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A novel balloon colonoscope detects significantly more simulated polyps than a standard colonoscope in a colon model
ORIGINAL ARTICLE: Experimental Endoscopy
A novel balloon colonoscope detects significantly more simulated polyps than a standard colonoscope in a colon model Nazia Hasan, MD, MPH,1 Seth A. Gross, MD,1 Ian M. Gralnek, MD, MSHS, FASGE,2 Mark Pochapin, MD,1 Ralf Kiesslich, MD, PhD,3 Zamir Halpern, MD4 Haifa, Israel
Background: Although standard colonoscopy is considered the optimal test to detect adenomas, it can have a significant adenoma miss rate. A major contributing factor to high miss rates is the inability to visualize adenomas behind haustral folds and at anatomic flexures. Objective: To compare the diagnostic yield of balloon-assisted colonoscopy versus standard colonoscopy in the detection of simulated polyps in a colon model. Design: Prospective, cohort study. Setting: International gastroenterology meeting. Subject: A colon model composed of elastic material, which mimics the flexible structure of haustral folds, allowing for dynamic responses to balloon inflation, with embedded simulated colon polyps (n Z 12 silicone “polyps”). Interventions: Fifty gastroenterologists were recruited to identify simulated colon polyps in a colon model, first using standard colonoscopy immediately followed by balloon-assisted colonoscopy. Main Outcome Measurements: Detection of simulated polyps. Results: The median polyp detection rate for all simulated polyps was significantly higher with balloon-assisted as compared with standard colonoscopy (91.7% vs 45.8%, respectively; P ! .0001). The significantly higher simulated polyp detection rate with balloon-assisted versus standard colonoscopy was notable both for non-obscured polyps (100.0% vs 75.0%; P ! .0001) and obscured polyps (88.0% vs 25.0%; P ! .0001). Limitations: Non-randomized design, use of a colon model, and simulated colon polyps. Conclusion: As compared with standard colonoscopy, balloon-assisted colonoscopy detected significantly more obscured and non-obscured simulated polyps in a colon model. Clinical studies in human participants are being pursued to further evaluate this new colonoscopic technology. (Gastrointest Endosc 2014;80:1135-40.)
Colonoscopy is the criterion standard for the detection of adenomas; however, several studies that used tandem colonoscopy methodology have reported adenoma miss rates up to 31%.1-4 Although adenoma miss rates have
been linked to variations in colonoscope withdrawal techniques,5 even meticulous examinations by experienced endoscopists have been associated with significant miss rates.6,7 It has been suggested previously that adenoma
Abbreviations: FUSE, Full Spectrum Endoscopy; TER, Third Eye Retroscope.
of Gastroenterology, Rambam Health Care Campus, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel (2), Department of Internal Medicine and Gastroenterology, St. Marienkrankenhaus, Frankfurt, Germany (3), Institute of Gastroenterology, Tel Aviv Sourasky Medical Center and Tel Aviv University, Tel Aviv, Israel (4).
DISCLOSURE: Z. Halpern is a consultant for Smart Medical, who partially funded this study. No other financial relationships relevant to this article were disclosed. Copyright ª 2014 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2014.04.024 Received November 10, 2013. Accepted April 15, 2014. Current affiliations: Division of Gastroenterology, New York University Langone Medical Center, New York, New York, USA (1), Department
www.giejournal.org
Reprint requests: Ian M. Gralnek, MD, MSHS, FASGE, Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, GI Outcomes Unit, Department of Gastroenterology, Rambam Health Care Campus, Haifa, Israel. If you would like to chat with an author of this article, you may contact Prof Gralnek at [email protected].
Volume 80, No. 6 : 2014 GASTROINTESTINAL ENDOSCOPY 1135
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Take-home Message By using a colon model and simulated colon polyps, the authors found that balloon-assisted colonoscopy yielded a significantly higher polyp detection rate (92%) when compared with standard colonoscopy (46%; P ! .0001). The higher diagnostic yield with balloon-assisted colonoscopy was especially notable for obscured polyps (88% vs 25%; P ! .0001). The practical strengths of balloon-assisted colonoscopy, including ease of handling and compatibility with current endoscopy platforms, make this an especially promising device. Further study with human participants is needed. Figure 1. NaviAid G-EYE colonoscope. (SMART Medical Systems, Ra’anana, Israel).
Figure 2. NaviAid SPARK2C inflation system.(SMART Medical Systems, Ra’anana, Israel).
miss rates, despite careful examination, may be caused by poor visualization of hidden anatomic regions within the colon, including anatomic flexures and proximal sides of haustral folds.8 Small polyps even may be hidden by normal mucosa folded over the polyp because of inadequate luminal distention.9 The difficulty of examining these “hidden” areas is related to the limited angle of view of current standard colonoscopes. Although visualization may be enhanced through skilled maneuvers of a standard colonoscope in an attempt to visualize obscure areas behind haustral folds, these maneuvers may not be routinely performed because of increased procedure time. Furthermore, the success of these maneuvers may be operator dependent.10,11 Several innovative devices have attempted to improve the ability to visualize these hidden regions. These new devices include transparent caps fitted to the end of standard colonoscopes, wide-angle colonoscopes, and through-thescope devices such as the Third-Eye Retroscope (Avantis Medical Systems, Inc., Sunnyvale, Calif).9,12-18 Despite these advances, a void remains for a device that surpasses the limitations of a standard colonoscope in achieving optimal visualization while being intuitive, easy to use, cost efficient, and compatible with existing endoscopic platforms. 1136 GASTROINTESTINAL ENDOSCOPY Volume 80, No. 6 : 2014
The NaviAid G-EYE colonoscope (SMART Medical Systems, Ra’anana, Israel) permanently integrates an inflatable, reusable balloon onto the flexible tip of a standard colonoscope. This balloon can be reprocessed and can be inflated by the endoscopist on colonoscope withdrawal to perform balloon-assisted colonoscopy. The mechanical flattening and straightening of haustral folds with the inflated balloon can allow visualization of hidden anatomic areas, thus increasing adenoma detection. The primary aim of this study was to compare the polyp detection rate of balloon-assisted colonoscopy by using the NaviAid G-EYE system versus standard colonoscopy, in the detection of simulated polyps in a colon model.
