Diagnostic yield of scope retroflexion in the right colon: A prospective cohort study

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).

Second exam of right colon improves adenoma detection rate: Systematic review and meta-analysis of randomized controlled trials

Background and study aims  A second examination of the right colon, either as a second forward view (SFV) or as retroflexion (RF) in the cecum, can increase adenoma detection rate (ADR) in the right colon. In this meta-analysis, we have evaluated the role of a second examination of the right colon in improving ADR. Methods  We reviewed several databases to identify randomized controlled trials that compared right colon SFV with no SFV, and RCTs that compared SFV with RF in the right colon, and reported data on ADR. Our outcomes of interest were ADR and polyp detection rate (PDR) with SFV vs no SFV, right colon and total withdrawal times, and additional ADR and PDR with SFV vs RF. For categorical variables, we calculated pooled risk ratios (RRs) with 95 % confidence intervals (CIs); for continuous variables, we calculated standardized mean difference (SMD) with 95 % CI. Data were analyzed using random effects model. Results  We included six studies with 3901 patients. Comparing SFV with no SFV, right colon ADR and PDR were significantly higher in the SFV group: ADR (RR [95 % CI] 1.39 [1.22,1.58]) and PDR (RR [95 % CI] 1.47 [1.30, 1.65]). We found no significant difference in right colon withdrawal time (SMD [95 % CI] 1.54 [-0.20,3.28]) or total withdrawal time (SMD (95 % CI) 0.37 [-0.39,1.13]) with and without SFV. We found no significant difference in additional ADR between SFV and RF. Conclusions  SFV of the right colon significantly increases right-sided and overall ADR.

Retroflexed view for reexamination of the right colon after forward view examination: Systematic review and meta-analysis

BACKGROUND

The effect of retroflexed view (RV) for the reexamination of the right colon after forward view (FV) examination has not been fully understood.

METHODS

We searched multiple databases including PubMed, Embase, and the Cochrane Library for prospective studies exploring the role of RV for reexamination of the right colon. A meta-analysis was performed on outcomes including lesion detection rates, lesion miss rates, and withdrawal time.

RESULTS

Four randomized controlled trials aimed to compare the impact of the second withdrawal from the right colon in RV vs. FV following a standard colonoscopy. Both the additional adenoma detection rate (AADR) and additional polyp detection rate (APDR) of the right colon were lower in the RV group compared with the FV group (risk ratio [RR] 0.73 for AADR; RR 0.76 for APDR); similar results were noted in comparisons of the adenoma miss rate and polyp miss rate. Six prospective cohort studies aimed to describe the effect of the RV examination of the right colon after one or two rounds of FV examination. Both the adenoma detection rate (ADR) and polyp detection rate (PDR) of the right colon were slightly higher in combined examinations with RV examination than single FV examination (RR 1.11 for ADR; RR 1.16 for PDR) or two FV examinations (RR 1.21 for ADR; RR 1.22 for PDR).

CONCLUSIONS

FV may detect more adenomas and polyps than RV during the second withdrawal from the right colon. RV may detect additional adenomas and polyps in the right colon after two FV examinations.

IMPACT OF RETROFLEXED VIEW ON THE DETECTION OF LESIONS IN THE PROXIMAL COLON: ASSESSMENT OF 393 PATIENTS IN A PRIVATE TERTIARY HOSPITAL

BACKGROUND

The gold standard test for colorectal cancer screening the colonoscopy. Although this is the test of choice, colonoscopy misses a significant number of lesions, mainly in the proximal colon. With the purpose of reducing the number of lesions missed, new techniques have been studied, amongst them, retroflexed view in the right side of the colon and the second direct forward view.

OBJECTIVE

Assessing the safety of the retroview in the proximal colon (cecum and ascending colon), its impact on the detection of lesions in the proximal colon and its advantage over the double right forward view using adenoma detection rate and adenoma miss rate.

METHODS

Three hundred and ninety-three patients who came to Hospital Mater Dei to undergo colonoscopy from March to July 2017, prospectively. Out of these, 372 were included in the study based on the following exclusion criteria: being under 18 years of age, inadequate bowel preparations (Boston scale <7), history of colectomy, inflammatory bowel disease or polypoid diseases. First, an endoscopist inserted the colonoscope into the cecum and examine the cecum and the ascending colon with a forward view twice. In the third insertion into the cecum, retroflexed view was performed, cecal mucosa was examined until the hepatic flexure in search of polyps missed on forward view. All lesions found were resected and sent for histological analysis.

