Underwater versus conventional endoscopic resection of nondiminutive nonpedunculated colorectal lesions: a prospective randomized controlled trial (with video)

Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2024

1:  ESGE recommends cold snare polypectomy (CSP), to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of diminutive polyps (≤ 5 mm).Strong recommendation, high quality of evidence. 2:  ESGE recommends against the use of cold biopsy forceps excision because of its high rate of incomplete resection.Strong recommendation, moderate quality of evidence. 3:  ESGE recommends CSP, to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of small polyps (6-9 mm).Strong recommendation, high quality of evidence. 4:  ESGE recommends hot snare polypectomy for the removal of nonpedunculated adenomatous polyps of 10-19 mm in size.Strong recommendation, high quality of evidence. 5:  ESGE recommends conventional (diathermy-based) endoscopic mucosal resection (EMR) for large (≥ 20 mm) nonpedunculated adenomatous polyps (LNPCPs).Strong recommendation, high quality of evidence. 6:  ESGE suggests that underwater EMR can be considered an alternative to conventional hot EMR for the treatment of adenomatous LNPCPs.Weak recommendation, moderate quality of evidence. 7:  Endoscopic submucosal dissection (ESD) may also be suggested as an alternative for removal of LNPCPs of ≥ 20 mm in selected cases and in high-volume centers.Weak recommendation, low quality evidence. 8:  ESGE recommends that, after piecemeal EMR of LNPCPs by hot snare, the resection margins should be treated by thermal ablation using snare-tip soft coagulation to prevent adenoma recurrence.Strong recommendation, high quality of evidence. 9:  ESGE recommends (piecemeal) cold snare polypectomy or cold EMR for SSLs of all sizes without suspected dysplasia.Strong recommendation, moderate quality of evidence. 10:  ESGE recommends prophylactic endoscopic clip closure of the mucosal defect after EMR of LNPCPs in the right colon to reduce to reduce the risk of delayed bleeding.Strong recommendation, high quality of evidence. 11:  ESGE recommends that en bloc resection techniques, such as en bloc EMR, ESD, endoscopic intermuscular dissection, endoscopic full-thickness resection, or surgery should be the techniques of choice in cases with suspected superficial invasive carcinoma, which otherwise cannot be removed en bloc by standard polypectomy or EMR.Strong recommendation, moderate quality of evidence.

Underwater versus conventional endoscopic mucosal resection for ≥10 mm sessile or flat colorectal polyps: A systematic review and meta-analysis

BACKGROUND AND AIM

Underwater endoscopic mucosal resection (UEMR) has been an emerging substitute for conventional EMR (CEMR). This systematic review and meta-analysis aimed at comparing the efficiency and safety of the two techniques for removing ≥10 mm sessile or flat colorectal polyps.

METHODS

PubMed, Cochrane Library and Embase databases were searched up to February 2023 to identify eligible studies that compared the outcomes of UEMR and CEMR. This meta-analysis was conducted on the en bloc resection rate, R0 resection rate, complete resection rate, procedure time, adverse events rate and recurrence rate.

RESULTS

Nine studies involving 1,727 colorectal polyps were included: 881 were removed by UEMR, and 846 were removed by CEMR. UEMR was associated with a significant increase in en bloc resection rate [Odds ratio(OR) 1.69, 95% confidence interval(CI) 1.36-2.10, p<0.00001, I2 = 33%], R0 resection rate(OR 1.52, 95%CI 1.14-2.03, p = 0.004, I2 = 31%) and complete resection rate(OR 1.67, 95%CI 1.06-2.62, p = 0.03, I2 = 0%) as well as a significant reduction in procedure time(MD ‒4.27, 95%CI ‒7.41 to ‒1.13, p = 0.008, I2 = 90%) and recurrence rate(OR 0.52, 95%CI 0.33-0.83, p = 0.006, I2 = 6%). Both techniques were comparable in adverse events rate.

CONCLUSION

UEMR can be a safe and efficient substitute for CEMR in removing ≥10 mm sessile or flat colorectal polyps. More studies verifying the advantages of UEMR over CEMR are needed to promote its application.

Cold polypectomy techniques for small and diminutive colorectal polyps: a systematic review and network meta-analysis of randomized controlled trials

OBJECTIVE

In the management of small and diminutive polyps, cold polypectomy is favored over electrocautery polypectomy. However, the optimal cold polypectomy technique is still controversial. Hence, this review aims to investigate the most effective cold technique for small and diminutive colorectal polyps.

METHODS

We conducted a systematic review and network meta-analysis synthesizing randomized controlled trials (RCTs) which were retrieved by systematically searching PubMed, EMBASE, Web of Science, SCOPUS, and Cochrane through 10 February 2023. R software, (R version 4.2.0) and meta-insight software were used to pool dichotomous outcomes using risk ratio (RR) presented with the corresponding confidence interval (CI). Our protocol was prospectively published in PROSPERO with ID: CRD42022345619.

RESULTS

Nineteen RCTs with 3649 patients and 4800 polyps were included in our analysis. Cold techniques (cold forceps polypectomy (CFP), jumbo forceps polypectomy (JFP), dedicated cold snare polypectomy (D-CSP), conventional cold snare polypectomy (C-CSP), underwater cold snare polypectomy (U-CSP), and cold snare endoscopic mucosal resection (CS-EMR) were included in our comparative analysis. CFP was less effective in achieving complete histological resection than C-CSP (RR: 1.10 with 95% CI [1.03-1.18]), CS-EMR (RR: 1.12 with 95% CI [1.02-1.23]), D-CSP (RR: 1.17 with 95% CI [1.04-1.32]), and U-CSP (RR: 1.21 with 95% CI [1.07-1.38]). However, the rest of the comparisons showed no difference.

CONCLUSION

CFP is the least effective method for small and diminutive polyps' removal, and any snare polypectomy technique will achieve better results, warranting more large-scale RCTs to investigate the most effective snare polypectomy technique.

Underwater versus conventional endoscopic mucosal resection for colorectal lesions: An updated meta-analysis of randomized controlled trials

Background and study aims Colorectal malignancy is a leading cause of death. Conventional endoscopic mucosal resection (CEMR) is a strategy used to resect precancerous lesions that involves injecting fluid beneath a polyp to create a gap for resection. Underwater endoscopic mucosal resection (UEMR) is a newer method that forgoes injection, instead filling the intestinal cavity with water to facilitate polyp resection. Our aim was to compare the safety and efficacy of these approaches by synthesizing the most contemporary evidence. Methods PubMed, Embase, and Cochrane libraries were searched from inception through November 11, 2022 for randomized controlled trials (RCTs) comparing UEMR and CEMR for resection of colorectal lesions. The primary outcome was the rate of en bloc resection and secondary outcomes included recurrence, procedure time, and adverse events (AEs). Results A total of 2539 studies were identified through our systematic literature search. After screening, seven RCTs with a total of 1581 polyps were included. UEMR was associated with significantly increased rates of en bloc resection (RR 1.18 [1.03, 1.35]; I 2 = 76.6%) versus conventional approaches. No significant differences were found in procedure time, recurrence, or AEs. Conclusions UEMR is a promising effective technique for removal of colorectal lesions. The most contemporary literature indicates that it improves en bloc resection rate without increasing procedure time, recurrence, or AEs (PROSPERO ID CRD42022374935).

