A colonoscopy is the procedure that doctors use to see the large bowel, or colon, directly. Doctors carry it out so that they can check out the possible causes of bowel symptoms. Bowel symptoms such as diarrhea, constipation, irregular bowels and pain, wind and bloating can come from many causes, and rather than guessing a colonoscopy allows doctors to view the bowel for a diagnosis. To perform a colonoscopy a small camera attached to the end of a flexible tube is put into the back passage and gently moved up the full length of the large bowel.
The patient lies on their side or back for the procedure, and many hospitals prefer to do the procedure while the patient is awake, but sedated. This means the patient is able to cooperate by moving in an advantageous way if necessary, and also eliminates the risks of a general anesthesia. Done this way the colonoscopy is a day procedure.
Before the colonoscopy can be performed the patient has to prepare their bowel. This means removing everything in there to allow a clear view of the bowel surface. The patient does this at home over the three days prior to the procedure. Certain foods are eliminated initially to leave a low reside, and then this residue is removed by the use of laxatives. Different surgeons prefer different regimes for this. One common method is drinking large quantities of a special solution, usually in conjunction with laxative tablets. The day before all solid food is eliminated from the diet although clear fluids are still allowed. The better this preparation is carried out the better the results will be. The surgeon will provide the exact details before the day of the procedure.
A patient can still take most of their drugs but should stop aspirin and iron. Other drugs may need to be stopped at varying times before the procedure. The doctor also needs to know if the patient is taking herbal supplements, or has had replacement joints, heart valve surgery or a pace maker.
Once the camera is inside the patient the surgeon will be able to see evidence of which diseases are present or absent. These include celiac disease, ulcerative colitis, diverticulitis, Crohns and cancer. A small biopsy or sample of tissue may be taken to confirm a diagnosis with a loop attached to the colonoscope. Polyps are pre cancerous growths on the wall of the bowel that are often removed during the procedure.
The main risk during a colonoscopy is of puncturing the bowel. There may also be bleeding due to trauma or from a biopsy site. Sometimes the severity of any bowel disease is such that the colonoscopy is stopped.
A virtual colonoscopy is performed without inserting a camera into the rectum. After following the bowel preparation procedure the patient lies on a table and a small amount of air is pumped into the large bowel via the rectum. A series of x-rays are then taken, or a CT scan performed, which a computer collates to give a virtual view of the bowel. This shows polyps, and constrictions, but is not as accurate at diagnosing the causes of any problems. A physical colonoscopy may still be necessary.
Following the colonoscopy the patient will often have mild bowel discomfort, indigestion and bloating because air has entered the bowel, or because of minor trauma. Some slight bleeding is common, but should be reported if it is severe or ongoing. Normal activities should be possible after twenty-four hours.