ORIGINAL ARTICLE

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Akira Horiuchi, MD,1 Kenji Hosoi, MD,2 Masashi Kajiyama, MD,1 Naoki Tanaka, MD,1

Kenji Sano, MD,3 David Y. Graham, MD4

Komagane, Tokyo, Matsumoto, Japan; Houston, Texas, USA

Background: Both cold-only snare and hot polypectomy snare are used for the removal of small colorectal polyps.

Objective: To compare the outcome of cold snare polypectomy of small colorectal polyps with a snareexclusively designed as a cold snare versus cold snare polypectomy by using a traditional polypectomy snare.

Design: Prospective, randomized, controlled study.

Setting: Municipal hospital in Japan.

Interventions: Patients with colorectal polyps 10 mm or smaller in diameter were randomized to dedicated coldsnare (dedicated cold snare group) or traditional cold snare (traditional cold snare group). The primary outcomemeasure was complete resection rates by cold snaring based on pathological examination. Secondary outcomesincluded bleeding within 2 weeks after polypectomy and identification of submucosal arteries and injured arteriesin the resected specimens.

Results: Seventy-six patients having 210 eligible polyps were randomized: dedicated cold snare group, N Z 37(98 polyps) and traditional cold snare group, N Z 39 (112 polyps). Patient demographic characteristics includingthe number, size, and shape of the polyps removed were similar in the 2 groups. The complete resection rate wassignificantly greater with the dedicated cold than with the traditional cold snare (91% [89/98] vs 79% [88/112],P Z .015), with a marked difference with 8- to 10-mm polyps, both flat and pedunculated. Immediate bleedingand hematochezia rates were similar (19% vs 21%, P Z .86; 5.4% vs 7.7%, P Z .69). No delayed bleedingoccurred. Histology demonstrated a similar prevalence of arteries and injured arteries in the submucosa (33%[32/96] vs 30% [31/104], P Z .59; 3.1% [3/96] vs 6.7% [7/104], P Z .24).

Limitations: Small sample size, single-center study.

Conclusion: Polypectomy by using a dedicated cold snare resulted in complete polyp removal more often thandid cold snaring with a traditional snare, especially polyps 8 to 10 mm in diameter, whether flat or pedunculated.(Clinical trial registration number: NCT02036047.) (Gastrointest Endosc 2015;-:1-7.)

n: ASA, American Society of Anesthesiologists.

E: All authors disclosed no financial relationships relevantle.

2015 by the American Society for Gastrointestinal Endoscopy36.00i.org/10.1016/j.gie.2015.02.012

tober 22, 2014. Accepted February 7, 2015.

ations: Digestive Disease Center, Showa Inan General Hospital,Japan (1), Department of Pediatrics, Juntendo UniversityMedicine, Tokyo, Japan (2), Department of LaboratoryShinshu University Hospital, Matsumoto, Japan (3),of Internal Medicine, Michael E. DeBakey VA Medical Center,ge of Medicine, Houston, Texas, USA (4).

ests: Akira Horiuchi, MD, Digestive Disease Center, Showa Inanpital, 3230 Akaho, Komagane 399-4117, Japan.

urnal.org

The success of colonoscopy for the prevention of colo-rectal cancer is based on the ability to detect and removepre-cancerous lesions from the colon and rectum.1,2 Recently,the Complete Adenoma Resection (CARE) study demon-strated incomplete resection of 17.3% in 10- to 20-mm and6.8% in 5- to 9-mm diameter polyps by using hot polypec-tomy in the blended coagulation mode.3 That studyopened the way for continued discussions regardingpolypectomy technique.4 For example, a previous studythat used histology to assess colonoscopic resection ofdiminutive polyps (%5 mm) compared cold snarepolypectomy and cold forceps and reported that the coldsnare method was significantly better (ie, 93.2% vs 75.9%,P Z .009). However, in that study, failure of tissue retrievalafter cold snaring was noted in 6.8% of polyps,5 which was

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Cold-only vs traditional cold polypectomy snare Horiuchi et al

higher than the U.S. Multi-Society Task Force recommenda-tion of more than 95% success polyp retrieval.6

