ORIGINAL ARTICLE: Clinical Endoscopy Factors associated with failed polyp retrieval at screening colonoscopy Yoriaki Komeda, MD, Noriko Suzuki, MD, PhD, Marshall Sarah, BA, Siwan Thomas-Gibson, MD, FRCP,
Margaret Vance, MSc, Chris Fraser, MD, MRCP, Kinesh Patel, MD, MRCP, Brian P. Saunders, MD, FRCP

London, United Kingdom Background: Colonoscopy reduces colorectal cancer mortality and morbidity principally by the detection and
removal of colon polyps. It is important to retrieve resected polyps to be able to ascertain their histologic
Objective: The aim of the study was to evaluate the cause of polyp retrieval failure.
Design: Bowel cancer screening colonoscopy data were collected prospectively.
Setting: The Bowel Cancer Screening Program in the National Health Service.
Patients: Screening participants were referred to our screening center after a positive fecal occult blood test
Intervention: A total of 4383 polyps were endoscopically removed from 1495 patients from October 2006 to
February 2011.
Main Outcome Measurements: The number, size, shape, and location of polyps; polyp removal method;
quality of bowel preparation; total examination time; and insertion and withdrawal times in collected data were
examined retrospectively.
Results: The polyp retrieval rate was 93.9%, and the failure rate was 6.1%, thus 267 polyps were not retrieved.
In univariate analysis, factors affecting polyp retrieval failure were small polyp size, sessile polyps, and cold snare
polypectomy (P ⬍ .001). Polyp retrieval was less successful in the proximal colon (P ⫽ .002). In multivariate
analysis, polyp size and method of removal were independent risk factors for polyp retrieval failure (P ⬍ .001).
Limitations: Retrospective study.
Conclusion: Small polyp size and cold snare removal were found to be significantly associated with polyp
retrieval failure. It was difficult to retrieve small, sessile, and proximal colon polyps. Optical diagnosis could be
an efficacious option as a surrogate for histologic diagnosis for these lesions in the near future. ( Gastrointest
Endosc 2013;77:395-400.)
Detection and removal of colon polyps is the most recommendations, the national target for retrieval of all significant benefit colonoscopy provides toward the re- resected polyps is over 90%. However, even qualified duction of colorectal cancer mortality and It is colonoscopists do not always achieve There are no important to retrieve resected polyps to ascertain their available data on the causes of polyp retrieval failure in histologic characteristics because not all polyps are neo- large-scale screening data. The aim of our study was to plasms, and this influences further colonoscopic follow- evaluate the factors contributing to polyp retrieval failure up. According to Bowel Cancer Screening Program (BCSP) in the National Health Service BCSP in England.
Abbreviations: BCSC, bowel cancer screening colonoscopy; BCSP, Bowel Current affiliations: The Wolfson Unit for Endoscopy, St. Mark's Hospital and Cancer Screening Program. Academic Institute, Imperial College London, London, United Kingdom.
DISCLOSURE: All authors disclosed no financial relationships relevant to Presented at United European Gastroenterology Week, October 22-26, this publication. 2011, Stockholm, Sweden.
Copyright 2013 by the American Society for Gastrointestinal Endoscopy Reprint requests: Yoriaki Komeda, MD, The Wolfson Unit for Endoscopy, St.
Mark's Hospital, Watford Road, Middlesex, London, United Kingdom HA1 Received May 29, 2012. Accepted October 5, 2012.
Volume 77, No. 3 : 2013 Factors associated with failed polyp retrieval A total of 2534 adults aged 60 to 69 years attended the Bowel Cancer Screening Colonoscopy (BCSC) program Small polyp size and the cold snare removal method were after positive fecal occult blood test results between Oc- independent factors associated with polyp retrieval tober 2006 and February 2011. The screening participants Macroscopic complete excision should be confirmed at were prepared with 10 senna tablets (Senokot; Forum the time of polypectomy.
