A retrograde-viewing device improves detection of adenomas in the colon: a prospective efficacy evaluation (with videos)

Efficacy of cecal retroflexion observed on adenoma missing of ascending colon during colonoscopy: A prospective, randomized, pilot trial

BACKGROUND

Although colonoscopic retroflexion has been proved effective in reducing missed adenomas, there is still a lack of comprehensive and in-depth research focused on the ascending colon. We aimed to conduct a randomized controlled trial and tandem colonoscopy to investigate whether cecal retroflexion observed during colonoscopy can reduce missed adenomas in the ascending colon.

METHODS

Men and women required to be between 45 and 80 years of age were screened for enrollment in the trial. Patients were randomly assigned according to a 1:1 ratio to either the trial group or control group. Patients in the trial group underwent 2 forward examination and a cecal retroflexion observed in the ascending colon, while patients in the control group underwent only 2 forward examinations in the ascending colon. The primary outcome was adenoma miss rate. The secondary outcomes contained adenoma detection rate, polyp miss rate, polyp detection rate, insertion time and withdrawal time. Differences between groups in the primary outcome and in the other categorical indicators were tested using chi-squared test and Fisher exact test. For the comparison of continuous outcomes, the Student t test was applied.

RESULTS

A total of 60 subjects were eligible for the study between April to June 2020, of which 55 were randomized and eligible for analysis (26 to the control group and 29 to the trial group). The characteristics of patients were no significant differences statistically between the trial group and the control group. Similarly, the characteristics of the colonoscopy procedures included cecal insertion distance, the length of cecum and ascending colon, insertion time, withdrawal time, quality of bowel preparation, numerical rating scale for pain, polyps detected, and adenomas detected, and there were no significant differences statistically between the 2 groups (P = .864, P = .754, P = .700, P = .974, P = .585, P = .835, P = .373, P = .489). The characteristics of the polyps were also no significant differences statistically between the 2 groups.

CONCLUSION

This pilot trial failed to show benefit of cecal retroflexion observed on adenoma missing of ascending colon during colonoscopy; however, further conclusions require a prospective study with a higher level of evidence. (NCT03355443).

Recent advances in devices and technologies that might prove revolutionary for colonoscopy procedures

INTRODUCTION

Colorectal cancer (CRC) is the third most common malignancy and second leading cause of cancer-related mortality in the world. Adenoma detection rate (ADR), a quality indicator for colonoscopy, has gained prominence as it is inversely related to CRC incidence and mortality. As such, recent efforts have focused on developing novel colonoscopy devices and technologies to improve ADR.

AREAS COVERED

The main objective of this paper is to provide an overview of advancements in the fields of colonoscopy mechanical attachments, artificial intelligence-assisted colonoscopy, and colonoscopy optical enhancements with respect to ADR. We accomplished this by performing a comprehensive search of multiple electronic databases from inception to September 2023. This review is intended to be an introduction to colonoscopy devices and technologies.

EXPERT OPINION

Numerous mechanical attachments and optical enhancements have been developed that have the potential to improve ADR and AI has gone from being an inaccessible concept to a feasible means for improving ADR. While these advances are exciting and portend a change in what will be considered standard colonoscopy, they continue to require refinement. Future studies should focus on combining modalities to further improve ADR and exploring the use of these technologies in other facets of colonoscopy.

Changes in Adenoma Detection Rate From Full-Spectrum Endoscopy to Standard Forward-Viewing Endoscopy

GOALS

The aim was to investigate the adenoma detection rate (ADR) of endoscopists who have used full-spectrum endoscopy (Fuse) for 3 years and revert back to traditional forward-viewing endoscopes (R-TFV) at an ambulatory surgical center.

BACKGROUND

Traditional forward viewing (TFV) endoscopes have 1 camera and provide an angle of view of 140 to 170 degrees, whereas Fuse provides a 330 degrees view through the addition of 2 side cameras. It has previously been reported that Fuse increased the ADR by 5.4% when compared with previous rates using TFV. Fuse is no longer commercially available. The ADR of endoscopists who revert back to TFV is unknown.

STUDY

We conducted a retrospective analysis of data examining the ADR from average risk screening colonoscopies at a 5-room ambulatory surgical center where endoscopists transitioned from TFV to Fuse in April 2014 and then reverted back to TFV in 2016. The primary outcome was ADR. Secondary outcomes were ADR for advanced and right-sided adenomas.

RESULTS

A total of 6110 procedures were reviewed. The ADR was 23.70% for TFV, 29.02% for Fuse and 28.88% for R-TFV. The ADR for advanced adenomas was 3.8% for TFV, 6.0% for Fuse and 7.3% for R-TFV. The ADR for right-sided adenomas was 13.0% for TFV, 16.7% for Fuse and 16.0% for R-TFV. The results for all 3 categories showed a statistical difference between TFV and Fuse as well as between TFV and R-TFV. There were no statistical differences between the ADR of Fuse compared with R-TFV.

CONCLUSIONS

During R-TFV, endoscopists are able to maintain their increased ability to detect adenomas. This would suggest that there was a change in behavior in endoscopists using Fuse that was durable.

Detection of colorectal lesions during colonoscopy

Owing to its high mortality rate, the prevention of colorectal cancer is of particular importance. The resection of colorectal polyps is reported to drastically reduce colorectal cancer mortality, and examination by endoscopists who had a high adenoma detection rate was found to lower the risk of colorectal cancer, highlighting the importance of identifying lesions. Various devices, imaging techniques, and diagnostic tools aimed at reducing the rate of missed lesions have therefore been developed to improve detection. The distal attachments and devices for improving the endoscopic view angle are intended to help avoid missing blind spots such as folds and flexures in the colon, whereas the imaging techniques represented by image‐enhanced endoscopy contribute to improving lesion visibility. Recent advances in artificial intelligence‐supported detection systems are expected to supplement an endoscopist's eye through the instant diagnosis of the lesions displayed on the monitor. In this review, we provide an outline of each tool and assess its impact on the reduction in the incidence of missed colorectal polyps by summarizing previous clinical research and meta‐analyses. Although useful, the many devices, image‐enhanced endoscopy, and artificial intelligence tools exhibited various limitations. Integrating these tools can improve their shortcomings. Combining artificial intelligence‐based diagnoses with wide‐angle image‐enhanced endoscopy may be particularly useful. Thus, we hope that such tools will be available in the near future.

The Use of Attachment Devices to Aid in Adenoma Detection

PURPOSE OF REVIEW

With the intent of maximizing adenoma detection rate (ADR), different devices and colonoscopic innovations have been introduced over the past few years. There are a variety of attachment devices available for use in colonoscopy, all intended to improve ADR. In this review, we evaluate the evidence surrounding the available attachment devices and their impact on ADR.

RECENT FINDINGS

Endocuff, Endoring, Transparent cap, G-EYE balloon, and Third Eye Retroscope were all included in this review. Three of the devices, Endocuff, Endoring, and transparent hood or cap, have been shown to increase ADR without significantly altering the use of the colonoscope. Although balloon-assisted colonoscopy is not currently FDA-approved, it has the potential to increase ADR as well.

SUMMARY

Mechanical enhancement has been shown to complement the current forward-viewing colonoscope, and Endocuff appears to be the most beneficial attachment to improve ADR.