One issue is how to accurately measure when a polyp iscompletely resected because the endoscopist’s visualimpression is likely to be inaccurate.4 We previouslyassessed complete resection rates after cold snarepolypectomy by using pathological examination and foundcomplete resection in 96% (95% confidence interval, 98%-90%) of small polyps (1-8 mm) and 94% (95% confidenceinterval, 97%-86%) of small polyps (1-10 mm) despite thefact that the snares used in the 2 studies were different.7,8

In our experience, the success of resection and polypretrieval with cold snare polypectomy depends on both thesnare used and operator-related factors. It remains unclearwhether ease of resection and retrieval of specimens for path-ological examination after cold snare polypectomy is morerelated to the characteristics of the cold snare used or tothe type of polyp removed, pointing out the need for studiescomparing different snares that also take into account polypcharacteristics (eg, size, shape, histology).

Other issues with cold snare polypectomy relate to postpo-lypectomy bleeding. Our previous comparison of cold andhot polypectomy in anticoagulated patients found no de-layed bleeding after cold snare polypectomy (78 polyps).8

However, endoscopic hemostasis for immediate and delayedbleeding was required after hot polypectomy.8 We examinedwhether the bleeding was related to injured submucosalarteries and showed that the presence of histologicallydemonstrable injured arteries in the submucosal layer aftercold snare polypectomy was significantly less than with hotpolypectomy (22% vs 39%, P Z .023). We hypothesized thatthe difference in arterial damage was responsible for thedifference in delayed bleeding between the 2 techniques;however, we have experienced delayed bleeding after coldsnare polypectomy for small colorectal polyps, even in theabsence of antithrombotic agents such that the relationshipbetween the snare used and the presence of injuredsubmucosal arteries is still an unanswered question.

The aim of this study was to compare cold snaring ofsmall colorectal polyps by using either a snare specificallydesigned as a cold snare or cold snaring by using a tradi-tional cold polypectomy snare. The study was based onthe hypothesis that cold polypectomy–specifically de-signed snares with thinner wires are likely to resect colo-rectal polyps more cleanly than is possible withtraditional cold polypectomy snares used without electro-cautery and that this difference would result in anincreased complete resection rate and less damage to thesubmucosal layer (ie, a lower delayed bleeding rate).

METHODS

Study designThis was a prospective, randomized, single-center com-

parison of 2 methods of cold polypectomies in patients

2 GASTROINTESTINAL ENDOSCOPY Volume -, No. - : 2015

with small colorectal polyps by using a snare designedonly for cold polypectomy and 1 designed for cold orhot polypectomy. The study was done at the Showa InanGeneral Hospital in Japan. The Institutional Review Boardof Showa Inan General Hospital approved the study proto-col, and all subjects gave written informed consent whenthe procedure was scheduled. The study was reported ac-cording to the CONSORT guidelines and was registered atwww.clinicaltrials.gov (NCT02036047).

Study populationSubjects referred and scheduled for screening, surveil-

lance, or diagnostic colonoscopy were prospectivelyenrolled between January 2014 and June 2014; duringthis time, 1393 patients underwent colonoscopy. Inclusioncriteria were patients with colorectal polyps up to 10 mmin diameter. Exclusion criteria included age younger than20 years, pregnant, history of colorectal surgical resection,American Society of Anesthesiologists (ASA) class III andIV, overweight (body weight O100 kg), or allergic to pro-pofol or its components (soybeans or eggs). Those inwhom less than 90% of mucosa was seen due to a mixtureof semisolid and solid colonic contents were also excludedbecause of poor bowel preparation. Antithrombotic agentsincluding antiplatelet agents and anticoagulant agents werenot discontinued in patients who were selected for thisstudy according to the basic policy of our endoscopyunit. The patient parameters that were recorded includeddemographic characteristics, indication for colonoscopy,antithrombotic use, and history of abdominal surgery.Enrolled patients were randomly assigned to 1 of the 2polypectomy snares (dedicated cold snare group and tradi-tional cold snare group) by using a computer-generatedrandom sequence if they qualified by having a polyp ofthe appropriate size. If a patient had 1 or more polyps,all eligible polyps were removed by using the initially as-signed polypectomy snare.

