Advertisement

A novel self-propelled disposable colonoscope is effective for colonoscopy in humans (with video)

Open AccessPublished:September 18, 2015DOI:https://doi.org/10.1016/j.gie.2015.08.083

      Background and Aims

      The self-propelled disposable colonoscope (SPDC) with a 360° view is designed to enhance visualization, minimize risks of perforation and infection transmission, and shorten operator training time associated with conventional colonoscopy (CC). We evaluated SPDC efficacy for cecal intubation and safety.

      Methods

      Prospective patients presenting for colorectal cancer screening underwent SPDC immediately followed by CC. Initial patients necessary for SPDC operators to achieve proficiency comprised the training cohort. Subsequent enrolled patients comprised the study cohort. SPDC colonoscopy was performed up to the cecum, where anatomic landmarks were photographed and mucosal suction marks were placed. During SPDC withdrawal, polyps were recorded and similarly marked. On the second pass (by using CC), any potential mucosal damage and suction marks from the SPDC as well as polyps were recorded. Main endpoints included SPDC cecal intubation rates, confirmed by anatomic landmarks and residual marks seen on subsequent CC, and frequency and severity of adverse events and mucosal damage with SPDC. The secondary endpoint was subjective procedure proficiency, evaluated by the operator based on the training cohort. The tertiary endpoint was documenting pathologies visualized with SPDC.

      Results

      Fifty-six of 58 enrolled subjects completed the study. Proficiency with SPDC was attained after 8 to 10 procedures. Cecal intubation was successful in 98.2% (55/56 subjects; 95% confidence interval [CI], 90.4%-99.9%), including 100% (95% CI, 90.7%-100%) of the study cohort and 94.4% (95% CI, 72.7%-99.9%) of the training cohort. No mucosal damage or adverse events were reported. SPDC detected 87.5% of polyps seen in tandem CC, including all polyps larger than 5 mm.

      Conclusions

      SPDC was highly successful, simple to use, and safe in achieving complete colonoscopy (cecal intubation). (Clinical trial registration number: 0692-12-TLV.)

      Abbreviations:

      CC (conventional colonoscopy), CI (confidence interval), CIR (cecum intubation rate), CRC (colorectal cancer), SPDC (self-propelled disposable colonoscope)
      Colorectal cancer (CRC) is the second leading killer among cancers in the Western world. The risk of the development of CRC and of CRC-related mortality is reduced by removal of adenomas and early detection and treatment of cancers. Colonoscopy is considered the criterion standard for colon inspection and removal of polyps, with recent reports suggesting a correlation between the increased adoption of screening colonoscopy and the reduced incidence of CRC.
      • Brenner H.
      • Chang-Claude J.
      • Jansen L.
      • et al.
      Reduced risk of colorectal cancer up to 10 years after screening, surveillance, or diagnostic colonoscopy.
      • Kahi C.J.
      • Myers L.J.
      • Slaven J.E.
      • et al.
      Lower endoscopy reduces colorectal cancer incidence in older individuals.
      Conventional colonoscopy (CC) is associated with risks, albeit limited and finite, which may be life threatening. These include bowel perforation and infectious disease transmission.
      • Kovaleva J.
      • Peters F.T.
      • van der Mei H.C.
      • et al.
      Transmission of infection by flexible gastrointestinal endoscopy and bronchoscopy.
      • Gonzalez-Candelas F.
      • Guiral S.
      • Carbo R.
      • et al.
      Patient-to-patient transmission of hepatitis C virus (HCV) during colonoscopy diagnosis.
      • Banerjee S.
      • Shen B.
      • Nelson D.B.
      • et al.
      Infection control during GI endoscopy.
      • Nelson D.B.
      Infectious disease complications of GI endoscopy: part II, exogenous infections.
      Infections may occur due to failure to meet standards of reprocessing
      • Seoane-Vazquez E.
      • Rodriguez-Monguio R.
      • Visaria J.
      • et al.
      Exogenous endoscopy-related infections, pseudo-infections, and toxic reactions: clinical and economic burden.
      or because of inherent difficulties with complete disinfection.
      • Herve R.
      • Keevil C.W.
      Current limitations about the cleaning of luminal endoscopes.
      • Chiu K.W.
      • Tsai M.C.
      • Wu K.L.
      • et al.
      Surveillance cultures of samples obtained from biopsy channels and automated endoscope reprocessors after high-level disinfection of gastrointestinal endoscopes.
      Although reported infection rates associated with colonoscopy are low, such infections may go unrecognized due to a lack of appropriate surveillance and reporting as well as a lack of acute symptoms.
      • Gonzalez-Candelas F.
      • Guiral S.
      • Carbo R.
      • et al.
      Patient-to-patient transmission of hepatitis C virus (HCV) during colonoscopy diagnosis.
      • Kovaleva J.
      • Meessen N.E.
      • Peters F.T.
      • et al.
      Is bacteriologic surveillance in endoscope reprocessing stringent enough?.
      • Nelson D.B.
      Hepatitis C virus cross-infection during endoscopy: is it the “tip of the iceberg” or the absence of ice?.
      Achieving proficiency in performing CC, including consistent cecal intubation and recognition of colon pathologies, requires a substantial learning process estimated to be at least 300 to 500 colonoscopy procedures.
      • Spier B.J.
      • Benson M.
      • Pfau P.R.
      • et al.
      Colonoscopy training in gastroenterology fellowships: determining competence.
      • Spier B.J.
      • Durkin E.T.
      • Walker A.J.
      • et al.
      Surgical resident's training in colonoscopy: numbers, competency, and perceptions.
      The self-propelled disposable colonoscope (SPDC) system (Aer-O-Scope; GI View Ltd, Ramat Gan, Israel) was designed to address these concerns (Fig. 1; Video 1, available online at www.giejournal.org). The SPDC includes an external workstation with full joystick control (Fig. 1A) over the inserted, fully disposable scanner unit. The scanner comprises a soft, flexible, light-weight cable (multilumen) attached to a system of pliable polyurethane balloons (Fig. 1B). Gentle propulsion of the scanner is achieved by inflating the balloons and colon with CO2, supplied by the workstation at a maximal pressure of 60 mbar. This minimizes the need for the operator to apply pushing force to the instrument and facilitates easy maneuvering around difficult anatomic flexures and colonic angulations. Pushing forces when applied by the operator to the soft cable of the SPDC are scattered over the entire surface area of the balloons before reaching the colon wall. This is in contrast to CC in which basal inflation pressure reaches 75 mbar, whereas forces as high as 2.5 kg are applied by the physician to the tip of the CC and are transmitted directly to the colon wall causing pressure as high as 1200 mbar.
      • Korman L.Y.
      • Haddad N.G.
      • Metz D.C.
      • et al.
      Effect of propofol anesthesia on force application during colonoscopy.
      An additional pulsating balloon located at the tip of the SPDC scanner further eases colonoscope intubation. The hydrophilic coating of the balloons and cable lowers friction by more than 90%, thus enhancing movement in the colon. At the scanner tip are openings for irrigation, suction, and insufflation as well as the optical head with a camera and light sources (Fig. 1C). A bending section toward the tip of the colonoscope allows full steering control of the optical head using the joystick at the workstation, which enables optimal visualization of suspected areas and easy navigation through tortuous turns in the colon. Altogether, these features have the potential to reduce the risks of colonic perforation. Because the SPDC scanner component is completely disposable, it carries no risk of infectious disease transmission and obviates the need for decontamination.
      Figure thumbnail gr1
      Figure 1Features of the self-propelled disposable colonoscope system. A, External workstation with full joystick control. B, Fully disposable scanner unit comprising a soft, flexible light-weight cable (multilumen) attached to a system of pliable polyurethane balloons. C, Scanner tip with openings for irrigation, suction, and insufflation as well as the optical head with a camera and light sources.
      The enhanced optical system contains white-light LEDs and a CMOS high-definition digital camera, providing standard forward views with a 57° field of view as well as simultaneous complete 360° (omni) view of a cylindrical strip of the colon 18° toward the front and 26° toward the rear (Fig. 2; Video 1, available online at www.giejournal.org). This allows the operator to have continuous visualization of the colon lumen even when the optical imaging head is flush against the colonic wall, aiding in steering and advancement of the SPDC around flexures and bends.
      Figure thumbnail gr2
      Figure 2Self-propelled disposable colonoscope visualization. A, The colonoscope is shown within the intestinal lumen. The spectrum of visualization is illustrated by white shading. A polyp behind a fold (green circle) is seen and picked up in the omni 360° view screen, shown on the right. B, Schematic of colonoscope fields of view.
      An initial pilot study performed with a prototype model
      • Pfeffer J.
      • Grinshpon R.
      • Rex D.
      • et al.
      The Aer-O-Scope: proof of the concept of a pneumatic, skill-independent, self-propelling, self-navigating colonoscope in a pig model.
      • Arber N.
      • Grinshpon R.
      • Pfeffer J.
      • et al.
      Proof-of-concept study of the Aer-O-Scope omnidirectional colonoscopic viewing system in ex vivo and in vivo porcine models.
      provided proof-of-concept of the SPDC system with regard to its ability to intubate the colon.
      • Vucelic B.
      • Rex D.
      • Pulanic R.
      • et al.
      The aer-o-scope: proof of concept of a pneumatic, skill-independent, self-propelling, self-navigating colonoscope.
      The aim of this study was to evaluate the ability of the new SPDC system to meet accepted efficacy benchmarks, specifically cecal intubation, in a group of patients referred for screening colonoscopy.

      Methods

      Design

      This was a prospective, single-center, noncomparative study performed at a tertiary care hospital. Subjects underwent colonoscopy examination with SPDC, immediately followed by CC, performed by the same operator. A follow-up telephone call was performed 24 to 48 hours after the procedure to query study subjects regarding delayed symptoms/adverse events.

      Study subjects

      Subjects were asymptomatic adults at average or increased CRC risk (based on family history) referred for screening colonoscopy. All subjects signed an institutional review board–approved informed consent. Each subject underwent an interview for relevant medical history and full physical examination before the colonoscopy procedures. As many as 10 initial subjects per operator were intended to be part of a training cohort, which was to be evaluated for device safety only. Operators could reduce the number of subjects in their training cohort if they believed that they had reached proficiency with the SPDC.

      Study endpoints

      The primary efficacy endpoint was documented cecal intubation with a goal of more than 90% of all study subjects. The primary safety endpoint was the frequency and severity of device-related serious adverse events, defined as resulting in death or serious injury. Because serious adverse events are rare, establishing safety requires high numbers of study subjects. Therefore, for the safety endpoint, this was a pilot study.
      Secondary study endpoints included SPDC ease of use compared with physicians’ experience with CC in general and overall visualization with SPDC compared with physicians’ experience with CC. Data pertaining to these secondary endpoints were subjective and obtained via a questionnaire completed by the operator by using a visual analog scale immediately after the procedure.
      Additional study endpoints included ascertaining the number of SPDC colonoscopies needed to acquire proficiency in device operation and documenting the number of pathologies visualized with SPDC compared with CC. The latter was a tertiary objective because a controlled visualization study intended to compare polyp detection between the SPDC and CC had already been performed in animals.
      • Gluck N.
      • Fishman S.
      • Melhem A.
      • et al.
      Aer-O-Scope, a self-propelled pneumatic colonoscope, is superior to conventional colonoscopy in polyp detection [abstract].
      Therefore, obtaining histological correlation for all visualized pathologies during tandem CC was not part of this protocol, and endoscopists could decide to retain hyperplastic-appearing diminutive rectosigmoid polyps during CC.

      Endoscopic procedure

      Subjects underwent bowel preparation by using split-dose MoviPrep, bisacodyl, metoclopramide, and a low-fiber diet (beginning 48 hours preprocedure) and signed a form confirming adherence to these prep instructions before colonoscopy.
      Two senior gastroenterologists (N.G., A.M.) with extensive experience in CC (>5 years, >1000 procedures annually) performed all colonoscopy procedures. One physician had performed 21 SPDC procedures in a previous swine study. The second physician performed 2 proctored procedures in humans a year earlier. Both physicians observed a presentation of the operating system and an initial training session on a model colon before the study. Both physicians were proctored during the training phase of the study.
      Subjects were sedated at the direction of the performing endoscopist, with intravenous fentanyl (0.05 mg), midazolam (2 mg), and propofol as needed. The SPDC was introduced into the rectum and advanced to the cecum. Once the cecum was intubated and anatomic landmarks (ileocecal valve and appendiceal orifice) were visualized and photographed, the cecal mucosa was marked by placing a suction mark as confirmation of cecal intubation. This mark could then be visualized during the subsequent CC. All pathologies were recorded and similarly marked. Findings and cecal intubation time were recorded on the case report forms.
      CC was performed immediately after the SPDC colonoscopy to monitor for any mucosal damage and to screen for colonic pathologies (during withdrawal). Findings during CC, including SPDC suction markings, were noted on the case report forms.
      Immediately after completion of both procedures, the endoscopists filled out a simple questionnaire by using a visual analog scale related to device ease of use and overall visualization during the SPDC colonoscopy. This allowed self-evaluation and also gave the operator an opportunity to note the learning curves and comfort of operation throughout the investigation.
      The study was approved by the institutional review board at the Tel Aviv Medical Center.

