This is half of a two-part debate — read the opposing argument. The opinions expressed here are that of the author and do not represent the position of AGA.
Adenoma detection rate (ADR) is an important quality indicator of colonoscopy. Studies have shown adenomas can be easily missed during colonoscopy and there is a wide variation in the ADR between different endoscopists. This continues to be the bane of colonoscopy as the resulting consequences in the form of interval cancer can be disastrous, both to the patient and the endoscopist. This defeats the very purpose of screening and surveillance colonoscopy, which is to prevent colorectal cancer. Seminal studies from Europe and the U.S. have shown that ADR of the endoscopist was significantly associated with the risk of interval cancer.1,2 Benchmarks of 30 percent ADR in males and 20 percent in females have been established.
Several reasons have been attributed for missing adenomas and include suboptimal bowel prep, subtle/flat lesions, short withdrawal time, poor inspection technique and lesions located on the proximal aspects of colonic folds. Detection aids have been developed to help the endoscopist examine the mucosa on the proximal aspect of folds to decrease the miss rate of lesions in these relatively blind mucosal areas. These include the transparent cap, Endorings, Endocuff, third eye retroscope and the wider angle colonoscope. The incremental yield in ADR with these have been modest in studies. But are these devices really required if you are good at detecting polyps with white light? The answer, in my opinion is no.
First and foremost, it is imperative that achieving optimal bowel preparation be the cornerstone of every colonoscopy practice. Using a split dose bowel prep should be the standard of care, with the second dose taken as close to the time of colonoscopy as possible. Split dosing not only improves the quality of prep but also the ADR.3,4 None of the detection aids can compensate for inadequate or poor bowel preparation.
A good withdrawal and mucosal inspection technique is also vital for detecting adenomas. This includes adequate insufflation of the colon and cleansing the mucosa of any residual solid and liquid stool as well as deliberate effort to inspect the back of folds. A video based study showed that high adenoma detectors have superior technique.5 Closely linked with good inspection technique is the withdrawal time. Longer withdrawal times correlate with higher ADR in some studies. A mean withdrawal time of greater than six minutes has been recommended as a quality indicator. Shorter mean withdrawal times have been independently associated with lower ADR and increased risk of interval colorectal cancer.6 As withdrawal technique is difficult to quantify objectively, withdrawal time has been used as its surrogate marker. However, aimless and non-purposive prolongation of withdrawal time will not improve ADR. If one employs good technique, it is intuitive that the withdrawal time will tend to be longer. Even expert endoscopists, with good technique, have a significantly higher adenoma miss rate with a three minute withdrawal time compared to six minutes.7 Therefore, employing good withdrawal technique and spending adequate time during the withdrawal phase, should be the goal of all colonoscopists in order to maximize their ADR.
Even with the given skill set that endoscopists possess, just monitoring and auditing the withdrawal times and ADR has a positive impact on this important quality metric, without any additional aid.
How can low adenoma detectors improve their ADR? Studies have shown that simply educating them about the different components of good withdrawal technique can significantly enhance their ADR and these gains were durable.8,9 Another study showed that discussion and implementation of careful inspection techniques by endoscopists employing a minimum of mean eight minute withdrawal time, significantly improved the ADR from 24 percent to 35 percent.10 Therefore, knowledge about different aspects of good withdrawal technique and implementing them into practice is a simple way of improving the ADR, especially for the low-level detectors.
Another intervention that can have a positive impact on ADR is periodic report card distribution. These highlight the individual ADR and other quality metrics achieved by the endoscopist. Providing feedback can change behavior and when endoscopists are made aware that their ADR is being monitored and tracked, they show an improvement in performance — the Hawthorne effect. One study showed that mere video recording of colonoscopy with the knowledge of the endoscopists increased both their inspection time and improved their technique significantly.11 It has also been shown that when endoscopists were aware that their withdrawal time was being monitored, there was a significant increment in both their withdrawal times and ADR. Thus, even with the given skill set that endoscopists possess, just monitoring and auditing the withdrawal times and ADR has a positive impact on this important quality metric, without any additional aid.
