several hours prior to the procedure, as well as an enema. The sigmoid colon must be free of stool so that the area may be examined thoroughly.
The instrument used for proctosigmoidoscopy is usually a sigmoidoscope, though proctoscopes and colonoscopes may be used as well. Generally, the flexible scope is preferred to the rigid model for comfort reasons. The chosen scope will likely have a light, camera, bellows, and a biopsy instrument.
During proctosigmoidoscopy, the doctor may use the bellows to blow air into the bowel. This inflates the area so that all areas may be properly visualized with the camera apparatus. If a polyp or other unusual lesion is observed, the biopsy instrument may be inserted through the scope to remove a sample of the tissue for lab analysis.
As with any medical procedure, there are risks to proctosigmoidoscopy. There is a rare chance of perforation of the bowel wall with the scope. If this occurs, surgery may be necessary to repair the torn tissue.