Endoscopy 2020; 52(S 01): S36-S37
DOI: 10.1055/s-0040-1704114
ESGE Days 2020 oral presentations
Saturday, April 25, 2020 11:00 – 13:00 Advances in endoluminal endoscopy Liffey Meeting Room 2
© Georg Thieme Verlag KG Stuttgart · New York


S Cadoni
1   ASSL Carbonia, CTO Hospital, Digestive Endoscopy Unit, Iglesias, Italy
S Ishaq
2   Birmingham City University, Russell Hall, Dept. of Gastroenterology, Birmingham, United Kingdom
C Hassan
3   Nuovo Regina Margherita Hospital, Gastroenterology, Rome, Italy
P Falt
4   Vitkovice Hospital, Digestive Diseases Center, Ostrava, Czech Republic
L Fuccio
5   S. Orsola-Malpighi University Hospital, Dept. of Medical and Surgical Sciences, Bologna, Italy
K Siau
6   Royal College of Physicians, JAG Clinical Fellow, Wolverhampton, United Kingdom
JW Leung
7   VA Medical Center Sacramento, Veteran Affairs, Sacramento, United States of America
KF Binmoeller
8   California Pacific Medical Center, San Francisco, United States of America
P de Groen
9   University of Minnesota, Minneapolis, United States of America
CJJ Mulder
10   VU University Medical Center, Gastroenterology, Arnhem, Netherlands
MD Rutter
11   University Hospital North Tees NHS, Dept. of Gastroenterology, Stockton-on-Tees, United Kingdom
J Anderson
12   Gloucestershire Hospitals NHS Foundation Trust, Gloucestershire, United Kingdom
P Bhandari
13   Portsmouth University Hospital, Dept. of Gastroenterology, Portsmouth, United Kingdom
E Albéniz-Arbizu
14   Complejo Hospitalario de Navarra B, Endoscopy Unit Gastroenterology Dept., Pamplona, Spain
N Suzuki
15   St Mark’s Hospital, Wolfson Unit for Endoscopy, London, United Kingdom
D Nylander
16   Newcastle Upon Tyne NHS Foundation Trust, Gastroenterology, Newcastle Upon Tyne, United Kingdom
R Ransford
17   Hereford County Hospital, Endoscopy, Hereford, United Kingdom
A Parra-Blanco
18   Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom
S Dolwani
19   Cardiff University, Cardiff, United Kingdom
T Kuwai
20   Kure Medical Center and Chugoku Cancer Center, Gastroenterology, Kure, Japan
M Arai
21   Chiba University, Gastroenterology, Chiba, Japan
M Barret
22   Cochin Hospital, Gastroenterology, Paris, France
P Bayupurnama
23   Sardjito General Hospital, Gadjah Mada University, Division of Gastroenterology and Hepatology, Yogyakarta, Indonesia
B Hayee
24   King’s College Hospital, Gastroenterology, London, United Kingdom
R Cheung
25   Stanford University, Division of Gastroenterology and Hepatology, Paolo Alto, United States of America
A Bak
26   University of British Columbia, Kelowna, Canada
H Neumann
27   I Medizinische Klinik und Poliklinik, Interventional Endoscopy Center, Mainz, Germany
H Cohen
28   VA Greater Los Angeles Health Care System, Los Angeles, United States of America
PV Draganov
29   University of Florida, Gainesville, United States of America
S Friedland
30   Stanford University School of Medicine, Stanford, United States of America
H Chris
8   California Pacific Medical Center, San Francisco, United States of America
H Harada
31   New Tokyo Hospital, Gastroenterology, Chiba, Japan
YH Hsieh
32   Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Dalin Township, Taiwan
H Muhammad
33   Roehampton University, Roehampton, United Kingdom
HL Ching
34   Sheffield Teaching Hospitals, Gastroenterology, Sheffield, United Kingdom
T Mizukami
35   NHO Kurihama Medical and Addiction Center, Endoscopy Center, Yokosuka, Japan
S Olafsson
36   Telemark Hospital, Gastroenterology, Skien, Norway
AY Wang
37   University of Virginia, Charlottesville, United States of America
Y Pan
38   Xijing Hospital, Gastroenterology, Xi´an, China
FC Ramirez
39   Mayo Clinic, Phoenix, United States of America
H Senturk
40   Bezmialem Vakif University Medicine Faculty, Dept. of Medicine, Istanbul, Turkey
J Rodriguez-Sanchez
41   Hospital Quirónsalud, Unidad de Endoscopia, Ciudad Real, Spain
S Sugimoto
42   Keio University School of Medicine, Division of Gastroenterology and Hepatology, Tokyo, Japan
H Thorlacius
43   Lund University Surgery, Dept. of Gastrointestinal Surgery, Malmö, Sweden
H Uchima
44   Hospital Germans Triasi Pujol/Teknon Medical Center, Gastroenterology, Barcelona, Spain
AW Yen
45   University of California Davis School of Medicine, Sacramento, United States of America
V Lorenzo-Zúñiga
46   University Hospital La Fe, Endoscopy Unit, Valencia, Spain
F Radaelli
47   Ospedale Valduce, Gastroenterology Unit, Como, Italy
N Uedo
48   Osaka International Cancer Institute, Dept. of Gastrointestinal Oncology, Osaka, Japan
FW Leung
49   David Geffen School of Medicine at UCLA, Medicine, North Hills, Los Angeles, U S A
› Author Affiliations
Further Information

Publication History

Publication Date:
23 April 2020 (online)


Aims Water immersion (WI) and water exchange (WE) are colonoscopy techniques utilizing water for colonoscopy practice. Controversies exists about their definitions, impact on some procedure outcomes, issues related to underwater resection of colorectal lesions (UWP). We conducted an international Delphi consensus among expert endoscopists with interest in WI, WE or conventional colonoscopy to address these controversial issues through a systematic search of literature.

