Rapid advances in artificial intelligence and machine learning technologies have revolutionized the software development domain. These technologies are also applied to software used as medical devices, such as computer-aided diagnosis (CAD) used in the field of gastroenterological endoscopy. Some CAD programs have received regulatory approval from the Pharmaceuticals and Medical Devices Agency (PMDA) in Japan. Further development of CAD is anticipated; and yet at the same time, regulatory issues associated with clinical implementation need attention. In this article, we present an overview of the current scenario with regard to regulatory approval by the PMDA for the application of software as a medical device.

Endoscopy is widely performed in Japan and has made a significant contribution to the diagnosis of organic diseases. However, endoscopy is used only to rule out the diagnosis of organic diseases in cases of functional disorders. Achalasia is a major esophageal motility disorder, and recent studies have reported new endoscopic findings, including esophageal rosette, gingko-leaf sign, champagne glass sign, and pinstripe pattern in patients with achalasia. Therefore, endoscopy is increasingly being recognized as a useful diagnostic modality in cases of suspected achalasia. Endoscopic findings of spiral contractions, multiple simultaneous contractions, and esophageal narrowing with reduced distensibility may also indicate an esophageal motility disorder in patients with dysphagia. Esophageal evaluation with the endoscope fixed in the middle section of the esophagus is important for accurate diagnosis of esophageal motility disorders. High-resolution manometry (HRM) is the gold standard for the diagnosis of achalasia; however, its diagnostic accuracy is not absolute. Therefore, clinicians should consider esophageal motility disorder in patients who present with dysphagia, and comprehensive evaluation using endoscopy, esophagography, and HRM should be performed for accurate diagnosis.

AIM: To investigate the risk factors associated with aspiration pneumonia (AP) during the perioperative period following ESD for gastric tumors.

METHODS: Between 2014 and 2017, 393 patients (422 lesions) underwent ESD for gastric tumors at our hospital. Of these, 15 patients (group A) developed AP during the perioperative period following ESD, and 378 patients did not show this complication. Patients’ backgrounds and course during hospitalization were retrospectively compared.

RESULTS: The number of patients with findings of cardia opening was significantly higher in group A. We observed no significant intergroup differences in age, medical history, treatment duration, antibiotic prophylaxis, or overtube use. Treatment discontinuation due to pneumonia was not observed in any patient, and there was no significant difference in the length of hospital stay.

CONCLUSION: Open cardia was a significant risk factor for AP during the perioperative period following gastric ESD. Close attention is important to monitor the onset of AP during the perioperative period in patients with the aforementioned risk factor.

A woman in her 80s, who was fed through a gastrostomy tube because of cerebral infarction sequelae, developed two episodes of vomiting after she received enteral nutrition. A back flow of blood components through the gastrostomy tube was observed when the clamp of the tube was released; therefore, she was transferred to our hospital on an emergency basis. Upper gastrointestinal endoscopy revealed multiple submucosal hematomas with air bubbles, which extended from the middle to the lower esophagus. Some hematomas had already ruptured and the remaining were easily ruptured following endoscopic manipulation. The bleeding was venous in origin, and endoscopic hemostasis was not performed. Abdominal computed tomography (CT) performed after endoscopy revealed mild thickening of the esophageal wall and gas in the portal veins. Endoscopy performed the following day revealed rupture of most hematomas with reduction in the number of hematomas. On the third day of hospitalization, the patient resumed enteral nutrition through the gastrostomy tube without complications. CT performed on the fourth day of hospitalization revealed disappearance of gas in the portal veins. Endoscopy performed on the fifth day revealed disappearance of the hematomas, with only partial erosion of the esophageal mucosa. Therefore, the patient was discharged on the sixth day of hospitalization. Endoscopy performed after discharge (on the 19^th day of hospitalization.) revealed no abnormal findings in the esophagus. We report a rare case of multiple spontaneous esophageal submucosal hematomas containing air bubbles associated with gas in the portal veins.

An 82-year-old man with a history of left thoracolaparotomic lower esophagectomy and proximal gastrectomy for esophageal cancer, as well as right renal cancer and bladder cancer surgery visited our hospital with hematemesis. Electrocardiography revealed inferior wall ST-segment elevation and anterior wall ST-segment depression, and he was diagnosed with ST-segment elevation myocardial infarction and upper gastrointestinal bleeding. Endoscopic hemostasis was performed prior to cardiac catheterization. Exposed blood vessels were observed on the jejunal aspect of the anastomotic segment between the interposed jejunum and the residual stomach, and hemostasis was performed. During cardiac catheterization, the right coronary artery (the 4AV branch) showed complete occlusion. Rebleeding from the site of endoscopic hemostasis was observed following attempts to widen the #4AV branch. Therefore, we concluded that the exposed blood vessels at the site of the anastomotic ulcer represented the #4AV branch. The Graftmaster stent system (2.75 × 16 mm) was inserted into the #3-#4PD branch for hemostasis.

To date, no study has reported an anastomotic ulcer penetrating the right coronary artery; we describe this rare phenomenon in this case report.

