Colonoscopy: What Is This Medical Test Used For?

A medical diagnostic procedure that can detect various diseases.

If we hear the word colonoscopy, most of us know what it is talking about, and we will probably react with some anguish or discomfort to the idea that it may be necessary to have 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 are going to see what a colonoscopy is, what it is for and how it is performed.

Colonoscopy as a Medical Procedure

Colonoscopy is a type of medical exploratory test or procedure in which through the insertion of a colonoscope (a tube-shaped instrument with a micro-camera at its end) it is possible to examine and evaluate the condition of the colon and large intestine of the patient. 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 system, in which, in addition to visualization through the camera, it is possible to obtain data through 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 suck or extract foreign bodies or to close small lesions.

Basic procedure

When performing a colonoscopy, first of all it is necessary that the part of the organism to be visualized is free of matter that could prevent the correct analysis of the organ. That is why previously elements such as laxatives or enemas are usually used that allow the client to evacuate and not have fecal material in the colon.

Once this is done, depending on the case, the administration of an anesthetic or analgesic may be recommended in order 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 the device is placed: the patient is laid on his side and with his knees bent to introduce the device through the anus.

Air is then introduced into the area to be examined in order to facilitate the examination, and finally this is carried out. Depending on what is found, if there is something strange, the doctor may decide to take samples or take other actions.

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

Generally, the subject usually stays for a few hours under observation until the effects of the anesthesia have worn off.


The procedure that 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 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. Computerized Tomography Colonography or Virtual Colonoscopy

This aspect of colonoscopy is less bothersome and invasive. Contrast measures are previously administered. A colonoscope is inserted through the rectum, but without the need to penetrate very far into the body: only air is introduced to facilitate observation. The images will be taken by X-rays from the outside.

4. Capsule colonoscopy

This type of alternative colonoscopy is one of the newer modalities and is much less invasive than the previous ones. The patient has to swallow a small capsule with built-in micro-cameras that will send images to sensors placed on the patient’s abdomen (although they will have previously performed 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 data obtained will be analyzed.

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

Uncomfortable as it is, this test is critically important. Currently it is one of the most effective ways to detect diseases such as colon cancer or polyps that can degenerate into it. This extraction is also usually done by colonoscopy. It is often carried out in people over fifty years of age.

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 due to foreign bodies are also visible using this technique.

Colonoscopy, as we have said, not only allows you to take images. It is also possible to perform biopsies of suspicious contents for later analysis or even perform procedures such as cauterization, sutures or extirpations.


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

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

Bibliographic references:

  • Lieberman, DA; Rex, DK; Winawer, SJ; Giardiello, FM; Johnson, DA & Levin, TR 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.

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