      Statistical methods

      Cecum intubation rates (CIRs) were calculated for the training cohort, study cohort, and all procedures along with corresponding 2-sided 95% confidence intervals (CIs) by using the exact method for binomial proportions. The polyp miss rate was calculated along with the corresponding 2-sided 95% CI by using the exact method for binomial proportions. The data were analyzed by using SAS version 9.1 (SAS Institute, Cary, NC). Adverse events were coded according to coding dictionaries (MedDRA version 16.1).
      The study was originally planned as a 2-phase sequential trial, aiming to obtain results from the first phase before proceeding to the second. The planned sample size at each phase was 40 subjects in the study cohort, aiming to provide 36 subjects in the study cohort per phase allowing a dropout rate as high as 10%. The effects of early termination on type I error and bias in estimated CIR were evaluated by using actual probabilities under binomial distributions determined by maximum per-phase sample size of 40, a dropout rate of 10%, and a CIR ranging from 80% (probability of early stopping = 0) to 99.5%.

      Results

      Subjects

      Fifty-eight subjects (34 male and 24 female, body mass index ranging from 20.2-39.6) 27 to 72 years of age were enrolled in this study between August and November 2013 (younger subjects were examined based on family history). Two subjects were withdrawn due to poor bowel preparation (solid stool that could not be irrigated). Fifty-six subjects remained and are reported on here.
      The 2 participating physicians required 8 and 10 procedures, respectively, to feel competent in operating the SPDC. Thus, the training cohort was defined as including 18 subjects, with the remaining 38 subjects considered the study cohort. No subjects were lost to follow-up.

      Safety of SPDC operation

      During the intubation phase of CC, no colonic mucosal damage, which may have been caused by the immediately preceding SPDC colonoscopy procedure, was detected. There were no reported adverse events or device failures.

      Cecal intubation by using SPDC

      Cecal intubation was successful in 55 of 56 subjects (98.2%) (95% CI, 90.4%-99.9%), including 38 of 38 (100%) in the study cohort (95% CI, 90.7%-100%), and 17 of 18 (94.4%) in the training cohort (95% CI, 72.7%-99.9%). In 1 subject, colonoscopy with the SPDC was successful, but CC failed to reach the cecum due to inadequate patient prep. The confirmation of cecal intubation was obtained by visualizing SPDC suction marking during CC in 52 of 55 subjects (94.5%) (Fig. 3) and by SPDC documentation of cecal landmarks in all other cases.
      Figure thumbnail gr3
      Figure 3Characteristic round suction mark of a self-propelled disposable colonoscope (yellow circle) near the ileal orifice as seen by tandem conventional colonoscope.

      Early termination

      Effects of early termination on type I error and bias in the estimated CIR were minimal. The probability of obtaining 38 successes in 38 subjects (the result in the study cohort of the first phase) is less than 1.3% for a CIR that is lower than the goal (≤90%); the coverage levels of the exact binomial 2-sided 95% CIs exceeded the nominal 95% for CIRs ranging from 80% to 99.5%. Bias was less than 0.1% for CIRs less than 90%, and less than 0.3% for CIRs 90% or greater. Based on these results, the study was terminated for efficacy after the first phase.

      Study times

      Retroflexion of the optical head, revealing the distal balloon on the omni view (Fig. 4), occurred in all subjects, was 100% specific to the cecum and was documented at a mean of 10:59 ± 7:13 minutes. Formal confirmation of all cecal landmarks was obtained at a mean of 13:28 ± 7:58 minutes. Exclusion of 2 subjects with exceptionally tortuous colons resulted in a mean of 9:55 and 12:15 minutes for cecal retroflexion and formal confirmation, respectively. Mean withdrawal time was 14:04 ± 5:18 minutes.
      Figure thumbnail gr4
      Figure 4Retroflexed distal balloon in the cecum (green arrow) as seen with a self-propelled disposable colonoscope.

      Ease of use and overall visualization

      Both participating endoscopists rated all technical aspects of SPDC use and visualization as excellent on a subjective visual analog scale (Supplementary Table 1, available online at www.giejournal.org).