Methods A multi-society taskforce, I WATERS [International Water-Aided Techniques in Endoscopy (Education) and Research Society], was assembled to evaluate evidence-based statements on WI, WE and UWP: technique definitions; impact on procedural outcomes, bowel cleanliness and adenoma detection rate (ADR); and outcomes of UWP. The quality of evidence was appraised using the GRADE framework, consensus was defined as reaching 80%+ agreement on each statement. Responses were returned anonymously.

Results A three-round Delphi process was conducted, statements were revised by the organizers based on respondents´ comments. 56 colonoscopists (16 countries) participated, 30% were endoscopists with great expertise but not routinely using WI or WE, with the aim to minimize possible bias. Consensus in the final round was reached for 11 evidenced-based statements ([Table 1]). In particular, WE improves bowel cleanliness and increases adenoma detection rate, both techniques decrease procedure pain. UWP can facilitate resections and improve outcomes.

Conclusions This first Delphi process related to WI, WE and UWP enables and facilitates improved understanding of the techniques. The results of the systematic search of the literature favors WI, WE and UWP over gas insufflation colonoscopy regarding some key colonoscopy outcomes.

Tab. 1

Results of water-assisted colonoscopy DELPHI assessment




Consensus (Agreement)

Technique definitions

1) In Water Immersion (WI) colonoscopy water is infused to facilitate scope progression and cecal intubation; gas insufflation (GAS, room air or carbon dioxide) may be used as needed during insertion; most of the infused water is aspirated during withdrawal. 2) Water exchange is a standardized insertion technique in which infused water is removed mainly during insertion to allow progression in clear water, without any gas insufflation and removing all residual gas pockets trying to achieve the best possible degree of colon cleanliness.

1) moderate quality evidence (9 RCT, 1 retrospective study) WI +; WE - 2) high quality evidence (15 RCT, 1 retrospective study) WI -; WE +

1) Yes (98%) 2) Yes (100%)

Procedural outcomes. Impact on bowel cleanliness, adenoma detection and pain score.

3) In both unsedated and sedated colonoscopy (excluding deep sedation and general anaesthesia), cecal intubation rate can be higher using water immersion or water exchange than gas insufflation colonoscopy. 4) Compared with gas insufflation colonoscopy, water exchange cecal intubation time requires an average of 2-4 additional minutes. 5) Water exchange colonoscopy increases total procedure time by a mean of 2 minutes compared with gas insufflation colonoscopy. 6) Water exchange colonoscopy is associated with higher quality of the bowel preparation. 7) Water exchange colonoscopy is associated with higher adenoma detection rate than gas insufflation colonoscopy. 8) Use of WI or WE during insertion is associated with less patient discomfort when compared to gas insufflation colonoscopy.

3) Moderate quality evidence (1 MA, 9 RCT) WI +; WE + 4) low quality evidence (4 MA, 11 RCT) WI -; WE + 5) moderate quality evidence (2 MA, 20 RCT, 1 performance improvement study) WI -; WE + 6) moderate quality evidence (11 RCT, 2 MA) WI -; WE + 7) low quality evidence (3 RCT, 4 MA) WI -; WE + (9 high quality evidence (2 MA, 6 RCT) WI +; WE +

3) Yes (88%) 4) Yes (94%) 5) Yes (98%) 6) Yes (98%) 7) Yes (85%) 8) Yes (97%)

Underwater polypectomy or endoscopic mucosal resection

9) Underwater endoscopic mucosal resection increased the proportion of R0 and en-bloc resections for 10-20 mm non-pedunculated colorectal lesions. 10) Available studies suggest that complications in underwater polypectomy and endoscopic mucosal resection seem to be comparable with conventional endoscopic mucosal resection.

9) very low quality evidence (2 MA, 1 RCT, 1 observational prospective study, 1 retrospective study) WI, not applicable; WE, not applicable 10) very low quality evidence (2 MA, 1 RCT, 1 retrospective study) WI, not applicable; WE, not applicable 11) low quality evidence (8 prospective studies, 3 retrospective studies) WI, not applicable; WE, not applicable

9) Yes (94%) 10) Yes (95%) 11) Yes (95%)

ADR, adenoma detection rate; BBPS, Boston Bowel Preparation scale; GAS, air or carbon dioxide (CO2); MA; meta analysis; RCT, randomized controlled trial; UWP, underwater polypectomy, UEMR, underwater endoscopic mucosal resection; WE, water exchange colonoscopy; WI, water immersion colonoscopy. The “+” sign after the technique acronym means that the technique meets the content of the statement. The sign “-” means that it does not. Authors not included in authorship due to space limit: Silvia Paggi, Arnaldo Amato (Gastroenterology Unit, Ospedale Valduce, Como, Italy); Mauro Liggi, Donatella Mura (Digestive Endoscopy Unit, Sirai Hospital, ASSL Carbonia, Italy); Chih-Wei Tseng (Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan).