Colonoscopy – Q&A
By DOUGLAS K. REX, M.D.
Colorectal cancer is the second leading cause of cancer death in the United States, it affects both men and women and it almost always starts in a benign growth called a polyp. Polyps originate in the inner lining of the colon, where they may be visible during the popular screening test known as colonoscopy.
Whether you’re going for your first colonoscopy or are a veteran of the process, the following questions and answers contain important information about maximizing the procedure’s effectiveness and safety. Did you think that colonoscopy was completely effective at preventing colorectal cancer? Think again. The level of protection in various studies has ranged from a high of 80 percent to a low of no protection at all.
Here’s what you need to know to get the maximum benefit from colonoscopy at the lowest risk.
Q. Why is effective bowel preparation important?
A. Bowel preparation for colonoscopy refers to the laxatives taken before the procedure to clean the colon of fecal debris. A colonoscope is a long, flexible tube with a television camera on the tip. The camera can’t see through fecal debris. So any fecal debris left in the colon could obscure identification of a polyp or even a small cancer.
Several studies have shown that fewer small and large polyps are detected in patients with less-than-optimal bowel preparation. And poor preparation has several potential consequences during the procedure itself.
First, your colonoscopy may last longer because the doctor will need to take time to clear out debris.
Second, your doctor may lack confidence that the colon lining was seen adequately and may ask you to return for a subsequent screening earlier than would be otherwise recommended – say 1 year, rather than 5 or 10 years. This will subject you to increased costs and risk.
Finally, if the preparation is very poor, the doctor may have to stop the procedure entirely, and you will need to reschedule.
Q. How can I maximize my chance of an effective bowel preparation?
A. First, ask if the doctor recommends what is called split-dosing. Split-dosing refers to taking half the laxative prescription the night before colonoscopy, and the other half on the day of the procedure, usually about four to five hours before the procedure is scheduled. Several studies have shown that split-dosing significantly improves the quality of the preparation for colonoscopy.
In the past, it was common for doctors to have patients take all the prescription the night before colonoscopy. This effectively cleaned out the fecal debris, but left the potential for a different problem that can develop when the time between the end of the preparation process and the start of the colonoscopy is prolonged. Thick mucus and intestinal secretions empty out of the small intestine during that interval and stick to the first parts of the colon. [See Figures]
This area, called the cecum and ascending colon, is an important area to see with the colonoscope because cancers commonly develop there. It’s also the most likely area for cancers to develop after a normal colonoscopy. Flat polyps are common in this area and can be hard to see even when bowel preparation is perfect.
The solution to this problem is split-dosing, though there are still doctors who don’t recommend it. One reason given for sticking with a single dose is that a patient scheduled to have a colonoscopy early in the morning would have to get up at 2 or 3 a.m. to take the second half of the laxatives. That doesn’t sound great, does it?
Look at it this way, though. You may undergo colonoscopy as infrequently as every 10 years. Therefore, you want the doctor to have the best possible shot at making sure your colon is normal. If you get up during the night for things like crying babies or sick family members, you can do it to avoid dying from colorectal cancer. So if you want that early morning appointment, let the doctor know you’re willing to get up and take the second half of the preparation.
Another reason that split-dosing is not used is that some anesthesiologists won’t let patients drink fluids after midnight, or for six to eight hours before they are sedated. They are worried that the patient may vomit and inhale fluids during the procedure. But this concern is misplaced. The evidence shows that when people are drinking only clear liquids, the same amount of liquid is left in the stomach whether you stop fluid intake two hours before the procedure or many hours before. Guidelines from the American Society of Anesthesiologists say that patients may take clear liquids by mouth until two hours prior to the time of sedation.
In addition to split-dosing, the next step is to get written preparation instructions from the endoscopy unit and to read through them at least a few days before the procedure is scheduled. This will allow you time to get all the materials you need and adjust your schedule if necessary for the day or evening before the procedure. Most bowel preparation regimens can cause some dehydration, so make plans to stay well hydrated. Sport drinks are better than water for this purpose. It’s good to start the hydration process before you start the laxatives and to continue to hydrate during the period of laxative ingestion and even after you complete the procedure. You’ll feel better and stronger if you stay hydrated.