Safety, Feasibility, and Efficacy of Pancolonic Retroflexed Viewing Using a Short-turn Radius Colonoscope

GOALS

The goal of this study was to evaluate the safety and feasibility of routine segmental retroflexed withdrawal viewing (RV) of the colon with the RetroView colonoscope.

MATERIALS AND METHODS

This was a prospective, single-center, 2-stage diagnostic trial. After cecal intubation, mucosal evaluation by forward viewing (FV) and RV was performed by segment (right, transverse, left, and sigmoid colon, and rectum). Lesions detected during FV were removed and/or marked before retroflexion. Safety and feasibility were measured through adverse event and technical success rates. All lesions detected and removed endoscopically were recorded.

RESULTS

Two hundred twenty-five patients underwent colonoscopy with the RetroView colonoscope. Retroflexion by segment was successful in the right, transverse, left, and sigmoid colon, and rectum in 98.9%, 100%, 100%, 82.6%, and 100% of cases, respectively. The mean total procedure time was 16.6 minutes. Ninety-four lesions were detected through retroflexion evaluation, for an increase in the lesions' detection rate of 30.7%. The per-adenoma miss rate of standard colonoscopy (FV) was 35.71%. The adenoma detection rate (ADR) for FV was 16%, whereas, when performing FV and RV, the ADR increased to 24.9%. Adverse events were recorded in 0.4% of cases. Therapeutic procedures were performed successfully through the retroflexed position in 81/225 patients.

CONCLUSIONS

Routine retroflexion evaluation of the colonic mucosa by segment using the RetroView colonoscope is safe and feasible. Retroflexion evaluation increases the detection rate of colonic lesions behind folds, including the number of adenomas per colonoscopy and ADR, offering a complete screening colonoscopy. All therapeutic procedures are feasible through retroflexion.

Development of a real-time endoscopic image diagnosis support system using deep learning technology in colonoscopy

Gaps in colonoscopy skills among endoscopists, primarily due to experience, have been identified, and solutions are critically needed. Hence, the development of a real-time robust detection system for colorectal neoplasms is considered to significantly reduce the risk of missed lesions during colonoscopy. Here, we develop an artificial intelligence (AI) system that automatically detects early signs of colorectal cancer during colonoscopy; the AI system shows the sensitivity and specificity are 97.3% (95% confidence interval [CI] = 95.9%–98.4%) and 99.0% (95% CI = 98.6%–99.2%), respectively, and the area under the curve is 0.975 (95% CI = 0.964–0.986) in the validation set. Moreover, the sensitivities are 98.0% (95% CI = 96.6%–98.8%) in the polypoid subgroup and 93.7% (95% CI = 87.6%–96.9%) in the non-polypoid subgroup; To accelerate the detection, tensor metrics in the trained model was decomposed, and the system can predict cancerous regions 21.9 ms/image on average. These findings suggest that the system is sufficient to support endoscopists in the high detection against non-polypoid lesions, which are frequently missed by optical colonoscopy. This AI system can alert endoscopists in real-time to avoid missing abnormalities such as non-polypoid polyps during colonoscopy, improving the early detection of this disease.

Randomized control trial of adenoma detection rate in Endocuff-assisted colonoscopy versus transparent hood-assisted colonoscopy

BACKGROUND AND AIM

Transparent hood-assisted colonoscopy (TAC) has been reported to improve the cecal insertion rate and adenoma detection rate (ADR). An endoscopic cap (Endocuff) with two rows of soft wings was recently developed to improve ADR, by flattening the mucosal folds during withdrawal. This randomized prospective control study aimed to compare ADR between Endocuff-assisted colonoscopy (EAC) and TAC.

METHODS

A total of 513 patients undergoing colon adenoma screening were included. EAC was performed in 256 patients and TAC in 260 patients. Cecal intubation rate, cecal intubation time, ADR, and mean adenoma number per patient (MAP) were investigated in both groups (clinical trial registration: UMIN000016278).

RESULTS

We excluded six patients in the EAC group and two patients in the TAC group because of colonic stenosis due to colonic adenocarcinomas. Finally, 250 patients (151 men/99 women, median age 62.1 years) were assigned to EAC and 258 patients (165 men/93 women, median age 64.3 years) were assigned to TAC. There were no significant differences in cecal intubation rate, intubation time, withdrawal time, and cleanliness score between groups. The ADR was 50.8% in EAC and 52.7% in TAC, with no significant difference (P = 0.666). The MAP was 1.35 in EAC and 1.20 in TAC, with no significant difference (P = 0.126). However, The MAP of diminutive adenomas (< 5 mm) tended to be higher in EAC than in TAC (P = 0.077). There was no significant difference in MAP in each segment between groups.

CONCLUSIONS

Endocuff-assisted colonoscopy might be equivalent to TAC in cecal intubation time, ADR, and MAP.

An Additional 30-s Observation of the Right-Sided Colon with Narrow Band Imaging Decreases Missed Polyps: A Pilot Study

INTRODUCTION

Previous narrow-band imaging (NBI) was dark and reported not to be useful for polyp detection. In this study, we analyzed the efficacy of an additional 30-s observation of the right-sided colon with the recent bright high-resolution NBI.

METHODS

We enrolled patients undergoing colonoscopy from February 2015 to May 2017 in two institutions. All procedures were performed with the latest system (EVIS LUCERA ELITE, Olympus). The cecum and ascending colon were first observed with white light imaging (WLI) in both the NBI and WLI group. Then, the colonoscope was re-inserted, and the cecum and ascending colon were observed for an additional 30 s. In this second observation, NBI was performed for the first 130 patients in the NBI group and WLI for the next 130 in the WLI group. The number of adenoma and sessile serrated polyps (ASPs) in the second observation were examined in both groups. According to our initial pilot study, the sample size was estimated at 126.

RESULTS

In the first observation, the number of ASPs was 72 in the NBI group and 72 in the WLI group (p = 1.0). In the second observation, the number of ASPs was 23 in the NBI group and 10 in the WLI group (p = 0.02). The polyp and adenoma detection rates in the second observation were 16.2% and 12.3% in the NBI group and 7.7% (p = 0.03) and 6.2% (p = 0.09) in the WLI group.

CONCLUSIONS

The additional 30-s observation with recent NBI decreased missed polyps in the right-sided colon.

Changes in Adenoma Detection Rate With Implementation of Full-spectrum Endoscopy: A Report of 3998 Screening Colonoscopies

GOALS

To investigate the effect of implementing full-spectrum endoscopy (Fuse) on adenoma detection rate (ADR) at an ambulatory surgical center (ASC).

BACKGROUND

Traditional forward viewing (TFV) endoscopes have 1 camera and provide an angle of view of 140 to 170 degrees, whereas Fuse provides a 330 degrees view through the addition of 2 side cameras. Although randomized studies have shown that Fuse decreases adenoma miss rates, its impact on ADR in a screening population is currently unknown.

STUDY

We conducted a retrospective analysis of data from average risk screening colonoscopies at a 5-room ASC. This ASC transitioned from TFV to Fuse in April 2014. The primary outcome was ADR defined as the percentage of patients who underwent screening colonoscopy and were found to have at least 1 adenomatous polyp.

