Patients undergoing a colonoscopy need to know certain guidelines about this medical test. Generally, a doctor recommends it when they need to look for abnormalities or diseases in the large intestine, specifically the colon.
This test is done with a colonoscope, a thin, flexible tube that has a light and camera attached to it. The colon helps form the lower portion of the gastrointestinal tract. It is in charge of absorbing nutrients and eliminating waste. It is attached to the anus through the rectum and is where feces are expelled. During a colonoscopy, your doctor may also take tissue samples to biopsy or remove abnormal tissue, such as polyps.
Why is it done?
This test may be done to screen for colorectal cancer and other problems. The exam can help a doctor look for signs of cancers, explore the cause of unexplained changes in bowel habits, assess for symptoms of abdominal pain or bleeding, or even find a reason for unexplained weight loss, such as chronic constipation or diarrhea.
Health professionals recommend getting tested once every 10 years for people aged 50 to 75, who are at risk for colorectal cancer and have a life expectancy of at least 10 years.
However, there are also experts who advise a one-time colonoscopy for people ages 50 to 79 who are at risk for colorectal cancer and have at least a 3 percent chance of developing colorectal cancer within 15 years.
If you are at increased risk for this type of cancer, you may need frequent testing. Typically, people who may need to be screened every 1 to 5 years are usually those who have had polyps removed during a previous colonoscopy, a history of colorectal cancer, or inflammatory bowel disease.
What is virtual colonoscopy?
An alternative to the classic is a virtual colonoscopy. This is a technique that uses a CT scan to obtain images of the colon that are similar to the views of the colon obtained by direct observation through colonoscopy. The images are built using the CT images, so they do not represent real images, they are virtual images.
In preparation for the virtual, the day before the colon will have to be cleaned with laxatives. During the exam, a tube is inserted into the anus and used to inject air into the colon. CT scans are then performed with the colon inflated, and the scans are analyzed and manipulated to form a virtual image of the colon. When done correctly, virtual colonoscopy can be effective. You can even find "hidden" polyps behind folds that are occasionally missed in the classical test.
However, there are several limitations. For example, it has difficulty identifying small polyps (less than 5 mm in size) that are easily seen during a colonoscopy, although it is true that small polyps are less likely to be cancerous. It is also difficult to identify flat cancers or premalignant lesions that do not protrude, meaning they are not polyps.
Furthermore, it does not allow for the removal of any polyps that are found. If polyps are found using a virtual test, a colonoscopy must be performed to remove them. Therefore, many people who undergo a virtual test will require a second procedure.
Due to these limitations, virtual screening has not replaced classical screening as the primary screening tool for people at increased risk for polyps or colon cancer. It is currently an option for people at normal risk for polyps and colon cancer who cannot or will not have a colonoscopy.
What are the risks?
Although a colonoscopy itself is relatively safe, there are several factors that could contribute to problems during the procedure. If a doctor removes a polyp during the test, for example, the chances of complications may increase slightly.
In rare cases, deaths have been reported after these medical tests, especially in people who had suffered intestinal perforations. That is why it is recommended to go to specialized centers to reduce the risk. However, the risks associated with colonoscopy are as outlined below.
perforated intestine
Intestinal perforations are small tears in the wall of the rectum or colon. They can be accidentally performed during the procedure using an instrument. It is usually a little more likely that these punctures occur if a polyp is removed, although it is not a recurring norm in the operating room either.
Perforations can be treated with watchful waiting, bed rest, and antibiotics. However, larger tears are medical emergencies that require surgical repair.
Bleeding
If a tissue sample is taken or a polyp is removed, you may notice some bleeding from the rectum or blood in your stool a day or two after the test. This is usually nothing to worry about, and in no time you can be back to leading a completely normal life.
However, if the bleeding is heavy or does not stop, it is important to tell your doctor. Letting it slide could hide an underlying problem that puts you in danger.
Post-polypectomy electrocoagulation syndrome
This complication is quite rare and can cause severe abdominal pain, rapid heart rate, and fever after a colonoscopy. It usually originates from an injury to the intestinal wall that results in a burn. Surgical repair is required in rare cases and can usually be treated with bed rest and medication.
Sometimes it can be confused with an intestinal perforation because they have similar symptoms. However, it will be a specialist who analyzes the seriousness of the matter.
Risks for older adults
Because colon cancer grows slowly, colonoscopies are not always recommended for people over the age of 75 and those who have medical problems that put them at higher risk of complications.
Bowel preparations can sometimes be a concern for older adults because they can lead to dehydration or electrolyte imbalance. Those with left ventricular dysfunction or congestive heart failure may react poorly to preparation solutions containing polyethylene glycol. These can increase intravascular water volume and cause complications such as edema.
Prepared drinks containing sodium phosphate may also have a negative influence, as they can cause kidney complications in some older people.
How should we prepare for a colonoscopy?
Your doctor will give you instructions for bowel preparation. It is best to follow a clear liquid diet for 24 to 72 hours before the test. This diet typically includes broth or stock, gelatin, plain coffee or tea, pulp-free juice, and sports drinks like Gatorade. It is important not to drink any liquids containing red or purple dye because they can discolor the colon and affect the test results.
You should tell your doctor about any medications you are taking, including over-the-counter drugs or supplements. If they could affect your colonoscopy, your doctor may advise you to stop taking them a few hours beforehand. The most common ones are blood thinners, iron-containing vitamins, and certain diabetes medications.
You may also be given a laxative to take the night before your appointment. You will most likely be advised to use an enema to cleanse your colon on the day of the test.
How is the test performed?
Right before the colonoscopy, you'll need to change into a hospital gown. Most people receive a sedative and pain reliever through an IV so that the test is painless and patients are relaxed.
During the procedure, you will lie on your side on a padded examination table. The doctor may position you with your knees close to your chest to get a better view of your colon.
While you are lying on your side and sedated, the doctor will slowly and gently guide the colonoscope through your rectum and into your colon. The camera at the end of the colonoscope transmits images to a monitor that the doctor will be watching. Once the colonoscope is in place, the doctor will inflate your colon with carbon dioxide . This gives them a better view for more accurate results.
The doctor may remove polyps or a tissue sample for biopsy during this procedure. The patient is usually awake during the colonoscopy, so the doctor can explain what is happening. The entire procedure can take between 15 minutes and an hour.
What happens after a colonoscopy?
Once the test is finished, you will need to wait approximately one hour for the sedative to wear off. You will be advised not to drive for the next 24 hours , until all effects have disappeared. If the doctor removes tissue or a polyp during a biopsy, it will be sent to a laboratory for analysis. The doctor will inform you of the results when they are ready, which is usually within a few days.
You'll likely experience some gas and bloating for the next few hours due to the gas that was placed in your colon. It's important to allow it time to pass through your digestive system. If this continues for several days afterward, it could indicate a problem, and you should discuss it with your doctor.
Additionally, it's normal to have a little blood in your stool after the procedure. However, you should see a specialist if you continue to pass blood or blood clots, experience abdominal pain, or develop a fever higher than 37,8°C.