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Multicenter Study
. 2014 Aug 21;20(31):10927-37.
doi: 10.3748/wjg.v20.i31.10927.

Risk factors associated with missed colorectal flat adenoma: a multicenter retrospective tandem colonoscopy study

Li Xiang  1 , Qiang Zhan  1 , Xin-Hua Zhao  1 , Ya-Dong Wang  1 , Sheng-Li An  1 , Yang-Zhi Xu  1 , Ai-Min Li  1 , Wei Gong  1 , Yang Bai  1 , Fa-Chao Zhi  1 , Si-De Liu  1
Affiliations
Multicenter Study

Risk factors associated with missed colorectal flat adenoma: a multicenter retrospective tandem colonoscopy study

Li Xiang et al. World J Gastroenterol. .

Abstract

Aim: To determine the miss rate for colorectal flat adenomas during colonoscopy and the risk factors.

Methods: Flat adenomas are frequently missed during colonoscopy. However, the risk factors that influence their miss rates are unclear. This was a multicenter, retrospective study in which patients diagnosed with colorectal adenomas at a diagnostic colonoscopy and followed within 3 mo by a second therapeutic colonoscopy were pooled out from the established database. The "per-patient" and "per-adenoma" adenoma miss rates (AMR) for overall adenomas and flat adenomas, and patient-, adenoma-, and procedure-related risk factors potentially associated with the "per-adenoma" AMR for flat adenomas were determined.

Results: Chromoscopy and high-definition colonoscopy were not taken under consideration in the study. Among 2093 patients with colorectal adenomas, 691 (33.0%) were diagnosed with flat adenomas, 514 with concomitant protruding adenomas and 177 without. The "per-patient" AMR for flat adenomas was 43.3% (299/691); the rates were 54.3% and 11.3%, respectively, for those with protruding adenomas and those without (OR = 9.320, 95%CI: 5.672-15.314, χ (2) = 99.084, P < 0.001). The "per-adenoma" AMR for flat adenomas was 44.3% (406/916). In multivariate analysis, older age, presence of concomitant protruding adenomas, poor bowel preparation, smaller adenoma size, location at the right colon, insufficient experience of the colonoscopist, and withdrawal time < 6 min were associated with an increased "per-adenoma" AMR for flat adenomas. The AMR for flat adenomas was moderately correlated with that for overall adenomas (r = 0.516, P < 0.0001). The AMR for flat adenomas during colonoscopy was high.

Conclusion: Patient's age, concomitant protruding adenomas, bowel preparation, size and location of adenomas, proficiency of the colonoscopist, and withdrawal time are factors affecting the "per-adenoma" AMR for flat adenomas.

Keywords: Colonoscopy; Colorectal cancer; Flat adenoma; Miss rate; Risk factor.

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Figures

Figure 1
Figure 1
Flowchart of patient screening in this study. A total of 2093 patients with adenomas satisfied the inclusion and exclusion criteria, including 691 with flat adenomas (514 with and 177 without protruding adenomas), and 1402 with only protruding adenomas.
See this image and copyright information in PMC

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