RESULTS

In 334 (89.8%) patients, retroflexed view was performed successfully, 65.8% of failures were attributed to the loops of the device which prevented the maneuver. The direct view identified 175 polyps in the proximal colon in 102 people. Retroflexed view detected 26 polyps missed by the direct view in 24 (6.5%) people, with a missing rate of 12.9% in the test with only the forward view. Out of the 26 polyps found in retroview, 21 (80.76%) were adenomas, one of them with a high-grade dysplasia. Eleven patients had polyps seen only in retroflexed view. Retroview has increased the polyp detection rate from 27.41% to 31.72% and the adenoma detection rate from 21.77% to 25%. The adenoma miss rate by the double direct view was 12.8%. Without the retroview, one polyp in every 13.91 colonoscopies would be missed (number needed to treat - NNT=13.91). There was no adverse event.

CONCLUSION

The retroflexed view technique in the proximal colon was shown to be safe, fast and feasible in most cases. It increased the adenoma detection rate and was shown to be advantageous in this study wit benefit beyond the double direct view.

Colonoscopy screening and surveillance guidelines

The Colonoscopy Screening and Surveillance Guidelines were developed by the Japan Gastroenterological Endoscopy Society as basic guidelines based on the scientific methods. The importance of endoscopic screening and surveillance for both detection and post-treatment follow-up of colorectal cancer has been recognized as essential to reduce disease mortality. There is limited high-level evidence in this field; therefore, we had to focus on the consensus of experts. These clinical practice guidelines consist of 20 clinical questions and eight background knowledge topics that have been determined as the current guiding principles.

New insights on missed colonic lesions during colonoscopy through artificial intelligence-assisted real-time detection (with video)

BACKGROUND AND AIMS

Meta-analysis shows that up to 26% of adenomas could be missed during colonoscopy. We investigated whether the use of artificial intelligence (AI)-assisted real-time detection could provide new insights into mechanisms underlying missed lesions during colonoscopy.

METHODS

A validated real-time deep-learning AI model for the detection of colonic polyps was first tested in videos of tandem colonoscopy of the proximal colon for missed lesions. The real-time AI model was then prospectively validated in a total colonoscopy in which the endoscopist was blinded to real-time AI findings. Segmental unblinding of the AI findings were provided, and the colonic segment was then re-examined when missed lesions were detected by AI but not the endoscopist. All polyps were removed for histologic examination as the criterion standard.

RESULTS

Sixty-five videos of tandem examination of the proximal colon were reviewed by AI. AI detected 79.1% (19/24) of missed proximal adenomas in the video of the first-pass examination. In 52 prospective colonoscopies, real-time AI detection detected at least 1 missed adenoma in 14 patients (26.9%) and increased the total number of adenomas detected by 23.6%. Multivariable analysis showed that a missed adenoma(s) was more likely when there were multiple polyps (adjusted odds ratio, 1.05; 95% confidence interval, 1.02-1.09; P < .0001) or colonoscopy was performed by less-experienced endoscopists (adjusted odds ratio, 1.30; 95% confidence interval, 1.05-1.62; P = .02).

CONCLUSIONS

Our findings provide new insights on the prominent role of human factors, including inexperience and distraction, on missed colonic lesions. With the use of real-time AI assistance, up to 80% of missed adenomas could be prevented. (Clinical trial registration number: NCT04227795.).

Retroflexion, a costless endoscopic maneuver, increases adenoma detection rate in the ascending colon

Background

Missed polyps during colonoscopy are considered an important factor for interval cancer appearance, especially in the ascending colon (AC). We evaluated the contribution of retroflexion to polyp and adenoma detection in the AC.

Methods

This prospective observational study included consecutive patients who underwent a complete colonoscopy between 06/2017 and 06/2018. The AC was examined in 2 phases: the first included 2 forward views from the hepatic flexure to the cecum; the second involved a retroflexion in the cecum, inspection up to the hepatic flexure and reinsertion to the cecum.

