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.

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.

Objective: To perform a systematic review and meta-analysis evaluating the efficacy of middle meningeal artery embolization in terms of both clinical and radiographic outcomes, when performed with different embolic agents. Methods: A systematic literature review and meta-analysis was performed to evaluate the impact of embolic agents on outcomes for middle meningeal artery (MMA) embolization. The use of polyvinyl alcohol (PVA) with or without (±) coils, N-butyl cyanoacrylate (n-BCA) ± coils, and Onyx alone were separately evaluated. Primary outcome measures were recurrence, the need for surgical rescue and in-hospital periprocedural complications. Results: Thirty-one studies were identified with a total of 1,134 patients, with 786 receiving PVA, 167 receiving n-BCA, and 181 patients receiving Onyx. There was no difference in the recurrence rate (5.5% for PVA, 4.5% for n-BCA, and 6.5% for Onyx, with P=0.71) or need for surgical rescue (5.0% for PVA, 4.0% for n-BCA, and 6.9% for Onyx, with P=0.89) based on the embolic agent. Procedural complications also did not differ between embolic agents (1.8% for PVA, 3.6% for n-BCA, and 1.6% for Onyx, with P=0.48). Conclusions Rates of recurrence, need for surgical rescue, and periprocedural complication following MMA embolization are not impacted by the type of embolic agent utilized. Ongoing clinical trials may be used to further investigate these findings.