Endoscopists and equipmentAll procedures were performed by 1 of 2 experienced

endoscopists (having performed O10,000 colonoscopieseach). A pediatric variable-stiffness colonoscope (OlympusPCF-Q260AZI; Olympus Medical Systems, Tokyo, Japan)was used in all subjects. The instrument has a distal tipdiameter of 11.7 mm and an insertion tube diameter of11.8 mm (working length, 133 cm; accessory channel diam-eter, 3.2 mm). As is our standard practice, a transparentshort cap (Olympus D-201-12704) with an outer diameterof 13.4 mm and an inner diameter of 12 mm was attachedto the tip of the colonoscope in an attempt to improve theadenoma detection rate.9 The edge of the cap protrudesapproximately 4 mm beyond the tip of the colonoscope.Retroflexion in the rectum was routinely performed.

The standard bowel preparation was performed by us-ing 2 L of polyethylene glycol electrolyte lavage solutionplus ascorbic acid (Ajinomoto Pharmaceutical Co, Tokyo,

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Horiuchi et al Cold-only vs traditional cold polypectomy snare

Japan) in all subjects. All of the procedures wereconducted under nurse-administered propofol sedation(AstraZeneca, Osaka, Japan).10

Figure 1. Left, Dedicated cold polypectomy snare (Exacto cold snare, USEndoscopy, Mentor, Ohio). Right, Traditional cold polypectomy snare(Snare Master, Olympus, Tokyo, Japan).

ProcedureCecal intubation was verified by identification of the ap-

pendiceal orifice and ileocecal valve. Endoscopists were in-structed to measure polyp by using the size of the snarecatheter or the snare diameter. Polyps were measured inincrements of 1 mm. The time taken to reach the cecum,the intubation rate of the terminal ileum, the proceduretime, the location of polyps (right side was defined as ator proximal to the splenic flexure), and the size andmorphology (flat type was defined as height!2.5 mm asmeasured by the diameter of the 2.4- or 2.6-mm snare cath-eter) of each polyp were recorded. The size of polyp wasalso estimated by using the open-forceps technique (for-ceps span Z 7.3 mm). All colorectal polyps up to 10 mmfound, except for tiny hyperplastic polyps in the rectumand distal sigmoid colon, were removed.

The dedicated cold snare (Exacto cold snare; US Endos-copy, Mentor, Ohio) (Fig. 1, left) was designed to be usedexclusively for cold polypectomy snare and has a maximalsnare diameter of 9 mm. The traditional cold polypectomysnare was the Snare Master snare (SD-210U-10; Olympus,Tokyo, Japan) (Fig. 1, right) with a maximal snarediameter of 10 mm that was designed for hotpolypectomy. The snare wire diameter of the Exacto coldsnare is 0.30 mm and 0.47 mm for the Snare Mastersnare. The instrument was rotated for polypectomy toalign the polyp with the instrument channel at the 6o’clock position. The snare was opened enough to allowa rim of normal tissue to be ensnared and resected(Fig. 2A). The colonoscope was angled into the colonwall while the snare was pushed forward. The polyp andsmall rim of normal tissue were snared closely withouttenting and guillotined (Fig. 2B). If submucosa tissue wastrapped, the captured tissue was guillotined repeatedlyto remove the polyp completely. The absence of visibleresidual polyp tissue was also confirmed endoscopically(Fig. 2C) and by using narrow-band imaging (Fig. 2D)before the completeness of the polyp resection wasdetermined pathologically. If the residual polyp was seenat the polypectomy site, it was resected again. Thetransected small polyps (%6 mm) were sucked into atrap. Larger resected polyps (R7 mm) were retrieved byusing retrieval forceps without the use of the endoscopicsuction channel to avoid fragmenting the samples.

When snaring a pedunculated polyp, the snare wasplaced approximately half way up the stalk, and the stalkwas cut. Submucosal injection of saline solution beforepolyp removal was not performed. Prophylactic clipping af-ter polyp removal was not routinely performed; however,hemostatic clipping was carried out during the procedurefor immediate bleeding. When a vessel was visible after

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the removal of a polyp of the pedunculated type, hemo-static clipping was also performed.

The size, shape, and location of all polyps wererecorded. All patients who underwent polypectomy visitedour hospital 2 weeks after polypectomy to be informed ofthe pathological results of polyps removed. Adverse eventsand all GI symptoms within 2 weeks after each polypec-tomy were recorded.