Safety and efficacy of underwater versus conventional endoscopic mucosal resection for colorectal polyps: Systematic review and meta-analysis of RCTs

Background and study aims Conventional endoscopic mucosal resection (C-EMR) is limited by low en-bloc resection rates, especially for large (> 20 mm) lesions. Underwater EMR (U-EMR) has emerged as an alternative for colorectal polyps and is being shown to improve en-bloc resection rates. We conducted a systematic review and meta-analysis comparing the two techniques. Methods Multiple databases were searched through November 2022 for randomized controlled trials (RCTs) comparing outcomes of U-EMR and C-EMR for colorectal polyps. Meta-analysis was performed to determine pooled proportions and relative risks (RRs) of R0 and en-bloc resection, polyp recurrence, resection time, and adverse events. Results Seven RCTs with 1458 patients (U-EMR: 739, C-EMR: 719) were included. The pooled rate of en-bloc resection was significantly higher with U-EMR vs C-EMR, 70.17% (confidence interval [CI] 46.68-86.34) vs 58.14% (CI 31.59-80.68), respectively, RR 1.21 (CI 1.01-1.44). R0 resection rates were higher with U-EMR vs C-EMR, 58.1% (CI 29.75-81.9) vs 44.6% (CI 17.4-75.4), RR 1.25 (CI 0.99-1.6). For large polyps (> 20 mm), en-bloc resection rates were comparable between the two techniques, RR 1.24 (CI 0.83-1.84). Resection times were comparable between U-EMR and C-EMR, standardized mean difference -1.21 min (CI -2.57 to -0.16). Overall pooled rates of perforation, and immediate and delayed bleeding were comparable between U-EMR and C-EMR. Pooled rate of polyp recurrence at surveillance colonoscopy was significantly lower with U-EMR than with C-EMR, RR 0.62 (CI 0.41-0.94). Conclusions Colorectal U-EMR results in higher en-bloc resection and lower recurrence rates when compared to C-EMR. Both techniques have comparable resection times and safety profiles.

Cold resection for colorectal polyps: where we are and where we are going?

INTRODUCTION

Endoscopic resection of colonic precancerous lesions has been demonstrated to significantly decrease colorectal cancer (CRC) incidence and mortality. Among resection techniques, cold snare polypectomy (CSP) has been shown as a highly feasible, effective and safe option and is widely used in clinical practice, being regarded as the first-line technique for removal of small and diminutive colorectal polyps. On the other hand, conventional hot snare polypectomy (HSP) and endoscopic mucosal resection (EMR), namely the gold standard treatments for larger polyps, may be occasionally associated to complications due to electrocautery injury.

AREAS COVERED

To overcome these shortcomings of electrocautery-based resection techniques, in the last few years CSP has been increasingly assessed as a treatment option for additional indications, with a focus on nonpedunculated colorectal polyps ≥10 mm.

EXPERT OPINION

This review aims to present current and widened indications of CSP discussing the latest findings from the most remarkable studies, with an insight into technical issues, novelties and potential advances in the near future.

Underwater versus conventional EMR of large nonpedunculated colorectal lesions: a multicenter randomized controlled trial

BACKGROUND AND AIMS

Underwater EMR (UEMR) is an alternative procedure to conventional EMR (CEMR) to treat large, nonpedunculated colorectal lesions (LNPCLs). In this multicenter, randomized controlled clinical trial, we aimed to compare the efficacy and safety of UEMR versus CEMR on LNPCLs.

METHODS

We conducted a multicenter, randomized controlled clinical trial from February 2018 to February 2020 in 11 hospitals in Spain. A total of 298 patients (311 lesions) were randomized to the UEMR (n = 149) and CEMR (n = 162) groups. The main outcome was the lesion recurrence rate in at least 1 follow-up colonoscopy. Secondary outcomes included technical aspects, en bloc resection rate, R0 resection rates, and adverse events, among others.

RESULTS

There were no differences in the overall recurrence rate (9.5% UEMR vs 11.7% CEMR; absolute risk difference, -2.2%; 95% CI, -9.4 to 4.9). However, considering polyp sizes between 20 and 30 mm, the recurrence rate was lower for UEMR (3.4% UEMR vs 13.1% CEMR; absolute risk difference, -9.7%; 95% CI, -19.4 to 0). The R0 resection showed the same tendency, with significant differences favoring UEMR only for polyps between 20 and 30 mm. Overall, UEMR was faster and easier to perform than CEMR. Importantly, the techniques were equally safe.

CONCLUSIONS

UEMR is a valid alternative to CEMR for treating LNPCLs and could be considered the first option of treatment for lesions between 20 and 30 mm due to its higher en bloc and R0 resection rates. (Clinical trial registration number: NCT03567746.).

Underwater versus conventional endoscopic mucosal resection for sessile colorectal polyps: an updated systematic review and meta-analysis

BACKGROUND

underwater endoscopic mucosal resection (uEMR) without submucosal injection for sessile colorectal polyps was introduced as a new replacement for conventional EMR (cEMR). However, the optimal resection strategy remains a topic of debate. Hence, this meta-analysis was performed to compare the efficacy and safety of uEMR and cEMR in patients with sessile colorectal polyps.

METHODS

a comprehensive search of the literature from 2000 till January 2022 was performed from Medline, CENTRAL and Embase for randomized controlled trials (RCTs) comparing cEMR vs uEMR for colorectal polyps. The evaluated outcomes included en bloc resection, R0 resection, procedure time, overall bleeding and recurrence. Pooled risk ratios (RR) with 95 % confidence interval were calculated using a random effect model.

RESULTS

six studies were included, out of which four were full-text articles and two were conference abstracts. En bloc resection (RR 1.26, 95 % CI: 1.00-1.60), R0 resection (RR 1.10, 95 % CI: 0.96-1.26), overall bleeding (RR 0.85, 95 % CI: 0.54-1.34) and recurrence rate (RR 0.75, 95 % CI: 0.45-1.27) were comparable between uEMR and cEMR. However, uEMR was associated with a shorter procedure time (mean difference [MD] -1.55 minutes, 95 % CI: -2.71 to -0.39). According to the subgroup analysis, uEMR led to a higher rate of en bloc resection (RR 1.41, 95 % CI: 1.07-1.86) and R0 resection (RR 1.19, 95 % CI: 1.01-1.41) for polyps ≥ 10 mm in size.

CONCLUSION

both uEMR and cEMR have a comparable safety and efficacy. For polyps larger than 10 mm, uEMR may have an advantage over cEMR and should be the topic for future studies.

Efficacy and Safety of Gel Immersion Endoscopic Mucosal Resection for Non-Pedunculated Colorectal Polyps

Underwater endoscopic mucosal resection (UEMR) has become a popular endoscopic resection method for large colorectal neoplasms. However, visualization can be poor during UEMR due to the presence of intestinal fluid. Gel immersion endoscopic mucosal resection (GIEMR), using a specially developed gel (Viscoclear®, Otsuka Pharmaceutical Factory, Tokushima, Japan), can improve the visual field. However, reports of GIEMR for colorectal polyps are limited. Herein, we evaluated the short-term outcomes of GIEMR for non-pedunculated colorectal neoplasms (NPCRN). This single-center, retrospective, and observational study includes 25 lesions in 20 patients with NPCRN who underwent GIEMR between January and October 2022. The short-term outcomes and adverse events were evaluated. The lesion locations were as follows: right colon, 18 lesions; left colon, 7 lesions; and rectum, none. The median tumor diameter was 15 (IQR, 10–18) mm. Histological classification was as follows: sessile serrated lesion, 9 cases; adenoma, 12 cases; and intramucosal adenocarcinoma, 4 cases. The overall en bloc resection rates and R0 resection rates were 80% (20/25) and 72% (18/25). For NPCRN in 10–19 mm, the en bloc resection rate was 75% (12/16), with an R0 resection rate of 69% (11/16). No post-polypectomy bleeding, perforation, or post-coagulation syndrome were observed. The findings of our study provide preliminary evidence of the efficacy and safety of GIEMR for NPCRN. Therefore, GIEMR may be a promising novel endoscopic resection method for NPCRN.

