Virtual Colonoscopy

Generality

Virtual colonoscopy is a relatively young diagnostic technique, which is proposed as a valid alternative to the traditional colonoscopic examination.

Benefits

Born in 1994, virtual colonoscopy allows you to study the internal walls of the colon in a non-invasive way, saving the patient the hassles and embarrassments associated with the traditional procedure; it is also not necessary to use sedatives and painkillers, the duration of the examination is shorter and immediate discharge, with the possibility of driving and resuming normal daily activities as soon as possible.

Small annoyances

Even for virtual colonoscopy, however, there remains the need for adequate dietary preparation, with the aid of special laxatives. In addition, carbon dioxide must be blown into the patient's rectum immediately before the examination by means of a small rectal probe. administration of Buscopan to reduce the sense of discomfort (unless contraindicated to the use of the medicine). All this in order to stretch the walls of the colon and allow an easier study of the same; this need can produce a modest sensation of abdominal distension due to the blown air, but overall the virtual colonoscopy remains an almost painless examination, especially when compared to the classical method.

When Execute

In addition to being a first-level method for the screening of colorectal cancer, in subjects over the age of 50, virtual colonoscopy is also indicated as a second-level investigation in the evaluation of individuals who tested positive for the presence of occult blood in the stool.

Colorectal cancer

It represents the second cause of mortality from neoplasia both in males, after that of the lung, and in women, after that of the breast.

The good news is that this type of neoplasm is characterized by a "slow evolution from polyps or adenomas, which can be exported before they turn into a malignant form of cancer. If you are over 50 or if there are any been other cases of colorectal cancer, contact your doctor for more information on screening tests, a real bulwark against the development of colorectal cancer.

In patients who refuse to undergo traditional colonoscopy, the virtual method can be performed in the presence of symptoms such as abdominal pain, rectal bleeding, chronic constipation or diarrhea, frequent alterations of the alvus (periods of constipation alternating with diarrheal episodes), iron deficiency anemia unknown origin, tenesmus (sensation of incomplete evacuation of faeces), emission of ribbon-like excrements and abundant presence of mucus in the faeces Many of these symptoms are also attributable to cancerous forms of colorectal cancer.

How does it work

Virtual colonoscopy uses a technique called multilayer spiral CT and a constantly updated software capable of reconstructing the colic walls on the screen. All this is made possible by the use of ionizing radiations, which are passed through the patient's body; at the opposite end a suitable receiver is able to record such radiations, which come out of the patient with different degrees of attenuation according to the tissues. crossed (the denser they are, the greater the attenuation). By converting this data into an electrical signal, it is possible to reconstruct, with the aid of a special program, the anatomy of the irradiated tissues and organs. The radiologist can then observe the "inside the colon" virtually ", as if you were doing a conventional colonoscopy. In theory, moreover, there is the possibility of examining the other abdominal organs, identifying any pathological extracolic changes.

The scan lasts a few seconds and the amount of ionizing radiation administered is minimal and considerably lower than a standard CT scan of the abdomen.

Benefits

Since its introduction, the sensitivity and specificity of virtual colonoscopy have gradually improved. If it is indeed important to ensure the non-invasiveness of the procedure and to minimize discomfort for the patient, it is equally important to ensure that this technique is effectively able to recognize suspicious lesions affecting the colon. This characteristic has always been proportional to their size, being excellent for formations with a diameter greater than one centimeter and poor for those with a radius of less than 3 mm (which have an extremely low probability of transforming into malignant tumors); not surprisingly, the continuous improvements to which virtual colonoscopy is subject are aimed precisely at ensuring correct recognition of the smallest lesions.

Thanks to this constant work of improvement, it is likely that in the next few years virtual colonoscopy will replace the traditional method and rectosigmoidoscopy as the elective screening test for colorectal cancer.

Rectosigmoidoscopy, in addition to maintaining a certain invasiveness, is not able to identify any adenomatous polyps or tumors located in the proximal and central tracts of the large intestine. For its part, colonoscopy is burdened by a higher rate of complications and poor tolerance on the part of patients.

Another advantage of virtual colonoscopy over traditional colonoscopy is the ability to fully visualize the entire colon, which due to its particular conformation or the presence of stenosis and diverticula may not make it possible to examine some features (such as the cecum-ascending ) with the normal optical colonoscopy. The virtual method therefore finds a further indication in all those cases of incomplete traditional colonoscopy, or not executable due to the patient's refusal or due to the presence of contraindications to its development (for example in cardiopaths and chronic bronchitis ).

Contraindications and Disadvantages

Due to the need to insufflate air into the colon, virtual colonoscopy remains contraindicated, like the traditional one, in the presence of acute diverticulitis, toxic megacolon and recent surgery in this part of the intestine.

The main limit or disadvantage of virtual colonoscopy compared to traditional colonoscopy remains the impossibility of intervening during the examination itself to perform small biopsy samples or to remove an abnormal polyp. Unfortunately, inevitably, in situations in which colonoscopy identifies anomalies (approximately one case out of 10), these operations are indispensable and the patient will therefore have to undergo the traditional examination in spite of himself.

Although the dose of X-rays administered to the patient is very low and far below the maximum limits established by the authorities in force, colonoscopy should not be performed during pregnancy. Finally, a low ability to identify flat lesions should be noted.

Preparation

If at the time of examination the colic walls are not thoroughly cleaned, the virtual colonoscopy can exchange simple fecal residues for abnormal masses. To prevent this possibility, the digestive endoscopy center provides the patient with a series of recommendations to follow during the examination. approach to the examination. The preparation is often similar to that used for traditional optical colonoscopy, although it is generally less restrictive.