Rectosigmoidoscopy is a partial colonoscopy. The purpose is to detect diseases in this area and, if necessary, to remove polyps with a small surgical procedure. In rare cases, the procedure may cause injury to the lower portion of the bowel.
What is rectosigmoidoscopy?
Rectosigmoidoscopy is a partial colonoscopy. The purpose is to detect disease and, if necessary, remove polyps with a minor surgical procedure. Rectosigmoidoscopy is used to examine the first part of the colon, rectum and anus. It can be used to detect diseases in this area or to monitor its progress. In this context, rectosigmoidoscopy is also called small colonoscopy. In contrast to colonoscopy or large colonoscopy, where the entire large intestine is mirrored, only the last section of the large intestine (approx. 30 – 60 cm), the rectum and the anus are subject to examination during rectosigmoidoscopy. In preparation for the examination, the rectum must be emptied by two enemas. Adequate bowel cleansing is also possible by taking laxatives. Medications do not need to be administered during rectosigmoidoscopy, unlike colonoscopy. However, they are still sometimes used. Both sigmoidoscopes and colonoscopes are used in the examination.
Function, effect, and goals
Small colonoscopy (sigmoidoscopy or rectosigmoidoscopy) requires the use of a flexible endoscope called a sigmoidoscope. The sigmoidoscope consists of a tube approximately 80 cm long that contains a light source and a small camera at the end. The camera can be used to examine the intestinal wall. Polyps or suspicious areas of mucous membrane can be removed using forceps or a loop on the endoscope. Samples are taken from these pieces of tissue and examined in the laboratory. Alternatively, the small colonoscopy can be taken with a colonoscope, which is longer and usually used for colonoscopy. To prepare for rectosigmoidoscopy, either a laxative is drunk or an enema is given. In total, the small endoscopy takes only five minutes, and it is not necessary to take medication. However, sleeping pills are still usually injected into the arm vein for sedation. Then the flexible endoscope is pushed through the anus into the lower part of the colon. During this process, special accessories are used to take samples. Although no medication is necessary for a small colonoscopy, sometimes sleeping pills are injected to prevent possible painful sampling. A disadvantage of small colonoscopy is also often the painfulness of the examination if no medication is administered. The area where the small colonoscopy is performed is where about two-thirds of potential colon cancers grow. Usually, this area is also the first to be affected by polyps. If polyps are found there, a large colonoscopy is usually recommended. However, colonoscopy is more time-consuming and involves a higher risk. Investigations into whether colonoscopy achieves better screening results than rectosigmoidoscopy have yet to show detailed study results. So far, it has been shown that even the small bowel examination drastically reduces the risk of colorectal cancer by removing polyps. According to available studies conducted within eleven years, 5 out of 1000 people died of colorectal cancer without small bowel examination (rectosigmoidoscopy). With rectosigmoidoscopy, only 3 to 4 out of 1000 people died of colorectal cancer in the same period. The large colonoscopy, in turn, is performed with a colonoscope, which works like a sigmoidoscope. However, it is 150 cm long and can view the entire colon. For the examination, it is passed over the anus, the rectum and through the entire colon until it reaches the border with the small intestine. To prepare for the examination, nothing is eaten 24 hours beforehand. A laxative with plenty of fluid then causes the bowel to empty completely. Similar to partial colonoscopy, samples are taken and any polyps are removed. To dilate the bowel, carbon dioxide is introduced into the bowel to better access all bowel segments.
Risks, side effects and dangers
Unfortunately, rectosigmoidoscopy can also cause side effects and, in some cases, carries risks. For example, without the administration of painkillers or sleeping pills, there is often moderate to severe pain during the examination. More common side effects represent temporary bloating caused by the distension of the bowel by carbon dioxide. In addition, the laxatives that had to be drunk before the examination may cause diarrhea for days after the rectosigmoidoscopy. In rare cases, complications occur with small colonoscopies. For example, severe bleeding and intestinal perforation can occur in 4 out of 10,000 cases. The risk of complications is much greater with large colonoscopies. Thus, approximately 26 to 35 out of 10,000 people suffer serious complications during colonoscopy. Mainly, these complications are bleeding during the removal of polyps. In very rare cases, rupture of the bowel may occur. Another complication factor is the medication administered. Thus, allergic reactions can occur. Cardiovascular disorders are also possible, caused by the drugs. After the examination, there is always flatulence caused by the carbon dioxide gas introduced into the intestine. The drugs have a sedative effect, so the patient is not fit to drive after the rectosigmoidoscopy or colonoscopy and needs an escort to go home. In any case, the risks of rectosigmoidoscopy or colonoscopy are infinitely lower than those of undetected colorectal cancer.
