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Colonoscopy: what is this medical test used for?

Colonoscopy: what is this medical test used for?

July 18, 2024

If we hear the word colonoscopy, most people know what they are talking about , and probably react with some anguish or discomfort to the idea that it may be necessary to perform one at some point in life.

Although it is usually considered unpleasant, it is a necessary procedure that allows diagnosing and treating various pathologies. In this article we will see what a colonoscopy is, what it is for and how it is performed.

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Colonoscopy as a medical procedure

Colonoscopy is a type of test or medical exploratory procedure in which through the insertion of a colonoscope (a tube-shaped instrument with a microcamera at its end) it is possible to examine and evaluate the condition of the colon and the large intestine of the patient.

It is a type of objective examination that allows the recognition and evaluation of the state of part of the digestive system and especially the excretory, in which in addition to the visualization through the camera it is possible to obtain data through the performance of biopsies. In some cases, colonoscopy is also performed therapeutically, since some instruments can be inserted through cavities in the colonoscope itself that can help, among other things, to suction or extract foreign bodies or close small lesions.

Basic procedure

When performing a colonoscopy, first of all it is necessary that the part of the organism that you want to visualize is free of matter that could prevent the correct analysis of the organ. That is why previously they usually use elements such as laxatives or enemas that allow the client to evacuate and have no fecal material in the colon.

Once this is done, depending on the case, it may be advisable to administer an anesthetic or analgesic so as to avoid possible pain or discomfort in the patient. The doctor performs a digital rectal examination to check for obstructions and at the same time to dilate the anus. Then proceed to place the device: the patient is placed on his side and with the knees bent to introduce the device through the anus.

Next, air is introduced into the area to be examined in order to facilitate the exploration , and finally this is done. Depending on what is found, if there is something strange, it is possible that the doctor decides to take samples or perform other actions.

Finally the device is removed with care, at which time observations can also be made. It is common that, given that air has been introduced, some pains or gases appear that can even be expelled at the moment of extraction of the colonoscope.

Usually the subject usually stays a few hours under observation until they have passed the effects of anesthesia.


The procedure we have indicated above is the one that is used most frequently. However, we can find different subtypes of colonoscopy.

1. Conventional colonoscopy

The most used, refers to the basic procedure described above: the colonoscope is inserted through the anus and rectum to make a tour and analysis of the interior of the colon. In conventional colonoscopy, the entire colon is examined.

2. Flexible sigmoidoscopy or proctosigmoidoscopy

Like the conventional colonoscopy, the colonoscope (in this case sigmoidoscope) is used to visualize only a part of the colon, specifically its lower third or sigmoid. In this case sedatives are not usually used.

3. Colonography by Computerized Tomography or Virtual Colonoscopy

This side of colonoscopy is less bothersome and invasive. Previous contrast measurements are administered. A colonoscope is inserted through the rectum but without the need to go deeply into the body: only air is introduced to facilitate observation. The images will be taken by X-rays from the outside.

4. Colonoscopy with capsule

This type of alternative colonoscopy is one of the most recent modalities and is much less invasive than the previous ones. The patient has to swallow a small capsule with built-in microcameras that will send images to sensors placed in the patient's abdomen (although previously he will have done a colon cleansing in order to obtain useful images). This does not need to remain hospitalized or any sedation. Once the capsule is excreted, the obtained data will be analyzed.

In which cases is it used and what can it detect?

Although it is uncomfortable, this test is of fundamental importance . Currently, it is one of the most effective ways to detect diseases such as colon cancer or polyps that can degenerate in it. Said extraction is also usually done by colonoscopy.It is frequent to be carried out in people over fifty years old.

Another frequent reason for its use is the study of the causes of the appearance of blood in the process of defecation or simply bleeding from the rectum. It allows to see its causes and detect diseases such as irritable bowel syndrome. In cases of persistent pain and sudden weight loss it is also recommended. Fissures, abscesses or blockages by foreign bodies are also visible by this technique.

Colonoscopy, as we have said, not only allows you to take pictures. It is also possible to perform biopsies of suspicious contents for further analysis or even perform procedures such as cauterizations, sutures or removals.


Although it is a very useful and necessary test, it can pose some risks . In particular, it can occasionally cause perforations in the colon or intestine, causing hemorrhages. However, this extreme only occurs in very rare cases.

The use of techniques such as virtual and capsule colonoscopy reduce these risks, although they may not be as effective. Other possible discomforts are the presence of abdominal pain and gas.

Bibliographic references:

  • Lieberman, D.A .; Rex, D.K .; Winawer, S.J .; Giardiello, F.M .; Johnson, D.A. & Levin, T.R. Guidelines for colonoscopy surveillance after screening and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology 2012; 143 (3): 844-857.

What happens during and after a colonoscopy? (July 2024).

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