Other simple maneuvers have been shown to improve ADR. Second inspection of the right colon either in retroflexion or forward view increases the detection given the ability of flat lesions to hide behind prominent folds in this region. Position change during the withdrawal phase to keep the segment of the colon being inspected higher up and therefore well inflated (eg. right lateral position for the left colon) has also shown promising results in improving ADR especially for low detectors. One study showed that the implementation of a simple, inexpensive, evidenced based bundle of measures — including withdrawal time of greater than or equal to six minutes, use of hyoscine butylbromide, position change and rectal retroflexion — was associated with higher global ADR, driven by improvements amongst the poorest performing colonoscopists.12
Active participation by nurses and trainees watching the video monitor during the inspection phase can also improve ADR and the endoscopist should encourage this. Fatigue, distraction and poor focus can play a role in missing adenomas. Endoscopist should assess their workload and tailor their schedule appropriately to either whole day versus half day blocks of procedures, whichever is more suitable.
All these aforementioned strategies to improve ADR come at no extra cost. On the contrary, the distal attachment devices add to the cost of colonoscopy and offer only a modest improvement in ADR based on a recent network meta-analysis and other studies. With several other competing screening tests for colon cancer, it is imperative that gastroenterologists contain the cost of colonoscopy without compromising the quality. In this era of decreasing reimbursement for procedures as well as depleting health care resources, adding to the cost of colonoscopy by using a detection aid does not make fiscal or clinical sense. We should resist from indiscriminately embracing these devices before attempts to refine the inspection techniques and other simpler methods outlined above have been instituted. The detection aids should not be used as a crutch to compensate for inadequate technique.
In conclusion, good bowel prep, meticulous withdrawal technique, and ensuring adequate inspection time should be the cornerstone strategies to optimize ADR and will give us the maximum bang for the buck. These can be further supported with other interventions like second inspection of the right colon, dynamic position change during withdrawal, active involvement of nurses during inspection, and periodic audit and feedback regarding ADR. If these measures are implemented effectively in practice, then in my opinion, we do not need detection aids to improve ADR.
Dr. Rastogi has received research funding from Olympus America. He has also consulted for Olympus America and Cook Endoscopy. Dr. Rastogi is an associate editor for Gastrointestinal Endoscopy.
1. Corley, D.A., Jensen, C.D., Marks, A.R. et al, Adenoma detection rate and risk of colorectal cancer and death. N Engl J Med. 2014; 370(14): 1298-306.
2. Kaminski, M.F., Wieszczy, P., Rupinski, M. et al, Increased Rate of Adenoma Detection Associates With Reduced Risk of Colorectal Cancer and Death. Gastroenterology. 2017; 153(1): 98-105.
3. Gurudu, S.R., Ramirez, F.C., Harrison, M.E., Leighton, J.A., Crowell, M.D. Increased adenoma detection rate with system-wide implementation of a split-dose preparation for colonoscopy. Gastrointest Endosc. 2012; 76(3): 603-8 e1.
4. Radaelli, F., Paggi,S., Hassan, C. et al, Splitdose preparation for colonoscopy increases adenoma detection rate: a randomised controlled trial in an organised screening programme. Gut. 2017; 66(2): 270-277.
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8. Coe, S.G., Crook, J.E., Diehl, N.N., Wallace, M.B. et al, An endoscopic quality improvement program improves detection of colorectal adenomas. Am J Gastroenterol. 2013; 108(2): 219-26; quiz 227.
9. Ussui, V., Coe, S., Rizk, C., Crook, J.E., Diehl, N.N., Wallace, M.B. et al, Stability of increased adenoma detection at colonoscopy. Follow-up of an endoscopic quality improvement program-EQUIP-II. Am J Gastroenterol. 2015; 110(4): 489-96.
10. Barclay, R.L., Vicari, J.J., Greenlaw, R.L. Effect of a time-dependent colonoscopic withdrawal protocol on adenoma detection during screening colonoscopy. Clin Gastroenterol Hepatol. 2008; 6(10): 1091-8.
11. Rex, D.K., Hewett, D.G., Raghavendra, M., Chalasani, N. The impact of videorecording on the quality of colonoscopy performance: a pilot study. Am J Gastroenterol. 2010; 105(11): 2312-7.
12. Rajasekhar, P.T., Rees, C.J., Bramble, M.G. et al, A multicenter pragmatic study of an evidence-based intervention to improve adenoma detection: the Quality Improvement in Colonoscopy (QIC) study. Endoscopy. 2015; 47(3): 217-24.