Byung Moo Yoo

Ajou University · Department of Gastroenterology

Considering the critical roles of cancer-associated fibroblasts (CAFs) in pancreatic cancer, recent studies have attempted to incorporate stromal elements into organoid models to recapitulate the tumor microenvironment. This study aimed to evaluate the feasibility of patient-derived organoid (PDO) and CAF cultures by using single-pass endoscopic ul...

Clearance of a difficult biliary stone can be obtained using various interventional techniques such as endoscopic sphincterotomy followed by endoscopic papillary large balloon dilation, mechanical lithotripsy, peroral cholangioscopy-assisted intraductal electrohydraulic/laser lithotripsy, temporary plastic stent insertion, percutaneous transhepatic...

Background Endoscopic access to the targeted site is a major challenge for the endoscopic retrograde cholangiopancreatography (ERCP) in patients undergoing Roux-en-Y (R-Y) reconstruction after total or subtotal gastrectomy. We aimed to evaluate the feasibility, reproducibility, and safety of mechanistic loop resolution strategies using a short-type...

Background Drain fluid amylase is commonly used as a predictor of pancreatic fistula after pancreaticoduodenectomy (PD). This study aimed to determine the ideal cut-off value of drain fluid amylase on postoperative day 1 (DFA1) for predicting pancreatic fistula after pancreaticogastrostomy (PG). Methods Prospective data of 272 consecutive patients...

Detection rates of pancreatic cystic lesions (PCLs) have increased, resulting in greater requirements for regular monitoring using imaging modalities. We aimed to evaluate the capability of ultrasonography (US) for morphological characterization of PCLs as a reference standard using endoscopic ultrasonography (EUS). A retrospective analysis was con...

Endoscopic retrograde cholangiopancreatography (ERCP) in patients who have undergone a Billroth II gastrectomy is a major challenge. This study aimed to evaluate the outcomes of the road-map technique for duodenal intubation using a side-viewing duodenoscope for ERCP in Billroth II gastrectomy patients with naïve papilla, and to analyze the formati...

Background and Aim Transpapillary biliary forceps biopsy (TBFB) is a common method to obtain histological evidence for the differential diagnosis of biliary stricture. This study aimed to evaluate the factors associated with a positive cancer diagnosis from TBFB and the number of tissue samples required to increase the diagnostic yield in patients...

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Endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) has been performed as an alternative to percutaneous drainage in surgically high-risk patients. Technical failures of EUS-GBD made by beginners are often attributed to failure of over-the-wire insertion of a fistula-dilating device or stent delivery system into the gallbladder, or stent mi...

Background: A radical surgery is mandatory for advanced gallbladder cancer. However, the appropriate surgical procedure for T2 gallbladder cancer remains controversial because of the difficulty associated with accurate preoperative diagnosis. The aims of the study were to analyze the clinicopathologic features of patients diagnosed with T2 gallbla...

Background and Aim Although endoscopic papillary large balloon dilation (EPLBD) has been widely used to facilitate the removal of difficult common bile duct stones; however, the outcomes have not yet been investigated in terms of the diameter of the balloon used. We aimed to compare the clinical outcomes between EPLBD using smaller (12‐15 mm, S‐EPL...

Background/aims: Little evidence is available about the effect of change in nonalcoholic fatty liver disease (NAFLD) status on risk of diabetes mellitus (DM) development. In this study, we tried to analyze the DM risk according to change in NAFLD status over time. Methods: Among a total of 10,141 individuals for whom routine healthcare assessmen...

Background/aims: Barcelona clinic liver cancer (BCLC) C stage demonstrates considerable heterogeneity because it includes patients with either symptomatic tumors (performance status [PS], 1-2) or with an invasive tumoral pattern reflected by the presence of vascular invasion (VI) or extrahepatic spread (EHS). This study aimed to derive a more rele...

Background/aims: The mucosal healing process after endoscopic submucosal dissection (ESD) is mostly scarring change (flat type), but a protruded lesion is occasionally found. We investigated the factors influencing the mucosal healing process, such as the flat and protruded types. Methods: A total of 2,096 ESD cases were performed from February...