Health Products Ltd, United Kingdom) and two sachets ofcitric acid and magnesium oxide (Citramag; SanochemiaDiagnostics UK Ltd, United Kingdom)/sodium picosulfate(Picolax; Ferring Pharmaceuticals Ltd, United Kingdom) or Cold snare polypectomy. Cold snare (Exacto 9 mm;
polyethylene glycol (Klean-Prep; Norgine Pharmaceuticals US Endoscopy or SD-210U-10; Olympus, Japan) was ap- Ltd, United Kingdom), depending on renal function.
plied to remove polyps between 2 and 6 mm in size. A Our data were obtained from a purpose-built, high- polyp is ensnared and then transected, based on direct quality, administrative database that was specifically de- visual observation. The polyp almost invariably remains veloped by the United Kingdom's BCSP. The procedure- on or near the site, allowing suction through the endo- related data were directly entered into the database by scope into a trap.
specialist screening practitioners (nurses) who attend to Hot snare polypectomy. Sessile and pedunculated
the BCSC during the procedures. A total of 4383 polyps polyps ⬎5 mm were treated with a snare (SD-210U-10, 15, were endoscopically resected. BCSC data were collected 20, 25; Olympus, Japan) with electrocautery. When using prospectively. The number, size, shape, polyp location, the ICC200, we used the diathermy setting of Endocut removal method, quality of bowel preparation, total ex- (effect 3) at 120 W. In using the VIO200D, forced coagu- amination time, insertion time, and withdrawal time in lation 35 W and 30 W was applied, respectively, in the left collected BCSC data were retrospectively examined. Given and right hemicolon. After resection of polyps ⬍6 mm, we the retrospective nature of this study, and only anonymousdata used in this study, it was exempted from approval by applied suction to draw the polyp through the endoscope the local ethics committee.
channel. The specimen was then collected into an at-tached trap device (1-Trap; PIP Medical, France). Larger polyps (⬎10 mm) were normally retrieved by grasping the Bowel preparation was categorized as follows: excel- polyp with forceps, a snare, or a retrieval net (Roth Net; US lent (no or minimal solid stool and only clear fluid requir- ing suction), adequate (collections of semi-solid debristhat are cleared with washing/suction), and inadequate (solid or semi-solid debris that cannot be cleared EMR was indicated for sessile or flat polyps ⬎2 cm. EMR involves injecting a submucosal solution (1:200,000 saline-epinephrine-methylene blue) to create a bleb and then hot Polyp removal and retrieval methods
snaring the lesion either en bloc or in piecemeal Cold forceps polypectomy (cold biopsy). Cold for-
The diathermy setting in EMR was the same as that used in ceps (FD-230; Olympus, Japan) are widely used as the hot snare polypectomy. Large polyps (⬎10 mm) were method of choice for smaller polyps, particularly those retrieved by holding the polyp with a snare or a net. The net device was always used when we retrieved multiple Hot forceps polypectomy (hot biopsy). Hot forceps
fragments of the specimen after piecemeal EMR and for polypectomy (Radial Jaw 3 Hot Biopsy Forceps; Boston retrieval of large en bloc specimens after endoscopic sub- Scientific, Natick, Mass) is similar to the cold forceps tech- mucosal dissection.
nique except it uses electrocautery to destroy residualpolyp tissue intentionally left For hot forcepselectrocautery, forced coagulation at 30 W by using the VIO200D (ERBE, Germany) or forced coagulation at 25 W Multiple-level logistic regression was used for analysis.
by using the ICC200 (ERBE, Japan) is applied after captur- Initially, the effect of each factor on the polyp retrieval was ing the surface of the polyp. The polyp is pulled into the examined separately in a series of univariate analyses. The colon lumen to create a tent-like effect, and electrocautery second stage of the analysis jointly examined the effect of is applied to destroy the polyp base while preserving the the various factors together in a multivariate analysis. This polyp tissue inside the forceps as a histologic is because there are several polyps for some patients, and This used to be a widely used technique to remove polyps thus values are not all independent of each other. A back- between 3 and 6 mm in size but is now rarely used ward selection procedure was used to retain only the because of complications with bleeding and statistically significant factors.