RESULTS

A total of 1696 screening colonoscopies were performed with TFV and 2302 with Fuse. Overall ADR was 23.7% with TFV and 29.0% with Fuse (P<0.01), an absolute increase of 5.3%. ADR for the proximal colon increased from 13.0% with TFV to 16.7% with Fuse (3.8% increase, P<0.01). ADR for advanced adenomas improved from 3.8% with TFV to 6.0% with Fuse (2.2% increase; P<0.01). The mean number of adenomas detected per colonoscopy increased from 0.32 to 0.41 (P<0.01). In multivariate analysis, the adjusted odds ratio for detecting an adenoma with Fuse versus TFV was 1.30 (P<0.01; 95% confidence interval, 1.11-1.51).

CONCLUSIONS

ADR significantly increased after adopting Fuse endoscopes at an ASC. Further studies are warranted to further understand the effects of Fuse on ADR in real-world settings.

Efficacy of Endocuff-assisted colonoscopy in the detection of colorectal polyps

BACKGROUND AND STUDY AIMS

Colonoscopy is the gold standard for detecting colorectal adenomas and cancers. Endoscopic surveillance has been shown to be effective for preventing colorectal cancer. Although detection of colorectal polyps at an early stage is important, endoscopic visualization of early neoplasia can be difficult. The Endocuff is a new device that can be attached to the tip of the colonoscope to hold the colonic folds away from the field of view during withdrawal. The aim of this study was to compare the adenoma detection rate (ADR) and the mean number of adenomas detected per patient (MAP) achieved using Endocuff-assisted colonoscopy (EAC) and standard colonoscopy (SC).

PATIENTS AND METHODS

This randomized prospective study was conducted at two academic endoscopy departments in Japan. A total of 447 patients underwent a complete colonoscopic examination between April 2015 and September 2015. The EAC group included 239 patients. The cecal intubation rate, insertion time, withdrawal time, pain score, complications, polyp detection rate (PDR), ADR, the mean number of polyps detected per patient (MPP), and the MAP were assessed.

RESULTS

There were no differences between the EAC and SC groups in terms of cecal intubation rate, insertion time, withdrawal time, or pain scores. The PDR in patients increased by about 12 % (61.9 % vs. 49.2 %, P  = 0.013) and ADR increased by 15 % (52.5 % vs. 39.2 %, P  = 0.001) with the use of the Endocuff. The advanced ADR was higher in the EAC group but no statistically significant difference was found (7.7 % vs. 4.6 %, P  = 0.17). Both MPP and MAP were also higher in the EAC group (mean ± SD: 1.33 ± 1.43 vs. 0.83 ± 0.99 per patient; P  < 0.01, 1.11 ± 1.41 vs. 0.66 ± 0.99 per patient; P  < 0.01, respectively). No major complications occurred.

CONCLUSIONS

 EAC not only enabled a higher ADR but also significantly increased the mean number of adenomas identified per patient, as compared with SC.

New endoscopy advances to refine adenoma detection rate for colorectal cancer screening: None is the winner

Colorectal cancer (CRC) is the third most common cancer in males and second in females, and globally the fourth cause for cancer death worldwide. Oncological screening of CRC has a major role in the management of the disease and it is mostly performed by colonoscopy. Anyway, effectiveness of endoscopic screening for CRC strictly depends on adequate detection and removal of potentially precancerous lesions, and accuracy of colonoscopy in detection of adenomas is still suboptimal. For this reason, several technological advances have been implemented in order to improve the diagnostic sensitivity of colonoscopy in adenoma detection. Among these: (1) Visual technologies such as chromoendoscopy and narrow band imaging; (2) optical innovation as high definition endoscopy, full-spectrum endoscopy or Third Eye Retroscope; and (3) mechanical advances as Cap assisted colonoscopy, Endocuff, Endoring and G-Eye endoscope. All these technologies advances have been tested over time by clinical studies with mixed results. Which of them is more likely to be successful in the next future?

Technological advances for improving adenoma detection rates: The changing face of colonoscopy

Worldwide, colorectal cancer is the third commonest cancer. Over 90% follow an adenoma-to-cancer sequence over many years. Colonoscopy is the gold standard method for cancer screening and early adenoma detection. However, considerable variation exists between endoscopists' detection rates. This review considers the effects of different endoscopic techniques on adenoma detection. Two areas of technological interest were considered: (1) optical technologies and (2) mechanical technologies. Optical solutions, including FICE, NBI, i-SCAN and high definition colonoscopy showed mixed results. In contrast, mechanical advances, such as cap-assisted colonoscopy, FUSE, EndoCuff and G-EYE™, showed promise, with reported detections rates of up to 69%. However, before definitive recommendations can be made for their incorporation into daily practice, further studies and comparison trials are required.

New endoscopes and add-on devices to improve colonoscopy performance

Colonoscopy is the gold standard for colorectal cancer prevention; however, it is still an imperfect modality. Precancerous lesions can be lost during screening examinations, thus increasing the risk of interval cancer. A variety of factors either patient-, or endoscopist dependent or even the procedure itself may contribute to loss of lesions. Sophisticated modalities including advanced technology endoscopes and add-on devices have been developed in an effort to eliminate colonoscopy's drawbacks and maximize its ability to detect potentially culprit polyps. Novel colonoscopes aim to widen the field of view. They incorporate more than one cameras enabling simultaneous image transmission. In that way the field of view can expand up to 330°. On the other hand a plethora of add-on devices attachable on the standard colonoscope promise to detect lesions in the proximal aspect of colonic folds either by offering a retrograde view of the lumen or by straightening the haustral folds during withdrawal. In this minireview we discuss how these recent advances affect colonoscopy performance by improving its quality indicators (cecal intubation rate, adenoma detection rate) and other metrics (polyp detection rate, adenomas per colonoscopy, polyp/adenoma miss rate) associated with examination's outcomes.

[New Colonoscopy Devices to Improve Colon Neoplasm Detection]

Early detection and removal of adenomatous polyps can prevent the development of colorectal cancer. However, it is fairly common-up to 20%-for polyps to be undetected in a colonoscopy due to poor visualization of the proximal aspect of colonic folds and anatomical flexures. To overcome these limitations, many new endoscopes and accessories have been developed. A wide-angle colonoscopy did not improve the detection of adenoma compared with the standard colonoscopy. An extra-wide angle and Retroview colonoscopies showed a significantly lower miss rate of polyps in the colon model. However, clinical trials are mandatory in the future. The recently introduced full spectrum endoscopy system showed a significantly higher adenoma detection rate than the standard forward-viewing colonoscopy. In accessories, The cap-assisted colonoscopy showed only a marginal or no benefit on the detection of polyps and adenomas. In contrast, a colonoscopy with Endocuff, EndoRings, and G-eye have showed significantly lower adenoma miss rates. The Third Eye, which provides additional retrograde viewing, has revealed a significant improvement in the detection of adenoma and polyp. However, the Third Eye Retroscope was limited by its deployment through the working channel of the scope. Recently, the Third Eye Panoramic cap, which was designed to overcome the limitation of the Third Eye Retroscope, was introduced. In the future, this would be needed to evaluate the effectiveness, efficiency and safety for these new colonoscopies and accessories.