Underwater versus conventional EMR for nonpedunculated colorectal lesions: a randomized clinical trial

BACKGROUND AND AIMS

Conventional endoscopic mucosal resection (CEMR) is the standard modality for removing nonpedunculated colorectal lesions. Underwater endoscopic mucosal resection (UEMR) has emerged as an alternative method. There are few comparative studies between these techniques, especially evaluating recurrence. Therefore, the purpose of this trial was to compare CEMR and UEMR for the resection of colorectal lesions with respect to efficacy, safety, and recurrence rate.

METHODS

This was a randomized controlled trial of UEMR versus CEMR for naïve and nonpedunculated lesions measuring between 10 and 40 mm. The primary outcome was adenoma recurrence at 6 months after the resection. Secondary outcomes were rates of technical success, en bloc resection, and adverse events. Block randomization was used to assign patients. Tattooing was performed to facilitate localization of the scars and eventual recurrences. Endoscopic follow-up was scheduled at 6 months after the procedure. The sites of resections were examined with white-light imaging, narrow-band imaging (NBI), and conventional chromoscopy with indigo carmine followed by biopsies.

RESULTS

One hundred five patients with 120 lesions were included, with a mean size of 17.5 ± 7.1 (SD) mm. Sixty-one lesions were resected by UEMR and 59 by CEMR. The groups were similar at baseline regarding age, sex, average size, and histologic type. Lesions in the proximal colon in the CEMR group corresponded to 83% and in the UEMR group to 67.8% (P = .073). There was no difference between groups regarding success rate (1 failure in each group) and en bloc resection rate (60.6% UEMR vs 54.2% CEMR, P = .48). Intraprocedural bleeding was observed in 5 CEMRs (8.5%) and 2 UEMRs (3.3%) (P = .27). There was no perforation or delayed hemorrhage in either groups. Recurrence rate was higher in the CEMR arm (15%) than in the UEMR arm (2%) (P = .031). Therefore, the relative risk of 6-month recurrence rate in the CEMR group was 7.5-fold higher (95% CI, 0.98-58.20), with a number needed to treat of 7.7 (95% CI, 40.33-4.22). The higher recurrence rate in the CEMR group persisted only for lesions measuring 21 to 40 mm (35.7% vs 0%; P = .04).

CONCLUSION

This study demonstrated that UEMR was associated with a lower adenoma recurrence rate than was CEMR. Both endoscopic techniques were effective and had similar rates of adverse events for the treatment of nonpedunculated colorectal lesions.

Efficacy and safety of underwater endoscopic mucosal resection for ≤20 mm superficial non-ampullary duodenal epithelial tumors: Systematic review and meta-analysis

Background and aims

Superficial non-ampullary duodenal epithelial tumors (SNADETs) as a rare disease have gradually increased in recent years. Underwater endoscopic mucosal resection (UEMR) has emerged as a newly available option for the endoscopic resection of SNADETs. This study aimed to evaluate the efficacy and safety of UEMR for ≤20 mm SNADETs.

Methods

A literature search was performed across multiple databases, including PubMed, Embase, Scopus, and Clinical trials for studies containing tumors ≤20 mm published from January 1, 2012, to August 8, 2022. Outcomes examined were the pooled rates of en bloc resection, R0 resection, adverse events, and recurrence. Subgroup analyses of the resection rate were conducted stratified by sample size and polyp size.

Results

A total of 10 studies with UEMR performed in a total of 648 tumors were included for analysis. The pooled rate of en bloc resection and R0 resection was 88.2% (95% confidence interval (CI): 82.1-93.2) and 69.1% (95% CI: 62.2-76.1), respectively. The results showed pooled rate of intraoperative bleeding rate was 2.9% (95% CI: 0-9.0), delayed bleeding rate was 0.9% (95% CI: 0.1-2), recurrence rate was 1.5% (95% CI: 0-4.9). In the subgroup analysis, R0 and en-bloc resection rates were significantly higher in <10 mm than 10-20 mm SNADETs subgroups (R0 resection rate 83.1 vs. 48.6%; en bloc resection rate 100.0 vs. 84.0%, P < 0.05).

Conclusion

Underwater endoscopic mucosal resection was an effective and safe technique for the optional treatment for ≤20 mm SNADETs, especially of <10 mm.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022340578.

Different endoscopic treatments for small colorectal polyps: A systematic review, pair-wise, and network meta-analysis

Background and study aims

In recent years, cold snare polypectomy (CSP) has been increasingly used for small polyps (<10 mm) instead of hot snare polypectomy (HSP). However, evidence-based research regarding the effectiveness and safety of CSP and HSP are still lacking. Additionally, for 4-10 -mm non-pedunculated polyps, the polyp removal method is still controversial. Therefore, it is clinically significant to conduct pair-wise and network meta-analyses to assess such resection methods.

Methods

We searched PubMed, Embase, and the Cochrane library for randomized controlled trials (RCTs). Only studies that involved the resection of polyps <10 mm were included. Outcomes included the complete resection rate, polyp retrieval rate, procedure-related complications, and procedure times.

Results

Overall, 23 RCTs (5,352 patients) were identified. In meta-analysis compared CSP versus HSP for polyps <10 mm, CSP showed lower complete resection rate than HSP although with no statistically significant difference [odds ratio (OR): 0.77, 95% confidence interval (CI): 0.56-1.06]. CSP showed a lower risk of major post-polypectomy complications compared to HSP (OR: 0.28, 95% CI: 0.11-0.73). In the network meta-analysis for 4-10 mm non-pedunculated polyps, HSP, and endoscopic mucosal resection (EMR) showed a higher complete resection rate than CSP (OR: 2.7, 95% CI: 1.3-9.2 vs. OR: 2.6, 95% CI: 1.0-10) but a significantly longer time than CSP (WMD: 16.55 s, 95% CI [7.48 s, 25.25 s], p < 0.001), (WMD: 48.00 s, 95% CI [16.54 s, 79.46 s], p = 0.003). Underwater CSP ranked third for complete resection with no complications.

Conclusion

For <10 mm polyps, CSP is safer than HSP, especially for patients taking antithrombotic drugs. For 4-10 mm non-pedunculated polyps, HSP, and EMR have higher complete resection rates than CSP.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022315575.

Comparative efficacy and safety of resection techniques for treating 6 to 20mm, nonpedunculated colorectal polyps: A systematic review and network meta-analysis

INTRODUCTION

Various endoscopic resection techniques have been proposed for the treatment of nonpedunculated colorectal polyps sized 6-20 mm, however the optimal technique still remains unclear.

METHODS

A comprehensive literature review was conducted for randomized controlled trials (RCTs), investigating the efficacy of endoscopic treatments for the management of 6-20 mm nonpedunculated colorectal polyps. Primary outcomes were complete and en bloc resection rates and adverse event rate was the secondary. Effect size on outcomes is presented as risk ratio (RR; 95% confidence interval [CI]).