      Polyp detection

      A total of 40 polyps were visualized in 23 subjects on second-pass CC (a polyp detection rate of 41.1%). Thirty-five of these 40 polyps (87.5%) had been previously detected by SPDC colonoscopy. Thus, the SPDC colonoscopy polyp miss rate was 12.5% (95% CI, 4.2%-26.8%). Missed polyps were located in the rectum, sigmoid (2 polyps), ascending colon, and ileocecal valve. Thirty-three polyps were resected from all segments of the colon: 25 adenomas, 7 hyperplastic polyps, and 1 sessile serrated polyp.
      Subgroup analysis was performed for polyp miss/detection rates of diminutive (≤5 mm) and clinically significant (≥6 mm) polyps by SPDC colonoscopy. The miss rate for diminutive polyps was 15.2% (5/33) (95% CI, 5.1%-31.9%). However, the detection rate for polyps 6 mm or larger was 100% (7/7) (95% CI, 59%-100%). Thus, the miss rate for large polyps was 0%.
      Fourteen subjects who underwent polyp resection by CC had histology of adenomas (adenoma detection rate of 25%). In 12 of 14 subjects (86%, 21.4% of the total number of subjects), these adenomas had been definitely identified and marked using suction in the preceding SPDC colonoscopy.

      Discussion

      This prospective study demonstrates for the first time the safety and efficacy of the current SPDC system in a human cohort. No colonic mucosal damage or adverse events occurred. High cecal intubation rates, exceeding the study's a priori target of 90%, were observed, even in naïve system operators. Subjective operator competence with the device was high and was achieved after 10 or fewer subjects.
      The SPDC has several important novel features. By being disposable, the labor and cost involved in disinfecting and maintaining endoscopy equipment, as well as the liability of possible transmitted diseases such as HIV and chronic hepatitis
      • Gonzalez-Candelas F.
      • Guiral S.
      • Carbo R.
      • et al.
      Patient-to-patient transmission of hepatitis C virus (HCV) during colonoscopy diagnosis.

      Office of Inspector General Healthcare inspection. Use and reprocessing of flexible fiberoptic endoscopes at VA medical facilities. Available at: Department of Veterans Affairs, Washington (DC), 2009:1–45. Available at: http://www.va.gov/oig/54/reports/VAOIG-09-01784-146.pdf. Accessed October 8, 2015.

      in cases of breaches in the disinfection routine, are eliminated, and infectious disease transmission is prevented. A number of studies have found biological proof of residual contamination despite high-level disinfection of colonoscopes.
      • Herve R.
      • Keevil C.W.
      Current limitations about the cleaning of luminal endoscopes.
      • Chiu K.W.
      • Tsai M.C.
      • Wu K.L.
      • et al.
      Surveillance cultures of samples obtained from biopsy channels and automated endoscope reprocessors after high-level disinfection of gastrointestinal endoscopes.
      When coupled with emerging reports of resistant bacteria
      • Noronha A.M.
      • Brozak S.A.
      21st century nosocomial issue with endoscopes.
      including several clusters of CRE infections associated with duodenoscopes,
      • Epstein L.
      • Hunter J.C.
      • Arwady M.A.
      • et al.
      New Delhi metallo-beta-lactamase-producing carbapenem-resistant Escherichia coli associated with exposure to duodenoscopes.

      US Food and Drug Administration. Design of endoscopic retrograde cholangiopancreatography (ERCP) duodenoscopes may impede effective cleaning: FDA safety communication. Available at: www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm434871.htm. Accessed February 19, 2015.

