Colonoscopy is one of the most important and most frequently performed endoscopic examinations of the digestive tube. In ideal case, it allows to investigate the whole length of colon and terminal part of the small intestine.


The flexible endoscopic device is inserted into patient's rectum and the doctor gently introduces it further into the colon. The device is equipped with a video camera and a light source. The video is projected on a screen where it is visible by the examiner. The visibility can be increased by many methods such as the chromoendoscopy.


The endoscope allows using small forceps to painlessly take a small sample of suspiciously looking mucosa or other found lesions for histological examination. In addition, it is possible to use many working tools to perform therapeutic procedures. Perhaps the most commonly performed intervention is polyp removal by polypectomy.


The day before the examination, the patient should eat only a small breakfast (white yoghurt) and then it is advisable to drink only colorless liquids. Few hours before the procedure, the examined must drink special bowel-cleansing solution. There are more types of such solutions working on different principle, but their goal is similar – to cause acute diarrhea and clean the inside of the intestines to allow good visibility during the colonoscopy.


Because many therapeutic procedures during the colonoscopy can cause bleeding (typically more extensive polypectomy), it is advisable to discontinue stronger anticoagulants (or substitute them for another type) in certain time before the examination. However, some anticoagulants are essential and their discontinuation must be always indicated by a doctor.


Just before the colonoscopy, the patient is usually given a sedative injection to calm down. In such case, the patient is asked not to drive motor vehicles for the rest of the day.


Colonoscopy is indicated when we have suspicion of a pathology of the large intestine. It may be performed in chronic dyspeptic problems including chronic diarrhea, constipation, abdominal pain, weight loss, blood in stool (including positive FOBT) and others. It helps to diagnose inflammatory bowel diseases as the ulcerative colitis and certain forms of Crohn's disease. Probably the biggest importance of colonoscopy is removal of intestinal polyps that could develop into the colorectal cancer.


Colonoscopy is a relatively safe and relatively painless examination. However, some patients do not tolerate it well. The problem is an unpleasant feeling when the intestine is stretched by the endoscopic tube and when the intestine is distended by air. Therapeutic intervention may cause bleeding into the intestine, which is however usually only mild and self-limiting. Probably the worse complication is perforation of the large intestine. The risk of this situation is increased in the elderly and in large intestine affected by other disease (serious inflammation, diverticulosis, etc.). The perforation is a serious complication that threatens the patient by peritonitis. Small hole can be quickly closed endoscopically; large perforation must be solved surgically.


The biggest advantage is the possibility to see the inside of colon by the video camera, the possibility to take biopsies and therapeutically remove intestinal polyps. In addition, the patient is not exposed to any harmful radiation during the procedure.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources