Colonoscopy: Information for women

A colonoscopy 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 see 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 the tissue, which 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 looking at the walls of the colon. Throughout the procedure, the colon is inflated with 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 and/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 causes you to fall asleep for a short while and makes the examination less unpleasant. 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.

It is usually possible to push the colonoscope up to the appendix to view the entire large intestine. Sometimes the colonoscopy needs to be stopped because it's too unpleasant or because the colonoscope can't be pushed far enough. That may be due to abnormal anatomical features, scars or growths in the abdominal cavity. This problem is more likely in people who have had abdominal surgery in the past.

In colonoscopies, the entire colon is examined to find polyps and potentially cancerous tissue. Larger colorectal polyps are usually discovered that way. 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 cancer that has already started growing is nearly always found during colonoscopies, though. It is estimated that 95% of all colorectal cancers are discovered in this way.

Several studies have looked into the pros and cons of colonoscopies. These 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.

Inflating the bowel with air sometimes causes temporary problems such as pain or bloating. The sedative or anesthetic used may lead to problems like dizziness or cardiovascular issues.

In about 1 to 2 out of 1,000 women, colonoscopies lead to complications that need to be treated. The most common of these is bleeding caused by the removal of polyps. The bleeding can usually be treated well in an outpatient setting.

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. A bowel perforation 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 few, small polyps are found, and they're not considered to be abnormal, the next endoscopy can be done ten years later.

But if several, abnormal or larger 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's necessary to have a second colonoscopy because it wasn't possible to completely remove a polyp during the first. In Germany, the statutory health insurers cover the costs of any further examinations that are needed.

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