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STATE-OF-THE-ART LECTURE
J Interv Gastroenterol 4:2, 43-46; April/May/June 2014; © 2014 Journal of Interventional Gastroenterology
Digestive Disease Week 2014 Colonoscopy Topic
Forum - Novel methods for polyps detection
- State of the Art Lecture on optimizing polyp
detection
Felix W. Leung1,2, Sergio Cadoni3, Přemysl Falt4, Yu-Hsi Hsieh5,6, Joseph W. Leung7,8, Yanglin Pan9, Franco Radaelli10, Andrew W. Yen7,8
Sepulveda Ambulatory Care Center, Veterans Affairs Greater Los Angeles Healthcare System and 2David Geffen School of Medicine at University of California at Los Angeles,
North Hills, CA, United States; 3Digestive Endoscopy Unit, S. Barbara Hospital, Iglesias, Italy; 4Digestive Diseases Center, Vı´tkovice Hospital, Faculty of Medicine, University
of Ostrava, Ostrava, Czech Republic; 5Division of Gastroenterology, Department of Medicine, Buddhist Dalin Tzu Chi General Hospital, Chia-Yi, Taiwan; 6Buddhist Tzu Chi
University, School of Medicine, Hualien, Taiwan; 7Gastroenterology, Sacramento Veterans Affairs Medical Center, Veterans Affairs Northern California Health Care System,
Mather, CA, and 8Gastroenterology, University of California at Davis Medical Center, Sacramento, CA, United States; 9Xijing Hospital of Digestive Diseases, Fourth Military
Medical University, Xi’an, China; 10Division of Gastroenterology, Valduce Hospital, Como, Italy
1
Key words: adenoma detection rate; water exchange colonoscopy
Abbreviations: ADR, adenoma detection rate; AI, air insufflation; ASGE, American Society for Gastrointestinal Endoscopy;
BBPS, Boston Bowel Prep Score; DDW, Digestive Disease Week; FUSE, full spectrum endoscope; RCT, randomized controlled
trial; WE, water exchange; WI, water immersion
This State of the Art Lecture was presented at an American
Society for Gastrointestinal Endoscopy (ASGE) Topic Forum
entitled Novel Methods for Polyp Detection on May 4, during
the 2014 Digestive Disease Week (DDW) meetings in Chicago.
The Topic Forum covered five papers. A prospective, randomized,
controlled trial (RCT) showed that L-Menthol sprayed onto the
colonic mucosa increases adenoma detection rate (ADR) from
42.6% to 60.2% (p=0.0083).1 A RCT of EndoCuff-assisted
colonoscopy showed a significant increase in polyp detection
rate from 42% to 56% (p=0.001).2 The detection rate of polyps,
adenomas, hyperplastic polyps, and sessile serrated adenomas
varied significantly among colonoscopists, and the classification
rates of hyperplastic polyps and sessile serrated adenomas varied
significantly between pathologists.3 Two studies suggested that
capsule colonoscopy is a safe and clinically effective tool for
detecting significant colonic lesions with high accuracy and high
patient acceptability;4 and has a high specificity and sensitivity for
detection of clinically relevant colorectal neoplasia in a screening
population.5
Defined as the proportion of patients with at least 1 adenoma,
ADR is an indicator of quality in colonoscopy. An interval cancer
is one found within 3 to 5 years after a screening colonoscopy.6,7
High ADR predicts fewer interval cancers.8 Missed polyps account
for the lower than expected reduction in colorectal cancer mortality
in the right colon after screening.9 In a tandem study missed rate
is defined as the number of additional adenomas divided by the
total number found.10 Such a measure, however, has not been
directly linked to interval cancers. Optimal withdrawal techniques
*Correspondence to: Felix W. Leung; Email: [email protected]
Submitted: May/04/2014; Revised: May/24/2014; Accepted: May/26/2014
DOI: 10.7178/jig.152
www.jigjournal.org
associated with fewer missed adenomas, include looking behind
folds, adequate distension of the lumen, adequate withdrawal time,
and cleaning residual pools in the lumen.11 Recent developments
suggest that while more mucosa is seen after cleaning, cleaning
during withdrawal may distract from focused inspection and the
principal task of searching for lesions.12,13
Table 1 summarizes the retrospective, observational and RCT
related to interventions believed to have an impact on ADR. Poor
bowel preparation has a negative impact, increasing missed polyps.