Results

The study included 655 patients, 628 (95.88%) with successful retroflexion (mean age: 62.5±10.8 years, 332 male). Indications for colonoscopy were screening in 33.28%, follow up in 36.03%, and diagnostic assessment in 30.69%. In total, 286 polyps and 220 adenomas were detected in the AC. Phase 1 identified 119 adenomas, yielding an adenoma detection rate (ADR) in the AC of 14.2% (95% confidence interval [CI] 11.52-16.84%) while phase 2 identified 86 additional adenomas, improving the ADR in the AC to 22.75% (95%CI 19.54-25.96%; P<0.01). Adenoma miss rate was 39.1% (86/225) and per-patient adenoma miss rate was 11.15% (73/655). Retroflexion proved beneficial mainly in the upper third of the AC (odds ratio [OR] 4.29, 95%CI 1.84-11.56; P<0.01) and for small (<5 mm) adenomas (OR 1.61, 95%CI 1.02-2.56; P=0.04). Multivariate analysis showed that age >60 years, detection of adenomas in forward views and the indication “follow up” influenced ADR during retroflexion.

Conclusion

Retroflexion is a simple and safe maneuver that increases the ADR in the AC and should complete a second forward view.

Efficacy of repeat forward-view examination of the right-sided colon during colonoscopy: A prospective randomized controlled trial

BACKGROUND AND AIM

Generally, colonoscopy is less effective for detecting colorectal adenomas in the right-sided colon compared with the distal colon. Repeat forward-view (RF) examination of the right-sided colon has been suggested to increase the adenoma detection rate (ADR). However, studies investigating the efficacy of RF examination are lacking. Thus, the aim of this study was to determine whether RF examination in the right-sided colon enhances right-sided ADR.

METHODS

We performed a prospective, randomized controlled trial, including asymptomatic subjects who underwent screening colonoscopy. Subjects were randomized to the RF group, in which the right-sided colon was examined twice in the forward view, or to the standard forward-view (SF) group, in which the right-sided colon was examined once in the forward view. The primary outcome was the right-sided ADR on RF examination of the right-sided colon.

RESULTS

A total of 640 subjects completed the study protocol (RF group, n = 320; SF group, n = 320). The right-sided ADR in the RF group was significantly higher than that in the SF group (17.5% vs 11.9%, respectively; P = 0.044). In the RF group, an additional 31 adenomas were found, resulting in an increased detection rate of adenomas of 38.3% compared with the first forward view. The ADR of the whole colon was similar between the groups.

CONCLUSIONS

In our prospective randomized controlled trial, RF examination of the right-sided colon, which can be easily performed in clinical practice, was associated with an increased rate of detection of right-sided ADR.

Proximal retroflexion versus second forward view of the right colon during screening colonoscopy: A multicentre randomized controlled trial

BACKGROUND

Colonoscopy is the gold standard investigation for the detection of colorectal cancer, but the right colon is more difficult to examine than the left colon. A second examination of the proximal colon has the potential to reduce rates of missed pathology.

OBJECTIVE

To determine whether proximal retroflexion improves the adenoma detection rate or other outcomes in the right colon compared with the forward view.

METHODS

We performed a multicentre randomized controlled trial of patients from the colorectal cancer screening programme with a positive faecal immunochemical test. Patients were randomized to a second right colon examination using proximal retroflexion or forward view.

RESULTS

A total of 692 patients were included. A second examination of the right colon, with an average additional procedure time of 1.62 min, increased the adenoma detection rate by 11%, regardless of the method used (9% proximal retroflexion vs. 12% second forward view, p = 0.21). The adenoma miss rate was 19% (17% proximal retroflexion vs. 20% forward view, p = 0.28) The success rate of retroflexion was 83%, without secondary complications. In the 15.6% of patients in whom lesions were detected during the second pass, endoscopic follow-up was modified by reducing the time of the next colonoscopy.

CONCLUSIONS

A second examination of the right colon, either from retroflexion or second forward view, can increase adenoma detection rate and shorten surveillance intervals in patients undergoing screening colonoscopy. This should be emphasized during colonoscopy training and integrated into diagnostic colonoscopy practice.

Success, safety, and usefulness of right colon retroflexion for the detection of additional colonic lesions not visualized with standard frontal view

BACKGROUND

Missed adenomas are the main concern for endoscopists. Right colon retroflexion (RCR) seems to increase the adenoma detection rate (ADR), but important variation in success and usefulness of this maneuver has been reported in the literature AIMS: Primary objective: to assess additional adenoma detection rate (AADR) detected during the RCR attempt. Secondary objectives: to assess success rates of RCR, variables associated with it, and safety of RCR.

METHODS

This is a prospective, unicentric, non-randomized study. Consecutive colonoscopies done by six endoscopists (3 of them with < 3 years of experience and 3 with > 3 years) from March to May 2017 were included. Olympus colonoscopes were used (CF-H190, CF-H180) Demographic, clinical, and endoscopic variables were collected.

RESULTS

463 colonoscopies were included. RCR success rate was 93.1% (431/463 colonoscopies). Forty additional lesions were visualized during RCR in 34/463 colonoscopies (7.3%). Additional adenomas were detected in 31/463 colonoscopies (6.7%; OR 0.07).

HISTOLOGY

low-grade dysplasia adenomas in 29/40 (72.5%) lesions; 3/40 (7.5%), adenomas with high-grade dysplasia; and 7/40 (17.5%) sessile serrated lesions. Additional adenoma detection contributed to modify the colonoscopy surveillance interval in 25 patients (5.4% of the cohort). Variables associated with RCR success in multivariate analysis were no previous abdominal surgery, length of colonoscope insertion in cecum < 80 cm, and use of Olympus 190 series colonoscopes. No differences between endoscopists' experience were found. RCR was a safe maneuver, with no adverse events in our study.

CONCLUSIONS

RCR is a feasible and safe maneuver that can increase ADR, so its routine inclusion in colonoscopy practice should be considered.

Effect of fellow involvement on colonoscopy outcomes: A systematic review and meta-analysis

BACKGROUND AND AIMS

The effect of fellow involvement on colonoscopy outcomes is controversial. Thus, we evaluated this effect on adenoma detection rate (ADR) and on other colonoscopy quality indicators.

METHODS

MEDLINE and Cochrane central register of controlled trials were searched up to September 2018 for studies evaluating fellow-involved colonoscopies vs. attending physicians-only examinations in terms of colonoscopy outcomes. Primary outcome was ADR, while advanced ADR (AADR), mean number of adenomas per colonoscopy (MAC), cecum intubation rate (CIR) and adverse events rate comprised the secondary outcomes. The effect size on study outcomes was calculated using random-effects model and it is presented as Odds Ratio (OR) or Mean Difference (MD) with 95% confidence interval (CI).

RESULTS

Nineteen observational studies involving 34,059 patients (fellow-involved 16,875, attending physician-only 17,184) were included. Compared to the attending physician-only group, fellow involvement marginally increased ADR [OR (95%CI) = 1.12 (1.00-1.26); p = 0.06, I² = 76%]. Attending physicians with low-to-moderate ADR (<35%) benefited most from fellow's participation [OR (95%CI): 1.26 (1.13-1.40) vs. 1.12 (1.00-1.26); p = 0.03 when ADR < 35% and OR (95%CI): 1.29 (1.13-1.46) vs. 0.95 (0.78-1.16); p = 0.01 when ADR < 30%, respectively]. Moreover, fellow-involved group had higher MAC compared to attending-only group [MD (95%CI) = 0.12 (0.04-0.20); p = 0.002, I² = 53%]. No benefit from fellow involvement was detected either for AADR, CIR or adverse events rate.

CONCLUSIONS

Fellow involvement during colonoscopy is associated with more adenomas detected per procedure and with higher ADR when the attending physician-only group ADR is less than 35%.

Increasing adenoma detection rates in the right side of the colon comparing retroflexion with a second forward view: a systematic review

BACKGROUND AND AIMS

Right-sided lesions are often missed during standard colonoscopy (SC). A second forward-view examination or retroflexion in the right side of the colon have both been proposed as techniques to improve adenoma detection rate (ADR) in the right side of the colon. Comparative data on examining the right side of the colon with a second forward view or retroflexion is not known in a pooled analysis. We performed a systematic review of the literature to assess the yield of a second forward view compared with retroflexion examination for the detection of right-sided adenomas.

