The water method combined with chromoendoscopy enhances adenoma detection

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.

Chromocolonoscopy

Chromocolonoscopy is the process of endoscopically examining the colon mucosa after it has been stained with dye. The goal is to allow the endoscopist to identify subtle features in the mucosa, such as morphologically flat polyps or crypt patterns. Studies examining the efficacy of chromocolonoscopy to identify adenomas missed by conventional colonoscopy have shown that although chromocolonoscopy increases polyp yield, most additional lesions are small in size. Staining can also help in differentiating neoplastic from non-neoplastic polyps. Perhaps the most useful aspect of chromocolonoscopy is increasing the yield for dysplasia in patients undergoing colonoscopy for inflammatory bowel disease surveillance.

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.

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.

Indigocarmine added to the water exchange method enhances adenoma detection - a RCT

PURPOSE

Chromoendoscopy with dye spray and the water method both increase adenoma detection.

HYPOTHESIS

Adding indigocarmine to the water method will enhance further the effectiveness of the latter in adenoma detection.

METHODS

Screening colonoscopy was performed with the water method (control) or with 0.008% indigocarmine added (study) by two endoscopists. Randomization was based on computer-generated codes contained in blocks of pre-arranged opaque sealed envelopes. High resolution colonoscopes were used. Upon insertion into the rectum, air was suctioned. With the air pump turned off, water was infused using a blunt needle adaptor connected to the scope channel and a foot pump to facilitate scope insertion until the cecum was reached. Residual stool causing cloudiness was suctioned followed by infusion of clear or colored water (water exchange) to facilitate scope passage with minimal distention of the colonic lumen. Upon seeing the appendix opening under water, water was suctioned and air was insufflated to facilitate inspection on scope withdrawal.

STATISTICS

Sample size calculation revealed 168 patients (84/group) needed to be randomized. Study was IRB-approved and registered (NCT01383265).

RESULTS

There were no significant differences in mean age, gender distribution, BMI, and family history of colon cancer. Cecal intubation success rate was 100% in both groups. The overall adenoma detection rate was 44% (water only) versus 62% (water with indigocarmine), respectively (p=0.03). One cancer was detected in each group.

CONCLUSION

In a RCT, indigocarmine at 0.008% concentration, added to the water method, significantly enhanced further the effectiveness of the latter in detecting adenomas.

Removal of infused water predominantly during insertion (water exchange) is consistently associated with a greater reduction of pain score - review of randomized controlled trials (RCTs) of water method colonoscopy

INTRODUCTION: Variation in the outcomes in RcTs comparing water-related methods and air insufflation during the insertion phase of colonoscopy raises challenging questions regarding the approach. This report reviews the impact of water exchange on the variation in attenuation of pain during colonoscopy by water-related methods. METHODS: Medline (2008 to 2011) searches, abstracts of the 2011 Digestive Disease Week (DDW) and personal communications were considered to identify RcTs that compared water-related methods and air insufflation to aid insertion of the colonoscope. Results: Since 2008 nine published and one submitted RcTs and five abstracts of RcTs presented at the 2011 DDW have been identified. Thirteen RcTs (nine published, one submitted and one abstract, n=1850) described reduction of pain score during or after colonoscopy (eleven reported statistical significance); the remaining reports described lower doses of medication used, or lower proportion of patients experiencing severe pain in colonoscopy performed with water-related methods compared with air insufflation (Tables 1 and 2). The water-related methods notably differ in the timing of removal of the infused water - predominantly during insertion (water exchange) versus predominantly during withdrawal (water immersion). Use of water exchange was consistently associated with a greater attenuation of pain score in patients who did not receive full sedation (Table 3). CONCLUSION: The comparative data reveal that a greater attenuation of pain was associated with water exchange than water immersion during insertion. The intriguing results should be subjected to further evaluation by additional RcTs to elucidate the mechanism of the pain-alleviating impact of the water method.