RESULTS

Fourteen RCTs (5219 polypectomies) were included. Endoscopic mucosal resection(EMR) significantly outperformed cold snare polypectomy(CSP) in terms of complete [(RR 95%CI): 1.04(1.00-1.07)] and en bloc resection rate [RR:1.12(1.04-1.21)]. EMR was superior to hot snare polypectomy (HSP) [RR:1.04(1.00-1.08)] regarding complete resection, while underwater EMR (U-EMR) achieved significantly higher rate of en bloc resection compared to CSP [RR:1.15(1.01-1.30)]. EMR yielded the highest ranking for complete resection(SUCRA-score 0.81), followed by cold-snare EMR(CS-EMR,SUCRA-score 0.76). None of the modalities was different regarding adverse event rate compared to CSP, however EMR and CS-EMR resulted in fewer adverse events compared to HSP [RR:0.44(0.26-0.77) and 0.43(0.21-0.87),respectively].

CONCLUSION

EMR achieved the highest performance in resecting 6-20 mm nonpedunculated colorectal polyps, with this effect being consistent for polyps 6-9 and ≥10 mm; findings supported by very low quality of evidence.

Resection depth and layer of underwater versus conventional endoscopic mucosal resection of intermediate-sized colorectal polyps: A pilot study

Background and study aims  Curability of colorectal tumors is associated with resection depth and layer in endoscopic resection. Underwater endoscopic mucosal resection (UEMR) has not undergone sufficient histopathological evaluation. We conducted a pilot study to compare the effectiveness, including resection depth and layer, of UEMR and conventional endoscopic mucosal resection (CEMR). Patients and methods  This study was a single-center, retrospective study. Patients with colorectal lesions were treated by UEMR or CEMR between January 2018 and March 2020. Eligible patients were selected from included patients in a 1:1 ratio using propensity score matching. We compared the resection depth and layer and treatment results between the UEMR and CEMR groups. Results  We evaluated 55 patients undergoing UEMR and 291 patients undergoing CEMR. Using propensity score matching, we analyzed 54 lesions in each group. The proportion of specimens containing submucosal tissue was 100 % in both groups. The median thickness of the submucosal tissue was significantly greater in the CEMR group than in the UEMR group [1235 µm (95 % confidence interval [CI], 1020-1530 µm) vs. 950 µm (95 % CI, 830-1090 µm), respectively]. However, vertical margins were negative in all lesions in both groups. Conclusions  Our findings suggest that the median thickness of submucosal tissue in the UEMR group was about 1,000 μm. Even though the resection depth achieved with UEMR was more superficial than that achieved with CEMR, UEMR may be a treatment option, especially for colorectal lesions ≤ 20 mm in diameter without suspicious findings of submucosal deeply invasive cancer.

Safety and effectiveness of underwater cold snare resection without submucosal injection of large non-pedunculated colorectal lesions

Background and study aims  Adverse events are uncommon with cold snaring, but cold techniques are generally reserved for lesions ≤ 9 mm out of concern for incomplete resection or inability to mechanically resect larger lesions. In a non-distended, water-filled lumen, colorectal lesions are not stretched, enabling capture and en bloc resection of large lesions. We assessed the effectiveness and safety of underwater cold snare resection (UCSR) without submucosal injection (SI) of ≥ 10 mm non-pedunculated, non-bulky (≤ 5 mm elevation) lesions with small, thin wire snares. Patients and methods  Retrospective analysis of an observational cohort of lesions removed by UCSR during colonoscopy. A single endoscopist performed procedures using a small thin wire (9-mm diameter) cold or (10-mm diameter) hybrid snare. Results  Fifty-three lesions (mean 15.8 mm [SD 6.9]; range 10-35 mm) were removed by UCSR from 44 patients. Compared to a historical cohort, significantly more lesions were resected en bloc by UCSR (84.9 % [45/53]; P  = 0.04) compared to conventional endoscopic mucosal resection (EMR) (64.0 % [32/50]). Results were driven by high en bloc resection rates for 10- to 19-mm lesions (97.3 % [36/37]; P  = 0.01). Multiple logistic regression analysis adjusted for potential confounders showed en bloc resection was significantly associated with UCSR compared to conventional EMR (OR 3.47, P  = 0.027). Omission of SI and forgoing prophylactic clipping of post-resection sites did not result in adverse outcomes. Conclusions  UCSR of ≥ 10 mm non-pedunculated, non-bulky colorectal lesions is feasible with high en bloc resection rates without adverse outcomes. Omission of SI and prophylactic clipping decreased resource utilization with economic benefits. UCSR deserves further evaluation in a prospective comparative study.

A Comparison of Incomplete Resection Rate of Large and Small Colorectal Polyps by Cold Snare Polypectomy

BACKGROUND & AIMS

There are limited data regarding the safety and efficacy of cold snare polypectomy (CSP) for large colorectal polyps. We evaluated factors affecting the clinical outcomes of CSP for polyps between 5 and 15 mm in size.

METHODS

This was a prospective single-center observational study involving 1000 patients undergoing colonoscopy. Polyps (5-15 mm) were removed using CSP, and biopsies were taken from the resection margin. The primary outcome was the incomplete resection rate (IRR), and was determined by the presence of residual neoplasia on biopsy. Correlations between IRR and polyp size, morphology, histology, and resection time were assessed by generalized estimating equation model.

RESULTS

A total of 440 neoplastic polyps were removed from 261 patients. The overall IRR was 2.27%, 1.98% for small (5-9 mm) vs 3.45% for large (10-15 mm) polyps (P = .411). In univariate analysis, the IRR was more likely to be related to sessile serrated lesions (odds ratio [OR], 6.93; 95% confidence interval [CI], 1.88-25.45; P = .004), piecemeal resection (OR, 11.83; 95% CI, 1.20-116.49; P = .034), and prolonged resection time >60 seconds (OR, 7.56; 95% CI, 1.75-32.69; P = .007). In multivariable regression analysis, sessile serrated lesions (OR, 6.45; 95% CI, 1.48-28.03; P = .013) and resection time (OR, 7.39; 95% CI, 1.48-36.96; P = .015, respectively) were independent risk factors for IRR. Immediate bleeding was more frequent with resection of large polyps (6.90% vs 1.42%; P = .003). No recurrence was seen on follow-up colonoscopy in 37 cases with large polyps.

CONCLUSIONS

CSP is safe and effective for removal of colorectal polyps up to 15 mm in size, with a low IRR. (ClinicalTrials.gov; Number: NCT03647176).

Underwater endoscopic mucosal resection for colorectal lesions: Can it be an “Underwater” revolution?

Underwater endoscopic mucosal resection (UEMR) is a newly developed technique for the removal of colorectal, duodenal, esophageal, gastric, ampullary, and small intestinal lesions. We performed a PubMed literature search for articles reporting UEMR outcomes for colorectal polyps. Four randomized controlled trials, nine non‐randomized prospective trials, 16 retrospective studies, and 27 case reports were selected for assessment of the efficacy and safety of UEMR. We summarized the therapeutic outcomes of UEMR in each category according to the lesion characteristics [small size (<10 mm), intermediate size (10–19 mm), large size (≥20 mm), recurrent lesion, and rectal neuroendocrine tumor], and calculated the incidence of adverse events among the included articles. As the treatment outcomes for small polyps appeared similar between UEMR and conventional endoscopic mucosal resection (CEMR), UEMR can be a standard procedure for small colorectal polyps suspicious for high‐grade dysplasia to avoid incomplete removal of occult invasive cancer by cold snare polypectomy. As UEMR showed satisfactory outcomes for intermediate‐size lesions and recurrent lesions after endoscopic resection, UEMR can be a standard procedure for these lesions. Regarding large lesions and rectal neuroendocrine tumors, comparisons of UEMR with current standard methods for them were lacking, and further investigations are warranted. Adverse events appeared comparable or less frequent for UEMR compared with CEMR but still existed. Therefore, careful implementation of this new technique in clinical practice is important for its widespread use.