      a device that could prevent superbug contamination of other endoscopes may become relevant. A disposable device could be particularly appealing for patients who are at high risk of transmitting infections or those with a compromised immune system who are at higher risk of becoming infected.
      Operators of the SPDC in this study felt comfortable operating this new device and interpreting endoscopic images quickly, despite the different characteristics of navigation, insertion tube, and optics provided. Although this study was not designed to provide more objective measures evaluating the learning curve (which will require further studies), this study does suggest that experienced endoscopists can begin using the SPDC with minimal training. These preliminary data, although encouraging, cannot speak to a potential de novo learning curve for operators who have not previously performed colonoscopy, and this will need to be addressed independently. Likewise, although not a study endpoint, the intubation and withdrawal times appear reasonable, in view of this being a preliminary study using a novel device. The lag in time between detecting cecal retroflexion of the SPDC and confirming landmarks in the cecum was also a result of the learning curve. All times are expected to shorten with further use.
      A unique feature of the SPDC is its 360° optics for colonic visualization. Polyps that arise in concealed locations can be difficult to detect with conventional forward-viewing colonoscopy and may account for a proportion of missed adenomas
      • Jover R.
      • Zapater P.
      • Polania E.
      • et al.
      Modifiable endoscopic factors that influence the adenoma detection rate in colorectal cancer screening colonoscopies.
      and subsequent interval colorectal cancers. A number of devices that detect polyps behind colonic folds and at anatomic flexures have recently been introduced to the market in an attempt to increase the polyp detection rate through improved device optics.
      • Leufkens A.M.
      • DeMarco D.C.
      • Rastogi A.
      • et al.
      Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study.
      • Gralnek I.M.
      • Siersema P.D.
      • Halpern Z.
      • et al.
      Standard forward-viewing colonoscopy versus full-spectrum endoscopy: an international, multicentre, randomised, tandem colonoscopy trial.
      • Halpern Z.
      • Gross S.A.
      • Gralnek I.M.
      • et al.
      Comparison of adenoma detection and miss rates between a novel balloon colonoscope and standard colonoscopy: a randomized tandem study.
      Although polyp detection was not a primary endpoint of our study, it is interesting to note that the polyp miss rate by using SPDC colonoscopy was 12.5%. This is lower than what was found in similar tandem studies performed with other colonoscopes.
      • Hixson L.J.
      • Fennerty M.B.
      • Sampliner R.E.
      • et al.
      Prospective study of the frequency and size distribution of polyps missed by colonoscopy.
      • Rex D.K.
      • Cutler C.S.
      • Lemmel G.T.
      • et al.
      Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.
      • Rex D.K.
      Colonoscopic withdrawal technique is associated with adenoma miss rates.
      • Rex D.K.
      • Bond J.H.
      • Winawer S.
      • et al.
      U.S. Multi-Society Task Force on Colorectal Cancer
      Quality in the technical performance of colonoscopy and the continuous quality improvement process for colonoscopy: recommendations of the U.S. Multi-Society Task Force on Colorectal Cancer.
      Importantly, the only missed polyps in our study were diminutive polyps (≤5 mm). Larger comparative studies are planned to confirm this important finding.
      The current SPDC is a diagnostic device. In contrast to CT colonography or colon capsule, it is intended for use in any clinic providing screening colonoscopy services, whereby patients who have polyps needing resection would undergo immediate targeted CC while under the same preparation and sedation. Although 41% of subjects in this study had findings, most polyps (33/40) were 5 mm or smaller. Ultimately, a practice that would save many of these patients a tandem procedure may evolve. This is in line with the common practice of CT colonography, which has low sensitivity for detecting these diminutive polyps in the first place and with recent allowances for optical diagnosis and retention of diminutive hyperplastic-appearing polyps in the rectosigmoid.
      • Rex D.K.
      • Kahi C.
      • O'Brien M.
      • et al.
      ASGE Technology and Standards of Practice Committee
      The American Society for Gastrointestinal Endoscopy PIVI (Preservation and Incorporation of Valuable Endoscopic Innovations) on real-time endoscopic assessment of the histology of diminutive colorectal polyps.
      That said, SPDC technology allows incorporation of a working channel in future models.
      A strength of the study design is that it provides external validity of both the safety and the efficacy of SPDC by using second-pass (tandem) conventional colonoscopy that documented intact colonic mucosa and SPDC cecal intubation (as documented by observation of purposefully created cecal suction markings).
      The limitations of this study are its nonrandomized design and the small size of the study cohort. The latter was somewhat compensated for by a minimal subject withdrawal rate, high follow-up rates, and high efficacy rates in the training cohort that allowed their inclusion in the overall study efficacy analyses. The performance of tandem CC by the same operator is a potential source of bias in the detection of damage to the colonic mucosa possibly caused by SPDC and visualized during CC. The primary endpoint, namely, cecal intubation, relies on objective documentation of cecal landmarks and therefore is not compromised by this bias. The use of 1 physician to perform tandem colonoscopy in a comparative study has been practiced in other recent studies.
      • Leufkens A.M.
      • DeMarco D.C.
      • Rastogi A.
      • et al.
      Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study.
      • Gralnek I.M.
      • Siersema P.D.
      • Halpern Z.
      • et al.
      Standard forward-viewing colonoscopy versus full-spectrum endoscopy: an international, multicentre, randomised, tandem colonoscopy trial.
      • Halpern Z.
      • Gross S.A.
      • Gralnek I.M.
      • et al.
      Comparison of adenoma detection and miss rates between a novel balloon colonoscope and standard colonoscopy: a randomized tandem study.
      Additionally, the ease-of-use assessment was subjective, obtained by the operator of the device, albeit via a standardized scale. In terms of safety, because of the rarity of bowel perforation, particularly in diagnostic procedures, this study is underpowered for determining a specific perforation rate relative to CC and can only be considered a pilot study, similar to recent studies with other novel colonoscopy devices.
      • Leufkens A.M.
      • DeMarco D.C.
      • Rastogi A.
      • et al.
      Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study.
      • Gralnek I.M.
      • Siersema P.D.
      • Halpern Z.
      • et al.
      Standard forward-viewing colonoscopy versus full-spectrum endoscopy: an international, multicentre, randomised, tandem colonoscopy trial.
      • Halpern Z.
      • Gross S.A.
      • Gralnek I.M.
      • et al.
      Comparison of adenoma detection and miss rates between a novel balloon colonoscope and standard colonoscopy: a randomized tandem study.
      Further investigation will be needed to substantiate the full safety profile of the SPDC.
      In conclusion, the SPDC appears effective and easy to use in humans, with high performance in detecting colon polyps. Additional studies are required to confirm these initial encouraging data.