Telephone reminder about dietary compliance on the day before
colonoscopy improves bowel preparation score and has a positive
impact. The consistent feature of mixed results, i.e. with studies
reporting both positive and negative or no impact, is applicable
to split dose and same day bowel preparation, sedation, insertion
polypectomy, retroflex examination, dynamic position change, and
withdrawal time >6 minutes. At the 2014 DDW, one presentation
suggested that withdrawal technique is more important than
withdrawal time.14 Third eye retroscope, cap assisted colonoscopy,
chromoendoscopy, and narrow band imaging all require excellent
bowel preparation for effective application, and similar mixed
results have been reported.
Full spectrum colonoscope (FUSE)15 (with 330 degree field of
view) reduces the adenoma miss rate by 12% (from 17% to 5%).
Importantly, there is no impact on ADR, 28% for standard versus
34% for FUSE. FUSE is limited by incomplete cecal intubation
(2%) and poor bowel prep (1%). Topical L-menthol decreases
peristalsis, and increases ADR.1 It is limited by poor bowel prep
(6.8%). Endocuff manipulates folds to increase mucosa seen.
It enhances ADR and poor bowel preparation is a limitation.2
Whether future reports will confirm or refute these findings
remain to be determined.
Water-aided methods are broadly classified into 2 categories:
J Interv Gastroenterol
43
Table 1. Retrospective, observational and RCT related to interventions with an impact on polyp detection or adenoma detection rate
Interventions
Retrospective
Observational
Randomized
Impact on ADR
Positive
Negative
Positive
Negative
Positive
Negative
✓
✓
Poor bowel preparation
Telephone re-education
✓
Split dose preparation
✓
Same day preparation
✓
✓
Sedated vs. unsedated
✓
Propofol vs. conscious sedation
✓
Insertion polypectomy
Dynamic position change
Retroflex examination
✓
✓
Withdrawal time >6 min
✓
✓
✓
✓
Withdrawal technique vs. time
✓
3rd eye retroscope
✓
✓
Cap assisted
✓
Dye spray chromoendoscopy
✓
Narrow band imaging
Full spectrum colonoscope
L-menthol
Endocuff
✓ indicates report(s) exist(s) for the reference category. ADR, adenoma detection rate; RCT, randomized controlled trial.
water immersion (WI) and water exchange (WE).16,17 Water
immersion is an excellent example of the long established
adjunct to air insufflation to facilitate insertion. When excessive
residual feces are encountered, suction removal is considered
impractical or cumbersome; air insufflation is used to create an
air compartment to permit insertion. Of note is that the infused
water is removed predominantly during withdrawal. Early18,19
and even recent observational studies of water immersion used in
difficult colonoscopy20 did not report data on polyp or adenoma
detection. Interestingly, the WI method attracted investigators to
assess its efficacy in minimizing pain in unsedated, on demand
and minimal sedation patients in recent years. These randomized
controlled trials reported mixed results on ADR showing both
numerically higher21 and lower ADR.22
Water exchange is modified from WI to develop the least
painful insertion method in unsedated patients when Dr. FW
Leung lost the ability to perform sedated colonoscopy at his
practice site in 2002 as a result of a severe nursing shortage. The air
pump is turned off to avoid inadvertent air insufflations and colon
elongation. Residual air is suctioned to minimize angulations.
Water infusion is used to confirm correct tip orientation for scope
advancement. To remove feces to clear the view, and to reduce
distension and looping to minimize insertion pain, the infused
water is suctioned predominantly during insertion. With dual
channel colonoscope, the simultaneous suction and infusion of
water create turbulence at the tip, suspending residual feces in
the luminal water for efficient removal. Water exchange enhances
cecal intubation. Retrospective studies and RCT have reported
consistent data to support an increase in ADR. No negative study
has been reported yet.
