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ESGIE DDW: Colonoscopy

Introduction.

Polyps prevalence.

Withdrawal Time

Procedure timing.

Screening & surveillance colonoscopy.

Improved endoscopic techniques.

Introduction

CRC is the second leading cause of Ca−related deaths in the West. Detection of CRC at an early stage improves the prognosis

considerably. Adenomas are the benign precursors of CRC& their removal

results in a lower than expected incidence of CRC. Adenomas( occur in 25% males/ 15% females > 50 ys.

Polyp prevalence The effectiveness of colonoscopy in reducing the incidence of CRC

depends on adequate visualization / inspection of the colonic mucosa.

Adequate colonoscopy reduces the risk of interval neoplasia & further improves the effectiveness of CRC screening /surveillance programs.

Withdrawal time

Recently WT added to ASGE quality guidelines for colonoscopy. A WT of > 6 mins is recommended for a -ve colonoscopy. Measurement/ documentation of WT resulted in a significant

increase polyps detection rates. Continuous recording / feedback are required to maintain

adequate WTs.

Procedural timing Significantly more polyps were detected during the first than

during the last colonoscopy of the day.

Screening colonoscopy Screening for CRC recommended by ASGE for average−risk

individuals > 50. Colonoscopy seems to be the most effective screening strategy to

offset the rising costs of new, expensive therapies for CRC. The reduction in CRC incidence was 53% with colonoscopy

screening, 47% with sigmoidoscopy, 46% with FOBT compared to no screening.

Colonoscopy may be the most likely screening strategy.

Screening colonoscopy Colonoscopy screening seems to be feasible /safe& results in a

high detection rate of advanced neoplasia& early carcinoma, suggesting a possible reduction in mortality.

Colonoscopy capacity remains an important issue for nationwide CRC screening.

The uptake of screening colonoscopy is low even in western countries with established screening programs.

Surveillance intervals The risk for metachronous advanced neoplasia after 5 years was very low among subjects with

a normal baseline colonoscopy. Earlier surveillance colonoscopy should be offered to subjects with three adenomas or more or

with advanced neoplasia at baseline. Advanced neoplasia occurs more in older age, males, multiple adenomas ( five or more) & size

at baseline colonoscopy. Importance of risk stratification in patients after polypectomy: The number of adenomas. Advanced histological features Size. Proximal adenoma.

Interval cancer The need for high quality baseline colonoscopy to reduce the

proportion of missed lesions & complete resection of neoplasia to reduce incidence of interval cancers.

Improved endoscopic techniques:NBI Using standard white−light colonoscopy, a substantial polyp miss rate of 5±24%. Polyp detection may improve with novel colonoscopy techniques &optimized visualization

methods as NBI. In one study miss rate for polyps / adenomas is lower with NBI than with standard colonoscopy. In a large multicenter RT, no difference in the detection rate of adenomas (32% in the NBI vs.

34% in the standard colonoscopy). The detection rates of right−side lesions, advanced adenomas, flat adenomas did not differ

between NBI& standard colonoscopy. Exact role of NBI for the detection of adenoma is not yet proved NBI shows promise for differentiating between adenomatous &nonadenomatous tissue for

selective polypectomy.

Improved endoscopic techniques: Fluorescence colonoscopy increase visibility of adenomas,using an

enema with the photosensitizer.

Improved endoscopic techniques:

Reduce the blind spots bythe use of a wide angle colonoscope , or third Eye Retroscope (TER), passed down the instrument channel, provides a retrograde view by turning the tip of the device to look behind folds/ flexures , to avoid missing polyps due to blind spots behind the folds of the colon.

Value of diminutive & small colonic polyps ACR recommends that diminutive polyps (< 5 mm) should not be

reported on CTC. Patients with one or two small polyps 6-9mm in size should

undergo CTC surveillance after 3 years in lieu of polypectomy at the time of detection.

Standard colonoscopy detected significantly more adenomas smaller than 5-9mm in size.

Biopsy/histopathology of small polyps is not cost effective.

Summary: Quality indicators as withdrawal time proven to be effective, although continuous

feedback seems to be necessary. Procedural timing of colonoscopy was introduced as a new factor influencing

polyp yield. For prevention of CRC, a colonoscopy screening program seems to be the most

cost-effective strategy, but colonoscopy capacity is a major issue. DDW 2008 did not solve the ongoing discussion on the optimal screening strategy. Surveillance should be targeted at patients at high risk of colorectal neoplasia,

including patients with advanced or multiple adenomas.

Summary: In the near future, new endoscopy techniques will be introduced

on a broad basis, increasing the detection of polyps, especially diminutive& small polyps& may improve the endoscopic assessment of polyps &thereby decrease the need for& cost of histological examinations.

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Prepared by: Dr.Mohammad Shaikhani