Q. Are there certain medications I should stop taking before colonoscopy?
A. Some doctors tell patients to stop taking aspirin, which has blood-thinning properties, 7 to 10 days before the procedure, reasoning that if a polyp is removed you’ll be less likely to bleed from that site. The evidence that aspirin causes bleeding from polypectomy sites is weak, and the American Society for Gastrointestinal Endoscopy says you don’t need to stop taking it before a colonoscopy, regardless of whether a polyp is removed. If you’re on aspirin for a good reason like a prior heart attack or stroke, it’s better to continue taking it.
Whether to temporarily discontinue more potent blood thinners like Coumadin (warfarin) and Plavix (clopidogrel) is more complicated. You should not decide to stop these medicines on your own, and the management of these drugs should be handled either by the doctor who prescribed them or the doctor doing the colonoscopy – or by both in consultation.
The exact management depends on why you need the medication, how long you’ve been taking it and what the colonoscopist plans to do during the procedure. Although the possibility of bleeding from the colonoscopy procedure is scary, the risk of bleeding when taking these medicines is related primarily to removal of large polyps, which most patients don’t have. In some cases it’s better to risk some bleeding from the procedure by continuing the medications than to risk a heart attack or stroke by stopping them. Let your doctors decide what to do.
Few patients need antibiotics before colonoscopy. Although you might expect colonoscopy to carry a high risk of bacteria entering the bloodstream, the risk is actually much lower than for other procedures, like dental work. Patients with heart problems like mitral valve prolapse and even artificial heart valves do not need antibiotics before colonoscopy.
Some colonoscopists give antibiotics to patients who have liver disease with fluid in the abdominal cavity, a condition called ascites.. Antibiotics are also sometimes prescribed for patients who have had vascular grafts, like those used to repair an abdominal aortic aneurysm, in the previous year, or for those who have had artificial joints put in place in the last six months. But the evidence to support these policies is weak, the risk of infection in these conditions is low, and the wisdom of using antibiotics in these situations is uncertain.
Q. Are all colonoscopists equally effective at finding polyps and cancers during colonoscopy?
A. Colonoscopy is what we in medicine call a highly “operator dependent” procedure. That is, some doctors are not only better than others at doing colonoscopy, they are a lot better.
Stated in reverse, some doctors are really bad at doing colonoscopy. Virtually every study that has looked for evidence that some people are better than others has found it, and the differences between doctors in how many precancerous polyps they find varies by 4- to 10-fold.
Q. How can I be sure that my colonoscopist will do a careful examination?
A. Current guidelines for measuring the quality of performance of colonoscopy recommend that doctors measure their “adenoma detection rate.” That is, they should determine whether they are being careful by counting the percent of patients in whom they identify one or more precancerous polyps, or adenomas, during screening.
Minimum thresholds for the adenoma detection rate have been determined. Doctors doing colonoscopy should find one or more adenomas in at least 25 percent of men and 15 percent of women who are age 50 or older and undergoing screening colonoscopy. Most doctors who do colonoscopy still haven’t measured their adenoma detection rate and therefore can’t tell you whether they are careful or not. The only way you can find out is to ask whether the rate has been measured and what it was.
It has also been recommended that doctors doing colonoscopy should take at least six minutes to examine the colon as they withdraw the colonoscope. Doctors who take six minutes or longer find more precancerous polyps, though the correlation between withdrawal time and polyp detection is not perfect.
Other factors also come in to play, including the quality of the preparation, how well the doctor sees flat lesions and how hard the doctor works to see the hidden portions of the colon on the opposite side of folds and bends. The doctor’s skill and care will be reflected in the adenoma detection rate.
You can help by making sure your colon is thoroughly cleansed. Find a doctor who has measured his or her adenoma detection rate and can show you that it exceeds the recommended thresholds. And ask the doctor to be careful and take enough time.