Volume 77, No. 3 : 2013 Factors associated with failed polyp retrieval high complication Cold snare polypectomy is ap-plied for small polyps, resulting in loss of the resected A total of 4383 polyps were endoscopically removed specimens on some occasions. Small specimens resected from 1495 patients from October 2006 to February 2011 with a cold snare may be lost from sight when they shift (polyp retrieval rate: 93.9%; failure rate: 6.1%), meaning hidden between folds, mix with liquid stool or blood after that 267 polyps were not retrieved. The result from uni- resection, or even slip through the polyp trap. In contrast variate analysis is shown in Polyp retrieval failure to our experience, previous reports have suggested that was significantly higher with smaller polyps (P ⬍ .001).
cold snare polypectomy can produce high rates of suc- Retrieval of sessile polyps was lower than for peduncu- cessful colon polyp This may be related to lated and flat polyps (P ⬍ .001). Polyp retrieval was least the method applied in the study, which involves ensnaring successful in the proximal colon (P ⫽ .002) and was the polyp, drawing it into a colonoscope working channel, highest in the sigmoid colon. The least successful of the applying suction, and transecting the polyp within the polypectomy techniques for retrieving polyps was cold colonoscope. When the snare is withdrawn, suction brings snare resection (P ⬍ .001). The result from a multivariate the transected polyp back into the trap. Our method is analysis is shown in The results show that polyp different from that of previous reports, which covered size and removal method were independent factors for prospective studies. A high success rate also may be polyp retrieval failure (P ⬍ .001).
achieved through careful research and by placing the In terms of polyp morphology and size distribution, in focus entirely on polyp retrieval.
sessile polyps, 2911 of 3599 (80.9%), 555 of 3599 (15.4%), Retrieval of sessile polyps was less successful than that and 133 of 3599 (3.7%) were 0 to 5 mm, 6 to 10 mm, and of pedunculated and flat polyps. Most of sessile polyps 11⫹ mm in diameter, respectively. In pedunculated pol- were diminutive, and their size was generally less than that yps, 65 of 600 (10.8%), 74 of 184 (40.2%), and 26 of 184 of pedunculated and flat polyps in this study. Flat polyps (14.1%), were 0 to 5 mm, 6 to 10 mm, and 11⫹ mm in usually are resected by using EMR, in which the polyp diameter, respectively. In the flat type, 84 of 184 (45.7%), tissue may be highlighted with a colored injection solu- 74 of 184 (40.2%), and 26 of 184 (14.1%) polyps were 0 to tion. The bigger sample that results from injecting into the 5 mm, 6 to 10 mm, and 11⫹ mm in diameter, respectively.
submucosal layer of normal tissue leads to easier identifi-cation of resected specimens.
The polyp-location results indicated that polyp retrieval on the right side of the colon is less successful than that on In a 3-year analysis of the BCSP in the United Kingdom, the left side. This may be because the proximal colon is 49,054 polyps were identified, of which 1.9% were malig- normally capacious and has prominent folds, and it has nant. Stratified by size (0-9 mm, 10-19 mm, 20-29 mm), been reported that the forward-viewing approach had not 0.3%, 4.4%, and 8%, respectively, were Even revealed the area on the proximal sides of haustral folds small polyps that have a very low risk of harboring cancer on It is therefore more difficult to retrieve pol- are routinely sent for histology, because the number of yps with a forward-viewing approach, once a resected adenomas is a good determinant of the long-term risk of specimen shifts to the blind areas.
advanced neoplasia and it allows an informed decision on Human factors such as fatigue or lapses in concen- future surveillance This evidence underpins tration conceivably could play a role in failure to re- and emphasizes the importance of polyp retrieval. The trieve polyps. However, there were no significant cor- Quality Assurance Guidelines for Colonoscopy in the Na- relations found between retrieval rate and the number tional Health Service cancer screening program set a target of polyps per patient, quality of bowel preparation, or of 90% of all resected polyps to be retrieved. However, length of procedure.
during the first 3 years of the BCSP in our institute, even Furthermore, we hypothesized that there may be an in- accredited endoscopists sometimes did not meet this na- verse relationship between the adenoma detection rate and tional According to previous reports of polyp re- the polyp retrieval rate. As more small polyps are found and trieval, the percentage of polyps lost after polypectomy resected, it will contribute to a lower polyp retrieval rate.
ranges from 2.1% to However, this was not confirmed statistically, which was In univariate analysis, this study demonstrates that mainly due to the small numbers of data points in this study polyp retrieval failure increased significantly with smaller (only 5 endoscopists).