METHODS

A systematic literature search was performed using the following databases: PubMed, Embase, Web of Science, and Cochrane. Only full-length published articles that provided information on adenoma detection and miss rates during either a second forward view or retroflexed view of the right side of the colon after the initial standard forward withdrawal (SC) were included. The following outcomes were assessed: comparison of adenoma miss rate (AMR) for second forward view versus retroflexion after SC, AMR of SC compared with second forward view, AMR of SC compared with retroflexion, and right-sided adenoma detection with second forward view and retroflexion. Pooled rates were reported as risk difference or odds ratios (OR) with 95% confidence intervals (CI) with a P value <.05 indicating statistical significance. Statistical analysis was performed with Review Manager v5.3.

RESULTS

We identified 4 studies with 1882 patients who underwent a second forward view of the right side of the colon after an initial SC. The average age of the patients was 58.3 years. Data on right-sided ADR were available from all 4 studies for the second forward view; however, only 2 of the studies provided information on right-sided ADR with retroflexion. The pooled estimate of AMR of a single SC was 13.3% (95% CI, 6.6%-20%) compared with a second forward-view examination (n = 4), whereas it was 8.1% (3.7%-12.5%) compared with a retroflexion examination (n = 3). However, when the second forward view was compared with retroflexion in terms of AMR from an analysis of 3 eligible studies, there was no statistically significant difference (7.3% vs 6.3%; pooled OR, 1.2; 95% CI, 0.9-1.61; P = .21). Second forward view of the right side of the colon increased the right-sided ADR by 10% (n = 4; second forward view vs SC, 33.6% vs 26.7%) with a pooled risk difference of 0.09 (95% CI, 0.03-0.15; P < .01). Retroflexion increased the right-sided ADR by 6% (n = 3; retroflexion vs SC, 28.4% vs 22.7%) with a pooled risk difference of 0.06 (95% CI, 0.03-0.09; P < 01).

CONCLUSION

After SC withdrawal, a second forward view and retroflexed view of the right side of the colon are both associated with improvement in ADR. One of these techniques should be considered during SC to increase ADR and to improve the quality of colonoscopy.

Impact of retroflexion in the right colon after repeated forward-view examinations

Background and Aim

Right colon polyps can especially be overlooked when they are located on the backs of haustral folds. Previous studies have reported that repeated forward‐view examinations in the right colon were effective in reducing adenoma miss rates. The aim of this study was to clarify the impact of retroflexion in the right colon after repeated forward‐view examinations.

Methods

This multicenter, prospective, observational study was conducted at three institutions in Kumamoto, Japan, between February 2014 and December 2015. Subjects who were over 40 years old and scheduled for colonoscopy were recruited. For the forward view, after cecal intubation, the colonoscope was withdrawn to the hepatic flexure. The colonoscope was sequentially reinserted to the cecum and then withdrawn to the hepatic flexure. For the retroflexion view (RV), the colonoscope was reinserted to the cecum, retroflexed, and then withdrawn to the hepatic flexure. All polyps were resected at the time of detection. The primary outcome of this study was the adenoma miss rate for the repeated forward‐view examinations.

Results

Of the 777 enrolled participants, retroflexion was successful in 730 (94.0%). The repeated forward‐view withdrawal technique detected 291 adenomas, while the third withdrawal in the RV detected 53. The adenoma miss rate for the repeated forward‐view withdrawal was 15.4%. No severe adverse events occurred during retroflexion.

Conclusion

Because adenomas located on potential blind spots can be missed when only using forward‐view examinations, retroflexion in the right colon after repeated forward‐view examinations might improve colonoscopy detection rates.

Adenoma miss rate determined by very shortly repeated colonoscopy: Retrospective analysis of data from a single tertiary medical center in China

Adenoma miss rate (AMR) has been calculated in several tandem colonoscopy studies, but it costs overmuch to carry out a clinical trial.We aimed to put forward AMR by taking advantage of retrospective data, and to judge the comparability between AMRs from prospective and retrospective data.Data of the patients accepting repeated colonoscopies during January to September 2016 was retrospectively collected and analyzed. Information was recorded, including bowel preparation quality of the first colonoscopy, size, location, histology and whether missed within the first colonoscopy of each single adenoma. AMR was compared by different risk factors through χ test and multivariable logistic regression.Around 267 adenomas were detected during 309 pairs of repeated colonoscopies, of which 66 were missed during the first colonoscopies. AMRs of the lesions small in size, nonadvanced in histology, in poor bowel preparation context and located in the proximal colon, were significantly higher than the opposite ones, and old age and male were related to adenoma missing (P < .05). In multivariable logistic regression analysis, adenoma-related factors (diminutive in size, poor bowel preparation and located in ascending colon, transverse colon or sigmoid colon), and patient-related factors (older than 60 years, male and poor bowel preparation) were found to be independently associated with missing adenomas (P < .05).AMR of retrospective data is comparable to that of tandem studies. Several risk factors influence AMR dramatically, which should be paid attention to.