In the first uncontrolled, non-randomized, consecutive group
study of WE versus AI in the scheduled unsedated patients,23 cecal
intubation rate was significantly increased from 76% to 97%.
44
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
Likely because of cleansing effect of the WE during insertion, the
proportion of the patients with poor bowel preparation during
withdrawal decreased from 12% to 1.6%. Several related RCT
are reported at the 2014 DDW. In unsedated patients in China,
in addition to a significantly higher cecal intubation rate, WE
produced a significantly higher overall Boston Bowel Prep Score
(BBPS) (confirming salvage cleaning even in patients receiving
same day bowel preparation).24 In Italian patients with the option
of on demand sedation, WE produced a significantly higher
overall and proximal colon BBPS.25 In minimally sedated subjects
in Taiwan, WE produced significantly higher overall and right
colon BBPS.26 Of note is that in both studies, WE enhances BBPS
even in patients with split dose preparation.
Table 2 summarizes the 6 published RCT comparing WE
versus AI.27-32 The WE method consistently demonstrated higher
overall ADR compared with AI, shown in the last column. The
increase in ADR occurs in patients receiving no sedation,31,32 on
demand,27,30 minimal29 or even full28 sedation. In addition to the
further enhancement of BBPS alluded to above, the increase in
ADR also occurs in those receiving split dose preparation.29,30 The
aggregate data (Table 2) of these 6 RCT show a significant 8%
increase in overall ADR. When the proximal colon is separately
considered, WE also shows a significantly higher ADR. This, in
fact, is due to a significant increase of the diminutive adenoma
detection rate.33
Water exchange provides salvage cleaning.34 Up to 2 to 4 L
of exchanged dirty water in the suction bottle could be removed
during insertion from a patient with a poor bowel preparation.
From patients with good or fair bowel preparation, the water
exchanged has a smaller volume, and appears less dirty. In a
sub-optimally prepared colon, the residual feces could obscure
polyps. Alternatively, to improve the cleanliness for inspection,
considerable washing and suction would be needed during
J Interv Gastroenterol
Volume 4 Issue 2
Table 2. RCT of AI vs. WE - overall and proximal colon ADR27-32
RCT*
Jadad
Split-dose
Number of
Number of patients with 1 adenoma
number
score
bowel
patients
Proximal
Proximal
Overall
site
prep
<10 mm
All sizes
All sizes
USA
USA
USA
USA
Taiwan
Italy
Aggregate data
3
3
3
3
3
3
No
No
No
No
Yes
Yes
Ref
Difference in overall
ADR*
WE
AI
WE
AI
WE
AI
WE
AI
WE - AI, %
42
50
177
50
68
338
40
50
191
50
68
334
7
20
74
18
36
26
3
10
59
14
25
13
7
20
81
20
22
34
3
12
67
14
11
16
15
20
101
27
38
87
9
18
88
24
29
64
36%-23%=13%
40%-36%=4%
57%-46%=11%
54%-48%=6%
56%-43%=13%
26%-19%=7%
31
27
28
32
29
30
Total
725
733
181
124
184
123
288
232
ADR (%)
25
17
25
17
40
32
ADR difference
8%
8%
8%
p**
0.002
0. 0001
0.015
*p<0.05, Rank sum test; **Fisher’s exact test. ADR, adenoma detection rate; RCT, randomized controlled trial; AI, air insufflation; WE, water exchange.
Table 3. Effect of combining water exchange with new imaging methods29,30,35-37
ADR (%)
New methods
Overall
WE
57
26
↑
62
↑
C
p
High definition (RCT)
43
0.10
High definition (RCT)
19
0.03
Indigocarmine (RCT)
44
0.03
Indigocarmine (RCT)
Cap (Consecutive group)
59
75
0.02
↑
ADR, adenoma detection rate; RCT, randomized controlled trial; C, control; WE, water exchange.
withdrawal, causing distraction from the principal task of finding
polyps. When WE is used during insertion, there is less need for
cleaning, and the colonoscopist can focus on inspection during
withdrawal.12 A less distracted examination, in a cleaner colon,
perhaps, is a plausible explanation of the significant increase in
ADR.