Advances in image enhancement in colonoscopy for detection of adenomas

High-quality colonoscopy is mandatory to prevent adenoma recurrence and colorectal cancer. In the past few years, technical advances have been developed with the purpose of improving adenoma detection rate (ADR), one of the most important validated colonoscopy quality benchmarks. Several techniques or devices are used to optimize visualization: observation techniques; add-on devices; auxiliary imaging devices; colonoscopes with increased field of view; and colonoscopes with an integrated inflatable reusable balloon. Image-enhanced endoscopy (IEE) facilitates the detection and characterization of polyps and especially nonpolypoid colorectal neoplasms. Indigo carmine is the most frequently used dye in colonoscopy as it deposits in depressed areas, improving detection of flat and depressed lesions. Virtual chromoendoscopy has emerged as an effective contrast enhancement technology without the limitation of preparing dyes and applying them through the colonoscope working channel. Narrow-band imaging (NBI) enhances the capillary pattern and surface of the mucosa using optical filters, and second-generation NBI provides a twofold brighter image than the previous system, yielding promising ADR results. Moreover, a second-generation blue laser imaging system, LASEREO, has been reported to improve not only polyp detection rate but also ADR, becoming a promising IEE modality. Herein, we describe technical advances in colonoscopy imaging and their effect on ADR.

Recent Advances in Diagnostic Colonoscopy for Colorectal Cancer Screening: An Update for Radiologists

OBJECTIVE

Colonoscopy accuracy in detecting colorectal neoplasia is critical for colorectal cancer prevention but has been shown to be operator- and technology-dependent. This article will discuss several recent improvements in the technique and technology of colonoscopy.

CONCLUSION

More rigorous training and retraining programs, active monitoring of endoscopist technique and outcomes, and exclusion of poorly performing endoscopists are urgently needed to improve the ultimate efficacy of colorectal cancer screening programs.

Colonoscopy: Advanced and Emerging Techniques-A Review of Colonoscopic Approaches to Colorectal Conditions

A complete colonoscopy is key in the diagnostic and therapeutic approaches to a variety of colorectal diseases. Major challenges are incomplete polyp removal and missed polyps, particularly in the setting of a difficult colonoscopy. There are a variety of both well-established and newer techniques that have been developed to optimize polyp detection, perform complete polypectomy, and endoscopically treat various complications and conditions such as strictures and perforations. The objective of this article is to familiarize the colorectal surgeon with techniques utilized by advanced endoscopists.

The clinical impact of serrated colorectal polyps

Serrated polyps (SPs) of the colorectum pose a novel challenge to practicing gastroenterologists. Previously thought benign and unimportant, there is now compelling evidence that SPs are responsible for a significant percentage of incident colorectal cancer worldwide. In contrast to conventional adenomas, which tend to be slow growing and polypoid, SPs have unique features that undermine current screening and surveillance practices. For example, sessile serrated polyps (SSPs) are flat, predominately right-sided, and thought to have the potential for rapid growth. Moreover, SSPs are subject to wide variations in endoscopic detection and pathologic interpretation. Unfortunately, little is known about the natural history of SPs, and current guidelines are based largely on expert opinion. In this review, we outline the current taxonomy, epidemiology, and management of SPs with an emphasis on the clinical and public health impact of these lesions.

[Additional polyp detection rate using colonoscopic retroflexion in right colon]

BACKGROUND/AIMS

There have been several studies showing that retroflexion (RF) in the right colon (RC) could reduce the polyp miss rate of proximal colon during colonoscopy. This study was conducted to evaluate the additional benefit of RF technique in the RC.

METHODS

Patients who underwent colonoscopy from May 2008 to April 2011 were enrolled in the study. Data were obtained by retrospectively reviewing the medical records. RF was attempted in every patients undergoing colonoscopy since May 2008 except in cases of small RC vault, co-morbidity, severe diverticulosis, failed RF despite two trials, complaints of severe abdominal pain, or time burden. At first, RC was examined under direct vision. It was then examined by RF to detect missed polyps during the initial observation. Finally, the RC was re-examined with direct view.

RESULTS

The cumulative RF success rate in the RC was 78.84% (1,805 of 2,319). The RF success rate increased with the number of cases (50% at 160 cases, 70% at 400 cases, and reached near 90% over 1,000 cases). Few polyps (4.88%) were detected only with RF and the additional adenoma detection rate was 3.32%. The additional polyp/adenoma detection rates were higher in the old age group (p<0.01). There were no RF associated perforation or severe complication.

CONCLUSIONS

Using RF examination, additional 4.88% of polyps could be detected in the RC. This technique could be a useful and safe method to detect hidden polyp during colonoscopy.

Can Technology Improve the Quality of Colonoscopy?

In order for screening colonoscopy to be an effective tool in reducing colon cancer incidence, exams must be performed in a high-quality manner. Quality metrics have been presented by gastroenterology societies and now include higher adenoma detection rate targets than in the past. In many cases, the quality of colonoscopy can often be improved with simple low-cost interventions such as improved procedure technique, implementing split-dose bowel prep, and monitoring individuals' performances. Emerging technology has expanded our field of view and image quality during colonoscopy. We will critically review several technological advances in the context of quality metrics and discuss if technology can really improve the quality of colonoscopy.

Interval Colorectal Cancer After Colonoscopy: Exploring Explanations and Solutions

There is good evidence that colorectal cancer (CRC) screening has been successful at reducing both CRC incidence and death. Colonoscopy, utilized as either a primary screening tool or a follow-up exam when other screening tests are positive, has significantly contributed to these encouraging trends. However, it is well recognized that colonoscopy is not perfectly sensitive for the detection of neoplasia and that CRC can be diagnosed within a short interval following a colonoscopy that did not detect one. The literature surrounding these cases has rapidly expanded over the last decade. Specifically, studies aimed at understanding the frequency of these events and the likely explanations for their occurrence have been performed. This review will highlight current knowledge around the epidemiology of interval post colonoscopy CRC (PCCRC). The common explanations for these cancers including missed lesions, new lesions, and incompletely resected lesions will be reviewed and their contribution to interval PCCRC estimated. Finally, the relationship of these putative explanations to potential opportunities to prevent interval PCCRC will be explored. Current approaches to prevention largely center on consistent adherence to quality colonoscopy standards. Future approaches include advances in technology to better visualize the colon and adequately resect detected neoplasia. Finally, improvement in training as well as development of a culture of continuous quality improvement will be essential to maximize the benefits of colonoscopy in daily clinical practice.

Mechanisms of hyoscine butylbromide to improve adenoma detection: A case-control study of surface visualization at simulated colonoscope withdrawal

BACKGROUND AND STUDY AIMS

Antispasmodics may improve mucosal visualization during colonoscope withdrawal, potentially improving polyp and adenoma detection. Meta-analysis and case-control studies suggest a 9 % to 13 % relative increase in adenoma and polyp detection. We aimed to assess the impact of hyoscine butylbromide on the expected visualization during colonoscope withdrawal using a CT colonography (CTC) simulation.

PATIENTS AND METHODS

Datasets from a previous CTC study examining the effect of antispasmodic were re-analyzed with customised CTC software, adjusted to simulate a standard colonoscopic view. Eighty-six patients received intravenous (IV) hyoscine butylbromide 20 mg, 40 mg or no antispasmodic. Main outcome measurements at unidirectional flythrough, simulating colonoscope withdrawal, were percentage colonic surface visualization, numbers and sizes of unseen areas, and colonic length.

RESULTS

Use of antispasmodic was associated with a significant relative increase in percentage surface visualization of 2.6 % to 3.9 %, compared with no antispasmodic, P < 0.006. Total numbers of missed areas and intermediate sized (300 - 1000 mm(2)) missed areas were significantly decreased, by approximately 20 %. There were no differences between the 20-mg and 40-mg doses. Mean colonic length (161 - 169 cm) was unchanged by antispasmodic.