METHODS This was a prospective cohort study whereby gastroenterologists were recruited at the Digestive Disease Week 2013 annual meeting in Orlando, Florida, USA, to perform back-to-back colonoscopies in a silicone colon model and identify simulated colon polyps by using standard colonoscopy immediately followed by balloon-assisted colonoscopy by using the NaviAid G-EYE system. Participants received a $10 voucher for coffee at the meeting site.
Balloon-assisted colonoscopy description The NaviAid G-EYE system includes the G-EYE balloon colonoscope and the NaviAid SPARK2C inflation system (Figs. 1 and 2). A standard adult colonoscope can be converted into a G-EYE colonoscope by the manufacturer (SMART Medical Systems) with the embedding of a permanently integrated, reusable balloon at the colonoscope’s bending section, located 2 to 3 cm from the colonoscope tip. Balloon integration eliminates the need for external mounting or any preprocedure preparation. The balloon is composed of a latex-free, biocompatible polymer, which, once integrated, increases the diameter of the colonoscope by !0.1 mm. The NaviAid SPARK2C inflation system is used to inflate the balloon on colonoscope withdrawal to 1 of 3 intermediate pressure levels, with a maximal inflation balloon diameter of 60 mm. The appropriate intermediate pressure is selected by the user according to the www.giejournal.org
Hasan et al
Novel balloon colonoscope
Figure 3. A, Intraluminal view with standard colonoscopy. B, Balloon-assisted colonoscopy in the same segment of the colon model.
TABLE 1. Demographic data Gastroenterologists, no. Age, mean ( SD), y Men, no. (%)
50 46 ( 10) 45 (90)
Years in practice, mean, no.
14
Colonoscopies per week, mean, no.
24
SD, Standard deviation.
anatomy of the colon. This allows for a controlled withdrawal technique to engage the colon walls and provide mechanical straightening of haustral folds and flexures. The balloon can be inflated to a set pressure of 70 mbar (millibar) to anchor the colonoscope and stabilize it within the colon lumen during an intervention (eg, biopsy, polypectomy), thereby minimizing movement of the colonoscope. In order to prevent excessive balloon insufflation, the NaviAid SPARK2C includes several pressure sensors with dedicated software. During its operation, the system continuously monitors balloon pressure and maintains a constant pressure, as selected by the user, automatically inflating or deflating the balloon, based on the local colon lumen diameter. In addition, there are several safety mechanisms in the mechanical, electrical, and software technology, which verify the safety of the system. Moreover, SMART Medical Systems has completed balloon colonoscope reprocessing and long-term usability validation studies in accordance with regulatory requirements. In long-term durability studies, the balloon was found to be durable for thousands of uses.
the length of a human colon, with a withdrawal time of 2 minutes corresponding to 6 minutes in a human colon. The elastic material of the colon model mimicked the flexible structure of haustral folds, allowing for a dynamic response to balloon inflation. There were 12 simulated pedunculated polyps, measuring from 3 to 5 mm in size, embedded in the model. The embedded polyps were made of the same elastic material. Eight of the 12 simulated polyps were obscured behind colon folds, and the 4 remaining polyps were placed in more obvious locations, allowing for easier detection. Each of the 3 colon segments included 2 to 3 obscured and at least 1 non-obscured polyp. Each endoscopist was instructed to begin in the cecum and use their own standard withdrawal technique to detect simulated polyps on 2 separate withdrawals: initially with the use of standard colonoscopy (with the balloon deflated) followed by the use of balloon-assisted colonoscopy (with the balloon inflated) (Fig. 3A and B). All endoscopists were blinded to the number, size, and location of the simulated polyps. None of the participants had any prior experience using the NaviAid G-EYE system.
Primary and secondary study endpoints The primary study endpoint was the detection of simulated colon polyps by using balloon-assisted colonoscopy with the NaviAid G-EYE system versus standard colonoscopy. Secondary endpoints included colonoscope withdrawal times and endoscopists’ subjective evaluations of balloon-assisted technology. The evaluations included intuitiveness, ease of handling, and confidence in the increased ability to detect simulated and in vivo polyps by using balloon-assisted colonoscopy.
Statistical analysis Colon model and colonoscopy procedure The colon model used in this study was composed of silicone and had 3 main colon segments with identical luminal caliber throughout the model, approximately 45 mm. The model was 80 cm in length, shorter than www.giejournal.org
All measured variables and derived parameters were tabulated by using descriptive statistics. Data summary tables were provided with sample size, minimum, maximum, arithmetic mean, median, and standard deviation of continuous variables. Because of the limited number of polyps to Volume 80, No. 6 : 2014 GASTROINTESTINAL ENDOSCOPY 1137
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Figure 4. Percentage of polyps detected by standard colonoscopy versus balloon-assisted colonoscopy. BAT, Balloon-assisted colonoscopy.
