Clin Endosc.  2022 Jul;55(4):540-548. 10.5946/ce.2022.017.

Factors influencing endoscopic estimation of colon polyp size in a colon model

• Beukema KR
• Simmering JA
• Brusse-Keizer M
• John S
• Quispel R
• Mensink PB

• KMID: 2531948
• DOI: http://doi.org/10.5946/ce.2022.017

Abstract

Background/Aims
Colorectal polyps are removed to prevent progression to colorectal cancer. Polyp size is an important factor for risk stratification of malignant transformation. Endoscopic size estimation correlates poorly with pathological reports and several factors have been suggested to influence size estimation. We aimed to gain insight into the factors influencing endoscopic polyp size estimation.
Methods
Images of polyps in an artificial model were obtained at 1, 3, and 5 cm from the colonoscope’s tip. Participants were asked to estimate the diameter and volume of each polyp.
Results
Fifteen endoscopists from three large-volume centers participated in this study. With an intraclass correlation coefficient of 0.66 (95% confidence interval [CI], 0.62–0.71) for diameter and 0.56 (95% CI, 0.50–0.62) for volume. Polyp size estimated at 3 cm from the colonoscope’s tip yielded the best results. A lower distance between the tip and the polyp was associated with a larger estimated polyp size.
Conclusions
Correct endoscopic estimation of polyp size remains challenging. This finding can affect size estimation skills and future training programs for endoscopists.

Keyword

Colonic polyps; Colonoscopy; Endoscopy

Figure

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  Fig. 1. The colon model with a colonoscope inside it, showing the image of an artificial polyp on the monitor. The inner diameter of the colon model is 65 mm.

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  Fig. 2. The pedunculated and nonpedunculated polyps used in the study, with the photograph obtained at a distance of 3 cm between the tip of the colonoscope and the polyp. A pedunculated polyp sized (A) 5 mm, (B) 8 mm, (C) 10 mm, (D) 15 mm, and (E) 20 mm; a nonpedunculated polyp sized (F) 30 mm, (G) 35 mm, and (H) 38 mm.

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  Fig. 3. Comparison of the endoscopically estimated size and measured size for all pedunculated and nonpedunculated polyps. (A) Polyp size in diameter (mm). (B) Polyp size in volume (mm3).

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  Fig. 4. Comparison of the endoscopically estimated size and measured size for all pedunculated and nonpedunculated polyps. The endoscopic size estimations were further divided according to the distance between the tip of the colonoscope and the polyp (1, 3, or 5 cm). A clear pattern was observed, suggesting that a smaller distance between the tip of the colonoscope and the polyp (1 cm) resulted in a larger estimated polyp size. (A) Polyp size in diameter (mm). (B) Polyp size in volume (mm3).

Reference

1. Winawer SJ, Zauber AG, Ho MN, et al. Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. N Engl J Med. 1993; 329:1977–1981.

2. Zauber AG, Winawer SJ, O’Brien MJ, et al. Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths. N Engl J Med. 2012; 366:687–696.

3. de Jonge V, Sint Nicolaas J, van Leerdam ME, et al. Systematic literature review and pooled analyses of risk factors for finding adenomas at surveillance colonoscopy. Endoscopy. 2011; 43:560–572.

4. Lieberman DA, Rex DK, Winawer SJ, et al. Guidelines for colonoscopy surveillance after screening and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2012; 143:844–857.

5. van Heijningen EM, Lansdorp-Vogelaar I, Kuipers EJ, et al. Features of adenoma and colonoscopy associated with recurrent colorectal neoplasia based on a large community-based study. Gastroenterology. 2013; 144:1410–1418.

6. Hassan C, Quintero E, Dumonceau JM, et al. Post-polypectomy colonoscopy surveillance: European Society of Gastrointestinal Endoscopy (ESGE) Guideline. Endoscopy. 2013; 45:842–851.

7. Hassan C, Antonelli G, Dumonceau JM, et al. Post-polypectomy colonoscopy surveillance: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - update 2020. Endoscopy. 2020; 52:687–700.

8. Gupta S, Lieberman D, Anderson JC, et al. Recommendations for follow-up after colonoscopy and polypectomy: a consensus update by the US multi-society task force on colorectal cancer. Am J Gastroenterol. 2020; 115:415–434.

9. Wieszczy P, Kaminski MF, Franczyk R, et al. Colorectal cancer incidence and mortality after removal of adenomas during screening colonoscopies. Gastroenterology. 2020; 158:875–883.e5.

10. Ponugoti PL, Cummings OW, Rex DK. Risk of cancer in small and diminutive colorectal polyps. Dig Liver Dis. 2017; 49:34–37.

11. Yoshida N, Naito Y, Siah KT, et al. High incidence of metachronous advanced adenoma and cancer after endoscopic resection of colon polyps ≥20 mm in size. Dig Endosc. 2016; 28:194–202.

