Colonoscopy: Information for women

A colonoscopy (sometimes also called coloscopy) is an examination of the entire large intestine with a special endoscope called a colonoscope. This is a long flexible tube about 1.5 meters long and 1 cm in diameter. The end of the colonoscope has a light attached to it and a tiny video camera so that the doctor can view the inside wall of the bowel. If polyps or abnormal areas of mucous membrane are found during the procedure, they can be removed right away. A small wire loop or forceps can be pushed through the colonoscope and used to remove them. The tissue sample is then examined more closely in a laboratory.

The colonoscope is inserted into the anus and pushed up to where the small and large intestine meet (roughly where the appendix is, as in the illustration). The doctor then slowly pulls the colonoscope out while viewing the walls of the colon. Throughout the procedure, the colon is widened using air or carbon dioxide to make it easier for the doctor to see the walls of the bowel.

Before having a colonoscopy, you will have a doctor's appointment to discuss the procedure and how to prepare for it. Your entire large intestine has to be as empty as possible for the examination. Depending on what time of day it is carried out, you will take a laxative with two to four liters of fluids the evening before or on the morning of the procedure. You can drink water, broth, tea or juice. You are not supposed to eat any solid foods from two to three hours before taking the laxative until after the colonoscopy. After cleansing your colon in this way, only a clear liquid should come out when you go to the toilet.

It is usually possible to eat again right afterwards. If larger polyps were removed it may be a good idea to wait a while, though.

You will be offered a sedative before the colonoscopy. This allows you to sleep so that you will hardly be aware of the examination. If you take a sedative you should not drive or operate any machinery for the next 24 hours. The examination takes about 15 to 45 minutes.

Sometimes a colonoscopy is stopped if it becomes too unpleasant. It's also not always possible to push the endoscope far enough into the large intestine because of particular anatomic features. This problem is more common in people who have had abdominal surgery in the past because that can cause tissue to scar and stick together in the abdominal cavity, making the intestinal loops too inflexible.

In colonoscopies, the entire colon is examined to find polyps and potentially cancerous tissue. Larger colorectal polyps are usually detected. But even colonoscopies don't offer complete protection against colorectal cancer. Some abnormalities may be overlooked, especially small or flat polyps that are harder to see. It also isn't always possible to fully cleanse the bowel before the examination. Then it's more difficult to get a clear view of the walls of the bowel.

Any tumors that have already started growing are nearly always found during colonoscopies. It is estimated that 95% of all tumors are discovered in this way.

Several studies have looked into the advantages and disadvantages of colonoscopies. The pros and cons depend on various factors, including the age of the person being examined. The following tables show the main results for 55-year-old women and for 65-year-old women. Each table describes what could happen within a period of ten years after having one colonoscopy.

Colonoscopy is the screening examination for colorectal cancer that takes the most time and effort. Preparing for it – drinking large amounts of fluid and completely emptying your bowels – can be unpleasant and bothersome.

Widening the bowel with air quite often causes temporary side effects such as mild pain or bloating. The sedative or anesthetic used may lead to problems like dizziness or cardiovascular issues.

Overall, complications that require medical treatment occur in about 1 to 2 out of 1,000 colonoscopies. The most common of these is bleeding following the removal of polyps. The bleeding can usually be treated without having to stay in the hospital.

In fewer than 1 out of 1,000 colonoscopies, cardiovascular problems or bowel perforations that require treatment occur. The bowel may become perforated if the tip of the colonoscope is pushed against the wall of the bowel with too much force, or if the wall of the bowel is injured when a polyp is removed. This can be life-threatening and immediate surgery is needed.

Polyps are discovered in about one third of all women who have a colonoscopy. If only a single, small, normal polyp is found, the next colonoscopy can be done ten years later.

But if an abnormal or larger polyp is found, or if more than three polyps are removed during the procedure, there is a greater risk of more polyps developing in the next few years. If that happens, doctors recommend having the next colonoscopy in three to five years. In rare cases it is necessary to have a second colonoscopy because it wasn't possible to completely remove a polyp during the first. In Germany, the costs of these examinations are covered by statutory health insurers.

Because it isn't possible to predict which polyps will become cancerous and which won't, many "harmless" polyps will be removed too. But that is an inevitable consequence of screening.