Figure 5. Endoscopists’ mean ratings of balloon-assisted colonoscopy on a Likert Scale.
be detected, a signed-rank test (non-parametric test) was applied for testing differences between standard colonoscopy and balloon-assisted colonoscopy for the number of simulated polyps detected. All tests applied were 2-tailed, with P ! .05 considered statistically significant. All data were analyzed by using SAS version 9.2 for Windows (SAS Institute, Cary, NC).
RESULTS Fifty gastroenterologists (45 male [90%], mean [ standard deviation {SD}] age 46 10 years) participated in this study. The mean number of years in gastroenterology practice was 14 (range 2-51 years), with an average of 24 colonoscopies performed by each participant per week (Table 1). On withdrawal by using standard colonoscopy (with balloon deflated), the number of simulated polyps (median þ range) detected per endoscopist was 5.5 of 12 (range 1-11), a 45.8% polyp detection rate. In contrast, when balloon-assisted colonoscopy was used, there was a significant increase in the number of simulated polyps 1138 GASTROINTESTINAL ENDOSCOPY Volume 80, No. 6 : 2014
detected per endoscopist (11.0 of 12 [range 3-12], a 91.7% polyp detection rate; P ! .0001). In addition, the significantly higher simulated polyp detection rate with balloon-assisted versus standard colonoscopy was notable both for non-obscured simulated polyps (4.0, 100%, range 1-4 vs 3.0, 75%, range 1-4, respectively; (P ! .0001) as well as for the purposefully hidden simulated polyps (7.0, 88%, range 2-8 vs 2.0, 25%, range 0-8; P ! .0001) (Fig. 4). Moreover, balloon-assisted colonoscopy exhibited significantly shorter withdrawal times than did standard colonoscopy (1 minute, 48 seconds vs 2 minutes, 16 seconds, respectively; P ! .01).
Endoscopists’ subjective ratings of balloonassisted colonoscopy On a Likert scale of 1 to 5, with 1 representing “absolutely disagree” and 5 representing “absolutely agree,” the mean ( SD) score for intuitiveness of the NaviAid G-EYE system was 4.6 ( 0.6), ease of handling was 4.5 ( 0.7), self-described improvement in ability to detect simulated polyps was 4.8 ( 0.4), and expected improvement in polyp detection rate during in vivo colonoscopy www.giejournal.org
Hasan et al
was 4.5 ( 0.7) (Fig. 5). In addition, participants were given the opportunity to provide additional comments regarding the handling of the colonoscope and their experiences with the colon model. None of these comments suggested a difference in the colon traction or friction during standard or balloon-assisted colonoscopy.
DISCUSSION Despite mounting evidence suggesting significant adenoma miss rates with standard colonoscopy,1-4,8,19-20 it is the standard of care. Novel techniques to overcome the visualization limitations of standard colonoscopy such as cap-fitted colonoscopy,21,22 examination with retroflexion,10,11 and wide-angle view colonoscopy23 have been studied; however, they have shown only modest improvements in adenoma detection rates. The Third Eye Retroscope (TER) (Avantis Medical, Sunnyvale, Calif), a self-contained endoscopic accessory that can be advanced through the working channel of a standard colonoscope, has shown promise in several studies.4,15-18 Leufkens et al4 conducted a prospective, randomized, multicenter trial with 5 European and 5 U.S. study sites, with a total of 359 patients. A per-protocol analysis demonstrated a net additional polyp detection rate of 29.8% and adenoma detection rate of 23.2% with TER. Unfortunately, the clinical use of TER has been limited by a number of practical drawbacks including increased procedure time because of the time needed for the exchange of equipment through the accessory channel,4 the need for 2 endoscopy system units and 2 video monitors, and the associated cost of disposables. More recently, there have been promising results with the Full Spectrum Endoscopy (FUSE) colonoscope (Endochoice, Alpharetta, Ga). This colonoscope allows the endoscopist to view 330 while maintaining features of a standard colonoscope including colonoscope length and diameter, full tip deflection, and a 3.8-mm working channel. Gralnek et al24 demonstrated significantly higher simulated polyp detection in a colon model comparing the FUSE colonoscope with a standard forward-viewing colonoscope. Subsequently, in their “first in human study,” these same investigators demonstrated the feasibility and safety of FUSE colonoscopy in a prospective cohort study of 50 patients.25 Although the results from the FUSE study are intriguing, the routine use of the platform may be limited by the incompatibility of the FUSE system with existing standard colonoscopes, processors, and video monitors and by the learning curve associated with colonoscopy examinations that use 3 separate video monitors. In our study, results showed significantly higher simulated polyp detection rates in a colon model with balloon-assisted colonoscopy by using a novel balloon colonoscope, the G-EYE, as compared with standard colonoscopy. Similar to other aforementioned technologies, www.giejournal.org
Novel balloon colonoscope
balloon-assisted colonoscopy can be used to overcome a significant factor in adenoma miss rates, the inability to detect lesions behind haustral folds and flexures. However, balloon-assisted colonoscopy by using the G-EYE colonoscope may provide an advantage over other novel devices because it is intuitive to use, easy to maneuver, and does not require any change in endoscopists’ standard withdrawal techniques. Moreover, this technology is reusable with standard reprocessing techniques and can be integrated into any existing endoscopy platform in endoscopy units. Our study is limited by several design factors including the use of the same colonoscope with a deflated balloon as the control “standard colonoscope,” lack of randomization of the order of the colonoscopies, subsequent loss of blinding of simulated polyp location during performance of the second colonoscopy by using balloon-assisted colonoscopy, and an unclear effect of the location of polyps identified, because this information was not recorded. Moreover, within the colon model itself, the luminal diameter is constant at 45 mm, so we do not know how the G-EYE balloon colonoscope will function with varying luminal diameters. In conclusion, the increased ability to detect simulated polyps, along with several practical strengths of the GEYE colonoscope, provides us with a promising new technology for more effective colonoscopic examinations. A randomized study with human participants is necessary to determine the clinical utility of this colonoscope.