Background Several animal and human studies have reported that sphincter of Oddi (SO) motility shows cyclical changes during the fasting state. However, to date, the relationship between the SO motility and the migrating motor complex (MMC) of the small bowel (SB) remains unclear in humans. Aims We observed SO motility over a long study period and...

Background: Endoscopic ultrasound (EUS)-guided tissue acquisition has become the most effective method of obtaining specimens from a solid lesion adjacent to the gastrointestinal tract. No data exist regarding the use of a stylet in the core biopsy needle during EUS-guided tissue acquisition. The aims of this study were to evaluate the feasibility...

Background/aims: Although endoscopic bilateral stent-in-stent placement is challenging, many recent studies have reported promising outcomes regarding technical success and endoscopic reintervention. This study aimed to evaluate the technical feasibility of stent-in-stent placement using large cell-type stents in patients with inoperable malignant...

Background: Wire-guided cannulation has been widely accepted as a useful technique for achieving selective biliary access because it has significantly increased the success rate of biliary cannulation compared with conventional contrast-assisted cannulation. Unlike conventional guidewires with a straight tip, a loop-tip guidewire (LGW) has a close...

Objectives: Recurrence of primary common bile duct (CBD) stone commonly occurs after complete removal of CBD stones in patients with cholecystectomy. This study aimed to investigate potential risk factors for the recurrence of primary CBD stones after endoscopic treatment. Materials and methods: Between January 2005 and December 2015, the endoscopi...

The rendezvous approach is a salvage technique after failure of endoscopic retrograde cholangiography (ERC). In certain circumstances, percutaneous-endoscopic rendezvous (PE-RV) is preferred, and endoscopic ultrasound-guided rendezvous (EUS-RV) is difficult to perform. We aimed to evaluate PE-RV outcomes, describe the PE-RV techniques, and identify...

Early post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) prediction may allow safe same-day outpatients discharge after ERCP and earlier proper management. This study aimed to assess the usefulness of the 4-hour post-ERCP serum amylase and lipase levels for PEP early prediction and to investigate predictive cut-off values...

Background: Although sorafenib is the only available drug with proven efficacy for patients with advanced hepatocellular carcinoma (HCC), the clinical efficacy of sorafenib is variable and unpredictable. The aim of the current study was to identify potential serum biomarkers predicting cancer progression and overall survival (OS) in patients with...

Objectives: This study was performed to evaluate long-term outcome of indeterminate nodules detected on cirrhotic liver and to develop risk prediction model for hepatocellular carcinoma (HCC) progression of indeterminate nodules on hepatitis B virus (HBV)-related cirrhotic liver. Methods: Indeterminate nodules up to 2 cm with uncertain malignant...

Background . The aim of this study was to compare the outcomes of the endoscopic hands-off technique and the conventional technique when repositioning an endoscopic nasobiliary drainage (ENBD) tube from the mouth to the nose. Methods . We conducted a retrospective cohort study of all endoscopic retrograde cholangiopancreatographies (ERCPs) performe...

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Objectives: Wnt/β-catenin signaling has a pivotal role in the pathogenesis of hepatocellular carcinoma (HCC). The present study aimed to determine whether genetic variation in the Wnt/β-catenin signaling pathway is associated with the development and/or progression of HCC and the survival of patients with hepatitis B virus (HBV)-associated HCC. D...

The aim of this study was to explore novel genomic biomarkers predicting hepatocellular carcinoma (HCC) prognosis by integrative analysis of DNA copy number aberrations (CNAs) and gene expression profiles. Array comparative genomic hybridization and expression array were performed on 45 and 31 HCC samples, respectively. To identify functionally imp...

Objective: Endoscopic transpapillary gallbladder drainage using a nasocystic tube or plastic stent has been attempted as an alternative to percutaneous drainage for patients with acute cholecystitis who are not candidates for urgent cholecystectomy. We aimed to assess the efficacy of single-step endoscopic drainage of the common bile duct and gall...

Background In cases of difficult bile duct cannulation, the use of wire-guided cannulation over a pancreatic stent (WGC-PS) or the double guidewire technique (DGT) may facilitate biliary cannulation. The aim of this study was to compare the outcomes of WGC-PS and DGT in patients with difficult biliary cannulation. Methods We conducted a retrospect...