CONCLUSIONS

IV hyoscine butylbromide at simulated colonoscope withdrawal was associated with significant increases in surface visualization, which might explain up to half the improvement in adenoma detection seen in clinical studies.

Colorectal cancer

Colorectal cancer had a low incidence several decades ago. However, it has become a predominant cancer and now accounts for approximately 10% of cancer-related mortality in western countries. The 'rise' of colorectal cancer in developed countries can be attributed to the increasingly ageing population, unfavourable modern dietary habits and an increase in risk factors, such as smoking, low physical exercise and obesity. New treatments for primary and metastatic colorectal cancer have emerged, providing additional options for patients; these treatments include laparoscopic surgery for primary disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases), radiotherapy for rectal cancer, and neoadjuvant and palliative chemotherapies. However, these new treatment options have had limited impact on cure rates and long-term survival. For these reasons, and the recognition that colorectal cancer is long preceded by a polypoid precursor, screening programmes have gained momentum. This Primer provides an overview of the current state of the art of knowledge on the epidemiology and mechanisms of colorectal cancer, as well as on diagnosis and treatment.

New technologies and techniques to improve adenoma detection in colonoscopy

Adenoma detection rate (ADR) is a key component of colonoscopy quality assessment, with a direct link between itself and future mortality from colorectal cancer. There are a number of potential factors, both modifiable and non-modifiable that can impact upon ADR. As methods, understanding and technologies advance, so should our ability to improve ADRs, and thus, reduce colorectal cancer mortality. This article will review new technologies and techniques that improve ADR, both in terms of the endoscopes themselves and adjuncts to current systems. In particular it focuses on effective techniques and behaviours, developments in image enhancement, advancement in endoscope design and developments in accessories that may improve ADR. It also highlights the key role that continued medical education plays in improving the quality of colonoscopy and thus ADR. The review aims to present a balanced summary of the evidence currently available and does not propose to serve as a guideline.

Techniques and technologies to maximize mucosal exposure

Performing high-quality colonoscopy is one of the important goals of gastroenterology practices and requires achieving a high level of bowel cleansing, performing good and safe polypectomy, and detecting all polyps present in the colon. This article summarizes currently available techniques and technologies to maximize mucosal visualization. Several maneuvers can be applied during insertion and withdrawal of the colonoscope to optimize mucosal visualization and decrease the number of missed polyps. Newly developed technologies support the endoscopist in the detection of polyps. Each technique is reviewed, with emphasis on the impact on colorectal polyp detection.

Short turn radius colonoscope in an anatomical model: Retroflexed withdrawal and detection of hidden polyps

AIM: To evaluate the new RetroView™ colonoscope and compare its ability to detect simulated polyps “hidden” behind colonic folds with that of a conventional colonoscope, utilizing anatomic colon models.

METHODS: Three anatomic colon models were prepared, with twelve simulated polyps “hidden” behind haustral folds and five placed in easily viewed locations in each model. Five blinded endoscopists examined two colon models in random order with the conventional or RetroView™ colonoscope, utilizing standard withdrawal technique. The third colon model was then examined with the RetroView™ colonoscope withdrawn initially in retroflexion and then in standard withdrawal. Polyp detection rates during standard and retroflexed withdrawal of the conventional and RetroView™ colonoscopes were determined. Polyp detection rates for combined standard and retroflexed withdrawal (combination withdrawal) with the RetroView™ colonoscope were also determined.

RESULTS: For hidden polyps, retroflexed withdrawal using the RetroView™ colonoscope detected more polyps than the conventional colonoscope in standard withdrawal (85% vs 12%, P = 0.0001). For hidden polyps, combination withdrawal with the RetroView™ colonoscope detected more polyps than the conventional colonoscope in standard withdrawal (93% vs 12%, P≤ 0.0001). The RetroView™ colonoscope in “combination withdrawal” was superior to other methods in detecting all (hidden + easily visible) polyps, with successful detection of 80 of 85 polyps (94%) compared to 28 (32%) polyps detected by the conventional colonoscope in standard withdrawal (P < 0.0001) and 67 (79%) polyps detected by the RetroView™ colonoscope in retroflexed withdrawal alone (P < 0.01). Continuous withdrawal of the colonoscope through the colon model while retroflexed was achieved by all endoscopists. In a post-test survey, four out of five colonoscopists reported that manipulation of the colonoscope was easy or very easy.

CONCLUSION: In simulated testing, the RetroView™ colonoscope increased detection of hidden polyps. Combining standard withdrawal with retroflexed withdrawal may become the new paradigm for “complete screening colonoscopy”.

Sessile serrated adenomas: an evidence-based guide to management

The concept of serrated colorectal neoplasia and a serrated pathway to colorectal cancer (CRC) is relatively new and continuing to evolve, but it has become highly relevant to gastroenterologists, pathologist, and oncologists alike. Sessile serrated adenomas (SSA) are now thought to be the major precursor lesion of serrated pathway cancers, which represent up to one-third of all sporadic CRC cases. However, despite their increasingly recognized importance, relatively little is known about the epidemiology and natural history of SSAs, and the molecular and epigenetic aspects are incompletely understood. Endoscopists must be aware of the unique features of SSAs so that the practice of colonoscopic screening for CRC can include optimized detection, removal, and appropriate surveillance of SSAs and other serrated precursor lesions. In this review, we discuss the history, epidemiology, and pathologic aspects of SSAs, as well as a recommended management approach and a discussion of uncertainties and opportunities for future research.

Emerging technological advancements in colonoscopy: Third Eye® Retroscope® and Third Eye® Panoramic(TM) , Fuse® Full Spectrum Endoscopy® colonoscopy platform, Extra-Wide-Angle-View colonoscope, and NaviAid(TM) G-EYE(TM) balloon colonoscope

Colonoscopy is the criterion standard for detecting colorectal adenomas and cancers. However, multiple studies have reported a significant percentage of adenomas are missed during standard, forward-viewing colonoscopy. Missed adenomas can lead to interval colorectal cancers. Aside from inadequate colon preparation, incomplete examinations (e.g. failure to intubate the cecum), short withdrawal times, and patient-related factors, the primary reason for missing colorectal adenomas and early cancers is poor visualization of the proximal aspect of colonic folds, at anatomical flexures, and in the ileocecal valve area. These anatomical sites tend to be hidden from the standard forward-viewing colonoscope (170-degree angle of view) and can often only be seen through manipulation of the colonoscope by the endoscopist. Thus, there is mounting evidence supporting the need to reduce the adenoma 'miss rate' of standard forward-viewing colonoscopy by improving upon current colonoscope technology and its current visualization/optics limitations. Recently, there are a number of emerging technologies that may help revolutionize how colonoscopy is carried out and that will significantly reduce adenoma miss rates. These include the Third Eye® Retroscope® and Third Eye® Panoramic(TM) (Avantis Medical Systems, Sunnyvale, CA, USA); Fuse® Full Spectrum Endoscopy® colonoscopy platform (EndoChoice Inc., Alpharetta, GA, USA); Extra-Wide-Angle-View colonoscope (Olympus, Tokyo, Japan), and the NaviAid(TM) G-EYE(TM) balloon colonoscope (SMART Medical Systems Ltd, Ra'anana, Israel).