Endoscopic Mucosal Resection: Best Practices for Gastrointestinal Endoscopists

Endoscopic mucosal resection (EMR) is an endoscopic technique used to remove sessile or flat lesions from the gastrointestinal tract. This article reviews EMR and focuses on large colorectal polyps, which constitute the most common indication for EMR. Various methods of polyp evaluation can help gastroenterologists determine whether EMR is feasible and whether referral to an advanced endoscopist may be necessary. Techniques for performing EMR include conventional hot-snare EMR with submucosal injection and electro-cautery snare removal of colorectal lesions, as well as alternative EMR techniques such as cold-snare EMR and underwater EMR. Key adverse events associated with EMR include bleeding, perforation, and post-polypectomy coagulation syndrome. Finally, as residual or recurrent polyp formation is possible regardless of EMR technique, this article addresses the importance of surveillance post-EMR and the patients who are at highest risk for polyp recurrence.

Is underwater endoscopic mucosal resection of colon polyps superior to conventional techniques? A network analysis of endoscopic mucosal resection and submucosal dissection

Background and study aims  Evidence from recent trials comparing conventional endoscopic mucosal resection (EMR) to underwater EMR (UEMR) have matured. However, studies comparing UEMR to endoscopic submucosal dissection (ESD) are lacking. Hence, we sought to conduct a comprehensive network meta-analysis to compare the efficacy of UEMR, ESD, and EMR. Methods  Embase and Medline databases were searched from inception to December 2020 for articles comparing UEMR with EMR and ESD. Outcomes of interest included rates of en bloc and complete polyp resection, risk of perforation and bleeding, and local recurrence. A network meta-analysis comparing all three approaches was conducted. In addition, a conventional comparative meta-analysis comparing UEMR to EMR was performed. Analysis was stratified according to polyp sizes (< 10 mm, ≥ 10 mm, and ≥ 20 mm). Results  Twenty-two articles were included in this study. For polyps ≥ 10 mm, UEMR was inferior to ESD in achieving en bloc resection ( P  = 0.02). However, UEMR had shorter operating time for polyps ≥ 10 mm ( P  < 0.001), and ≥20 mm ( P  = 0.019) with reduced perforation risk for polyps ≥ 10 mm ( P  = 0.05) compared to ESD. In addition, en bloc resection rates were similar between UEMR and EMR, although UEMR had reduced recurrence for polyps ≥ 10 mm ( P  = 0.013) and ≥ 20 mm ( P  = 0.014). UEMR also had shorter mean operating than EMR for polyps ≥ 10 mm ( P  < 0.001) and ≥ 20 mm ( P  < 0.001). Risk of bleeding and perforation with UEMR and EMR were similar for polyp of all sizes. Conclusions  UEMR has demonstrated technical and oncological outcomes comparable to ESD and EMR, along with a desirable safety profile. UEMR appears to be a safe and effective alternative to conventional methods for resection of polyps ≥ 10 mm.

Modified endoscopic mucosal resection techniques for treating precancerous colorectal lesions

Endoscopic mucosal resection (EMR) is a technique allowing efficacious and minimally invasive resection of precancerous lesions across the entire gastrointestinal tract. However, conventional EMR, involving injection of fluid into the submucosal space, is imperfect, given the high rate of recurrence of post-endoscopic resection adenoma, especially after piecemeal resection. In light of these observations, modifications of the technique have been proposed to overcome the weakness of conventional EMR. Some of them were designed to maximize the chance of en bloc resection—cap-assisted EMR, underwater EMR, tip-in EMR, precutting, assisted by ligation device—while others were designed to minimize the complications (cold EMR). In this review, we present their modes of action and summarize the evidence regarding their efficacy and safety.

Underwater vs Conventional Endoscopic Mucosal Resection of Large Sessile or Flat Colorectal Polyps: A Prospective Randomized Controlled Trial

BACKGROUND & AIMS

Conventional endoscopic mucosal resection (CEMR) with submucosal injection is the current standard for the resection of large, nonmalignant colorectal polyps. We investigated whether underwater endoscopic mucosal resection (UEMR) is superior to CEMR for large (20-40mm) sessile or flat colorectal polyps.

METHODS

In this prospective randomized controlled study, patients with sessile or flat colorectal polyps between 20 and 40 mm in size were randomly assigned to UEMR or CEMR. The primary outcome was the recurrence rate after 6 months. Secondary outcomes included en bloc and R0 resection rates, number of resected pieces, procedure time, and adverse events.

RESULTS

En bloc resection rates were 33.3% in the UEMR group and 18.4% in the CEMR group (P = .045); R0 resection rates were 32.1% and 15.8% for UEMR vs CEMR, respectively (P = .025). UEMR was performed with significantly fewer pieces compared to CEMR (2 pieces: 45.5% UEMR vs 17.7% CEMR; P = .001). The overall recurrence rate did not differ between both groups (P = .253); however, subgroup analysis showed a significant difference in favor of UEMR for lesions of >30 mm to ≤40 mm in size (P = .031). The resection time was significantly shorter in the UEMR group (8 vs 14 minutes; P < .001). Adverse events did not differ between both groups (P = .611).

CONCLUSIONS

UEMR is superior to CEMR regarding en bloc resection, R0 resection, and procedure time for large colorectal lesions and shows significantly lower recurrence rates for lesions >30 mm to ≤40 mm in size. UEMR should be considered for the endoscopic resection of large colorectal polyps.

Heat sink effect of underwater polypectomy in a porcine colon model

BACKGROUND

Underwater polypectomy without the need for submucosal injection has been reported. A heat-sink effect by immersing the polyp in water was proposed but no such experiment has been performed to support the claim. We compared the temperature rise on the serosal side during polypectomy between air- and water-filled colon.

METHOD

Freshly harvested porcine colons were placed in a metal tray with cautery electrode pad attached to its bottom. An upper endoscope was used with a cap and a rubber band mounted to the distal end. A mucosal site was randomly selected and identified on its serosal surface with a marker while suction was applied. Suction was applied again and a ligation band was applied to create a polyp. A cautery snare grasped the artificial polyp just below the band. An assistant placed the tip of a thermometer at the marked site on the serosal surface to record the baseline temperature before cautery and the highest temperature during polypectomy. Seven polypectomies in air and underwater were performed.

RESULTS

Mean (standard deviation) baseline temperature were 23.3 (0.6) °C and 23.4 (0.6) °C in the air and water groups, respectively. The maximum rise in temperature during polypectomy was 6.1 (4.5) °C and 1.4 (1.0) °C in the air and water groups, respectively (P = 0.004).

CONCLUSIONS

The maximum temperature rise during polypectomy was significantly less when polypectomy was performed underwater, supporting the hypothesis that a heat-sink effect does exist during underwater polypectomy.

Effectiveness and safety of the different endoscopic resection methods for 10- to 20-mm nonpedunculated colorectal polyps: A systematic review and pooled analysis

BACKGROUND

We performed a systematic review and pooled analysis to assess the effectiveness and safety of different endoscopic resection methods for 10- to 20-mm nonpedunculated colorectal polyps.