REFERENCES 1. Rex D, Cutler C, Lemmel G, et al. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies. Gastroenterology 1997;112: 24-8. 2. van Rijn J, Reitsma J, Stoker J, et al. Polyp miss rate determined by tandem colonoscopy: a systematic review. Am J Gastroenterol 2006;101: 343-50. 3. Heresbach D, Barrioz T, Lapalus MG, et al. Miss rate for colorectal neoplastic polyps: a prospective multicenter study of back-to-back video colonoscopies. Endoscopy 2008;40:284-90. 4. Leufkens AM, DeMarco DC, Rastogi A, et al. Effect of a retrogradeviewing device on adenoma detection rate during colonoscopy: the TERRACE study. Gastrointest Endosc 2011;73:480-9. 5. Rex DK. Colonoscopic withdrawal technique is associated with adenoma miss rates. Gastrointest Endosc 2000;51:33-6. 6. Rex DK, Cutler CS, Lemmel GT, et al. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies. Gastroenterology 1997;112:243-8. 7. Hixson LS, Fennerty MB, Sampliner RE, et al. Prospective study of the frequency and size distribution of polyps missed by colonoscopy. J Natl Cancer Inst 1990;82:1769-72. 8. Leufkens AM, van Oijen MGH, Siersema PD. Factors influencing the miss rate of polyps in a back-to-back colonoscopy study. Endoscopy 2012;44:470-5. 9. Rex DK, Chadalawada V, Helper DJ. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies. Am J Gastroenterol 2003;98: 2000-5.
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Novel balloon colonoscope 10. Harrison M, Singh N, Rex DK. Impact of proximal colon retroflexion on adenoma miss rates. Am J Gastroenterol 2004;99: 519-22. 11. Hewett DG, Rex DK. Miss rate of right-sided colon examination during colonoscopy defined by retroflexion: an observational study. Gastrointest Endosc 2011;74:246-52. 12. Rex DK. Accessing proximal aspects of folds and flexures during colonoscopy: impact of a pediatric colonoscope with a short bending section. Am J Gastroenterol 2003;98:1504-7. 13. Deenadayalu VP, Chadalawada V, Rex DK. 170 degrees wide-angle colonoscope: effect on efficiency and miss rates. Am J Gastroenterol 2004;99:2138-42. 14. Sanchez-Yague A, Kaltenbach T, Yamamoto H, et al. The endoscopic cap that can (with videos). Gastrointest Endosc 2012;76:169-78. 15. Triadafilopoulos G, Watts HD, Van Dam J, et al. A novel retrograde viewing auxiliary imaging device (Third Eye Retroscope) improves the detection of simulated polyps in anatomic models of the colon. Gastrointest Endosc 2007;65:139-44. 16. Triadafilopoulos G, Li J. A pilot study to assess the safety and efficacy of the Third Eye retrograde auxiliary imaging system during colonoscopy. Endoscopy 2008;40:478-82. 17. DeMarco DC, Odstrcil E, Lara LF, et al. Impact of experience with a retrograde-viewing device on adenoma detection rates and withdrawal times during colonoscopy: the Third Eye Retroscope study group. Gastrointest Endosc 2010;71:542-50.
Hasan et al 18. Waye JD, Heigh RI, Rex DK, et al. A retrograde-viewing device improves detection of adenomas in the colon: a prospective efficacy evaluation. Gastrointest Endosc 2010;71:551-6. 19. Hixson LJ, Fennerty MB, Sampliner RE, et al. Prospective blinded trial of the colonoscopic miss-rate of large colorectal polyps. Gastrointest Endosc 1991;37:125-7. 20. Pickhardt PJ, Nugent PA, Mysliwiec PA, et al. Location of adenomas missed by optical colonoscopy. Ann Intern Med 2004;141:352-9. 21. Matsushita M, Hajiro K, Okazaki K, et al. Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap. Endoscopy 1998;30:444-7. 22. Rastogi A, Bansal A, Rao DS, et al. Higher adenoma detection rates with cap-assisted colonoscopy: a randomised controlled trial. Gut 2012;61: 402-8. 23. Uraoka T, Tanaka S, Matsumoto T, et al. A novel extra-wide-angle-view colonoscope: a simulated pilot study using anatomic colorectal models. Gastrointest Endosc 2013;77:480-3. 24. Gralnek I, Carr-Locke DL, Segol O, et al. Comparison of standard forward-viewing mode versus ultrawide-viewing mode of a novel colonoscopy platform: a prospective, multicenter study in the detection of simulated polyps in an in vitro colon model (with video). Gastrointest Endosc 2013;77:472-9. 25. Gralnek IM, Segol O, Suissa A, et al. A prospective cohort study evaluating a novel colonoscopy platform featuring Fused“full spectrum endoscopyTM”. Endoscopy 2013;45:697-702.