A novel balloon colonoscope detects significantly more simulated polyps than a standard colonoscope in a colon model

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 = 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.

Diagnostic yield of third eye retroscope on adenoma detection during colonoscopy: A systematic review and meta-analysis

AIM: To determine the diagnostic yield of the “third eye retroscope”, on adenoma detection rate during screening colonoscopy.

METHODS: The “third eye retroscope” when used with standard colonoscopy provides an additional retrograde view to visualize lesions on the proximal aspects of folds and flexures. We searched MEDLINE (PubMed and Ovid), SCOPUS (including MEDLINE and EMBASE databases), Cochrane Database of Systemic Reviews, Google Scholar, and CINAHL Plus databases to identify studies that evaluated diagnostic yield of “third eye retroscope” during screening colonoscopy. DerSimonian Laird random effects model was used to generate the overall effect for each outcome. We evaluated statistical heterogeneity among the studies by using the Cochran Q statistic and quantified by I² statistics.

RESULTS: Four distinct studies with a total of 920 patients, mean age 59.83 (95%CI: 56.77-62.83) years, were included in the review. The additional adenoma detection rate (AADR) defined as the number of additional adenomas identified due to “third eye retroscope” device in comparison to standard colonoscopy alone was 19.9% (95%CI: 7.3-43.9). AADR for right and left colon were 13.9% (95%CI: 9.4-20) and 10.7 (95%CI: 1.9-42), respectively. AADR for polyps ≥ 6 mm and ≥ 10 mm were 24.6% (95%CI: 16.6-34.9) and 24.2% (95%CI: 12.9-40.8), respectively. The additional polyp detection rate defined as the number of additional polyps identified due to “third eye retroscope” device in comparison to standard colonoscopy alone was 19.8% (95%CI: 7.9-41.8). There were no complications reported with use of “third eye retroscope” device.

CONCLUSION: The “third eye retroscope” device when used with standard colonoscopy is safe and detects 19.9% additional adenomas, compared to standard colonoscopy alone.

Advances in colonoscopy

Colonoscopy with polypectomy has been established as the major prevention and detection strategy for colorectal cancer for over a decade. Over this period advances in colonoscopic imaging, polyp detection, prediction of histopathology and polypectomy techniques have all been seen; however, the true magnitude of the limitations of colonoscopy has only recently been widely recognized. The rate and location of missed or interval cancers after complete colonoscopy appears to be influenced by the operator-dependency of colonoscopy and failure of conventional practices to detect and treat adenomatous, and possibly more importantly, non-adenomatous colorectal cancer precursors. Consequently, studies that expand our understanding of these factors and advances that aim to improve colonoscopy, polypectomy, and cancer protection are of critical importance.

Endoscopic innovations to increase the adenoma detection rate during colonoscopy

Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures, and the presence of flat lesions that are difficult to detect. These numbers may however be conservative because they mainly come from back-to-back studies performed with standard colonoscopes, which are unable to visualize the entire mucosal surface. In the past several years, new endoscopic techniques have been introduced to improve the detection of polyps and adenomas. The introduction of high definition colonoscopes and visual image enhancement technologies have been suggested to lead to better recognition of flat and small lesions, but the absolute increase in diagnostic yield seems limited. Cap assisted colonoscopy and water-exchange colonoscopy are methods to facilitate cecal intubation and increase patients comfort, but show only a marginal or no benefit on polyp and adenoma detection. Retroflexion is routinely used in the rectum for the inspection of the dentate line, but withdrawal in retroflexion in the colon is in general not recommended due to the risk of perforation. In contrast, colonoscopy with the Third-Eye Retroscope^® may result in considerable lower miss rates compared to standard colonoscopy, but this technique is not practical in case of polypectomy and is more time consuming. The recently introduced Full Spectrum Endoscopy™ colonoscopes maintains the technical capabilities of standard colonoscopes and provides a much wider view of 330 degrees compared to the 170 degrees with standard colonoscopes. Remarkable lower adenoma miss rates with this new technique were recently demonstrated in the first randomized study. Nonetheless, more studies are required to determine the exact additional diagnostic yield in clinical practice. Optimizing the efficacy of colorectal cancer screening and surveillance requires high definition colonoscopes with improved virtual chromoendoscopy technology that visualize the whole colon mucosa while maintaining optimal washing, suction and therapeutic capabilities, and keeping the procedural time as low and patient discomfort as optimal as possible.

Standard forward-viewing colonoscopy versus full-spectrum endoscopy: an international, multicentre, randomised, tandem colonoscopy trial

BACKGROUND

Although colonoscopy is the accepted standard for detection of colorectal adenomas and cancers, many adenomas and some cancers are missed. To avoid interval colorectal cancer, the adenoma miss rate of colonoscopy needs to be reduced by improvement of colonoscopy technique and imaging capability. We aimed to compare the adenoma miss rates of full-spectrum endoscopy colonoscopy with those of standard forward-viewing colonoscopy.

METHODS

We did an international, multicentre, randomised trial at three sites in Israel, one site in the Netherlands, and two sites in the USA between Feb 1, 2012, and March 31, 2013. Patients aged 18-70 years referred for colorectal cancer screening, polyp surveillance, or diagnostic assessment underwent same-day, back-to-back tandem colonoscopy with standard forward-viewing colonoscope and the full-spectrum endoscopy colonoscope. The patients were randomly assigned (1:1), via computer-generated randomisation with block size of 20, to which procedure was done first. The endoscopist was masked to group allocation until immediately before the start of colonoscopy examinations; patients were not masked. The primary endpoint was adenoma miss rates. We did per-protocol analyses. This trial is registered with ClinicalTrials.gov, number NCT01549535.

FINDINGS

197 participants were enrolled. 185 participants were included in the per-protocol analyses: 88 (48%) were randomly assigned to receive standard forward-viewing colonoscopy first, and 97 (52%) to receive full-spectrum endoscopy colonoscopy first. By per-lesion analysis, the adenoma miss rate was significantly lower in patients in the full-spectrum endoscopy group than in those in the standard forward-viewing procedure group: five (7%) of 67 vs 20 (41%) of 49 adenomas were missed (p<0·0001). Standard forward-viewing colonoscopy missed 20 adenomas in 15 patients; of those, three (15%) were advanced adenomas. Full-spectrum endoscopy missed five adenomas in five patients in whom an adenoma had already been detected with first-pass standard forward-viewing colonoscopy; none of these missed adenomas were advanced. One patient was admitted to hospital for colitis detected at colonoscopy, whereas five minor adverse events were reported including vomiting, diarrhoea, cystitis, gastroenteritis, and bleeding.

INTERPRETATION

Full-spectrum endoscopy represents a technology advancement for colonoscopy and could improve the efficacy of colorectal cancer screening and surveillance.

FUNDING

EndoChoice.

Retroview colonoscopy

A retroview in the colon permits an 11-25% increase in the adenoma detection rate when compared with a standard straight forward view during colonoscopy. This can often be accomplished in the rectum or the proximal colon by using dial controls and shaft manipulation to turn the tip of a standard colonoscope 180°. A special slim caliber instrument, the "Third Eye Retroscope" (a backward viewing device) has been developed which is inserted through the working channel of a colonoscope. New colonoscopes are being developed that have the capability of side vision with accompanying light illumination which, with wide angle lenses, provide an almost complete retroview of the colon.

