What is colonoscopy?

Commonly referred to as pancolonoscopy, colonoscopy is an endoscopic examination that allows exploration of the large intestine. For this to be possible, the colon must be cleaned of its normal contents. The preparation phase, which must be started a few days before the examination, is particularly important for this purpose.

Preparation

In order to relieve the intestine from food slag, during the three days prior to the diagnostic survey, fruit and vegetables must be excluded from the diet, which makes feces less compact. The preparation itself takes place the day before the examination and is intended to completely empty the intestine. There are different types of laxatives to choose from: all have the purpose of provoking an abundant evacuation. In some particular cases, their use is impossible (patients who cannot overload themselves with liquids because of heart disease or kidney failure) or not sufficient (intestine too long, inability to finish the preparation). In these cases, enemas are used, which must have a volume of at least two liters and should be repeated until clear water comes out.

Following the preparation

On the day of the examination the patient must show up with an empty stomach, but it is best to consider the necessary distinctions in cases where the conditions of the person do not allow it or in the course of special therapies. During endoscopy, there may be a need to remove a tissue fragment to perform a biopsy. For this reason, any treatment with anti-coagulant drugs should be temporarily discontinued during such investigations and the doctor requires patients to present recent blood tests, not older than 15 days, which include blood clotting factors and complete blood count.

The examination

Endoscopic control is not painful, but may be annoying; it is carried out by means of the introduction of an instrument with a diameter of a few centimeters through the anal opening that is traced along the entire colon allowing its observation. During the exam, the person is lying on one side. Some diagnostic centers practice pre-medication, i.e. provide the patient with intravenous sedative when necessary. Since these drugs reduce the state of vigilance, it is always recommended that a friend or family member accompany those who have to undergo this type of examination: when released from the hospital, they may not be able to drive.

Colonoscopy is highly specific: false positives are virtually zero. However, the sensitivity of the examination (in this case the minimum degree of lesion that can be detected) depends on the skill of the operator and the difficulty of exploring certain parts (non-straight, blind zones). In order to facilitate observation, the intestine is spread out by air insufflation or washed by irrigation. The various instruments to remove the polyps, burn them, collect biopsies, and pass the air and washing fluids, run through a small operating canal along the apparatus: “the eye” is located on the tip of the endoscope. Some of these are fiber-optic and in this case it is as if the surgeon saw directly with his own eyes, but the most modern instruments are video-endoscopes, equipped with a camera. In this case, the impulses are processed by a processor that allows the image to be manipulated and enlarged. Magnification is currently developing, a term borrowed from English, which indicates a magnification pushed almost to the levels of the microscopic one: one can even see the capillaries and the blood flowing there. This method, combined with techniques of endoscopic staining of neoplastic tissue, makes it possible to diagnose cancer on degenerated areas.

Edited by Giorgia Diana