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1140 GASTROINTESTINAL ENDOSCOPY Volume 80, No. 6 : 2014
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A novel balloon colonoscope detects significantly more simulated polyps than a standard colonoscope in a colon model Nazia Hasan, MD, MPH,1 Seth A. Gross, MD,1 Ian M. Gralnek, MD, MSHS, FASGE,2 Mark Pochapin, MD,1 Ralf Kiesslich, MD, PhD,3 Zamir Halpern, MD4 Haifa, Israel
Background: Although standard colonoscopy is considered the optimal test to detect adenomas, it can have a significant adenoma miss rate. A major contributing factor to high miss rates is the inability to visualize adenomas behind haustral folds and at anatomic flexures. Objective: To compare the diagnostic yield of balloon-assisted colonoscopy versus standard colonoscopy in the detection of simulated polyps in a colon model. Design: Prospective, cohort study. Setting: International gastroenterology meeting. Subject: A colon model composed of elastic material, which mimics the flexible structure of haustral folds, allowing for dynamic responses to balloon inflation, with embedded simulated colon polyps (n Z 12 silicone “polyps”). Interventions: Fifty gastroenterologists were recruited to identify simulated colon polyps in a colon model, first using standard colonoscopy immediately followed by balloon-assisted colonoscopy. Main Outcome Measurements: Detection of simulated polyps. Results: The median polyp detection rate for all simulated polyps was significantly higher with balloon-assisted as compared with standard colonoscopy (91.7% vs 45.8%, respectively; P ! .0001). The significantly higher simulated polyp detection rate with balloon-assisted versus standard colonoscopy was notable both for non-obscured polyps (100.0% vs 75.0%; P ! .0001) and obscured polyps (88.0% vs 25.0%; P ! .0001). Limitations: Non-randomized design, use of a colon model, and simulated colon polyps. Conclusion: As compared with standard colonoscopy, balloon-assisted colonoscopy detected significantly more obscured and non-obscured simulated polyps in a colon model. Clinical studies in human participants are being pursued to further evaluate this new colonoscopic technology. (Gastrointest Endosc 2014;80:1135-40.)
Colonoscopy is the criterion standard for the detection of adenomas; however, several studies that used tandem colonoscopy methodology have reported adenoma miss rates up to 31%.1-4 Although adenoma miss rates have
been linked to variations in colonoscope withdrawal techniques,5 even meticulous examinations by experienced endoscopists have been associated with significant miss rates.6,7 It has been suggested previously that adenoma
Abbreviations: FUSE, Full Spectrum Endoscopy; TER, Third Eye Retroscope.
of Gastroenterology, Rambam Health Care Campus, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel (2), Department of Internal Medicine and Gastroenterology, St. Marienkrankenhaus, Frankfurt, Germany (3), Institute of Gastroenterology, Tel Aviv Sourasky Medical Center and Tel Aviv University, Tel Aviv, Israel (4).
DISCLOSURE: Z. Halpern is a consultant for Smart Medical, who partially funded this study. No other financial relationships relevant to this article were disclosed. Copyright ª 2014 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2014.04.024 Received November 10, 2013. Accepted April 15, 2014. Current affiliations: Division of Gastroenterology, New York University Langone Medical Center, New York, New York, USA (1), Department
www.giejournal.org
Reprint requests: Ian M. Gralnek, MD, MSHS, FASGE, Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, GI Outcomes Unit, Department of Gastroenterology, Rambam Health Care Campus, Haifa, Israel. If you would like to chat with an author of this article, you may contact Prof Gralnek at [email protected].
Volume 80, No. 6 : 2014 GASTROINTESTINAL ENDOSCOPY 1135
Novel balloon colonoscope
Hasan et al
Take-home Message By using a colon model and simulated colon polyps, the authors found that balloon-assisted colonoscopy yielded a significantly higher polyp detection rate (92%) when compared with standard colonoscopy (46%; P ! .0001). The higher diagnostic yield with balloon-assisted colonoscopy was especially notable for obscured polyps (88% vs 25%; P ! .0001). The practical strengths of balloon-assisted colonoscopy, including ease of handling and compatibility with current endoscopy platforms, make this an especially promising device. Further study with human participants is needed. Figure 1. NaviAid G-EYE colonoscope. (SMART Medical Systems, Ra’anana, Israel).
Figure 2. NaviAid SPARK2C inflation system.(SMART Medical Systems, Ra’anana, Israel).
miss rates, despite careful examination, may be caused by poor visualization of hidden anatomic regions within the colon, including anatomic flexures and proximal sides of haustral folds.8 Small polyps even may be hidden by normal mucosa folded over the polyp because of inadequate luminal distention.9 The difficulty of examining these “hidden” areas is related to the limited angle of view of current standard colonoscopes. Although visualization may be enhanced through skilled maneuvers of a standard colonoscope in an attempt to visualize obscure areas behind haustral folds, these maneuvers may not be routinely performed because of increased procedure time. Furthermore, the success of these maneuvers may be operator dependent.10,11 Several innovative devices have attempted to improve the ability to visualize these hidden regions. These new devices include transparent caps fitted to the end of standard colonoscopes, wide-angle colonoscopes, and through-thescope devices such as the Third-Eye Retroscope (Avantis Medical Systems, Inc., Sunnyvale, Calif).9,12-18 Despite these advances, a void remains for a device that surpasses the limitations of a standard colonoscope in achieving optimal visualization while being intuitive, easy to use, cost efficient, and compatible with existing endoscopic platforms. 1136 GASTROINTESTINAL ENDOSCOPY Volume 80, No. 6 : 2014
The NaviAid G-EYE colonoscope (SMART Medical Systems, Ra’anana, Israel) permanently integrates an inflatable, reusable balloon onto the flexible tip of a standard colonoscope. This balloon can be reprocessed and can be inflated by the endoscopist on colonoscope withdrawal to perform balloon-assisted colonoscopy. The mechanical flattening and straightening of haustral folds with the inflated balloon can allow visualization of hidden anatomic areas, thus increasing adenoma detection. The primary aim of this study was to compare the polyp detection rate of balloon-assisted colonoscopy by using the NaviAid G-EYE system versus standard colonoscopy, in the detection of simulated polyps in a colon model.