      Appendix

      Supplementary Table 1Visual analog scale rated by performing endoscopists immediately after SPDC colonoscopy (range 1-5 for very poor, poor, fair, good, and excellent, respectively)
      Study (N = 38)Training (n = 18)All patients (N = 56)
      MeanSDMeanSDMeanSD
      Insertion and sealing4.80.64.60.94.80.7
      Navigation of device (manual)4.90.24.80.44.90.3
      Navigation of device (air assisted)4.90.34.60.64.80.4
      Scan grade (withdrawal)4.80.74.90.34.90.6
      General visualization4.80.74.31.14.60.9
      Overall performance4.80.54.40.84.70.7
      Overall perceived proficiency4.90.24.50.74.80.5
      SPDC, Self-propelled disposable colonoscope.

      Supplementary data

      References

        • Brenner H.
        • Chang-Claude J.
        • Jansen L.
        • et al.
        Reduced risk of colorectal cancer up to 10 years after screening, surveillance, or diagnostic colonoscopy.
        Gastroenterology. 2014; 146: 709-717
        • Kahi C.J.
        • Myers L.J.
        • Slaven J.E.
        • et al.
        Lower endoscopy reduces colorectal cancer incidence in older individuals.
        Gastroenterology. 2014; 146: 718-725.e3
        • Kovaleva J.
        • Peters F.T.
        • van der Mei H.C.
        • et al.
        Transmission of infection by flexible gastrointestinal endoscopy and bronchoscopy.
        Clin Microbiol Rev. 2013; 26: 231-254
        • Gonzalez-Candelas F.
        • Guiral S.
        • Carbo R.
        • et al.
        Patient-to-patient transmission of hepatitis C virus (HCV) during colonoscopy diagnosis.
        Virol J. 2010; 7: 217
        • Banerjee S.
        • Shen B.
        • Nelson D.B.
        • et al.
        Infection control during GI endoscopy.
        Gastrointest Endosc. 2008; 67: 781-790
        • Nelson D.B.
        Infectious disease complications of GI endoscopy: part II, exogenous infections.
        Gastrointest Endosc. 2003; 57: 695-711
        • Seoane-Vazquez E.
        • Rodriguez-Monguio R.
        • Visaria J.
        • et al.
        Exogenous endoscopy-related infections, pseudo-infections, and toxic reactions: clinical and economic burden.
        Curr Med Res Opin. 2006; 22: 2007-2021
        • Herve R.
        • Keevil C.W.
        Current limitations about the cleaning of luminal endoscopes.
        J Hosp Infect. 2013; 83: 22-29
        • Chiu K.W.
        • Tsai M.C.
        • Wu K.L.
        • et al.
        Surveillance cultures of samples obtained from biopsy channels and automated endoscope reprocessors after high-level disinfection of gastrointestinal endoscopes.
        BMC Gastroenterol. 2012; 12: 120
        • Kovaleva J.
        • Meessen N.E.
        • Peters F.T.
        • et al.
        Is bacteriologic surveillance in endoscope reprocessing stringent enough?.
        Endoscopy. 2009; 41: 913-916
        • Nelson D.B.
        Hepatitis C virus cross-infection during endoscopy: is it the “tip of the iceberg” or the absence of ice?.
        Gastrointest Endosc. 2007; 65: 589-591
        • Spier B.J.
        • Benson M.
        • Pfau P.R.
        • et al.
        Colonoscopy training in gastroenterology fellowships: determining competence.
        Gastrointest Endosc. 2010; 71: 319-324
        • Spier B.J.
        • Durkin E.T.
        • Walker A.J.
        • et al.
        Surgical resident's training in colonoscopy: numbers, competency, and perceptions.
        Surg Endosc. 2010; 24: 2556-2561
        • Korman L.Y.
        • Haddad N.G.
        • Metz D.C.
        • et al.
        Effect of propofol anesthesia on force application during colonoscopy.
        Gastrointest Endosc. 2014; 79: 657-662
        • Pfeffer J.
        • Grinshpon R.
        • Rex D.
        • et al.
        The Aer-O-Scope: proof of the concept of a pneumatic, skill-independent, self-propelling, self-navigating colonoscope in a pig model.
        Endoscopy. 2006; 38: 144-148
        • Arber N.
        • Grinshpon R.
        • Pfeffer J.
        • et al.
        Proof-of-concept study of the Aer-O-Scope omnidirectional colonoscopic viewing system in ex vivo and in vivo porcine models.
        Endoscopy. 2007; 39: 412-417
        • Vucelic B.
        • Rex D.
        • Pulanic R.
        • et al.
        The aer-o-scope: proof of concept of a pneumatic, skill-independent, self-propelling, self-navigating colonoscope.
        Gastroenterology. 2006; 130: 672-677
        • Gluck N.
        • Fishman S.
        • Melhem A.
        • et al.
        Aer-O-Scope, a self-propelled pneumatic colonoscope, is superior to conventional colonoscopy in polyp detection [abstract].
        Gastroenterology. 2014; 114: AB406
      1. Office of Inspector General Healthcare inspection. Use and reprocessing of flexible fiberoptic endoscopes at VA medical facilities. Available at: Department of Veterans Affairs, Washington (DC), 2009:1–45. Available at: http://www.va.gov/oig/54/reports/VAOIG-09-01784-146.pdf. Accessed October 8, 2015.

