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A colonoscopy is a safe, fast, and minimally invasive procedure, in which a trained physician uses a special instrument called a colonoscope to view the gastrointestinal (GI) tract; specifically the colon and rectum. Colonoscopies are used to screen for bowel cancer, inflammatory bowel disease, and other conditions derived from the colon. The procedure is done on an outpatient basis, which allows patients to return home the same day as the exam.
Before the procedure, patients will need to fast for several hours, and drink a special liquid, or take medication to help empty the bowels. Quick access to the bathroom is helpful during preparation, as the medication or liquid will cause the patient’s bowels to evacuate often. Clear food and drink such as water and Jell-O may be allowed during the preparation period, depending on individual circumstances. It’s essential to follow the doctor’s instructions carefully, as prep is used to clear the bowels enough that an accurate assessment can be made during the exam.
On the day of the exam, sedation is administered intravenously by an anesthesiologist, so that the patient will be relaxed throughout the procedure. They lay on their left-hand side on an exam table during the procedure, and a thin, flexible colonoscope is inserted into the anus and passed through the rectum and large intestine. Air is then introduced gradually to expand the narrowed areas so that the physician can more easily see the video images that are projected onto the monitor from a special camera and light at the end of the colonoscope. As it moves through the colon, the doctor can pinpoint any troubling areas. If he or she wishes, they can biopsy any abnormal areas found during the colonoscopy. A biopsy is when a small sample is taken of the tissue or polyp(s) to test and determine whether it is cancerous (malignant) or not (benign). A special instrument is then passed through the colonoscope to gather the samples. The tissue is then sent to a lab for evaluation. Colonoscopies are typically very safe and only take about a half-hour to forty-five minutes.
A colonoscopy is usually prescribed to screen for colon cancer after a review of personal and family history is done to determine the patient’s risk. According to the American Cancer Society, colon cancer is the second leading cause of cancer-related death in the United States. The average adult has about a 1 in 20 chance of being diagnosed with colon cancer, although this varies widely, depending on individual risk factors. Even though colon cancer is on the rise in the US (an estimated 140,250 new cases in 2019), it is relatively treatable when caught early, which is why colon cancer screening is so important. It is estimated that increased awareness of and screening for colon cancer would save at least 30,000 lives each year. Colonoscopies may also be recommended by a doctor to diagnose the cause for symptoms such as rectal bleeding and chronic diarrhea.
It is often said that preparation is the hardest part of a colonoscopy. Doctors will explain dietary restrictions and cleansing routines on a patient-to-patient basis. In general, though, preparation includes limiting the diet to clear liquids 24 hours before the procedure and ingesting a large amount of special cleansing solution or prescribed oral laxatives. As mentioned, it is essential to follow instructions carefully, as the accuracy of the procedure will depend on the colon being clean. The following are some examples of required preparation:
Although most medications can be taken as usual, it is important to mention any medications because it is possible that they can interfere with screening preparation or procedure. In particular, make physicians aware of aspirin products, arthritis medications, anticoagulants (blood thinners such as warfarin or heparin), clopidogrel, insulin, or iron products. Allergies to any medications should also be mentioned before the exam.
As previously mentioned, during a colonoscopy, patients lie on their side in a comfortable position, and anesthesia is administered intravenously until they are in a light sleep. Once the patient is asleep, the physician slowly inserts a colonoscope into the anus, and along the large intestine to examine the lining. The lining will be inspected again as the colonoscope is withdrawn. Although patients should factor in 2-3 hours for waiting, preparation, and recovery, the procedure itself usually only takes about a half-hour to forty-five minutes. Colonoscopies are well-tolerated procedures and rarely cause the patient discomfort or pain.
As the colonoscope travels through the colon, the doctor can pinpoint any areas that may need further evaluation. If he or she wishes, they can biopsy any abnormal tissues found during the colonoscopy, and have them analyzed. Mentioned above, a biopsy is when a small sample of the colon lining is taken to test and determine whether it is cancerous (malignant) or not (benign). A special instrument is then passed through the colonoscope to gather the samples. The tissue is then sent to a lab for evaluation. However, biopsies are not always ordered to test for cancerous cells, and should not automatically cause concern. If polyps are found during the procedure, the physician will most likely remove them whether they are cancerous or not.
Colonoscopies can sometimes be used to identify sites of internal bleeding, in which case a physician may try to stop the bleeding by injecting medications through the colonoscope, by cauterization (sealing the blood vessels with heat), or by using small clips. These procedures, as well as the removal of polyps, do not usually cause the patient any discomfort.
As mentioned above, physicians can sometimes find polyps during the examination. Polyps are abnormal tissue growths that are often small, flat bumps, less than half an inch wide, but can vary in size from a tiny dot to several inches. In some cases, polyps develop in the colon and can be malignant (cancerous). However, this is not always the case. In fact, many people develop polyps, and in most cases, they are benign (non-cancerous). Frequently polyps don’t exhibit symptoms until they have grown very large, so frequent colonoscopies are the best way to detect them while they are small and very treatable. Cancer begins in the polyps, so removing them is an important way to prevent colorectal cancer.
There are a handful of ways that a physician will remove polyps. Fulguration, or burning, is used to destroy minuscule polyps. Another standard method is called “snare polypectomy,” which uses a wire snare and is implemented to remove large polyps. During a polypectomy, a doctor will advance a small wire loop through the colonoscope and remove the polyp with an electrical current. Physicians will also use biopsy instruments. None of these methods should cause the patient any pain or discomfort.
After the colonoscopy is completed, the patient will wake up within a few minutes. There will then be a period of time where the patient is monitored until most of the anesthesia has worn off, and then they can be discharged unless a physician instructs otherwise. The physician who performed the procedure will explain the results, and let the patient know if there were any biopsies performed, in which case there will likely be a delay in the results as the tissues are tested by a lab. If sedatives were administered, someone might have to drive the patient home and stay with them. Additionally, the stomach may feel cramped or bloated due to the introduction of additional air during the exam. These symptoms should disappear once the patient has passed gas. Patients may eat directly after the procedure unless their doctor gives other instructions; diet and exercise may be restricted after a colonoscopy, primarily if a polypectomy was performed, but a physician will advise on this.
Complications during a colonoscopy or polypectomy are rare, especially when the procedure is performed by a physician who is specially trained and schooled, and has experience in the field.
However, one possible complication is a perforation, or tear in the bowel wall. This could require surgery. There have also been instances of minor bleeding at the site of the polypectomy, but it will generally stop on its own, and rarely needs follow-up. More commonly, patients have an adverse reaction to the sedatives or complications due to existing heart or lung disease.
Colonoscopies are known for being very safe, but it is still essential to know the warning signs of possible complications. In the event of severe abdominal pain, fever, chills, or rectal bleeding, contact the center or physician immediately. It is possible for bleeding to occur several days after the procedure. Any concerns should be addressed as soon as possible in order to treat any early signs of issues as a direct result of the procedure.
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