METHODS This was a prospective cohort study whereby gastroenterologists were recruited at the Digestive Disease Week 2013 annual meeting in Orlando, Florida, USA, to perform back-to-back colonoscopies in a silicone colon model and identify simulated colon polyps by using standard colonoscopy immediately followed by balloon-assisted colonoscopy by using the NaviAid G-EYE system. Participants received a $10 voucher for coffee at the meeting site.
Balloon-assisted colonoscopy description The NaviAid G-EYE system includes the G-EYE balloon colonoscope and the NaviAid SPARK2C inflation system (Figs. 1 and 2). A standard adult colonoscope can be converted into a G-EYE colonoscope by the manufacturer (SMART Medical Systems) with the embedding of a permanently integrated, reusable balloon at the colonoscope’s bending section, located 2 to 3 cm from the colonoscope tip. Balloon integration eliminates the need for external mounting or any preprocedure preparation. The balloon is composed of a latex-free, biocompatible polymer, which, once integrated, increases the diameter of the colonoscope by !0.1 mm. The NaviAid SPARK2C inflation system is used to inflate the balloon on colonoscope withdrawal to 1 of 3 intermediate pressure levels, with a maximal inflation balloon diameter of 60 mm. The appropriate intermediate pressure is selected by the user according to the www.giejournal.org
Hasan et al
Novel balloon colonoscope
Figure 3. A, Intraluminal view with standard colonoscopy. B, Balloon-assisted colonoscopy in the same segment of the colon model.
TABLE 1. Demographic data Gastroenterologists, no. Age, mean ( SD), y Men, no. (%)
50 46 ( 10) 45 (90)
Years in practice, mean, no.
14
Colonoscopies per week, mean, no.
24
SD, Standard deviation.
anatomy of the colon. This allows for a controlled withdrawal technique to engage the colon walls and provide mechanical straightening of haustral folds and flexures. The balloon can be inflated to a set pressure of 70 mbar (millibar) to anchor the colonoscope and stabilize it within the colon lumen during an intervention (eg, biopsy, polypectomy), thereby minimizing movement of the colonoscope. In order to prevent excessive balloon insufflation, the NaviAid SPARK2C includes several pressure sensors with dedicated software. During its operation, the system continuously monitors balloon pressure and maintains a constant pressure, as selected by the user, automatically inflating or deflating the balloon, based on the local colon lumen diameter. In addition, there are several safety mechanisms in the mechanical, electrical, and software technology, which verify the safety of the system. Moreover, SMART Medical Systems has completed balloon colonoscope reprocessing and long-term usability validation studies in accordance with regulatory requirements. In long-term durability studies, the balloon was found to be durable for thousands of uses.
the length of a human colon, with a withdrawal time of 2 minutes corresponding to 6 minutes in a human colon. The elastic material of the colon model mimicked the flexible structure of haustral folds, allowing for a dynamic response to balloon inflation. There were 12 simulated pedunculated polyps, measuring from 3 to 5 mm in size, embedded in the model. The embedded polyps were made of the same elastic material. Eight of the 12 simulated polyps were obscured behind colon folds, and the 4 remaining polyps were placed in more obvious locations, allowing for easier detection. Each of the 3 colon segments included 2 to 3 obscured and at least 1 non-obscured polyp. Each endoscopist was instructed to begin in the cecum and use their own standard withdrawal technique to detect simulated polyps on 2 separate withdrawals: initially with the use of standard colonoscopy (with the balloon deflated) followed by the use of balloon-assisted colonoscopy (with the balloon inflated) (Fig. 3A and B). All endoscopists were blinded to the number, size, and location of the simulated polyps. None of the participants had any prior experience using the NaviAid G-EYE system.
Primary and secondary study endpoints The primary study endpoint was the detection of simulated colon polyps by using balloon-assisted colonoscopy with the NaviAid G-EYE system versus standard colonoscopy. Secondary endpoints included colonoscope withdrawal times and endoscopists’ subjective evaluations of balloon-assisted technology. The evaluations included intuitiveness, ease of handling, and confidence in the increased ability to detect simulated and in vivo polyps by using balloon-assisted colonoscopy.
Statistical analysis Colon model and colonoscopy procedure The colon model used in this study was composed of silicone and had 3 main colon segments with identical luminal caliber throughout the model, approximately 45 mm. The model was 80 cm in length, shorter than www.giejournal.org
All measured variables and derived parameters were tabulated by using descriptive statistics. Data summary tables were provided with sample size, minimum, maximum, arithmetic mean, median, and standard deviation of continuous variables. Because of the limited number of polyps to Volume 80, No. 6 : 2014 GASTROINTESTINAL ENDOSCOPY 1137
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Figure 4. Percentage of polyps detected by standard colonoscopy versus balloon-assisted colonoscopy. BAT, Balloon-assisted colonoscopy.
