What is a Colonoscopy?
A Colonoscopy is a procedure that allows your specialist to examination the lining of the large bowel (colon). This is performed using a narrow flexible tube called a colonoscope which has a camera in the tip that captures images of the inner lining of your bowel. These images are transmitted to a TV monitor which your specialist looks at during the examination. The colonoscope is inserted into your anus and is slowly advanced around the whole colon.
Why is a Colonoscopy is performed?
- To evaluate unexplained anaemia.
- To evaluate unexplained blood in the stool, abdominal pain, persistent diarrhoea, or abnormalities (such as polyps found on contrast x-rays – barium enema).
- To determine the type and extent of inflammatory bowel disease (ulcerative colitis and Crohn’s disease).
- To follow up a previous find of polyps, colon cancer or a family history of colon cancer.
- To obtain tissue specimen for biopsy.
- To screen for colorectal cancer.
What is the preparation for a Colonoscopy?
In order to obtain accurate results, the colon must be completely clean of stool. Instructions on how to cleanse your colon will be given to you by the MacMurray Centre. In general, this will include not eating high fibre foods two days before the test and taking laxatives. To avoid dehydration, drink plenty of clear liquids such as juices and broths during the preparation.
Inform your specialist of all prescription and non-prescription medication you are taking, as well as any allergies you may have. Unless otherwise instructed, continue taking any regularly prescribed medication. You may be told to stop taking blood-thinning medications for several days before the test. Stop taking iron supplements a week before the test (unless otherwise instructed by the health care provider) as iron residues produce a dark black stool which makes the view inside the bowel less clear.
How is a Colonoscopy is performed?
A colonoscopy is performed in a fully equipped examination room. In most instances you will be lying on your left side with your knees drawn up toward the chest. Your specialist will insert the colonoscope through the anus and gently advance to the lowest part of the small bowel.
Carbon dioxide is used to inflate the bowel to provide better views. You may experience a sensation of fullness, bloating, pressure or cramping as the scope moves inside. You may also feel the urge to defecate but your bowel is empty and any residual liquid is removed with suction.
As the instrument is withdrawn, a careful examination is made of the lining of the colon. Tissue samples may be taken with tiny biopsy forceps inserted through the scope. Polyps may be removed with electrocautery snares, and photographs may be taken. Specialised procedures, such as argon plasma coagulation, endoscopic polyp and tumour resection, and dilatation of narrow areas may also be done.
Intravenous sedation is usually given for the procedure. Most patients consider the test only slightly uncomfortable and many patients fall asleep during the procedure. The procedure generally takes about 30 minutes but could be longer particularly if you require any endoscopic treatment during the test.
What happens after a Colonoscopy?
After your colonoscopy you will be wheeled into the recovery room where you will rest to allow the sedation to wear off. You will be in the department for at least one hour after the procedure if you have received intravenous sedation.
When you wake up your specialist will discuss your examination results with you and a written summary will be given to you for your reference. A copy of your report will be sent to your GP.
A light snack will be served before you leave MacMurray. It is important to rehydrate (drink plenty of fluids) following your procedure. You are able to return to your normal diet following discharge.
If you have received sedation you must have someone to take you home after the test and stay with you, as you will be drowsy and unable to drive. The sedative may also affect your ability to recollect details about your procedure. Sedation should wear off in a few hours. You should stay off work the day of your procedure but can resume normal activities the following day.
If the doctor finds an area in the colon that needs further evaluation, a biopsy (small sample of tissue) can be obtained and sent to the pathology department for examination under a microscope. If a polyp is found, the specialist may remove the polyp at the same time. Polyps are small growths on the inner lining of the bowel. Most polyps are benign (not cancerous), but some polyps are precancerous.
You may be asked to make a follow up appointment with your specialist to discuss biopsy results. Biopsy results will also be sent to your GP (may take up to 10 working days).
Colonoscopy findings may include the following:
- Inflammatory bowel disease.
- Diverticulosis (abnormal pouches on the lining of the intestines, most often seen in older people).
- Lower gastrointestinal (GI) bleeding.
- Polyps (which can be removed through the colonoscope during the exam).
Safety and Risks
A colonoscopy is generally a very safe and simple test. Complications are rare but may include:
- Bowel perforation (a hole or tear in the wall of the colon), requiring a repair operation (fewer than 1 out of 1,000 tests).
- Heavy or persistent bleeding from biopsy or polyp-removal sites (1 out of 1,000 tests).
- Adverse reaction to sedative medication, causing breathing problems or low blood pressure (4 out of 10,000 tests).
- Infection requiring antibiotic therapy (very rare).
- Nausea, vomiting, bloating or rectal irritation.