Also ask for a copy of the report and the pictures taken. The report should document that the doctor reached the beginning of the colon (the cecum) and took photographs of the anatomic landmarks that prove it. Somewhere in the record the withdrawal time should be recorded. If you really want to push the issue (It’s your colon right?), ask for a video recording of the entire procedure. Many doctors don’t have the equipment to provide such a recording, and if they do you might have to pay for it. Knowing that a permanent record of the procedure is being made might be just what’s needed to help ensure a careful examination.
Q. How can I reduce the risk of a complication during colonoscopy?
A. The most dreaded complication of colonoscopy is perforation, or making a hole in the colon. Perforation usually requires surgical repair, often on an emergency basis. Perforation can occur either during insertion of the colonoscope, from the side of the instrument’s rupturing the lower colon, or it can occur during polyp removal.
The risk of rupture during insertion of the colonoscope is higher in the elderly. Risk is also higher in people with severe diverticulosis; in those with weakened colons because of prior radiation, chronic use of steroids or a serious colonic disease; and perhaps in those with adhesions around the colon in the pelvic area from surgeries like hysterectomy.
With a skilled operator, rupture of the colon is distinctly uncommon, particularly in the screening setting where the colon is usually anatomically and structurally normal. Although rupture occasionally occurs despite precautions and a skilled endoscopist, people at increased risk could ask the doctor to use a pediatric colonoscope. These colonoscopes are the same length as a standard instrument but are thinner and more flexible and exert less force on the colon wall. They have some disadvantages, and in certain circumstances the doctor could legitimately object to using one.
Perforations that occur during or after polyp removal are almost invariably caused by the application of electrocautery during the removal process. Electrocautery means electrical current is applied during removal to heat the tissue and seal off blood vessels to stop them from bleeding.
Polyps can be removed using a wire loop called a snare, or by forceps, which open and shut like a pair of jaws. Forceps should be used only for polyps that are five millimeters or smaller in maximum dimension. In my opinion, there is no reason to use electrocautery with forceps tools, and even snares can be used to cut off small polyps without electrocautery.
In fact, there is no need to use electrocautery for small polyps at all, since there are no large blood vessels to seal off. Still, many doctors use electrocautery to remove even small polyps.
Large polyps, on the other hand, are typically removed with a snare and require electrocautery to effectively cut through the tissue and seal the larger blood vessels sometimes found in those polyps.
Although a small polyp removed using electrocautery is much less likely to be associated with bleeding or perforation than a large polyp removed by electrocautery, small polyps are much more common than large polyps. Therefore, removal of small polyps results in most of the complications of colonoscopy over all. It is reasonable to ask the doctor to avoid using electrocautery to remove small polyps if possible.
Q. Should I try colonoscopy without sedation?
A. You should do this only if you’re highly motivated. The advantages of having colonoscopy unsedated are that you can watch the procedure on the television screen and you can get up and walk out after the procedure with no restrictions on your activity. But only 1 percent of colonoscopies in the United States are done without sedation.
People who are most interested in this option are typically highly educated and have low levels of anxiety, they more often are men, and they usually have no abdominal pain before the procedure. Because of anatomic factors, colonoscopy is usually easier in men, so men are better candidates for trying colonoscopy unsedated.
Colonoscopy is sometimes quite easy, causing very little discomfort, but a lot of people have significant discomfort if they try it without sedation. High levels of discomfort might make you less willing to have a colonoscopy in the future and might cause you to say negative things about the procedure to your friends and relatives, which would in turn make them less willing to undergo colonoscopy.
Most of us who do colonoscopy want our patients to be comfortable and to have an experience that is so easy they are surprised by it. We don’t want to push anyone to try it unsedated. But if you really want to skip sedation, you can probably get through it with a skilled doctor.
It has been shown recently that some unsedated patients tolerate colonoscopy better when the doctor uses “water immersion” to insert the instrument. In this technique the doctor fills the colon with water, rather than the air that is typically used, on the way in. Water stretches and elongates the colon less than air and is very safe, though air is still needed during the withdrawal to see the lining well. If you’re really interested in trying colonoscopy unsedated, you might ask whether the doctor can do water immersion.