Table 3 shows that when some of the new imaging methods
(high definition colonoscope, indigocarmine, cap-assisted
colonoscopy) are combined with water exchange there is a
consistent pattern of enhanced performance. The positive impact
appears to be applicable to overall, proximal and right-sided
adenomas.29,30,35-37
To follow up on the presentation regarding the significant
variation among colonoscopists and pathologists in the recognition
of sessile serrated adenomas,3 the question “Does WE impact the
recognition of sessile serrated polyps in the proximal colon?” can
be posed. The study using combined cap-assisted colonoscopy
and WE37 provides a possible answer. The proximal colon serrated
polyp detection rate in the AI group was 9.9% and that in the
combined group was 24%, a significant increase.
In summary, a negative impact on ADR has been described
with poor bowel preparation; a positive impact, with adequate
withdrawal techniques and telephone re-education regarding
compliance with dietary restrictions prior to colonoscopy. With
air insufflation, new techniques and methods show mixed (both
positive and negative or none) impacts on ADR. Air insufflation
does not provide salvage cleaning during insertion. Residual
www.jigjournal.org
Ref
C
[11]
5
35
48
Proximal [right]
WE
[27]
↑
10
↑
53
61

↑
↑
p
0.02
0.01
0.02
0.07
29
30
35
36
37
feces could obscure polyps during withdrawal; and withdrawal
cleaning could distract from the principal task of focused
inspection. Water exchange consistently increases ADR. Water
exchange decreases pain (in unsedated patients), and increases
cecal intubation. Insertion salvage cleaning could prevent polyps
from being obscured, and perhaps, could decrease distraction
from withdrawal examination. The benefits of improved bowel
preparation score and ADR appear to occur even with split dose
preparation with or without sedation, and when combined with
new techniques and methods for adenoma detection. A limitation
is that some of the available data on WE and ADR are from subanalyses of studies not primarily aimed at assessing the end point
of adenoma detection.27,29-32 Nonetheless, these provocative data
have prompted the initiation of new and adequately powered
studies which are ongoing (Table 4) to confirm the hypothesis
that WE has a favorable impact on overall and proximal ADR.
In conclusion, studies with ADR as the primary outcome,
comparing WE with usual AI should be performed with adequate
sample size to test the hypothesis that WE is superior in enhancing
ADR. Furthermore, WE may be an appropriate insertion platform
in the study of new techniques and methods to optimize polyp
and adenoma detection. The following hypothesis deserves to be
evaluated in future RCT: with optimal withdrawal techniques,
WE during insertion, with or without being combined with new
approaches, may enhance the detection rate of adenomas and
sessile serrated polyps.
J Interv Gastroenterol
45
Table 4. Ongoing RCT assessing the impact of water exchange colonoscopy on ADR
The Effects of the Water-exchanged Colonoscopy on Adenoma Detection Rate (NCT02135601)
Prospective Randomized Controlled Trial Comparing Water and Air Colonoscopy in a Community Based Setting (NCT01729416)
Water-aided Colonoscopy vs. Air Insufflation Colonoscopy in Colorectal Cancer Screening (NCT02041507)
Comparison of Adenoma Detection Rate Among Water, Carbon Dioxide and Air Methods of Minimal Sedation Colonoscopy (NCT01782014)
Effectiveness of Instillation of Blue Water (Indigo Carmin®) for Colonoscopy (GRAND BLEU) (NCT01937429)
Comparing the Adenoma Detection Rate With Air Insufflation, Water Immersion and Water Exchange (NCT01894191)
Comparative Efficacy of Water & Indigo Carmine vs. Water or Air Method on Adenoma Detection Rate (ADR) - a Randomized Controlled Trial (RCT)
(NCT01607255)
Comparison of Methods to Distend the Colon During Insertion: CO2, Air Insufflation, Water-aided Colonoscopy (NCT01954862)
ADR, adenoma detection rate; RCT, randomized controlled trial.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
46
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