Colonoscopy (assessment tests)




Colonoscopy is an examination that allows the doctor to explore the internal walls (in contact with the fecal contents) of the large intestine and rectum (read the Hoax).

It is particularly useful both to check (diagnose) the presence of intestinal diseases such as polyps, diverticula, ulcerative colitis, colon cancer, Crohn's disease, and to perform minor surgeries such as the removal of polyps (operative colonoscopy).

Colonoscopy is prescribed to ascertain (diagnose) the causes of:

  • rectal bleeding
  • presence of occult blood in the stool
  • weight loss with no apparent cause
  • unexplained abdominal pain
  • colorectal changes detected during the execution of a barium enema, CT scan or magnetic resonance

It is also used in the field of investigations (screening) to detect colorectal cancers at an early stage. It is prescribed if the screening test for colorectal cancer has given a positive result. In Italy, the screening test used in almost all screening programs it is the fecal occult blood test, performed every 2 years in people between the ages of 50 and 69. A small part of the screening programs active in Italy (particularly in the Piedmont region) use instead of search for occult blood another screening test, rectosigmoidoscopy performed only once at the age of 58-60 (Ministry of Health. Screening for colorectal cancer).

The test

The test

Colonoscopy is an invasive examination, generally does not require hospitalization and is performed by the doctor in the office. It consists in the "introduction into" the intestine, through the anus, of a thin flexible tube (colonoscope) of variable length containing a small camera and one, or more, channels through which various instruments can be introduced (biopsy forceps, needles) for removing polyps or for sucking up gas or liquids.

Preparation for colonoscopy

Three days before the date set for the exam, adequate preparation must be made, which is very important for a correct exploration of the colon.
All foods containing fiber (fruit, vegetables, cereals, legumes, smoothies, juices, herbal teas, red meats) should be eliminated from the diet and only the following foods should be eaten: lean meats, fish, meat broths, tea , chamomile, water.

In addition, to avoid that at the time of the examination in the intestine there may still be stool residues, it will also be necessary to take laxatives by mouth (oral route).

Generally, the exam preparation scheme is provided by the healthcare staff at the time of booking the exam.

How a colonoscopy is performed

The person who has to undergo the investigation is made to lie on his left side with his knees bent and, to avoid feeling discomfort or pain, is slightly asleep (sedated) with drugs injected intravenously. Colonoscopy can be performed, as well as with light sedation, even with general anesthesia practiced by the anesthetist who will provide assisted breathing throughout the duration of the investigation.

During the examination, the doctor introduces the colonoscope through the anus and then advances it through the rectum and colon.
For a better visualization of the mucous wall, air is introduced, through the instrument itself, to stretch the intestinal walls. At the end of the colonoscope there is a tiny camera that transmits images from inside the intestine to an external monitor, allowing the doctor to examine any changes in its surface.

If, during the investigation, the doctor notices the presence of polyps, small growths of a benign nature, on the intestinal mucosa, he may decide to eliminate them directly because, if they were left in place, over time they could degenerate into malignant tumors. Removing polyps early in their development can decrease the risk of getting colorectal cancer.

In addition, in the presence of suspicious formations, the doctor can take small portions of tissue to be examined later under a microscope (biopsy) to identify any signs of disease.

Colonoscopy is a low-risk examination, it is not dangerous and does not cause particular problems. However, even if rarely, some complications can occur during its execution such as:

  • bleeding following removal of polyps
  • accidental perforation of the intestine
  • cardiorespiratory problems due to drugs used for sedation

Duration of the exam

The time it takes to perform a colonoscopy depends on the specific situation of each person undergoing it. In cases where there are no particular problems, it can be completed in about 10/15 minutes. If there is a need to remove intestinal polyps, however, the examination can last up to 30/60 minutes.

If the investigation was performed under general anesthesia (deep sedation) you will have to remain under observation for a few hours; if it was carried out in light sedation, you can go home immediately but you will have to avoid driving the car in the hours immediately following. For this reason it is good to be accompanied by a family member or friend.



The result of the colonoscopy is reliable only in the presence of an excellent colon cleansing, therefore, if the doctor has noticed the presence of feces, he may suggest repeating the examination.
The result of the colonoscopy can be:

  • negative
  • positive

A negative result indicates the absence of abnormalities in the colon. In this case, if the patient is not at risk of developing colon cancer over time, the doctor will suggest repeating the examination after ten years.

A positive result indicates the presence of polyps or abnormal tissue in the colon. Most polyps are not cancerous but some can be pre-cancerous and, if not removed, over time could turn (degenerate) into malignant tumors. For these reasons the polyps present in the intestine must be removed and sent to an analysis laboratory to verify their nature.
Depending on the number and size of the polyps, the doctor will recommend the most appropriate investigations to be carried out.

If during the examination small polyps (diameter less than 1 centimeter) were found and eliminated from the colon and the person has no risk factors for colon cancer, the doctor will suggest repeating the examination every 5/10 years. In case of removal of larger polyps, more numerous or with certain cellular characteristics, the doctor's suggestion will be to repeat the examination every 3/5 years.

If polyps have been removed during the colonoscopy that the histological examination has ascertained to be cancerous, the doctor's recommendation will be to repeat the examination in a variable interval from 3 months to a year.

In the presence of a polyp of such size that it cannot be removed during a normal colonoscopy or in the presence of abnormal tissue, the doctor will recommend the patient to consult a gastroenterologist who specializes in this type of surgery.

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