12. Rex DK. Real-time endoscopic pathology assessment of colorectal polyps. Curr Gastroenterol Rep. 2013; 15:354.

13. Kessler WR, Imperiale TF, Klein RW, et al. A quantitative assessment of the risks and cost savings of forgoing histologic examination of diminutive polyps. Endoscopy. 2011; 43:683–691.

14. Schoen RE, Gerber LD, Margulies C. The pathologic measurement of polyp size is preferable to the endoscopic estimate. Gastrointest Endosc. 1997; 46:492–496.

15. Moug SJ, Vernall N, Saldanha J, et al. Endoscopists’ estimation of size should not determine surveillance of colonic polyps. Colorectal Dis. 2010; 12:646–650.

16. Rubio CA, Höög CM, Broström O, et al. Assessing the size of polyp phantoms in tandem colonoscopies. Anticancer Res. 2009; 29:1539–1545.

17. Eichenseer PJ, Dhanekula R, Jakate S, et al. Endoscopic mis-sizing of polyps changes colorectal cancer surveillance recommendations. Dis Colon Rectum. 2013; 56:315–321.

18. Anderson BW, Smyrk TC, Anderson KS, et al. Endoscopic overestimation of colorectal polyp size. Gastrointest Endosc. 2016; 83:201–208.

19. Watanabe T, Kume K, Yoshikawa I, et al. Usefulness of a novel calibrated hood to determine indications for colon polypectomy: visual estimation of polyp size is not accurate. Int J Colorectal Dis. 2015; 30:933–938.

20. Gopalswamy N, Shenoy VN, Choudhry U, et al. Is in vivo measurement of size of polyps during colonoscopy accurate? Gastrointest Endosc. 1997; 46:497–502.

21. Margulies C, Krevsky B, Catalano MF. How accurate are endoscopic estimates of size? Gastrointest Endosc. 1994; 40:174–177.

22. Kaz AM, Anwar A, O’Neill DR, et al. Use of a novel polyp “ruler snare” improves estimation of colon polyp size. Gastrointest Endosc. 2016; 83:812–816.

23. Kim JH, Park SJ, Lee JH, et al. Is forceps more useful than visualization for measurement of colon polyp size? World J Gastroenterol. 2016; 22:3220–3226.

24. Plumb AA, Nickerson C, Wooldrage K, et al. Terminal digit preference biases polyp size measurements at endoscopy, computed tomographic colonography, and histopathology. Endoscopy. 2016; 48:899–908.

25. Sakata S, Klein K, Stevenson ARL, et al. Measurement bias of polyp size at colonoscopy. Dis Colon Rectum. 2017; 60:987–991.

26. Elwir S, Shaukat A, Shaw M, et al. Variability in, and factors associated with, sizing of polyps by endoscopists at a large community practice. Endosc Int Open. 2017; 5:E742–E745.

27. Koo TK, Li MY. A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016; 15:155–163.

28. Morales TG, Sampliner RE, Garewal HS, et al. The difference in colon polyp size before and after removal. Gastrointest Endosc. 1996; 43:25–28.

29. Komeda Y, Suzuki N, Sarah M, et al. Factors associated with failed polyp retrieval at screening colonoscopy. Gastrointest Endosc. 2013; 77:395–400.

30. Barancin C, Pickhardt PJ, Kim DH, et al. Prospective blinded comparison of polyp size on computed tomography colonography and endoscopic colonoscopy. Clin Gastroenterol Hepatol. 2011; 9:443–445.

31. Summers RM. Polyp size measurement at CT colonography: what do we know and what do we need to know? Radiology. 2010; 255:707–720.

32. Pickhardt PJ, Pooler BD, Kim DH, et al. The natural history of colorectal polyps: overview of predictive static and dynamic features. Gastroenterol Clin North Am. 2018; 47:515–536.

33. Johnson CD, Chen MH, Toledano AY, et al. Accuracy of CT colonography for detection of large adenomas and cancers. N Engl J Med. 2008; 359:1207–1217.

34. Leng Q, Jin HY. Measurement system that improves the accuracy of polyp size determined at colonoscopy. World J Gastroenterol. 2015; 21:2178–2182.

35. Hyun YS, Han DS, Bae JH, et al. Graduated injection needles and snares for polypectomy are useful for measuring colorectal polyp size. Dig Liver Dis. 2011; 43:391–394.

36. Jin HY, Leng Q. Use of disposable graduated biopsy forceps improves accuracy of polyp size measurements during endoscopy. World J Gastroenterol. 2015; 21:623–628.

37. Ferlitsch M, Moss A, Hassan C, et al. Colorectal polypectomy and endoscopic mucosal resection (EMR): European Society of Gastrointestinal Endoscopy (ESGE) clinical guideline. Endoscopy. 2017; 49:270–297.