What to expect from a colonoscopy
There are all sorts of ‘‘oscopies’’ in medicine – colposcopy involves examination of the cervix, laparoscopy involves looking at the area inside the abdomen and pelvis and cystoscopy relates to the bladder, the list goes on.
In simple terms, an ‘‘oscopy’’ (more correctly known as an endoscopy) just means the insertion of a small tube directly into the body, to examine an organ or internal tissue in more detail.
This technique is hugely useful and has many different applications. Millions of ‘‘oscopies’’ are performed all over the world every year.
Colonoscopy refers to an internal examination of the colon, or large intestine. The colon is the part of the bowel that connects the stomach and small intestine with the rectum and anus (and then the outside world), and its role is to remove fluid, salts and some nutrients to form a solid bowel motion or stool.
Many bowel cancers develop in the colon, starting out as small growths or pre-cancers known as polyps and, if left untreated, can invade the wall of the colon and beyond.
Colonoscopy is used to check for the presence of polyps, or even bowel cancer itself, and to look for other conditions that can affect the colon as well. These include:
■ Inflammatory bowel disease, such as Crohn’s disease or Ulcerative colitis.
■ Diverticulitis, a condition where small pouches appear in the bowel wall, sometimes causing pain and diarrhoea.
■ Strictures or narrowings in the bowel passage that can lead to obstructions.
You might be referred for a colonoscopy if your doctor is concerned that you have ongoing bowel symptoms (such as pain, altered pattern of toileting, blood or mucous in your bowel motions, unexplained weight loss) and they want to find out the cause.
You might also be referred for a colonoscopy if you have had a positive bowel cancer ‘‘screening’’ test and need more formal assessment to rule out cancer.
Bowel cancer screening involves testing your stool for the microscopic presence of blood. If this is positive, it is more likely that you have bowel cancer or a polyp (which can be pre-cancerous, but can also be benign), but the only way to know for sure is to look inside the bowel with a colonoscope.
The other reason to do a colonoscopy is for surveillance or monitoring, either because you have a strong history of bowel cancers in your family and your risk is higher than the average person’s, or you suffer from a condition such as Crohn’s disease or polyps that require regular checking.
If you are referred for a colonoscopy, here is what you can expect:
■ As the specialist will insert a long flexible tube containing fibreoptic lighting and a camera into your bowel, it is important your bowel is empty so they can see. The clinic will provide you with some bowel ‘‘prep’’ and detailed instructions of how to use it. It may also recommend a particularly light or liquid diet for a day or two before. The bowel prep is basically a very strong laxative that ensures you pass anything in there before having the procedure.
■ Unless you are having anything more complicated done at the same time, colonoscopy itself is a simple, day-procedure, and you are usually home again in a few hours. It requires light sedation to relax you, but not a full anaesthetic. Because you have had sedation, you won’t be able to drive immediately afterwards.
■ The doctor will lie you on your side or back and will gently insert the tube into your back passage. It is uncomfortable rather than painful. They may need to inflate your bowel a little with some air and this can make your tummy feel quite distended and ‘‘windy’’.
■ As they move the tube and camera along your bowel, the colonoscope will record pictures of your bowel wall, enabling the doctor to see if there is anything abnormal there.
■ If they detect anything like a polyp or unusual growth, they will take a sample of it through the colonoscope, known as a biopsy. This tissue sample enables the lab to check if the cells are cancerous or benign. In some cases, polyps can be entirely removed by using the colonoscope, avoiding the need for surgery.
■ Ideally, the doctor will see the entire colon during this test. If for any reason they can’t do this, for example if there is an area of narrowing or it is too
The vast majority of times a colonoscopy is a simple, if not particularly dignified, procedure.
uncomfortable to do the whole thing, they will discuss it with you and refer you for further testing as indicated.
■ The whole procedure should take about 20-30 minutes and your doctor will discuss their findings afterwards. Any samples or biopsies taken will need to be analysed by a lab, so the results of those often aren’t available for a number of weeks.
Over recent years, new technology involving CT scans has helped to simplify colonoscopies for some people. Known as CT colonoscopy, or CTC, this way of looking at the bowel is much lessinvasive and much shorter, taking approximately 5-10 minutes, and giving very clear images of the internal bowel.
Although I am sure many people given a choice would opt for this, it isn’t suitable for everyone: it isn’t as good at picking up smaller polyps, and if a polyp or lump is found, traditional colonoscopy is then required to take the samples for further testing. Despite these drawbacks, CTC is an easy way to screen people for bowel cancer, and requires less ‘‘manpower’’ than normal colonoscopy. As yet, it isn’t universally available and often is only an option in the private sector, so funding is an issue.
Both types of colonoscopy are very safe. Occasionally people can get bleeding from the site of a biopsy or polyp-removal and, even more rarely, there can be a small puncture in the wall of the bowel known as a perforation, but the vast majority of times this is a simple, if not particularly dignified, procedure.
For more information, visit Bowel Cancer NZ at bowelcancernz.org.nz