Pathological examinationThe pathologist (K.S.) remained blinded to the snare

used for the cold snare polypectomy in this study (dedi-cated cold polypectomy snare or conventional cold poly-pectomy snare) until after all the analyses werecompleted. After removal, excised specimens weremounted with pins on Styrofoam plates and fixed in 10%formalin. They were examined grossly, and aftersectioning, they were examined by using hematoxylinand eosin staining. The resection was considered completehistologically if vertical and lateral margins were free ofneoplasia tissue. The submucosal layer of the resectedspecimens was also specifically examined for the presenceof arteries and injured arteries.

Outcome variablesThe primary outcome measure was a comparison of the

rate of complete resection of colorectal polyps as assessedby pathological examination. Secondary outcome mea-sures were postpolypectomy bleeding within 2 weeks aftercold snare polypectomy and the presence of arteries andinjured arteries in the submucosal layer in the resectedspecimens. When delayed bleeding was suspected withouta decrease in hemoglobin, the bleeding was judged to beslight postpolypectomy bleeding, which was designatedas hematochezia. Immediate bleeding that requires

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Figure 2. A, The snare is opened enough to allow a rim of normal tissue to be ensnared and resected. B, The polyp and small rim of normal tissue aresnared without tenting and guillotined vigorously. C, The absence of visible residual polyp tissue was confirmed endoscopically. D, Removal confirmed byusing narrow-band imaging.

Cold-only vs traditional cold polypectomy snare Horiuchi et al

hemostatic clipping was defined as spurting or oozing thatcontinued for more than 30 seconds.

Sample size calculation and statistical analysisSample size calculation was based on the primary

outcome measure of the study. Our previous studies foundthat the complete resection rates of cold snare polypec-tomy based on the pathological examination were 96%for small polyps of 1 to 8 mm and 94% for small polypsof 1 to 10 mm.7,8 Based on this experience, we hypothe-sized that the complete resection rate of relatively largerpolyps (8-10 mm) by cold snaring by using the exclusivelycold polypectomy snare to be more than 94%, whereasthat of the traditional cold polypectomy snare would be80%. We assumed that the dedicated cold snare groupwould increase the complete resection rate of polyps byat least 14% compared with the traditional cold snaregroup. At least 90 polyps per group were required todemonstrate a superior complete resection rate of thededicated cold snare group compared with the traditionalcold snare group, with a Z .05 and a power of 80%. Statis-tical differences were analyzed by c2 tests of independenceand the Fisher exact test or the Student t test. P values!.05were considered significant. Statistical analysis was per-formed by using JMP 9.0.2 version software (SAS InstituteInc, Cary, NC).

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RESULTS

PatientsEighty-three patients were recruited for the study. Seven

patients who had a polyp larger than 10 mm found duringthe procedure were dropped from the study; therefore 76patients (dedicated cold snare group; N Z 37 and tradi-tional cold snare group, N Z 39) were enrolled and under-went polypectomy. Patient demographic characteristics,indications for colonoscopy, and the use of antithromboticagents were similar between the 2 techniques (Table 1).For subjects with more than 1 polyp, each polypectomywas considered to be independent of the others.

PolypectomyThere were no significant differences in the cecal intuba-

tion rate, the mean cecal intubation time, the intubationrateof terminal ileum, and themeanprocedure timebetweenthe dedicated cold snare group and the traditional cold snaregroup (Table 2). The characteristics of number, size, andshape of polyps removed are shown in Table 2 and werealso similar between the 2 techniques (dedicated cold snaregroup: 98 polyps; average size, 6.5 mm; median size,6.5 mm; traditional cold snare group: 112 polyps; averagesize, 6.3 mm; median size, 6 mm).

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TABLE 1. Comparison of baseline characteristics in patients using thededicated cold polypectomy snare and traditional cold polypectomysnare

Characteristic

Group

Pvalue

Dedicatedcold snare

Traditionalcold snare

No. of patients 37 39

Age, mean (SD), y* 66.4 (13) 69 (10) .87

Femaley 10 15

Indication, no. (%)y .70

Hemo-positive stool 25 (68) 24 (62)

Screening 8 (22) 12 (31)

Other 4 (11) 3 (8)

Antithrombotic agentsused, no. (%)y

4 (11) 4 (10) .94

Warfarin 2 (5) 1 (3)

Dabigatran 1 (3) 0

Aspirin 1 (3) 3 (8)

*Differences between dedicated cold snare group and traditional cold snare groupcompared by the Student t test for continuous variables.yDifferences between dedicated cold snare group and traditional cold snare groupcompared by the c2 test for categorical data.