Figure 5. Endoscopists’ mean ratings of balloon-assisted colonoscopy on a Likert Scale.
be detected, a signed-rank test (non-parametric test) was applied for testing differences between standard colonoscopy and balloon-assisted colonoscopy for the number of simulated polyps detected. All tests applied were 2-tailed, with P ! .05 considered statistically significant. All data were analyzed by using SAS version 9.2 for Windows (SAS Institute, Cary, NC).
RESULTS Fifty gastroenterologists (45 male [90%], mean [ standard deviation {SD}] age 46 10 years) participated in this study. The mean number of years in gastroenterology practice was 14 (range 2-51 years), with an average of 24 colonoscopies performed by each participant per week (Table 1). On withdrawal by using standard colonoscopy (with balloon deflated), the number of simulated polyps (median þ range) detected per endoscopist was 5.5 of 12 (range 1-11), a 45.8% polyp detection rate. In contrast, when balloon-assisted colonoscopy was used, there was a significant increase in the number of simulated polyps 1138 GASTROINTESTINAL ENDOSCOPY Volume 80, No. 6 : 2014
detected per endoscopist (11.0 of 12 [range 3-12], a 91.7% polyp detection rate; P ! .0001). In addition, the significantly higher simulated polyp detection rate with balloon-assisted versus standard colonoscopy was notable both for non-obscured simulated polyps (4.0, 100%, range 1-4 vs 3.0, 75%, range 1-4, respectively; (P ! .0001) as well as for the purposefully hidden simulated polyps (7.0, 88%, range 2-8 vs 2.0, 25%, range 0-8; P ! .0001) (Fig. 4). Moreover, balloon-assisted colonoscopy exhibited significantly shorter withdrawal times than did standard colonoscopy (1 minute, 48 seconds vs 2 minutes, 16 seconds, respectively; P ! .01).
Endoscopists’ subjective ratings of balloonassisted colonoscopy On a Likert scale of 1 to 5, with 1 representing “absolutely disagree” and 5 representing “absolutely agree,” the mean ( SD) score for intuitiveness of the NaviAid G-EYE system was 4.6 ( 0.6), ease of handling was 4.5 ( 0.7), self-described improvement in ability to detect simulated polyps was 4.8 ( 0.4), and expected improvement in polyp detection rate during in vivo colonoscopy www.giejournal.org
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was 4.5 ( 0.7) (Fig. 5). In addition, participants were given the opportunity to provide additional comments regarding the handling of the colonoscope and their experiences with the colon model. None of these comments suggested a difference in the colon traction or friction during standard or balloon-assisted colonoscopy.
DISCUSSION Despite mounting evidence suggesting significant adenoma miss rates with standard colonoscopy,1-4,8,19-20 it is the standard of care. Novel techniques to overcome the visualization limitations of standard colonoscopy such as cap-fitted colonoscopy,21,22 examination with retroflexion,10,11 and wide-angle view colonoscopy23 have been studied; however, they have shown only modest improvements in adenoma detection rates. The Third Eye Retroscope (TER) (Avantis Medical, Sunnyvale, Calif), a self-contained endoscopic accessory that can be advanced through the working channel of a standard colonoscope, has shown promise in several studies.4,15-18 Leufkens et al4 conducted a prospective, randomized, multicenter trial with 5 European and 5 U.S. study sites, with a total of 359 patients. A per-protocol analysis demonstrated a net additional polyp detection rate of 29.8% and adenoma detection rate of 23.2% with TER. Unfortunately, the clinical use of TER has been limited by a number of practical drawbacks including increased procedure time because of the time needed for the exchange of equipment through the accessory channel,4 the need for 2 endoscopy system units and 2 video monitors, and the associated cost of disposables. More recently, there have been promising results with the Full Spectrum Endoscopy (FUSE) colonoscope (Endochoice, Alpharetta, Ga). This colonoscope allows the endoscopist to view 330 while maintaining features of a standard colonoscope including colonoscope length and diameter, full tip deflection, and a 3.8-mm working channel. Gralnek et al24 demonstrated significantly higher simulated polyp detection in a colon model comparing the FUSE colonoscope with a standard forward-viewing colonoscope. Subsequently, in their “first in human study,” these same investigators demonstrated the feasibility and safety of FUSE colonoscopy in a prospective cohort study of 50 patients.25 Although the results from the FUSE study are intriguing, the routine use of the platform may be limited by the incompatibility of the FUSE system with existing standard colonoscopes, processors, and video monitors and by the learning curve associated with colonoscopy examinations that use 3 separate video monitors. In our study, results showed significantly higher simulated polyp detection rates in a colon model with balloon-assisted colonoscopy by using a novel balloon colonoscope, the G-EYE, as compared with standard colonoscopy. Similar to other aforementioned technologies, www.giejournal.org
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balloon-assisted colonoscopy can be used to overcome a significant factor in adenoma miss rates, the inability to detect lesions behind haustral folds and flexures. However, balloon-assisted colonoscopy by using the G-EYE colonoscope may provide an advantage over other novel devices because it is intuitive to use, easy to maneuver, and does not require any change in endoscopists’ standard withdrawal techniques. Moreover, this technology is reusable with standard reprocessing techniques and can be integrated into any existing endoscopy platform in endoscopy units. Our study is limited by several design factors including the use of the same colonoscope with a deflated balloon as the control “standard colonoscope,” lack of randomization of the order of the colonoscopies, subsequent loss of blinding of simulated polyp location during performance of the second colonoscopy by using balloon-assisted colonoscopy, and an unclear effect of the location of polyps identified, because this information was not recorded. Moreover, within the colon model itself, the luminal diameter is constant at 45 mm, so we do not know how the G-EYE balloon colonoscope will function with varying luminal diameters. In conclusion, the increased ability to detect simulated polyps, along with several practical strengths of the GEYE colonoscope, provides us with a promising new technology for more effective colonoscopic examinations. A randomized study with human participants is necessary to determine the clinical utility of this colonoscope.