METHODS

Articles in PubMed, EMBASE, and the Cochrane Library related to the common endoscopic treatment of 10- to 20-mm nonpedunculated polyps published as of April 2020 were searched. Primary outcomes were the R0 resection rate and en bloc resection rate. Secondary outcomes were safety and the recurrence rate. Meta-regression and subgroup analysis were also performed.

RESULTS

A total of 36 studies involving 3212 polyps were included in the final analysis. Overall, the effectiveness of resection methods with a submucosal uplifting effect, including endoscopic mucosal resection (EMR), cold EMR and underwater EMR (UEMR), was better than that of methods without a nonsubmucosal uplifting effect [R0 resection rate, 90% (95% confidence interval (CI) 0.81-0.94, I² = 84%) vs 82% (95% CI 0.78-0.85, I² = 0%); en bloc resection rate 85% (95% CI 0.79-0.91, I² = 83%) vs 74% (95% CI 0.47-0.94, I² = 94%)]. Regarding safety, the pooled data showed that hot resection [hot snare polypectomy, UEMR and EMR] had a higher risk of intraprocedural bleeding than cold resection [3% (95% CI 0.01-0.05, I² = 68%) vs 0% (95% CI 0-0.01, I² = 0%)], while the incidences of delayed bleeding, perforation and post-polypectomy syndrome were all low.

CONCLUSIONS

Methods with submucosal uplifting effects are more effective than those without for resecting 10- to 20-mm nonpedunculated colorectal polyps, and cold EMR is associated with a lower risk of intraprocedural bleeding than other methods. Additional research is needed to verify the advantages of these methods, especially cold EMR.

Curative value of underwater endoscopic mucosal resection for submucosally invasive colorectal cancer

BACKGROUND AND AIM

Occasionally, colorectal tumors without characteristics of deep submucosal invasion are found to be invasive upon pathological evaluation after endoscopic resection (ER). Because the resection depth for underwater endoscopic mucosal resection (UEMR) has not been clarified, we evaluated the feasibility of UEMR for pathologically invasive colorectal cancer (pT1-CRC).

METHODS

We retrospectively investigated data on the backgrounds and outcomes of patients with pT1-CRC who underwent UEMR between January 2014 and June 2019 at our institute. As a reference standard, the backgrounds and outcomes of pT1-CRCs that had undergone conventional EMR (CEMR) were also investigated.

RESULTS

Thirty-one patients (median age, 68 years [range, 32-88 years]; 22 men [71%]) were treated with UEMR. Median lesion size was 17 mm (range, 6-50 mm). The endoscopic complete resection rate was 100%. The overall en bloc resection rate was 77%, and the VM0, HM0, and R0 resection rates were 81%, 58%, and 55%, respectively. In cases of pT1a (invasion <1000 μm)-CRC (n = 14), the en bloc, VM0, and R0 resection rates were 92%, 100%, and 71%, respectively. Seventeen patients (five with risk factors for lymph node metastasis and 12 without) were followed up, and no local recurrence and distant metastasis were observed during the follow-up period (median follow-up period, 18 months [range, 6-62 months]) after UEMR. The outcomes of UEMR seemed to be comparable with those of CEMR (n = 32).

CONCLUSIONS

The VM0 rate of UEMR for pT1-CRC, especially for pT1a-CRC, without characteristics of deep submucosal invasion seems feasible.

Efficacy and histologic accuracy of underwater versus conventional endoscopic mucosal resection for large (>20 mm) colorectal polyps: a comparative review and meta-analysis

BACKGROUND AND AIMS

Major limitations with conventional EMR (C-EMR) include high rates of polyp recurrence and low en-bloc resection rates, especially for lesions >20 mm in size. Underwater EMR (U-EMR) has emerged as an alternate technique for en-bloc resection of larger lesions. We conducted a systematic review and meta-analysis comparing the efficacy and safety of the 2 techniques.

METHODS

Multiple databases were searched through June 2020 for studies that compared outcomes of U-EMR and C-EMR for colorectal lesions. Meta-analysis was performed to determine pooled odds ratios (ORs) of successful R0, en-bloc, and piecemeal resection of colorectal lesions. We compared the rates of polyp recurrence at follow-up, diagnostic accuracy for colorectal cancer, and adverse events with the 2 techniques.

RESULTS

Eleven studies, including 4 randomized controlled trials (RCTs) with 1851 patients were included in the final analysis. A total of 1071 lesions were removed using U-EMR, and 1049 lesions were removed using C-EMR. Although U-EMR had an overall superior en-bloc resection rate compared with C-EMR (OR, 1.9; 95% confidence interval [CI], 1-3.5; P = .04), both techniques were comparable in terms of polyps >20 mm in size (OR, 0.8; 95% CI, 0.3-2.1; P = .75), R0 resection (OR, 3.1; 95% CI, 0.74-12.6; P = .14), piecemeal resection (OR, 3.1; 95% CI, 0.74-12.6; P = .13), and diagnostic accuracy for colorectal cancer (OR, 1.1; 95% CI, 0.6-1.8; P = .82). There were lower rates of polyp recurrence (OR, 0.3; 95% CI, 0.1-0.8; P = .01) and incomplete resection (OR, 0.4; 95% CI, 0.2-0.5; P = .001) with U-EMR. Both techniques have comparable resection times and safety profiles.

CONCLUSIONS

Our results support the use of U-EMR over C-EMR for successful resection of colorectal lesions. Further randomized controlled trials are needed to evaluate the efficacy of U-EMR for resecting polyps >20 mm in size.

GIE Editorial Board top 10 topics: advances in GI endoscopy in 2020

The American Society for Gastrointestinal Endoscopy's Gastrointestinal Endoscopy Editorial Board reviewed a systematic literature search of original endoscopy-related articles published during 2020 in Gastrointestinal Endoscopy and 10 other high-impact medical and gastroenterology journals. Votes from each individual board member were tallied to identify a consensus list of the 10 most significant topic areas in GI endoscopy over the calendar year of study using 4 criteria: significance, novelty, impact on national health, and impact on global health. The 10 areas identified were as follows: artificial intelligence in endoscopy, coronavirus disease 2019 and GI practice, third-space endoscopy, lumen-apposing metal stents, single-use duodenoscopes and other disposable equipment, endosonographic needle technology and techniques, endoscopic closure devices, advances in GI bleeding management, improvements in polypectomy techniques, and bariatric endoscopy. Each board member contributed a summary of important articles relevant to 1 to 2 topic areas, leading to a collective summary that is presented in this document of the "top 10" endoscopic advances of 2020.

Efficacy of Underwater Endoscopic Mucosal Resection for Nonpedunculated Colorectal Polyps: A Systematic Review and Meta-Analysis

Recently, underwater endoscopic mucosal resection (UEMR) without submucosal injection was introduced as a new replacement for conventional EMR (CEMR) and was reported to be useful for resecting large colonic polyps. Here, we aimed to assess the efficacy and safety of these two methods by a systematic review and meta-analysis. We comprehensively searched multiple databases until July 2021 to identify randomized controlled trials (RCTs) comparing UEMR with CEMR. The primary outcomes were the proportion of R0 resection and mean procedure time, and the secondary outcomes were the proportion of en bloc resection and all adverse events. Three reviewers independently searched for articles, extracted data, and assessed the risk of bias. We evaluated the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation approach. This study was registered in www.protocols.io (Protocol Integer ID: 40849). We included six RCTs (1,374 polyps). We judged that a meta-analysis was not available, and the data were summarized narratively for the proportion of R0 resection. Regarding procedure time, UEMR likely resulted in a large reduction (mean difference = -64.3 seconds; 95% confidence interval (CI) = -122.5 to -6.0 seconds; I2 = 86%; moderate certainty of evidence). UEMR likely resulted in a large increase in en bloc resection (odds ratio = 1.85; 95% CI = 1.15 to 2.98; I2 = 60%; moderate certainty of evidence). Percentages of adverse events were 0-17% with CEMR and 0-16% with UEMR. In summary, UEMR might have higher efficacy than CEMR in the endoscopic resection of nonpedunculated colorectal polyps, with likely a large reduction in procedure time.

