CLINICAL ASSOCIATE PROFESSOR, SYDNEY UNIVERSITY
GASTROENTEROLOGIST AND THERAPEUTIC ENDOSCOPIST
CHAIRMAN OF ENDOSCOPY, GASTROENTEROLOGY
SOCIETY OF AUSTRALIA
What is colonoscopy?
Colonoscopy enables your doctor to examine the lining of your colon (large intestine) for abnormalities. The instrument is a flexible tube about the same thickness as your finger and about 1.5m long. It is inserted into your back passage (anus) and slowly advancing it into the rectum and colon under sedation. Please ask your doctor about anything you don't understand.
What preparation is required?
Your doctor will tell you what dietary restrictions to follow and what preparation to use. The most common type used is called Picoprep or Moviprep but you will be given written Instructions. The colon must be completely clean for the procedure to be accurate and complete, so be sure to follow your doctor's instructions carefully.
Can I take my current medications?
Most medications can be continued as usual, but some medications can interfere with the preparation or the examination. Inform your doctor about medications you're taking, particularly aspirin products, arthritis medications, anticoagulants (blood thinners), insulin or iron products. Also, be sure to mention allergies you have to medications. Alert your doctor if you require antibiotics prior to dental procedures, because you might need antibiotics before a colonoscopy as well.
What happens during colonoscopy?
Colonoscopy is well-tolerated and rarely causes much pain. You might feel pressure, bloating or cramping during the procedure. You will lie on your side while your doctor slowly advances a colonoscope through your large intestine to examine the lining. Your doctor will examine the lining again as he slowly withdraws the colonoscope. The procedure itself usually takes 15 to 30 minutes, although you should plan on two to three hours for waiting, preparation and recovery.
In some cases, the doctor cannot pass the colonoscope through the entire colon to where it meets the small intestine. Although another examination might be needed, your doctor might decide that the limited examination is sufficient.
What are polyps and why are they removed?
Polyps are abnormal growths in the colon lining that are usually benign (noncancerous). They vary in size from a tiny dot to several inches. Your doctor can't always tell a benign polyp from a malignant (cancerous) polyp by its outer appearance, so he or she might send removed polyps for analysis. Because cancer begins in polyps, removing them is an important means of preventing colorectal cancer. A clean bowel preparation maximises polyp detection as does a slow and cautious examination.
How are polyps removed?
Your doctor might destroy tiny polyps by burning or by removing them with wire loops called snares or with biopsy instruments. Your doctor might use a technique called "snare polypectomy" to remove larger polyps. That technique involves passing a wire loop through the colonoscope and removing the polyp from the intestinal wall using an electrical current. You should not feel pain during the polypectomy.
For very large polyps we often use accessory devices to prevent complications and assist in the removal of these polyps. Which device or technique we use depends on the polyp and the circumstances during your procedure. Removing very large polyps carries a higher risk but every precaution is taken to prevent complications.
Many patients now take blood thinning medications for their heart such as aspirin and plavix. In some cases it is recommended by the cardiologist to continue these even when we have to remove large polyps. This increases the risk of bleeding from polyp removal but keeps the heart risk low.
If you have any suspicion that you are bleeding after polypectomy you must contact your doctor or the nearest hospital as soon as possible.
What happens after a colonoscopy?
Your physician will explain the results of the examination to you, although you'll probably have to wait for the results of any biopsies performed.
If you have been given sedatives during the procedure, someone must drive you home and stay with you. Even if you feel alert after the procedure, your judgment and reflexes could be impaired for the rest of the day. You might have some cramping or bloating because of the air introduced into the colon during the examination. This should disappear quickly when you pass gas.
You should be able to eat after the examination, but your doctor might restrict your diet and activities, especially after polypectomy.
What are the possible complications of colonoscopy?
Colonoscopy and polypectomy are generally safe when performed by doctors who have been specially trained and are experienced in these procedures.
One possible complication is a perforation, or tear, through the bowel wall that could require surgery. Bleeding might occur at the site of biopsy or polypectomy, but it's usually minor. Bleeding can stop on its own or be controlled through the colonoscope; it rarely requires follow-up treatment. Some patients might have a reaction to the sedatives or complications from heart or lung disease.
Although complications after colonoscopy are uncommon, it's important to recognize early signs of possible complications. Contact your doctor if you notice severe abdominal pain, fever and chills, or rectal bleeding of more than one-half cup. Note that bleeding can occur several days after the procedure.