TABLE 2. Comparison of outcomes and adverse events in patientsusing the dedicated cold polypectomy snare and traditional coldpolypectomy snare

Group

Pvalue

Dedicatedcold snare

Traditionalcold snare

Cecal intubation rate, %* 100 100

Cecal intubation time, miny 5.6 (5) 5.4 (6) .67

Intubation rate of terminalileum, %*

89 87 .79

Procedure time, mean (SD), miny 17 (8) 18 (9) .88

Total no. of polyps removed 98 112

No. of polyps removed perpatient, mean (SD)

2.6 (1.8) 2.9 (2.4) .68

Polyp size, mm, mean (SD) 6.5 (1.8) 6.3 (2.2) .32

Median polyp size, mm 6.5 6.0 .81

Complete resection rate, %* 91 (89/98) 79 (88/112) .015

No. of hemostatic clips perpatient, mean (SD)y

0.28 (1.0) 0.35 (0.8) .37

Postpolypectomy bleeding, %*

Immediate bleeding 19 (7/37) 21 (8/39) .86

Hematochezia 5.4 (2/37) 7.7 (3.39) .69

Delayed bleeding 0 0

Total 24 (9/37) 28 (11/39) .70

Perforation 0 0

Hematochezia (mild uninvestigated bleeding) and delayed bleeding within 2 weeksafter each polypectomy were recorded.*Differences between dedicated cold snare group and traditional cold snare groupcompared by the c2 test for categorical data.yDifferences between dedicated cold snare group and traditional cold snare groupcompared by the Student t test for continuous variables.

Horiuchi et al Cold-only vs traditional cold polypectomy snare

The complete resection rate in the dedicated cold snaregroup was significantly higher than that in the traditionalcold snare group (91% [89/98] vs 79% [88/112], P Z.015) (Table 2). The complete resection rates for polyps8 to 10 mm in diameter and either flat or pedunculatedin morphology, and adenoma or sessile serratedadenoma/polyp in the dedicated cold snare group weresignificantly greater than those of in traditional coldsnare group (83% [15/18] vs 45% [10/22], P Z .014)(Table 3). After resection, residual polyps were seen in 3lesions in the dedicated cold snare group and 8 lesionsin the traditional cold snare group. All 11 residual polypswere re-resected endoscopically, and all were defined asincomplete resection pathologically. When the incom-pletely resected polyps were adenomas or sessile serratedadenoma/polyps, these patients were scheduled to un-dergo colonoscopy 1 year after polypectomy.

There was no significant difference in the mean numberper patient of prophylactic hemostatic clips used afterpolypectomy in the 2 groups. The occurrence of immedi-ate bleeding and hematochezia during the both proce-dures was similar (19% vs 21%, P Z .86; 5.4% vs 7.7%,P Z .69). No delayed bleeding occurred in either group(Table 2). All 5 patients with hematochezia (milduninvestigated bleeding) in both groups were also usersof antithrombotic agents. No perforation was observed ineither group.

Pathological examinationTissue could be examined for arteries in the submucosal

layer in 98% (96/98) and 93% (104/112) of resected polyps

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in the dedicated cold snare group and traditional coldsnare group, respectively (Table 4). Submucosal arteriesdetected in the submucosal layer were similar betweenthe traditional cold snare group and the dedicated coldsnare group (33% [32/96] vs 30% [31/104], P Z .0.59)(relative risk, 1.1; 95% confidence interval, 0.74-1.7).There were fewer injured arteries detected in thesubmucosal layer in the dedicated cold snare group thanin the traditional cold snare group, but the differencewas not significant (3.1% [3/96] vs 6.7% [7/104], P Z.24) (relative risk, 0.46; 95% confidence interval, 0.12-1.7). In all 5 patients with hematochezia (milduninvestigated bleeding) in both groups, the injuredarteries were detected in the submucosal layer in theresected specimens.