The new view of colon cancer screening: forwards and backwards

Many different techniques for colon cancer screening are available. The fecal immunochemical test is best for fecal-based screening, although the DNA investigation may be more specific when further developed. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but has limitations. The flexible sigmoidoscopic examination markedly decreases the incidence of cancer in the visualized segments, but colonoscopy is currently the best procedure for evaluating the large bowel. Techniques for retroflexion or backward view of the colon have been investigated, with all showing increased polyp detection.

Polyp and adenoma detection rates in the proximal and distal colon

OBJECTIVES

Little is known about the correlation between the polyp detection rate (PDR) and the adenoma detection rate (ADR) in individual colonic segments. The adenoma-to-polyp detection rate quotient (APDRQ) has been utilized in retrospective study as a constant to estimate ADR from PDR. It has been previously stated that diminutive polyps in the rectum are more likely to be non-adenomatous, compared with more proximal segments, yet the APDRQ uses data from the entire colon. We sought to characterize and compare ADR and PDR in each colonic segment, estimate ADR using the conversion factor, APDRQ, and assess the correlation between estimated and actual ADR for each colonic segment.

METHODS

As part of a quality improvement program, a retrospective chart review was conducted of all outpatient colonoscopies performed by 20 gastroenterologists between 1 October 2010 and 31 March 2011 at a single academic tertiary-care referral center. PDR, ADR, and the APDRQ were calculated for each gastroenterologist, using data from the entire colon and then for each colonic segment separately. Actual ADR was compared with estimated ADR based on the measured APDRQ.

RESULTS

During 1,921 colonoscopies, 2,285 polyps were removed; 1,122 (49%) were adenomas. The mean (s.d.) PDR for the group was 49% (12.4%) (range, 16-64%). The mean (s.d.) ADR was 31% (7.4%) (range, 13-42%). PDR and ADR correlated well in segments proximal to the splenic flexure, but diverged in distal segments. ADR was significantly higher in the right colon (17.1%) than in the left (13.5%) (P=0.001). The correlation between estimated and actual ADR using the APDRQ was significantly higher in the right colon (r=0.95 (95% confidence interval (CI), 0.87-0.98)) than in the left (r=0.59 (95% CI, 0.17-0.83)) (P<0.05).

CONCLUSIONS

Although PDR and ADR correlate well in segments proximal to the splenic flexure, they do not correlate well in the left colon. Caution should be exercised when using PDR as a surrogate for ADR if data from the rectum and sigmoid are included.

Adenoma detection in patients undergoing a comprehensive colonoscopy screening

Measures shown to improve the adenoma detection during colonoscopy (excellent bowel preparation, cecal intubation, cap fitted colonoscope to examine behind folds, patient position change to optimize colon distention, trained endoscopy team focusing on detection of subtle flat lesions, and incorporation of optimum endoscopic examination with adequate withdrawal time) are applicable to clinical practice and, if incorporated are projected to facilitate comprehensive colonoscopy screening program for colon cancer prevention. To determine adenoma and serrated polyp detection rate under conditions designed to optimize quality parameters for comprehensive screening colonoscopy. Retrospective analysis of data obtained from a comprehensive colon cancer screening program designed to optimize quality parameters. Academic medical center. Three hundred and forty-three patients between the ages of 50 years and 75 years who underwent first screening colonoscopy between 2009 and 2011 among 535 consecutive patients undergoing colonoscopy. Comprehensive colonoscopy screening program was utilized to screen all patients. Cecal intubation was successful in 98.8% of patients. The Boston Bowel Preparation Scale for quality of colonoscopy was 8.97 (95% confidence interval [CI]; 8.94, 9.00). The rate of adenoma detection was 60% and serrated lesion (defined as serrated adenomas or hyperplastic polyps proximal to the splenic flexure) detection was 23%. The rate of precancerous lesion detection (adenomas and serrated lesions) was 66%. The mean number of adenomas per screening procedure was 1.4 (1.2, 1.6) and the mean number of precancerous lesions (adenomas or serrated lesions) per screening procedure was 1.6 (1.4, 1.8). Retrospective study and single endoscopist experience. A comprehensive colonoscopy screening program results in high-quality screening with high detection of adenomas, advanced adenomas, serrated adenomas, and multiple adenomas.

Precancerous lesions in inflammatory bowel disease

Reduction of mortality from colorectal cancer is a prime goal in the clinical management of patients with extensive, longstanding ulcerative colitis and colonic Crohn's disease. The cornerstone of current cancer prevention efforts is endoscopic surveillance for colorectal dysplasia, or intraepithelial neoplasia, the direct histological precursor of cancer. A diagnosis of dysplasia provides a reliable indicator of heightened cancer risk and an end-point for colonoscopic surveillance allowing most patients to undergo prophylactic colectomy before the development of incurable cancer. This article reviews the classification, pathological criteria and clinical implications of colorectal dysplasia, current recommendations for the performance of surveillance colonoscopy, recent technical advances in colonoscopic imaging to enhance the detection of dysplasia, and a summary of the molecular genetic events implicated in its development.

Colonoscopy for colorectal cancer screening

Colorectal cancer (CRC) is the second leading cause of cancer death in the United States. Many, if not most, cases arise from premalignant lesions (adenomas) which may be identified and removed prior to becoming frankly malignant. For over a decade, colonoscopy has been the preferred modality for both CRC screening and prevention in the US. Early reports suggested that colonoscopic screening imparted a 90% risk reduction for colorectal cancer. Subsequent studies showed that estimate to be overly optimistic. While still an outstanding CRC screening and detection tool, colonoscopy has several important limitations. Some of these limitations relate to the mechanics of the procedure such as the risk of colonic perforation, bleeding, adverse consequences of sedation, and the inability to detect all colonic polyps. Other limitations reflect issues with patient perception regarding colonoscopy which, at least in part, drive patient non-adherence to recommended testing. This review examines the literature to address several important issues. First, we analyze the effect of colonoscopy on CRC incidence and mortality. Second, we consider the patient-based, periprocedural, and intraprocedural factors which may limit colonoscopy as a screening modality. Third, we explore new techniques and technologies which may enhance the efficacy of colonoscopy for adenoma detection. Finally, we discuss the short and long-term future of colonoscopy for CRC screening and the factors which may affect this future.

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)

BACKGROUND

Although colonoscopy is the criterion standard for detecting colorectal adenomas and cancers, a significant percentage of adenomas are missed.

OBJECTIVE

To compare forward-viewing with ultrawide-viewing colonoscopy in the detection of simulated colon polyps in an in vitro colon model.

DESIGN

Prospective, multicenter.

SETTING

Six endoscopy units (3 in the United States and 3 in Israel).

PATIENTS

In vitro colon model with simulated colon polyps (n = 21 metallic beads).

INTERVENTIONS

Detection of simulated colon polyps on colonoscope withdrawal.

MAIN OUTCOME MEASUREMENTS

Incremental detection of simulated colon polyps and endoscopist evaluation of the usability, visibility, and maneuverability of ultrawide-viewing colonoscopy.