        • Noronha A.M.
        • Brozak S.A.
        21st century nosocomial issue with endoscopes.
        BMJ. 2014; 348: g2047
        • Epstein L.
        • Hunter J.C.
        • Arwady M.A.
        • et al.
        New Delhi metallo-beta-lactamase-producing carbapenem-resistant Escherichia coli associated with exposure to duodenoscopes.
        JAMA. 2014; 312: 1447-1455
      2. US Food and Drug Administration. Design of endoscopic retrograde cholangiopancreatography (ERCP) duodenoscopes may impede effective cleaning: FDA safety communication. Available at: www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm434871.htm. Accessed February 19, 2015.

        • Jover R.
        • Zapater P.
        • Polania E.
        • et al.
        Modifiable endoscopic factors that influence the adenoma detection rate in colorectal cancer screening colonoscopies.
        Gastrointest Endosc. 2013; 77: 381-389.e1
        • Leufkens A.M.
        • DeMarco D.C.
        • Rastogi A.
        • et al.
        Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study.
        Gastrointest Endosc. 2011; 73: 480-489
        • Gralnek I.M.
        • Siersema P.D.
        • Halpern Z.
        • et al.
        Standard forward-viewing colonoscopy versus full-spectrum endoscopy: an international, multicentre, randomised, tandem colonoscopy trial.
        Lancet Oncol. 2014; 15: 353-360
        • Halpern Z.
        • Gross S.A.
        • Gralnek I.M.
        • et al.
        Comparison of adenoma detection and miss rates between a novel balloon colonoscope and standard colonoscopy: a randomized tandem study.
        Endoscopy. 2015; 47: 238-244
        • Hixson L.J.
        • Fennerty M.B.
        • Sampliner R.E.
        • et al.
        Prospective study of the frequency and size distribution of polyps missed by colonoscopy.
        J Natl Cancer Inst. 1990; 82: 1769-1772
        • Rex D.K.
        • Cutler C.S.
        • Lemmel G.T.
        • et al.
        Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.
        Gastroenterology. 1997; 112: 24-28
        • Rex D.K.
        Colonoscopic withdrawal technique is associated with adenoma miss rates.
        Gastrointest Endosc. 2000; 51: 33-36
        • Rex D.K.
        • Bond J.H.
        • Winawer S.
        • et al.
        • U.S. Multi-Society Task Force on Colorectal Cancer
        Quality in the technical performance of colonoscopy and the continuous quality improvement process for colonoscopy: recommendations of the U.S. Multi-Society Task Force on Colorectal Cancer.
        Am J Gastroenterol. 2002; 97: 1296-1308
        • Rex D.K.
        • Kahi C.
        • O'Brien M.
        • et al.
        • ASGE Technology and Standards of Practice Committee
        The American Society for Gastrointestinal Endoscopy PIVI (Preservation and Incorporation of Valuable Endoscopic Innovations) on real-time endoscopic assessment of the histology of diminutive colorectal polyps.
        Gastrointest Endosc. 2011; 73: 419-422