REFERENCES 1. Rex D, Cutler C, Lemmel G, et al. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies. Gastroenterology 1997;112: 24-8. 2. van Rijn J, Reitsma J, Stoker J, et al. Polyp miss rate determined by tandem colonoscopy: a systematic review. Am J Gastroenterol 2006;101: 343-50. 3. Heresbach D, Barrioz T, Lapalus MG, et al. Miss rate for colorectal neoplastic polyps: a prospective multicenter study of back-to-back video colonoscopies. Endoscopy 2008;40:284-90. 4. Leufkens AM, DeMarco DC, Rastogi A, et al. Effect of a retrogradeviewing device on adenoma detection rate during colonoscopy: the TERRACE study. Gastrointest Endosc 2011;73:480-9. 5. Rex DK. Colonoscopic withdrawal technique is associated with adenoma miss rates. Gastrointest Endosc 2000;51:33-6. 6. Rex DK, Cutler CS, Lemmel GT, et al. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies. Gastroenterology 1997;112:243-8. 7. Hixson LS, Fennerty MB, Sampliner RE, et al. Prospective study of the frequency and size distribution of polyps missed by colonoscopy. J Natl Cancer Inst 1990;82:1769-72. 8. Leufkens AM, van Oijen MGH, Siersema PD. Factors influencing the miss rate of polyps in a back-to-back colonoscopy study. Endoscopy 2012;44:470-5. 9. Rex DK, Chadalawada V, Helper DJ. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies. Am J Gastroenterol 2003;98: 2000-5.
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Novel balloon colonoscope 10. Harrison M, Singh N, Rex DK. Impact of proximal colon retroflexion on adenoma miss rates. Am J Gastroenterol 2004;99: 519-22. 11. Hewett DG, Rex DK. Miss rate of right-sided colon examination during colonoscopy defined by retroflexion: an observational study. Gastrointest Endosc 2011;74:246-52. 12. Rex DK. Accessing proximal aspects of folds and flexures during colonoscopy: impact of a pediatric colonoscope with a short bending section. Am J Gastroenterol 2003;98:1504-7. 13. Deenadayalu VP, Chadalawada V, Rex DK. 170 degrees wide-angle colonoscope: effect on efficiency and miss rates. Am J Gastroenterol 2004;99:2138-42. 14. Sanchez-Yague A, Kaltenbach T, Yamamoto H, et al. The endoscopic cap that can (with videos). Gastrointest Endosc 2012;76:169-78. 15. Triadafilopoulos G, Watts HD, Van Dam J, et al. A novel retrograde viewing auxiliary imaging device (Third Eye Retroscope) improves the detection of simulated polyps in anatomic models of the colon. Gastrointest Endosc 2007;65:139-44. 16. Triadafilopoulos G, Li J. A pilot study to assess the safety and efficacy of the Third Eye retrograde auxiliary imaging system during colonoscopy. Endoscopy 2008;40:478-82. 17. DeMarco DC, Odstrcil E, Lara LF, et al. Impact of experience with a retrograde-viewing device on adenoma detection rates and withdrawal times during colonoscopy: the Third Eye Retroscope study group. Gastrointest Endosc 2010;71:542-50.
Hasan et al 18. Waye JD, Heigh RI, Rex DK, et al. A retrograde-viewing device improves detection of adenomas in the colon: a prospective efficacy evaluation. Gastrointest Endosc 2010;71:551-6. 19. Hixson LJ, Fennerty MB, Sampliner RE, et al. Prospective blinded trial of the colonoscopic miss-rate of large colorectal polyps. Gastrointest Endosc 1991;37:125-7. 20. Pickhardt PJ, Nugent PA, Mysliwiec PA, et al. Location of adenomas missed by optical colonoscopy. Ann Intern Med 2004;141:352-9. 21. Matsushita M, Hajiro K, Okazaki K, et al. Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap. Endoscopy 1998;30:444-7. 22. Rastogi A, Bansal A, Rao DS, et al. Higher adenoma detection rates with cap-assisted colonoscopy: a randomised controlled trial. Gut 2012;61: 402-8. 23. Uraoka T, Tanaka S, Matsumoto T, et al. A novel extra-wide-angle-view colonoscope: a simulated pilot study using anatomic colorectal models. Gastrointest Endosc 2013;77:480-3. 24. Gralnek I, Carr-Locke DL, Segol O, et al. Comparison of standard forward-viewing mode versus ultrawide-viewing mode of a novel colonoscopy platform: a prospective, multicenter study in the detection of simulated polyps in an in vitro colon model (with video). Gastrointest Endosc 2013;77:472-9. 25. Gralnek IM, Segol O, Suissa A, et al. A prospective cohort study evaluating a novel colonoscopy platform featuring Fused“full spectrum endoscopyTM”. Endoscopy 2013;45:697-702.
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