RESULTS

On forward-viewing colonoscopy, the number of simulated polyps (mean ± standard deviation) detected per endoscopist was 11.1 ± 2.3 polyps, a 52.9% detection rate. Simulated polyp detection rates per colon segment were 3.0 ± 0.93 (60.0%) right colon, 2.4 ± 0.87 (48.0%) transverse colon, and 5.7 ± 1.5 (51.8%) left colon. On ultrawide-viewing colonoscopy, the simulated polyp detection rate per endoscopist significantly increased to 18.0 ± 1.98 polyps, an overall 85.7% polyp detection rate (P < .001). Simulated polyp detection rates were also significantly higher by using the ultrawide-viewing mode in each colon segment, 4.5 ± 0.65 polyps (90.0%) right colon, 4.0 ± 0.87 (80.0%) polyps transverse colon, and 9.6 ± 1.28 polyps (87.3%) left colon (all comparisons, P < .001). Importantly, the ultrawide-viewing mode detected significantly more "hidden" simulated polyps (81.9% vs 31.9%, P < .0001).

LIMITATIONS

Nonrandomized design, use of a colon model, and "simulated" colon polyps.

CONCLUSIONS

Ultrawide-view colonoscopy significantly improved simulated polyp detection in a colon model. Clinical studies in human subjects should be pursued to further evaluate this new endoscopic technology.

A novel extra-wide-angle-view colonoscope: a simulated pilot study using anatomic colorectal models

BACKGROUND

A major factor that may contribute to a higher adenoma miss rate during colonoscopy is undetected lesions located behind haustral folds, flexures, or rectal valves.

OBJECTIVE

To assess the efficacy of a prototype, novel, extra-wide-angle-view colonoscope that provides a simultaneous lateral-backward view that complements the forward view lens.

DESIGN

A simulated pilot study of two anatomic colorectal models, each prepared with 8 polyps positioned in obvious locations and 8 polyps placed behind folds. Thirty-two endoscopists with different levels of experience performed examinations on models in a random order by using the extra-wide-angle-view colonoscope and a standard colonoscope.

MAIN OUTCOME MEASUREMENTS

The detection rates of simulated polyps.

RESULTS

The mean detection rate for all simulated polyps with the extra-wide-angle-view colonoscope was significantly higher than that with the standard colonoscope (68% vs 51%; P < .0001). The detection rate for polyps behind folds was significantly higher in the extra-wide-angle-view colonoscope than in the standard colonoscope (61.7% vs 46.9%; P = .0009).

LIMITATIONS

Not a clinical study.

CONCLUSION

The novel, extra-wide-angle-view colonoscope may represent an advancement in colorectal polyp detection. The value of the colonoscope for clinical use awaits further study.

Advanced colorectal polyp detection techniques

A long-term follow-up of the landmark National Polyp Study recently showed that colonoscopy was associated with critical clinical benefit, including reduced overall death rate, colorectal cancer (CRC) death rate, and CRC incidence Zauber et al. (N Engl J Med 366(8):687-96, 2012). This and other recent studies emphasize the need for high-quality colonoscopy to realize maximal benefit. Adenoma detection has emerged as an important predictor of quality colonoscopy. Studies from Europe have shown that individuals whose colonoscopy was performed by a physician with high adenoma detection have a much lower likelihood of interval CRC. Studies now suggest that it is possible to train endoscopists to improve their adenoma detection rate. The specific methods associated with higher quality colonoscopy include careful inspection behind folds, washing the colon surface, adequate insufflation, and recognition of subtle flat polyps. Use of high-definition white light colonoscopy, chromoendoscopy, and cap-fitted colonoscopy has also been studied as potential methods for increasing adenoma detection. We will review these methods and techniques in this article.

Nurse observation during colonoscopy increases polyp detection: a randomized prospective study

OBJECTIVES

To determine whether a second observer during colonoscopy increases adenoma detection.

METHODS

Consecutive patients undergoing screening colonoscopy were prospectively randomized to routine colonoscopy or physician and nurse observation during withdrawal.

RESULTS

Of 502 patients, 249 were randomized to routine colonoscopy, and 253 to physician plus nurse observation during withdrawal. A total of 592 polyps were detected, 40 identified by the endoscopy nurse only. With nurse observation, 1.32 polyps and 0.82 adenomas were found per colonoscopy, vs. 1.03 polyps and 0.64 adenomas in the routine group, demonstrating a 1.29-fold and a 1.28-fold increase in the average number of polyps and of adenomas detected, respectively. The overall adenoma detection rate (ADR) was 44.1%, with trends toward increased ADR and all-polyp detection rate with nurse observation.

CONCLUSIONS

Nurse observation during colonoscopy resulted in an increase in the number of polyps and adenomas found per colonoscopy, along with a trend toward improved overall ADR and all-polyp detection rate.

Advances in gastrointestinal endoscopy

Gastrointestinal endoscopy has undergone a remarkable expansion in its capabilities as a result of sophisticated technological advances in recent years. New imaging technologies, novel ablation and resection techniques, cutting-edge endoscope development and creative extraluminal applications have taken gastrointestinal endoscopy to an exciting new level. An update on some of these advances is presented for the physician audience.

Bringing top-end endoscopy to regional australia: hurdles and benefits

This paper focuses on recent experience in setting up an endoscopy unit in a large regional hospital. The mix of endoscopy in three smaller hospitals, draining into the large hospital endoscopy unit, has enabled the authors to comment on practical and achievable steps towards creating best practice endoscopy in the regional setting. The challenges of using what is available from an infrastructural equipment and personnel setting are discussed. In a fast moving field such as endoscopy, new techniques have an important role to play, and some are indeed cost effective and have been shown to improve patient care. Some of the new techniques and technologies are easily applicable to smaller endoscopy units and can be easily integrated into the practice of working endoscopists. Cost effectiveness and patient care should always be the final arbiter of what is essential, as opposed to what is nice to have. Close cooperation between referral and peripheral centers should also guide these decisions.

Water-aided colonoscopy: a systematic review

BACKGROUND

Water-aided methods for colonoscopy are distinguished by the timing of removal of infused water, predominantly during withdrawal (water immersion) or during insertion (water exchange).

OBJECTIVE

To discuss the impact of these approaches on colonoscopy pain and adenoma detection rate (ADR).

DESIGN

Systematic review.

SETTING

Randomized, controlled trial (RCT) that compared water-aided methods and air insufflation during colonoscope insertion.

PATIENTS

Patients undergoing colonoscopy.

INTERVENTION

Medline, PubMed, and Google searches (January 2008-December 2011) and personal communications of manuscripts in press were considered to identify appropriate RCTs.

MAIN OUTCOME MEASUREMENTS

Pain during colonoscopy and ADR. RCTs were grouped according to whether water immersion or water exchange was used. Reported pain scores and ADR were tabulated based on group assignment.

RESULTS

Pain during colonoscopy is significantly reduced by both water immersion and water exchange compared with traditional air insufflation. The reduction in pain scores was qualitatively greater with water exchange as compared with water immersion. A mixed pattern of increases and decreases in ADR was observed with water immersion. A higher ADR, especially proximal to the splenic flexure, was obtained when water exchange was implemented.

LIMITATIONS

Differences in the reports limit application of meta-analysis. The inability to blind the colonoscopists exposed the observations to uncertain bias.

CONCLUSION

Compared with air insufflation, both water immersion and water exchange significantly reduce colonoscopy pain. Water exchange may be superior to water immersion in minimizing colonoscopy discomfort and in increasing ADR. A head-to-head comparison of these 3 approaches is required.