polyps, especially for diminutive polyps (⬍5 mm) and In terms of potential limitations, the possibility of under- with cold snare polypectomy. The poor success rate does estimation of the adenoma detection rate as a consequence not arise from technical inexperience: 5 accredited colono- of endoscopist under-reporting of unretrieved polyps cannot scopists (average 96% cecal intubation rate) in the unit be excluded. However, if present, such under-reporting is performed all colonoscopies. Current local policy is to use likely to have occurred only rarely, given the high standard of cold forceps for polyps up to 3 mm and cold snares for accreditation requirements and operating guidelines of the those up to 6 mm. Hot forceps are rarely used because of BCSP at present.
Volume 77, No. 3 : 2013 Factors associated with failed polyp retrieval TABLE 1. The effect of each factor on polyp retrieval in univariate analyses
Polyp retrieval ratio
OR (95% CI)
Polyp per person, no. (%) Polyp size, no. (%), mm Polyp location, no. (%) Polyp shape, no. (%) Retrieval method, no. (%) Quality of bowel preparation, no. (%) Examination time, no. (%), min Volume 77, No. 3 : 2013 Factors associated with failed polyp retrieval TABLE 1. (continued)
Polyp retrieval ratio
OR (95% CI)
Insertion time, no. (%), min Withdrawal time, no. (%), min OR, Odds ratio; CI, confidence interval.
A total of 4383 polyps were endoscopically removed from 1495 patients from October 2006 to February 2011 (polyp retrieval rate: 93.9%; failure rate: 6.1%),meaning that 267 polyps were not retrieved. An OR of ⬎1 would imply a successful retrieval.
In conclusion, small polyp size and the cold snare removal TABLE 2. The effect of the various factors together in a
method were found to be independent factors associated with polyp retrieval failure. For small polyps, optical diagno-sis could be an efficacious option as a surrogate for histologic OR (95% CI)
diagnosis. This method, which mainly uses high-definition white light and non-magnified narrow-band imaging is ac-curate enough for the characterization of polyps of without histopathologic examination when applied by expe- rienced Once the efficacy of this surrogate method is confirmed among non-experienced endoscopists,the polyp retrieval rate could be applied only for larger We would like to thank Paul Bassett for his help with the statistical analyses of this article.
OR, Odds ratio; CI, confidence interval.
A total of 4383 polyps were endoscopically removed from 1495patients from October 2006 to February 2011 (polyp retrieval rate:93.9%; failure rate: 6.1%), meaning that 267 polyps were not retrieved. An OR of ⬎1 would imply a successful retrieval.
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Zeit für Begegnungen Sechs Porträts aus vier Ländern Vertrauen in Mensch Vom Zuckerrohrfeld und Natur Reichlich Zucchini in die Tüte „Größer sollen die Wurzeln nicht sein, und die letzten Bohnen denn sie werden als Ganzes serviert", „Wir haben ganz unten angefangen, ohne


Vestnik zoologii, 38(5): 57–66, 2004© I. A. Akimov, S. V. Benedyk, L. M. Zaloznaya, 2004 COMPLEX ANALYSIS OF MORPHOLOGICALCHARACTERS OF GAMASID MITEVARROA DESTRUCTOR (PARASITIFORMES, VARROIDAE) I. A. Akimov, S. V. Benedyk, L. M. Zaloznaya Schmalhausen Institute of Zoology NAS Ukraine,vul. B. Khmelnits'kogo, 15, Kyiv, 01601 Ukraine Accepted 23 October 2003 Complex Analysis of Morphological Characters of Gamasid Mite Varroa destructor (Parasitiformes, Var-roidae). Akimov I. A., Benedyk S. V., Zaloznaya L. M. — The study of seasonal variability of miteV. destructor was carried out. The summer generation of mites appears to be characterized by the largestmorphological variability whereas the winter one has stable characters. We failed to evolve the complexof morphological characters that would allow us to identify, with high level of reliability, certainphenotype of the mite. Significant stability of morphological characters of V. destructor in the course oftime was determined. The mean values of the length and width of the body allow to consider theUkrainian population of Varroa mite, which parasitize the honey bee Apis mellifera Linnaeus, as theKorean haplotype of Varroa destructor Anderson et Trueman, 2000.