Higher rate of en bloc resection with underwater than conventional endoscopic mucosal resection: A meta-analysis

OBJECTIVES

Previous meta-analysis including nonrandomized studies showed marginal benefit of underwater endoscopic mucosal resection(U-EMR) compared to conventional EMR(C-EMR) in terms of polypectomy outcomes. We evaluated U-EMR compared to C-EMR in the treatment of colorectal polyps with respect to effectiveness and safety by analyzing only randomized controlled trials(RCTs).

MATERIAL AND METHODS

PubMed and Cochrane Library databases were searched for RCTs published until 11/2020, evaluating U-EMR vs. C-EMR regarding en bloc resection, post-endoscopic resection adenoma recurrence, complete resection, adverse events rates and difference in resection time. Abstracts from Digestive Disease Week, United European Gastroenterology Week and ESGE Days meetings were also searched. Effect size on outcomes is presented as risk ratio(RR; 95% confidence interval[CI]) or mean difference(MD; 95%CI). The I² test was used for quantifying heterogeneity, while Grading of Recommendations Assessment, Development and Evaluation(GRADE) was used to assess strength of evidence.

RESULTS

Six RCTs analyzing outcomes from 1157 colorectal polypectomies(U-EMR589;C-EMR,568) were included. U-EMR associated with significant higher rate of en bloc resection compared to C-EMR [RR(95%CI):1.26(1.01-1.58); Chi² for heterogeneity=30.43, P<0.0001; I²=84%, GRADE: Very low]. This effect was more prominent regarding resection of polyps sized ≥20 mm compared to polyps <20 mm [RR(95%CI):1.64(1.22-2.20) vs. 1.10(0.98-1.23)]. Post-resection recurrence [RR(95%CI):0.52(0.28-0.94);GRADE:Low] was lower significantly in U-EMR group. In contrast, no significant difference was detected between U-EMR and C-EMR regarding complete resection [RR(95%CI): 1.06(0.91-1.24) GRADE:Very low] and adverse events occurrence[RR(95%CI):1.00 (0.72-1.39); GRADE:Low].

CONCLUSION

Meta-analysis of RCTs supports that U-EMR resection achieves higher rate of en bloc resection compared to conventional EMR. This effect is driven when resecting large(≥20 mm) polyps.

The efficacy and safety of underwater endoscopic mucosal resection for ≥10-mm colorectal polyps: systematic review and meta-analysis

BACKGROUND

Underwater endoscopic mucosal resection (UEMR) is a promising strategy for nonpedunculated colorectal polyp removal. However, the efficacy and safety of the technique for the treatment of ≥ 10-mm colorectal polyps remain unclear. We aimed to comprehensively assess the efficacy and safety of UEMR for polyps sized 10-19 mm and ≥ 20 mm.

METHODS

PubMed, EMBASE, and the Cochrane Library databases were searched for relevant articles from January 2012 to November 2019. Primary outcomes were the rates of adverse events and residual polyps. Secondary outcomes were the complete resection, en bloc resection, and R0 resection rates.

RESULTS

18 articles including 1142 polyps from 1093 patients met our inclusion criteria. The overall adverse event and residual polyp rates were slightly lower for UEMR when removing colorectal polyps of 10-19 mm vs. ≥ 20 mm (3.5 % vs. 4.3 % and 1.2 % vs. 2.6 %, respectively). The UEMR-related complete resection rate was slightly higher for colorectal polyps of 10-19 mm vs. ≥ 20 mm (97.9 % vs. 92.0 %). However, the en bloc and R0 resection rates were dramatically higher for UEMR removal of polyps of 10-19 mm vs. ≥ 20 mm (83.4 % vs. 36.1 % and 73.0 % vs. 40.0 %, respectively). In addition, univariate meta-regression revealed that polyp size was an independent predictor for complete resection rate (P = 0.03) and en bloc resection (P = 0.01).

CONCLUSIONS

UEMR was an effective and safe technique for the removal of ≥ 10-mm nonpedunculated colorectal polyps. However, UEMR exhibited low en bloc and R0 resection rates for the treatment of ≥ 20-mm polyps.

Underwater Endoscopic Mucosal Resection for 10 mm or Larger Nonpedunculated Colorectal Polyps: A Systematic Review and Meta-Analysis

Background/Aims

Recent studies have reported the favorable outcomes of underwater endoscopic mucosal resection (UEMR) for colorectal polyps. We performed a systematic review and meta-analysis evaluating the efficacy and safety of UEMR for nonpedunculated polyps ≥10 mm.

Methods

We performed a comprehensive search of multiple databases (through May 2020) to identify studies reporting the outcomes of UEMR for ≥10 mm nonpedunculated colorectal polyps. The assessed outcomes were recurrence rate on the first follow-up, en bloc resection, incomplete resection, and adverse events after UEMR.

Results

A total of 1276 polyps from 16 articles were included in our study. The recurrence rate was 7.3% (95% confidence interval [CI], 4.3–12) and 5.9% (95% CI, 3.6–9.4) for nonpedunculated polyps ≥10 and ≥20 mm, respectively. For nonpedunculated polyps ≥10 mm, the en bloc resection, R0 resection, and incomplete resection rates were 57.7% (95% CI, 42.4–71.6), 58.9% (95% CI, 42.4–73.6), and 1.5% (95% CI, 0.8–2.6), respectively. The rates of pooled adverse events, intraprocedural bleeding, and delayed bleeding were 7.0%, 5.4%, and 2.9%, respectively. The rate of perforation and postpolypectomy syndrome was 0.8%.

Conclusions

Our systematic review and meta-analysis demonstrates that UEMR for nonpedunculated colorectal polyps ≥10 mm is safe and effective with a low rate of recurrence.

Underwater versus conventional EMR for colorectal polyps: systematic review and meta-analysis

BACKGROUND AND AIMS

Underwater EMR (UEMR) has emerged as an attractive alternative to conventional EMR (CEMR) for the resection of colorectal polyps. The purpose of this systematic review and meta-analysis was to compare UEMR and CEMR for the resection of colorectal polyps with respect to efficacy and safety.

METHODS

A literature search was performed across multiple databases, including MEDLINE/PubMed, The Cochrane Library, CINAHL, Google Scholar, and Scopus, for studies that were published until May 2020. Only studies that compared the resection of colorectal polyps using UEMR with CEMR were included. Outcomes examined included rates of en bloc resection, recurrence, postprocedure bleeding, perforation, and resection time.