Q. If I undergo sedation, should it be given by an anesthesiologist?
A. This will depend a lot on where you live in the United States and what your doctor does routinely.
Traditionally, doctors who do colonoscopy have given the sedation for the procedure themselves or have supervised a registered nurse who administers the medicine. The professional fee for performance of a colonoscopy includes payment for the delivery of sedation.
But in the last 10 years, many endoscopy groups have begun working with anesthesiologists or nurse anesthetists to deliver sedation for the procedure. This practice tends to be concentrated in certain parts of the country, including the New York City and Philadelphia corridor as well as Florida.
Anesthesia specialists use a drug called propofol for sedation, which keeps patients quite comfortable and allows them to awaken very quickly after the procedure. Several gastroenterologists in the United States use propofol without an anesthesiologist, but anesthesia specialists and their professional society have resisted this trend as they would like to control the use of the drug.
The only downside of having an anesthesiologist or nurse anesthetist involved is that it increases the cost of the procedure substantially. Aetna pays an average of $700 extra when an anesthesiologist is involved, and in some settings having an anesthesiologist doubles the cost of the procedure. Many insurers restrict the circumstances under which they will pay for an anesthesiologist to help with endoscopy.
There is virtually no evidence that the procedure is any safer when an anesthesiologist is involved, and using an anesthesiologist for a routine procedure like colonoscopy, if you are healthy, is not a cost-effective medical practice. Gastroenterologists and other endoscopists typically have enormous experience with sedating patients for colonoscopy using medicines that are safe and that provide excellent patient satisfaction.
Given that our country is in dire financial straits and that health care costs are contributing to the struggles of many businesses, it would be better if people elected to have colonoscopy with sedation provided by the doctor doing the procedure. But depending where you live in the country, you may not have a choice.
Q. Do all colonoscopists follow the same rules to determine when my colonoscopy should be repeated?
A. Doctors have guidelines that recommend how often colonoscopy should be done depending on whether the colonoscopy is normal; the number, size and type of polyps found during the colonoscopy; the results of previous colonoscopies; and family history of colorectal cancer. These guidelines, issued by groups like the American Cancer Society and the U.S. Multi-Society Task Force (a collaboration of the gastroenterology professional societies and the American College of Physicians), recommend colonoscopy at sufficient intervals to prevent most colorectal cancers, provided that your colonoscopy was done carefully.
Several studies have shown that some doctors recommend repeat colonoscopies at intervals that are shorter than those recommended by professional guidelines. General surgeons and primary care physicians who perform colonoscopy are more likely than gastroenterologists to make recommendations for more frequent procedures. Recommending colonoscopy at intervals that are too short may reflect a lack of knowledge of the guidelines, or a lack of confidence in the quality of the doctor’s own inspection of the colon, neither of which is a good reason to shorten the interval. A more appropriate rationale for shortening the interval is if the bowel preparation was less than optimal.
Q. Why aren’t the problems with the delivery of colonoscopy already solved?
A. The American health care system is not nationalized, and the delivery of high quality health care is often up to the integrity of individual providers. Many providers deliver outstanding care, but quality problems in colonoscopy have only been fully appreciated in the last few years.
Recommendations for monitoring the quality of colonoscopy were made by gastroenterology specialty groups in 2002 and 2006, but there is no mandate for practitioners to follow the guidelines and no penalty for not following them. Insurance companies could step in with a monitoring system that rewards good-quality colonoscopy and penalizes poor-quality colonoscopy, but they have not done so. That means that finding a competent and careful colonoscopist is the responsibility of the patient.
Dr. Douglas K. Rex, a distinguished professor of medicine at Indiana University School of Medicine and clinical gastroenterologist at Indiana University Hospital, is past president of the American College of Gastroenterology.
Gastrocure in West Orange, NJ performs comprehensive cancer screenings for colon cancer and Barrett’s esophagus. He performs quality colonoscopy using high definition optical colonoscopy, narrow band imaging to identify early flat lesions in the right colon which could be missed during routine colonoscopy. In difficult cases we use a Water Immersion Colonoscopy technique to complete procedures which decrease pain and sedation amount for patients.