Pyloric gland adenoma is a rare neoplasm of the gastrointestinal tract that shows gastric pyloric gland differentiation and commonly occurs in the gastric body in older patients. A 78-year-old man was diagnosed with a submucosal tumor-like lesion with a well-defined depression in the anterior wall of the gastric body. White light endoscopy revealed a villous or papillary microstructures with branched extended vessels. Blue laser imaging using magnification revealed small, slightly irregular vessels. Endoscopic submucosal dissection was performed, and histopathological evaluation of the resected specimen confirmed the diagnosis of an inverted pyloric gland adenoma. An inverted pyloric gland adenoma is rare, and the lesion showed a peculiar appearance in our patient. Pyloric gland adenomas share phenotypic features with other low-grade tumors of gastric phenotype such as fundic gland type adenocarcinoma. Our case report highlights important features associated with cellular differentiation of low-grade gastric tumors and the endoscopic diagnosis of such lesions.

A pancreatic pseudocystocolonic fistula is rare. We report a case of a 53-year-old man who was transferred to the emergency department after a syncopal episode. He observed intermittent hematochezia one week prior to presentation and was diagnosed with internal hemorrhoids. Rectal examination, blood investigation results, and esophagogastroduodenoscopy did not reveal any significant abnormalities. After admission, we observed hematochezia accompanied by clots. Colonoscopy performed on day 2 of hospitalization revealed a large submucosal tumor-like eminence accompanied by a reddish membrane in the transverse colon (T/C). Computed tomography revealed a pancreatic pseudocyst concomitant with a large splenic aneurysm that compressed the T/C. Embolization was scheduled on day 3 of hospitalization; however, the patient developed acute abdominal pain and massive hematochezia accompanied by clots at midnight on day 2 and was transferred to another hospital to undergo an emergency operation. Histopathological evaluation showed the T/C penetration by a pancreatic pseudocyst concomitant with a splenic aneurysm. Major complications of pancreatic pseudocysts include infection, gastric outlet or biliary obstruction, bleeding, and perforation of adjacent organs. Based on findings reported in previous studies, a pancreatic pseudocystocolonic fistula refers to fistula formation at the splenic flexure. However, a submucosal tumor-like eminence without pulsations is observed in patients in whom the penetration of adjacent organs does not lead to fistula formation. Therefore, clinicians should consider a pancreatic pseudocystocolonic fistula in the differential diagnosis in patients who show a relatively large submucosal tumor-like eminence without pulsations at the splenic flexure.

Pancreatobiliary endoscopic treatment using balloon-assisted endoscopes for pancreatobiliary diseases in patients with surgically altered anatomy (excluding Billroth I procedure) has become a widespread first-line treatment method since it became covered by national health insurance in 2016. However, there are many technical difficulties, and the procedural success rate varies among institutions; moreover, the procedure has not yet been standardized. In this article, the tips for pancreatobiliary endoscopic treatment using balloon-assisted endoscopes (especially double-balloon endoscopes) and troubleshooting for technically difficult cases and adverse events are described.

Widespread application of colonoscopy has enhanced endoscopic detection and removal of colorectal tumors. Endoscopic snare resection is a safe, effective, and time-saving procedure for removing neoplasms measuring ≤ 20 mm. Lately, ESD is being widely used as a standardized technique for the resection of lesions larger than 20 mm and those with possible submucosal fibrosis or submucosal invasion. However, ESD is a challenging procedure owing to a high risk of adverse events, technical difficulties, prolonged operative time, and high medical costs. Hybrid ESD is a recently developed technique that combines the snare resection and ESD procedures. Previously, a hybrid ESD procedure required several devices, including ESD knives and snares. Presently, a newly launched, multifunctional SOUTEN^Ⓡ device enables completion of a hybrid ESD procedure using only a single device. This device can potentially overcome drawbacks of ESD and enhance benefits of snare resection. In this article, we have outlined the technical tips and discussed the potential indications for hybrid ESD using the SOUTEN^Ⓡ device.

Background and Aim: Colonic diverticulosis (CD) has been reported to be associated with presence of colon neoplasms (CNs) in Western patients, since most of the associated risk factors are common between them. However, such correlation has not been fully investigated in Asian patients. In this study, the association of CNs with CD was evaluated in a multicenter investigation.

Methods: We enrolled 5633 patients who underwent both colonoscopy and esophagogastroduodenoscopy due to annual follow-up, screening for positive occult blood testing and abdominal symptoms between January 2016 and December 2017 at three institutions. The relationship between the presence of CNs and CD was investigated, and predictors for presence of CNs were determined by multivariate logistic analysis.

Results: The enrolled patients consisted of 1799 (31.9％) with CD (average age 70.0 years, male 64.0％) and 3834 without CD (66.0 years, male 52.9％), with the prevalence of CNs in those groups 46.6％ and 44.2％, respectively (P ＝ 0.090). 　Predictors for early colon cancer were shown to be age (OR 1.02, 95％ CI 1.01-1.04, P ＝ 0.010), laxatives use (OR 1.76, 95％ CI 1.17-2.64, P ＝ 0.007), gastric neoplasms (OR 2.16, 95％ CI 1.23-3.81, P ＝ 0.008), and CD (OR 1.64, 95％ CI 1.16-2.31, P ＝ 0.005). 　Early colon cancer in the distal colon was most frequently detected in patients with right-sided CD (RR 2.50, P ＝ 0.001).

Conclusion: In Japanese patients, early colon cancer was more frequently found in those with as compared to those without CD. The presence of CD may be an important indicator for an index colonoscopy examination to detect colon cancer. (Clinical-trial-registry: UMIN000038985).