DISCUSSION

Cold snare polypectomy is frequently used for smallpolyps (%10 mm). However, it is often difficult tocompletely remove polyps 10 mm in diameter and flat orpedunculated in morphology by using cold snaring without

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TABLE 3. Comparison of complete resection rate of polyps removedin patients by using the dedicated cold polypectomy snare andtraditional cold polypectomy snare

Complete resection rate, %

P valueDedicated coldsnare group

Traditional coldsnare group

Total 91 (89/98) 79 (88/112) .015

Size, mm

%5 92 (35/38) 91 (41/45) .87

6-7 93 (39/42) 82 (37/45) .14

8-10 83 (15/18) 45 (10/22) .014

Location

Left colon 95 (38/40) 82 (40/49) .06

Right colon 88 (51/58) 76 (48/63) .10

Shape

Flat 74 (17/23) 42 (8/19) .037

Sessile 96 (64/67) 91 (74/81) .32

Pedunculated 100 (8/8) 50 (6/12) .017

Pathology

High-grade adenoma 100 (1/1)

Adenoma 89 (75/84) 78 (73/94) .039

SSA/P 100 (5/5) 50 (3/6) .064

Hyperplastic polyp 100 (9/9) 100 (11/11)

Differences between dedicated cold snare group and traditional cold snare groupcompared by the c2 test for categorical data.SSA/P, sessile serrated adenoma/polyp.

TABLE 4. Comparison of artery in submucosal layer in resectedspecimens with the dedicated cold polypectomy snare and traditionalcold polypectomy snare

Group

P value RR (95% CI)

Dedicatedcold snaregroup

Traditionalcold snaregroup

Total no. of polypsexamined

96 104

Polyp size, mm,mean (SD)*

6.5 (1.7) 6.4 (2.3) .33

Presence of arteriesin submucosay

33% (32/96) 30% (31/104) .59 1.1 (0.74-1.7)

Presence of injuredarteries insubmucosay

3.1% (3.96) 6.7% (7/104) .24 0.46 (0.12-1.7)

RR, Relative risk (presence in dedicated cold snare/presence in traditional cold snare);CI, confidence interval.*Differences between dedicated cold snare group and traditional cold snare groupcompared by the Student t test for continuous variables.yDifferences between dedicated cold snare group and traditional cold snare groupcompared by c2 test for categorical data.

Cold-only vs traditional cold polypectomy snare Horiuchi et al

electrocautery. This study demonstrated that the completeresection rate of small polyps (%10 mm) by using a snaredesigned exclusively for cold polypectomy was significantlybetter than when using a traditional cold polypectomysnare for cold snaring (91% [89/98] vs 79% [88/112], P Z.015). In particular, the rate of complete resection washighest in polyps 8 to 10 mm in diameter that were flator pedunculated in morphology (83% [15/18] vs 45% [10/22], P Z .014).

The difference in the complete resection rates with the2 types of snares used in this study is possibly related tothe different characteristics of the snares, likely the differ-ences in the diameter and shape of the snare wire (Exactocold snare, 0.30 mm, diamond-shaped; Snare Master snare,0.47 mm, oval shape). The Exacto cold snare was designedspecifically to be used for cold resection, and the devicewas tested and validated for this indication. It cannot beused for hot snaring is the sheath/catheter, which is notthermally/electrically insulated. We postulate that thedesign of the device, such as thinner wire and/or shieldshape, may be more effective for cold resection than thatof the traditional cold polypectomy snare and result inmore cutting than tearing through the mucosa or stalk,thus making resection of the polyp technically easy.

The definitions of complete resection rate andincomplete resection rate have not been standardized.

6 GASTROINTESTINAL ENDOSCOPY Volume -, No. - : 2015

One previous method of determining complete resectionwas to take 2 or more additional biopsy specimens fromthe base or edges of the polypectomy site for microscopicexamination.3-5 We used an adenoma-free condition of thehorizontal margins of the resected specimen as seen onpathological examination as our definition of completeresection of the polyp removed. In Japan, irrespective ofthe size of polyps, excised specimens of polypectomy aswell as EMR were mounted with pins on Styrofoam platesand fixed in 10% formalin and submitted for pathologicalexamination. Japanese pathologists are trained to examinethe lateral margin of all polyps and to report the results ofthe completeness of resection. Our pathologist isexperienced in this and has participated in our previousstudies.

