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Colonoscopy: reasons, procedure and risks

by Josephine Andrews
Published: Last Updated on 394 views

During a colonoscopy , the doctor uses a special optical device to inspect the inside of the intestine and can use special working channels to carry out minor interventions or take tissue samples. The large intestine is referred to as a colonoscopy, the small intestine is also called enteroscopy. Read all about the colonoscopy, its risks and what you as a patient have to consider. 

What is a colonoscopy?

A colonoscopy is a frequently performed examination in internal medicine, in which the doctor examines the inside of the intestine. A distinction is made between small bowel (enteroscopy) and large bowel (colonoscopy). The sole endoscopic examination of the rectum ( rectoscopy ) is also possible.

Further information: Rectoscopy

You can read about how the examination of the rectum (rectum) works and when it is performed in the article Rectoscopy .

While the large intestine can be viewed well with a tubular instrument, an endoscope (also known as a colonoscope), the small intestine is more difficult to reach. The doctor can assess the upper small intestine behind the outlet of the stomach, the duodenum , as part of an extended gastroscopy (gastroduodenoscopy); today, he uses what is known as capsule endoscopy for deeper sections.

When is a colonoscopy performed?

The colonoscopy is a frequently used examination, which serves both as a preventive measure and to clarify unclear symptoms or aftercare after interventions or, for example, tumor diseases. The following diseases can be diagnosed particularly well with the colonoscopy:

In the case of an intestinal obstruction , known acute diverticulitis or peritonitis , no colonoscopy should be performed!

Colonoscopy: prevention in Germany

The early detection of colorectal cancer is one of the most important indications for colonoscopy: the earlier a tumor is discovered, the better the chances of recovery. Patients with health insurance are entitled to a screening colonoscopy from the age of 55 even if they have no symptoms. Statutory or private health insurance pays for this.

Patients with an increased risk of colon cancer, for example if there is a family history of colon cancer or chronic inflammatory bowel disease, receive a colonoscopy earlier. The doctor can decide when it makes sense to have a colonoscopy in an individual case, taking into account the previous and family history.

Colonoscopy check-up: How often is it necessary?

Statutory health insurance companies recommend the first colonoscopy at the age of 50 for men and women over the age of 55 who have no known increased risk of colon cancer. If the findings are unremarkable, a new colonoscopy after ten years is sufficient. If the doctor finds abnormalities such as polyps during the colonoscopy, a closer check is often necessary.

What do you do during a colonoscopy?

In order for the doctor to see something during the colonoscopy, some preparations are necessary the day before. This includes cleaning the intestines. Anxious patients can be given a sedative immediately before the procedure if they wish.

Further information: Colonoscopy: Preparation

You can read about the measures the patient should take to prepare for the colonoscopy in the article Colonoscopy: Preparation .


The doctor pushes the colonoscope with a small camera through the anus into the rectum and from there further into the large intestine. The colonoscope is particularly flexible, allowing the doctor to easily pass through the convolutions of the intestine. The images transmitted by the colonoscope are displayed on a monitor. Depending on which section of the colon the doctor assesses, a distinction is made between:

  • Ileokoloscopy (additional assessment of the ileum)
  • high colonoscopy (assessment of the entire colon up to the appendix)
  • Sigmoidoscopy (examination of the sigmoid colon, part of the large intestine)
  • partial colonoscopy (assessment of the lower colon)

If necessary, he uses the instrument to take small samples, so-called biopsies, from the intestinal wall, which are then examined in the laboratory.

As an alternative to the classic colonoscopy with an endoscope, virtual colonoscopy, including CT colonoscopy, is also available. During this examination, a computer tomograph produces images of the intestine . In order for this to be clearly visible, it is previously inflated with air.

Small bowel endoscopy (capsule endoscopy and balloon endoscopy)

Due to its length and many convolutions, it is difficult to assess the entire small intestine with an endoscope. A relatively new procedure that solves this problem is the so-called capsule endoscopy. With this, the patient swallows a tiny video capsule, which passes through the stomach and intestines and takes pictures of its inner workings. She transmits the images live by radio to a receiver that the patient carries with them.

Since no tissue samples can be taken via the capsule, in the event of suspicious findings. a so-called balloon endoscopy can still be carried out.

Further information: Colonoscopy: procedure

You can read exactly how the colonoscopy of the small intestine and large intestine works in the article Colonoscopy: Procedure .

For colonoscopy in children, the gastroenterologist uses a special children’s endoscope. This is available in different sizes with diameters of five to thirteen millimeters, depending on the height of the child. In addition, children are usually given general anesthesia or a strong sedative for the colonoscopy.

What are the risks of a colonoscopy?

Risks that the doctor must explain to the patient include bleeding and the rare possibility of puncturing the intestinal wall with the endoscope. The short anesthesia can also lead to intolerance reactions and cardiovascular problems. In general, however, it is a very safe examination method with which complications only rarely occur.

Fear of colonoscopy: what to do?

Many patients are uncomfortable about their colonoscopy. The reason is often not only fear of the possible risks of colonoscopy, but also a certain shame about the examination. If necessary, the doctor can administer a sedative. Patients should tell their doctor their concerns early on so that he can react accordingly: With a calming medication, the patient can then survive the colonoscopy without any stress.

What do I have to consider after a colonoscopy?

If you were given a sedative during the examination, your ability to react will usually be significantly restricted for some time after the colonoscopy. Therefore, on the day of the examination, you are no longer allowed to actively participate in road traffic – neither by car, nor by bike, nor on foot .

After a colonoscopy during which you received sleeping pills, painkillers or sedatives, let an attendant or the taxi service take you home!

As a rule, you must specify who will pick you up before the examination at the practice. If you have a driver pick you up, it is best to contact your health insurance company to clarify who will cover the costs.

Operating machines or performing similar potentially dangerous activities is also taboo. You probably still feel a little exhausted even after a colonoscopy without a general anesthetic. In these cases, it is best to have an accompanying person pick you up.

Eating after a colonoscopy: what is allowed?

Since you as a patient have to be sober for a long time before the examination, you will probably be very hungry after the examination. The good news: Immediately after the colonoscopy, you can eat and drink whatever you want. For example, you can take a small snack with you to the doctor’s office. Sometimes medical practices also provide drinks and small items such as pretzel sticks.

Complaints after colonoscopy: what should I watch out for?

Diarrhea after a colonoscopy is a common side effect, since the laxatives taken previously can continue to have an effect for a few days. Because a lot of air gets into the intestines during the examination, flatulence and increased air leakage can also occur. This is perfectly normal and nothing to worry about.

On the other hand, severe pain after a colonoscopy of the large or small intestine is a warning signal that you should not ignore. Also consult your doctor if you have fever , sweating, severe dizziness , nausea, bleeding from the intestines or abdominal pain after a colonoscopy , so that he can react quickly. 

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