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The large intestine is the lower, final part of the human digestive tract. It is in it that the absorption of liquids and the formation of feces from the food bolus, as well as enzymatic reactions with the help of symbiotic microflora, take place. Despite the fact that the organ belongs to the category of less physiologically active compared, for example, with the small intestine and biliary system, it is subject to a huge number of pathologies. It is possible to fix, prevent and develop a therapeutic course with the help of computed tomography. What you need to know about the procedure, how to properly prepare for the diagnosis, what are the indications / contraindications for the study?
General characteristics of computed tomography
CT is one of the methods of modern diagnostics, which is based on x-rays. Special equipment captures the intensity of X-rays that pass into tissues of the human body of different density. Absolutely all devices use minimal radiation exposure, so the procedure is considered relatively safe. Despite this, the number of X-ray diagnostics is limited, and it is necessary to maintain a time interval between procedures.
For frequent examinations, doctors advise using non-radiation diagnostic methods. For example, colonoscopy and barium enema, magnetic resonance imaging or ultrasound.
Computed tomography of the colon often replaces painful and uncomfortable colonoscopy. This is an endoscopic diagnostic method that is used to examine and assess the condition of the colon. During the procedure, the doctor uses an endoscope to manipulate. An important advantage is that colonoscopy allows the doctor to perform surgery, and virtual colonoscopy (CT) is intended only for preliminary diagnosis.
Contrast tomography
To improve visualization and increase the overall information content of CT, contrast agents are used. What it is? These are special iodine-containing substances that increase the visual informativeness of the X-ray image of organs and blood vessels. The contrast is administered orally or intravenously, depending on the area being examined. For the organs of the gastrointestinal tract, the first option is suitable.
Before scanning, the patient is offered to drink an iodine-containing preparation dissolved in ordinary drinking water. After 20 minutes, start tomography. During this time, the liquid has time to pass through the gastrointestinal tract and stain the necessary organs. Oral contrast is absolutely safe for humans. The substance itself is quickly excreted from the body with the help of the kidneys with urine. The use of contrast is prohibited in case of individual intolerance to the drug and severe kidney pathologies.
| Показания | Противопоказания |
|---|---|
| Abnormal growth of tissue over the mucosa | Pregnancy |
| Cancer neoplasms, regardless of the nature of the tumor | Excess weight (if it is significantly more than the maximum weight that the CT machine can support) |
| Preventive examination of patients who are at risk | Individual intolerance to iodine-containing drugs and serious pathologies of the kidneys / thyroid gland (during a contrast study) |
| Infectious or inflammatory processes in the large intestine | |
| Examination before or after surgery to assess the condition of the organ and the results of the operation | |
| Internal bleeding |
Diagnosis can only be carried out with the direction of a doctor. Even preventive examinations should be discussed with the attending doctor, since x-rays are used for tomography.
How to properly prepare for the procedure?
The diet should be adjusted 2-3 days before the procedure. The patient must give up all products that increase gas formation. Among them are legumes, some dairy products and more. On the eve of the CT scan, the patient is given a cleansing enema or takes a laxative on his own. The diagnosis itself is carried out on an empty stomach. This is necessary for maximum visualization and reduced active peristalsis (shrinking of the walls can distort the XNUMXD image).
Further manipulations (allergy tests for a contrast agent, the use of other medications) are carried out only under the supervision of medical personnel. They can be specific and depend on the individual response of the patient. For example, with bloating, you should drink an enterosorbent, and to relieve spasm of smooth muscles, a person will be offered antispasmodic drugs.
Before a bowel scan, the patient must undergo extensive preparation. How and why does it differ from standard manipulations? To get the most informative result, the rectum will be filled with air. This helps to straighten the intestinal walls in order to visualize their condition more clearly. Normally, they present a lot of folds and bends that can confuse the doctor. The intestine is literally inflated so that the specialist can examine even the “hidden” parts of the organ.
Colon CT Technique
After preliminary preparation, the patient is placed on the retractable table of the scanner. He undresses below the waist and lies on the couch on his side. After manipulating the air and the large intestine, the laboratory assistant sets up the tomograph, goes into the next room and starts the machine. From this moment on, the dialogue between the medical officer and the client takes place through the speakerphone installed in the office. During the scan, you will have to hold your breath several times. The radiologist will announce this over the speakerphone. The main thing is to relax and strictly follow the instructions of the specialist.
The patient can stop scanning at any time – if he feels pain, discomfort or wants to stop the diagnostics for any other reason, he can inform the radiologist about it.
The duration of the procedure is approximately 15 minutes. It takes from 30 to 60 minutes to process the results, depending on the workload of the medical staff. The patient picks up the finished XNUMXD image on the day of admission and hands it over to the attending physician. The doctor compares the CT scan results with previous diagnostic studies and medical history, on the basis of which a diagnosis is made.
Evaluation of results
Both the radiologist and the attending physician evaluate the results. The first gives a general description of the results of tomography, and the second compares the image with the history of the disease. The attending physician also considers information obtained from other studies, which gives a clear picture of what is happening.
Tomography visualizes the relief of the organ, the thickness and structure of its walls. The procedure helps to identify cancerous growths, erosive changes, infectious or inflammatory foci, ulcers, and so on. It is important to bear in mind that CT equipment is not capable of detecting small lesions (from 1 millimeter or less) and diagnosing the disease at the first stages of development. Also, the procedure does not allow assessing the color of the mucous layer or obtaining material for further laboratory research.
What to choose: tomography or colonoscopy of the large intestine?
With the help of CT, every centimeter of the surface of the intestine can be examined without causing pain or serious discomfort to the patient. The equipment shows all pathological changes, the nature of the mucosa, the specifics of its blood supply and the composition of the muscle fiber. Nevertheless, colonoscopy is much more reliable and informative than CT. The probe, which is equipped with optical equipment, reveals to the specialist all the nuances of intestinal pathologies and indicates even the smallest changes, which the tomograph is not able to do. Moreover, during colonoscopy, a tissue sample can be taken for further laboratory manipulations (histological examination). The disadvantage of colonoscopy is a high risk of bleeding or damage to internal tissues with a probe.
In any case, the choice of diagnostic method always remains with the doctor. He assesses the patient’s condition, the features of the pathology, compares the indications / contraindications, and only after that makes a decision. The choice in favor of colonoscopy is made if a biopsy is necessary. This is the excision of a piece of tissue/organ for further microscopic diagnosis. With standard tomography, a specialist can only observe what is happening inside, which fetters the space for manipulation. For example, to diagnose Crohn’s disease, polyposis, or ulcerative colitis, a doctor prescribes a colonoscopy. With cancerous neoplasms, most often the choice falls on computed tomography in order to track the relief and study the sections in detail.
Both studies are often used in medical practice. Their benefits vary for each individual patient and their disease. The main thing is not to prescribe diagnostics and, moreover, treatment on your own, so as not to aggravate the pathology and not provoke side effects. Strictly follow the medical instructions and be healthy!