Underwater endoscopic mucosal resection (UEMR) was proposed by Binmoeller et al. in 2012, and has gradually become popular in Japan as increasing evidence has been reported. In this article, we extracted 119 English articles on UEMR for colorectal tumors from PubMed, categorized them according to lesion characteristics, and examined their efficacy and safety. The results showed that UEMR was comparable to conventional EMR (CEMR) for colorectal tumors < 10 mm and occasionally superior to CEMR for tumors 10-20 mm in size, with the trend being more pronounced for tumors > 20 mm. While ESD was superior in the en bloc resection rate for colorectal tumors > 20 mm, the difference in the recurrence rate was smaller, and UEMR was superior in procedure time and safety, making it an alternative to ESD for tumors 20-30 mm in diameter under certain conditions. UEMR also shows better outcomes than CEMR for recurrent lesions after endoscopic treatment and is comparable to ESD. Although simpler and more promising results have been reported for rectal neuroendocrine tumors with UEMR than with ESD, the effectiveness of UEMR over endoscopic submucosal resection with a ligation device is unknown and further evidence is needed.

The current evidence suggests that UEMR is not a complete replacement for conventional procedures, but it can be considered one option according to the endoscopistsʼ preference. As UEMR becomes more widespread, its true value will be shown.

Upper gastrointestinal endoscopy identified an erythematous, depressed lesion in the lower gastric body of a 71-year-old Japanese male who had previously undergone curative resection for early gastric cancer 16 years ago, along with Helicobacter pylori eradication. Following biopsy confirmation of adenocarcinoma, ESD was performed, revealing a well-differentiated tubular adenocarcinoma (tub1) located in the mucosa, with submucosal ectopic gastric glands immediately beneath it.

The majority of these ectopic gastric glands exhibited no cytological atypia; however, a small focus of tub1 was detected within the ectopic glands. Immunohistochemistry demonstrated that intramucosal tub1 exhibited an intestinal phenotype, whereas ectopic glands, including focal tub1, displayed a gastric phenotype.

To the best of our knowledge, this case is the first reported instance of ESD-resected early gastric cancer indicating the coexistence of phenotypically distinct intramucosal tub1 and focal tub1 within the submucosal ectopic gastric glands.

A 79-year-old male patient was admitted to the hospital with hematemesis and hemorrhagic shock. Emergency endoscopy revealed an A1 stage ulcer with exposed blood vessels on the posterior wall of the cardia and lesser curvature of the upper gastric body. Hemostasis was achieved via electrostatic coagulation using hemostatic forceps. Following hemostasis, contrast-enhanced CT revealed portal venous gasemia and gastric mucosal edema. Conservative management resulted in portal venous gas resolution without intestinal necrosis. Portal venous gasemia, a potential indicator of various gastrointestinal disorders, is often associated with poor prognosis when caused by intestinal necrosis. In this case, portal venous gasemia probably occurred during electrocoagulation hemostasis for the deep gastric ulcer. Air may have entered the portal vein from an exposed blood vessel because of the increased intragastric pressure resulting from air insufflation. Although rare, portal venous gasemia can occur during gastric ulcer hemostasis; therefore, CO₂ insufflation is recommended to mitigate the risk of air embolism in the lungs and cerebrovascular vessels.

A 69-year-old man underwent laparoscopic total gastrectomy with Roux-en-Y reconstruction for gastric cancer. He was subsequently readmitted for hematemesis and hemorrhagic stool. Emergency EGD and CS failed to reveal any bleeding foci. Massive gastrointestinal bleeding recurred on hospital day 10, and EGD through the Roux-en-Y anastomosis revealed a hemorrhagic ulcer at the duodenal stump. CT and angiography revealed no evidence of pseudoaneurysm. Continued endoscopic shielding with polyglycolic acid sheets and fibrin glue improved the ulcer, and the patient was discharged on hospital day 40. Bleeding from the duodenal stump should be considered in patients with postoperative gastrointestinal bleeding after gastrectomy with Roux-en-Y reconstruction.

A 76-year-old woman was diagnosed with multiple colonic tumors via colonoscopy. However, owing to a redundant colon, cecal intubation could not be achieved at the previous hospital. The patient was subsequently referred to our hospital. We attempted by endoscopic treatment using a single-balloon overtube, but despite this assistance, scope insertion was limited to the sigmoid colon. Consequently, we performed EMR/ESD on lesions located in the sigmoid colon. For the proximal colon lesions, we switched to using double-balloon endoscopy (DBE). Using DBE, ESD was successfully performed on three lesions in the ascending and transverse colon. A protruded lesion, 30-mm diameter, was observed in the hepatic flexure and was accessible by DBE; however, it was challenging to treat endoscopically because of extremely poor scope maneuverability. We opted for a motorized spiral endoscope to approach the hepatic flexure lesion. The motorized spiral endoscope significantly improved scope maneuverability, allowing en bloc resection of the lesion. Histopathological analysis confirmed the diagnosis of adenocarcinoma (tub1) arising from adenoma, with findings of pTis, Ly0, V0, pHM0, and pVM0.

ESD has become the standard treatment for early gastric cancer, and this technique has matured significantly over the years. However, perforation remains a major adverse event that can result in fatal outcomes. The multi-bending endoscope used for ESD allows close proximity to the dissection area by adjusting the up-and-down angles of the second bending section and contributes to improved safety and speed of submucosal dissection by maintaining parallelity of the high-frequency knife to the muscular layer. In addition, this endoscope has dual channels, thus allowing for the selective use of the left and right forceps channels during mucosal incision and submucosal dissection, as well as maintaining suction power during procedures. This article provides a detailed explanation of gastric ESD techniques using a multi-bending endoscope.

Objectives: Colonoscopy withdrawal times are associated with the adenoma detection rate (ADR). However, the relationship between ADR and cecal insertion time has been inadequately characterized. We aimed to evaluate endoscopist-related factors involved in the ADR, including the average individual colonoscopy insertion and withdrawal times.

Methods: This observational study used a colonoscopy database with pathology data from routine clinical practice in Japanese institutions. The odds ratios (OR) of endoscopist-related factors related to ADRs were examined using a generalized linear mixed model.

Results: Of the 186,293 colonoscopies performed during the study period, 47,705 colonoscopies by 189 endoscopists in four hospitals were analyzed for ADR. The overall ADR was 38.3% (95% confidence interval [CI] 37.8, 38.7). Compared to endoscopists with mean cecal insertion times of < 5 min, the OR of ADR for those with mean cecal insertion times of 5-9, 10-14, and ≥15 min were 0.84 (95% CI 0.71, 0.99), 0.68 (95% CI 0.52, 0.90), and 0.45 (95% CI 0.25, 0.78), respectively. Compared to endoscopists with mean withdrawal times of < 6 min, the OR of ADR for those with mean withdrawal times of 6-9, 10-14, and ≥15 min were 1.38 (95% CI 1.03, 1.85), 1.48 (95% CI 1.09, 2.02), and 1.68 (95% CI 1.04, 2.61), respectively. There were no significant differences in ADRs by endoscopist specialty, gender, or the total number of examinations performed.

Conclusion: Individual mean colonoscopy insertion time was associated with ADR and might be considered as a colonoscopy quality indicator as well as withdrawal time.

Trial registration: This study was registered in the University Hospital Medical Information Network as UMIN000040690.