The status of horizontal margins of the resected polyps8 to 10 mm in diameter and flat or pedunculated was his-tologically unclear more frequently after the use of thetraditional cold polypectomy snare than with the dedicatedcold snare (Table 3). We used cold snare polypectomy forall small polyps (%10 mm), irrespective of their shape.However, electrocautery is often used for pedunculatedand bulky sessile polyps in the 6- to 10-mm diameterrange with the thought that it is likely more effectivethan cold snaring.11,12 This study showed that the snare de-signed exclusively for cold polypectomy provided excellentresults with pedunculated polyps 8 to 10 mm in diameterand electrocautery was unnecessary.

Cold snare polypectomy has been previously reportedto be associated with a low rate of postpolypectomybleeding.13,14 We speculated that the cause of delayedbleeding was related to injury of blood vessels in the sub-mucosa layer caused by snaring. In a previous study, we

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Horiuchi et al Cold-only vs traditional cold polypectomy snare

demonstrated that injured submucosal arteries were seensignificantly less frequently after cold snare polypectomythan after hot polypectomy (22% vs 39%, P Z .023).8

This difference was also consistent with the increase indelayed bleeding associated with hot compared with coldpolypectomy.8 This study compared 2 different types ofsnare for cold snaring, and histologically injured arterieswere present in the submucosal layer in both groups.Although the difference was not significantly different,the rate was lower with the thinner, specially designedcold snare (3.1% [3/96] vs 6.7% [7/104], P Z .24). Inaddition, the mean number of patients receivingprophylactic hemostatic clips and the frequency ofpostpolypectomy bleeding with the thin wire was alsolower than with the hot snare, but again the differenceswere not significant (0.28 vs 0.35, P Z .37; 24% vs 28%,P Z .70). We excluded ASA class III patients becauseASA class III patients with severe systemic diseases wereexpected to possibly affect postpolypectomy bleedingrates. Larger studies including ASA class III patients areneeded to clarify whether the snare characteristics are animportant variable in this regard.

The use of a transparent cap in all cases has implicationsrelated to the external validity of the study because a trans-parent cap is not routinely used in the West for screeningcolonoscopy. In addition to an increased adenoma detec-tion rate, it is possible that the use of the cap may facilitatepolypectomy. We do not believe that the use of a trans-parent cap affects the primary and secondary outcomemeasures of this study; however, a randomized compari-son would be required if the issue were considered impor-tant enough.

If a small (%10 mm) polyp is detected and removedwith an exclusively designed cold snare and then a secondlarger polyp is seen, it may be necessary to use a secondhot snare for hot polypectomy. This would double thecost of the devices per colonoscopy. The cost of the Exactocold snare in Japan is also 1.5 times higher than that ofSnare Master (4500 JPY vs 3000 JPY). The Exacto cold snarecannot be used for hot polypectomy because it was not de-signed with attachments for electrocautery. It is unknownwhether the sheath is insulated for electrocautery. There-fore, the use of an exclusively designed cold snare couldincrease the cost of polypectomy compared with that ofa traditional cold polypectomy snare but with the advan-tage that fewer resections will leave residual polypmaterial.

This study has some limitations. The study could not beblinded because the endoscopist knew the type of snareused. It is possible that there was bias due to the differenttechniques used or other preexisting bias of the investiga-tors. In addition to a relatively small sample size, the studywas conducted at a single hospital and will need tobe confirmed in multicenter studies and in differentpopulations. We also examined only 1 specially designedsnare and 1 traditional cold polypectomy snare. Ideally, a

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snare could be developed that included the best character-istics of both.

In conclusion, the complete resection rate by using asnare designed exclusively for cold polypectomy was betterthan a snare designed for traditional cold polypectomy.The cold snare technique by using the thinner snare wasespecially designed for cold snaring and obtained a higherproportion of with complete adenoma removal than coldsnaring with a traditional cold polypectomy snare withused for colorectal polyps 8 to 10 mm in diameter whetherflat or pedunculated. In clinical practice, the majority ofcolorectal polyps encountered are less than 10 mm indiameter, suggesting that cold snare polypectomy with aspecially designed snare would improve polypectomyresults and likely result in more successful prevention ofcolorectal cancer.

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