Adenoma Detection Rate Coincides with Colonoscopy Prep



Good colon health is a two-way street that requires a committed partnership between you and your gastroenterologist. A patient’s responsibility prior to a colonoscopy is to thoroughly empty the bowel to create maximum visibility for the GI doctor to view any abnormalities in the colon. The doctor’s responsibility is to carefully examine the entire length of the colon and remove lesions or colon polyps that could become cancerous.

Dr. Paul Brown of Louisville Endoscopy Center has performed thousands of colonoscopies. Dr. Brown is the Medical Director of Louisville Gastroenterology Associates, specializing in internal medicine and gastroenterology. Dr. Brown explains the patient-physician partnership that is required to achieve a quality colonoscopy.

Of all the possible methods to screen the colon for colon cancer, why is a colonoscopy the preferred method?

A colonoscopy is considered the gold standard for colon cancer screening because it prevents colon cancer through the detection and removal of precancerous adenomatous polyps. This procedure allows the gastroenterologist to view the entire length of the colon to evaluate the health of your digestive tract.

The gastroenterologist inserts a long, flexible tube called a colonoscope  into the rectum with a camera attached to detect abnormalities. If any colon polyps are discovered during the procedure, the doctor can remove the adenomatous polyps during the colonoscopy, thus preventing colon cancer before it starts. No other colon cancer screening can provide this. Therefore, I tell my patients that a colonoscopy can be both a diagnostic and a therapeutic procedure.

What is Adenoma Detection Rate (ADR) and why is it important?

Adenoma Detection Rate (ADR) is the percentage of time that at least one adenomatous polyp is detected during a physician’s screening colonoscopies. The national average is 25 percent for men and 15 percent for women; our percentages at our surgery centers are much higher and range between 25 and 50 percent. Knowing a physician’s Adenoma Detection Rate is an important qualifying factor in selecting the GI specialist, which will give the patient added confidence when committing to the procedure.

Adenoma Detection Rate is a helpful tool because it is a direct measure of the effectiveness of the colonoscopy that a gastroenterologist offers. As patients interview potential physicians to perform their colonoscopy, they should remember that the higher the ADR, the lower the colon cancer risk.

How does a High Adenoma Detection Rate Relate to a Quality Colonoscopy?

A high Adenoma Detection Rate is essential for a quality colonoscopy and for colon cancer prevention. For every 1 percent increase in a physician’s ADR, the risk of a person developing colon cancer over the next year decreases 3 percent. Doctors who are effective in detecting and removing precancerous polyps have a high ADR and their patients are less likely to develop cancer.

Are there are any other criteria that patients should use to qualify a gastroenterologist?

Patients should ask physicians about their average withdrawal time during a colonoscopy. This refers to how quickly the colonoscope is removed from the colon once the scope reaches the cecum, the farthest point in the colon. The minimum time should be six minutes, so a withdrawal time greater than six minutes is associated with a higher ADR.

Another qualifying measure is known as cecal intubation rate, which refers to how often a physician sees the entire colon. The colonoscope should be advanced all the way to the cecum to allow visualization of the entire colon. A physician’s cecal intubation rate should be greater than 95 percent for screening colonoscopies.

Does it matter what type of bowel prep kit a patient uses?

The gastroenterologist will help choose the best bowel preparation for each patient based on their age, medical history and medications. Most importantly, patients must follow the directions exactly as they are written. A thorough colon cleanse is an essential part of the colonoscopy. The colon must be free from debris and waste so the GI speicalist can detect lesions, colon polyps and abnormalities. 

How has Colonoscopy Prep Changed Over the Years to Make it More Tolerable?

Much has changed regarding bowel preparation methods in the past decade. In the past, most doctors prescribed single-dose products such as Trilyte, Nulyte or Golytely. These bowel preparations were effective, but they had many disadvantages, the first being that patients had to consume 4 liters of liquid over a short period of time. This left patients feeling bloated, full and nauseous, and vomiting was common. If patients were not able to finish all of the purgative solution, their bowel preparation was often incomplete and exam results were inconclusive or compromised.

The split-dose method splits the purgative dose into two parts: The first half of the dose is taken in the evening, and the second half is taken very early in the morning (to allow for at least two hours of fasting before anesthesia). Almost all patients prefer the split-dose method because the volume of liquid is much more tolerable, and they do not have the symptoms of nausea, bloating and abdominal fullness that the single-dose method often causes.

Which Colonoscopy Prep method do you Prescribe to your Patients and why?

For the past three to four years, I have routinely prescribed Suprep and Moviprep using the split-dose method. I find that splitting the dose cleans the bowel more effectively, and I liken it to sending a car through the car wash twice instead of just once. The colon is more thoroughly flushed, which provides an optimum environment to detect precancerous polyps.

The split-dose method allows for better visualization of the colon, especially the right side where adenomatous polyps are often missed due to poor colonoscopy prep. The split dose method just results in a cleaner colon, which increases the Adenoma Detection Rate. This, in turn, increases polyp removal and decreases colon cancer incidence.

Are there any disadvantages of the split-dose method?

Most patients want to schedule a colonoscopy during the morning hours, so yes, they may see it as a disadvantage to wake up very early on the morning of their procedure to take the second dose of the bowel prep solution. However, this is where I have the opportunity to educate my patients. I remind them that, in order to achieve an optimal bowel prep, this will allow me to be successful in finding and removing all colon polyps. This sacrifice on their part is necessary. Most patients like to do their part in providing a well-prepped colon, so they are quite agreeable to wake up early when I give them this explanation.

Besides the prep, what are some other reasons why people don’t get a colonoscopy?

There are probably three major reasons why people do not schedule screening colonoscopies:

Fear of unknown. People may rather ignore the idea of getting a colonoscopy if they don’t understand what it is or why they need it.

People think a colonoscopy will be painful. When primary care physicians refer patients to a gastroenterologist for a colonoscopy, they can offer the reassurance that anesthesia makes the procedure painless. In fact, the vast majority of patients will not even remember the procedure.

People think that they will miss too much work. Because most people will take the first dose of purgative the night before the colonoscopy and take the second dose the morning of the procedure, they will only have to miss one day of work.

Colonoscopies are not scary, painful or a waste of time. They offer colon cancer detection as well as colon cancer prevention. Therefore, we can say that colonoscopies are both diagnostic and therapeutic. As primary care physicians educate their patients on the life-saving benefits of preventative colorectal screening, we will continue to see colon cancer incidence decrease.

Dr. Brown attended medical school at the University of Louisville, where he was Chief Medical Resident. He completed a fellowship in Gastroenterology at the University of Louisville and has dedicated his career to serving the Louisville community in the field of gastroenterology.

Among his many achievements, Dr. Brown has authored several articles relating to gastroenterology and has been voted “Top Doc” by his peers in eight successive surveys in Louisville Magazine. To learn more about Dr. Paul E. Brown and his gastroenterology practice, please visit