Characteristics of right-sided colonic neoplasia and colonoscopy barriers limiting their early detection and prognosis: a review of the literature

Colonoscopy provides less protection from colorectal cancer in the right colon than the left. Areas covered: This review examines patient outcomes and colonoscopy success rates to identify factors that limit the protective effect of colonoscopy in the right colon. The MEDLINE and Embase databases were searched for literature from 2000 onwards, on the long-term outcomes and differences in screening practice between the right and left colon. In total, 12 systematic reviews (including nine meta-analyses) and 44 primary data records were included. Differences in patient outcomes and colonoscopy practice were identified between the right and left colon, suggesting that several factors, many of which disproportionally affect the right colon, impact lesion detection rates. Shorter withdrawal times reduce detection rates, while longer times significantly increase detection; mostly of adenomas in the right colon. Colonoscope attachments often only show a significant improvement in detection rates in the right colon, suggesting detection is more challenging due to visibility of the right colonic mucosa. Higher bowel cleansing grades significantly improve detection rates in the right colon compared to the left. Expert commentary: These findings confirm the need for continued improvement of colonoscopy effectiveness, and obligatory quality assessment, overall and especially in the right colon.

Results of a second examination of the right side of the colon in screening and surveillance colonoscopy: a systematic review and meta-analysis

BACKGROUND

Screening colonoscopy is less effective in preventing proximal colon cancers than distal colon cancers. A repeat examination of the right side of the colon may increase the lesion detection. The study aimed to assess the results of a second examination of the right side of the colon with forward-view or retroflexion colonoscopy performed immediately after the initial examination.

MATERIALS AND METHODS

We carried out a meta-analysis of all primary studies that performed a second examination of the right side of the colon with forward-view or retroflexion colonoscopy performed immediately after the initial examination.

RESULTS

Six cohorts of five studies with 4155 participants were included in the final study. The adenoma detection rate (ADR) was 28.8% of the combined examinations compared with 24.1% of the single examination (P<0.001), for a pooled odds ratio of 1.34 [95% confidence interval (CI): 1.13-1.59]. For retroflexion assessment, ADR was achieved in 25.4% patients in the combined group, compared with 22.3% in the single examination group (P=0.002), for a pooled odds ratio of 1.19 (95% CI: 1.06-1.33). For forward-view assessment, ADR was achieved in 46.0% patients in the combined group, compared with 33.5% in the single examination group (P<0.001), for a pooled odds ratio of 1.76 (95% CI: 1.40-2.22).

CONCLUSION

For ADR of the right side of the colon, a repeat examination could lead to a modest improvement in the detection of lesions in the proximal colon, irrespective of forward-view or retroflexion assessment.

Strategies to Increase Adenoma Detection Rates

OPINION STATEMENT

The adenoma detection rate (ADR), i.e., the proportion of average risk patients with at least one adenoma detected during screening colonoscopy, is inversely associated with the development of interval colorectal cancer. Increasing the ADR is therefore an important proxy for increase in quality and efficacy of (screening) colonoscopy. Several potentially modifiable factors, such as, procedural and technological factors, and quality improvement programs, and their effect on the ADR will be reviewed. Procedural factors, such as, bowel preparation, withdrawal time, and position changes of the patient are associated with the ADR. While the relation of others, such as inspection during insertion, use of antispasmodic agents, and second inspection in the proximal colon, with the ADR is not completely clear. Many new colonoscopy technologies have been evaluated over recent years and are still under evaluation, but no unequivocal positive effect on the ADR has been observed in randomized trials that have mostly been performed by experienced endoscopists with high baseline ADRs. Several quality improvement programs have been evaluated and seem to have a positive effect on endoscopists' ADR. Increase in ADR is important for the protective benefit of colonoscopy. There are now extensive methods to measure, benchmark, and improve ADR but increased awareness of these is critical. We have provided an overview of potential factors that can be used to increase personal ADRs in every day practice.

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.