RESULTS

Seven studies totaling 1237 polyps were included: 614 polyps were resected with UEMR and 623 polyps with CEMR. UEMR was associated with a significant increase in the rate of overall en bloc resection (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.42-2.39; P < .001; I² = 38%), with subgroup analysis showing a significant increase in the rates of en bloc resection in polyps ≥20 mm (OR, 1.51; 95% CI, 1.06-2.14; P = .02; I² = 44%) but not in polyps <20 mm (OR, 1.07; 95% CI, .65-1.76; P = .80; I² = 27%), and with a significant reduction in the rate of recurrence (OR, .30; 95% CI, .16-.57; P = .0002; I² = 0%), again driven by improvements in polyps ≥20 mm. There was no significant difference in postprocedure bleeding (OR, 1.11; 95% CI, .57-2.17; P = .76; I² = 0%) or perforation (OR, .72; 95% CI, .19-2.83; P = .64; I² = 0%).

CONCLUSIONS

The results of this systematic review and meta-analysis demonstrate that UEMR is a safe and efficacious alternative to CEMR. With appropriate training, UEMR may be strongly considered as a first-line option for resection of colorectal polyps.

Room temperature water infusion during colonoscopy insertion induces rectosigmoid colon mucus production

BACKGROUND

Water filling during colonoscopy improves several colonoscopy outcomes. We evaluated an anecdotal observation that room temperature water filling during colonoscope insertion results in mucus production in the left colon, which may impair mucosal visualization during withdrawal.

METHODS

We performed 55 colonoscopies with either water or saline filling during insertion, and video recorded the examinations. Three blinded observers scored the amount of mucus visible on the video recordings.

RESULTS

29 patients had water filling and 26 patients had saline filling during insertion. Demographic features, procedure indications, volume of infused fluid, and insertion time to the cecum were similar in the two groups. All three blinded observers rated the mucus as greater after water filling than after saline (median 3 out of 5 vs. 1 out of 5; P < 0.001), with a kappa value for interobserver agreement of 0.364 (P < 0.001).

CONCLUSION

Room temperature water filling is associated with mucus production by the rectosigmoid colon, requiring additional cleansing during withdrawal.

Underwater versus conventional endoscopic mucosal resection for colorectal lesions: a systematic review and meta-analysis

Background and study aims  Underwater endoscopic mucosal resection (UEMR) for colorectal polyps has been reported to have good outcomes in recent studies. We conducted a systematic review and meta-analysis comparing the effectiveness and safety of UEMR to conventional EMR (CEMR). Methods  A comprehensive search of multiple databases (through May 2020) was performed to identify studies that reported outcome of UEMR and CEMR for colorectal lesions. Outcomes assessed included incomplete resection, rate of recurrence, en bloc resection, adverse events (AEs) for UEMR and CEMR. Results  A total of 1,651 patients with 1,704 polyps were included from nine studies. There was a significantly lower rate of incomplete resection (odds ratio [OR]: 0.19 (95 % confidence interval (CI), 0.05-0.78, P  = 0.02) and polyp recurrence (OR: 0.41, 95 % CI, 0.24-0.72, P  = 0.002) after UEMR. Compared to CEMR, rates overall complications (relative risk [RR]: 0.66 (95 % CI, 0.48-0.90) ( P  = 0.008), and intra-procedural bleeding (RR: 0.59, 95 % CI, 0.41-0.84, P  = 0.004) were significantly lower with UEMR. The recurrence rate was also lower for large non-pedunculated polyps ≥ 10 mm (OR 0.24, 95 % CI, 0.10-0.57, P  = 0.001) and ≥ 20 mm (OR 0.14, 95 % CI, 0.02-0.72, P  = 0.01). The rates of en bloc resection, delayed bleeding, perforation and post-polypectomy syndrome were similar in both groups ( P  > 0.05). Conclusions  In this systematic review and meta-analysis, we found that UEMR is more effective and safer than CEMR with lower rates of recurrence and AEs. UEMR use should be encouraged over CEMR.

Underwater vs conventional endoscopic mucosal resection in the management of colorectal polyps: a systematic review and meta-analysis

Background  Recently, underwater endoscopic mucosal resection (UEMR) has shown promising results in the management of colorectal polyps. Some studies have shown better outcomes compared to conventional endoscopic mucosal resection (EMR). We conducted this systematic review and meta-analysis to compare UEMR and EMR in the management of colorectal polyps. Methods  We searched several databases from inception to November 2019 to identify studies comparing UEMR and EMR. Outcomes assessed included rates of en bloc resection, complete macroscopic resection, recurrent/residual polyps on follow-up colonoscopy, complete resection confirmed by histology and adverse events. Pooled risk ratios (RR) with 95 % confidence interval were calculated using a fixed effect model. Heterogeneity was assessed by I ² statistic. Funnel plots and Egger's test were used to assess publication bias. We used the Newcastle-Ottawa scale (NOS) for assessment of quality of observational studies, and the Cochrane tool for assessing risk of bias for RCTs Results  Seven studies with 1291 patients were included; two were randomized controlled trials and five were observational. UEMR demonstrated statistically significantly better efficacy in rates of en bloc resection, pooled RR 1.16 (1.08, 1.26), complete macroscopic resection, pooled RR 1.28 (1.18, 1.39), recurrent/residual polyps; pooled RR 0.26 (0.12, 0.56) and complete resection confirmed by histology; pooled RR 0.75 (0.57, 0.98). There was no significant difference in adverse events (AEs); pooled RR 0.68 (0.44, 1.05). Conclusions  This meta-analysis found statistically significantly better rates of en bloc resection, complete macroscopic resection, and lower risk of recurrent/residual polyps with UEMR compared to EMR. We found no significant difference in AEs between the two techniques.

Underwater versus conventional endoscopic mucosal resection for small size non-pedunculated colorectal polyps: a randomized controlled trial : (UEMR vs. CEMR for small size non-pedunculated colorectal polyps)

BACKGROUND

Underwater endoscopic mucosal resection (UEMR) is a recently developed technique and can be performed during water-aided or ordinary colonoscopy for the treatment of colorectal polyps. The objective of this clinical trial was to evaluate the efficacy and safety of UEMR in comparison with conventional endoscopic mucosal resection (CEMR) of small non-pedunculated colorectal polyps.

METHODS

Patients with small size, non-pedunculated colorectal polyps (4-9 mm in size) who underwent colonoscopic polypectomy were enrolled in this multicenter randomized controlled clinical trial. The patients were randomly allocated to two groups, an UEMR group and a CEMR group. Efficacy and safety were compared between groups.

RESULTS

In the intention-to-treat (ITT) analysis, the complete resection rate was 83.1% (59/71) in the UEMR group and 87.3% (62/71) in the CEMR group. The en-bloc resection rate was 94.4% (67/71) in the UEMR group and 91.5% (65/71) in the CEMR group (difference 2.9%; 90% CI - 4.2 to 9.9%), showed noninferiority (noninferiority margin - 5.7% < - 4.2%). No significant difference in procedure time (81 s vs. 72 s, P = 0.183) was observed. Early bleeding was observed in 1.4% of patients in the CEMR group (1/71) and 1.4% of patients in the UEMR group (1/71). None of the patients in the UEMR group complained of postprocedural bloody stool, whereas two patients in the CEMR group (2/64) reported this adverse event.

CONCLUSION

Our results indicate that UEMR is safer and just as effective as CEMR in En-bloc resection for the treatment of small colorectal polyps as such, UEMR is recommended as an alternative approach to excising small and non-pedunculated colorectal adenomatous polyps.

TRIAL REGISTRATION

Clinical Trials.gov, NCT03833492 . Retrospectively registered on February 7, 2019.