Objectives: The objective of our study was to compare the diagnostic yield of endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) using a 25-gauge needle and ultrasound (US)-guided core needle biopsy (CNB) using an 18-gauge core needle for diagnosis of solid pancreatic lesions. Methods: This retrospective study was approved by our In...

Background Biopsy needles have recently been developed to obtain both cytological and histological specimens during endoscopic ultrasound (EUS). We conducted this study to compare 22-gauge (G) fine needle aspiration (FNA) needles, which have been the most frequently used, and new 25G fine needle biopsy (FNB) needles for EUS-guided sampling of solid...

Cholecystectomy is necessary for the treatment of symptomatic or complicated gallbladder (GB) stones, but oral litholysis with bile acids is an attractive alternative therapeutic option for asymptomatic or mildly symptomatic patients. This study was conducted to evaluate the efficacy of magnesium trihydrate of ursodeoxycholic acid (UDCA) and chenod...

We investigated the association between serum interleukin (IL)-8 levels and post-transarterial chemoembolization (TACE) outcomes in patients with hepatitis B virus (HBV)-associated HCC. We enrolled 119 TACE-treated patients with HBV-associated HCC; TACE refractoriness and liver transplantation (LT)-free survival were evaluated during follow-up. Pre...

Covered self-expandable metal stents (SEMSs) are increasingly used as alternatives to uncovered SEMSs for the palliation of inoperable malignant distal biliary obstruction to counteract tumor ingrowth. We aimed to compare the outcomes of partially covered and uncovered SEMSs with identical mesh structures and anti-migration properties, such as low...

We evaluated the efficacy of tenofovir (TDF)-based rescue therapy and compared the outcomes of TDF monotherapy and TDF-based nucleoside analog (NA) combination therapy in patients with suboptimal response (SOR) to adefovir (ADV) with or without NAs in lamivudine (LAM)-resistant chronic hepatitis B. All study subjects received ADV with or without NA...

Background and study aims: Endoscopists sometimes face paradoxical cases in which the endoscopic submucosal dissection (ESD) specimen reveals a non-neoplastic pathology result. The aims of the study were to determine the reasons for such results, and to compare the endoscopic characteristics of non-neoplastic and conventional neoplastic pathology g...

Solid pseudopapillary neoplasm (SPN) is a rare exocrine tumor of the pancreas with low malignant potential. This study was designed to evaluate surgical outcome of solid pseudopapillary neoplasm (SPN). From Between January 1994 to November 2013, 41 patients were diagnosed with SPN of the pancreas at Ajou University Medical Center and underwent surg...

Objectives: Inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) is associated with various diseases. We evaluated the diagnostic and prognostic significance of serum ITIH4 levels in healthy controls and patients with chronic hepatitis B (CHB), hepatitis B virus (HBV)-related liver cirrhosis, and HBV-related hepatocellular carcinoma (HCC). Design...

Endoscopic papillary large balloon dilation (EPLBD) with endoscopic sphincterotomy (EST) has been widely used as the alternative to EST along with endoscopic mechanical lithotripsy (EML) for the removal of large or difficult bile duct stones. Furthermore, EPLBD without EST was recently introduced as its simplified alternative technique. Thus, we sy...

Self-expandable metal stents are an alternative to preoperative and palliative colostomy for patients with malignant colorectal obstruction. However, self-expandable metal stent placement is considered unsuitable or contraindicated for patients with malignant lower rectal obstruction within 5 cm of the anal verge because the exposed stent portion c...

Background/aims: Most efforts to minimize pancreatic fistula after distal pancreatectomy (DP) have been focused on techniques of pancreatic transection and management of the pancreatic remnant. However, an ideal method of handling remnant pancreas after resection does not exist. This study evaluates surgical outcome of DP and describes how to redu...

Aim: To introduce robotic cholecystectomy (RC) using new port sites on the low abdominal area. Methods: From June 2010 to June 2011, a total of 178 RCs were performed at Ajou University Medical Center. We prospectively collected the set-up time (working time and docking time) and console time in all robotic procedures. Results: Eighty-three pa...

Background/aims: This study was designed to investigate clinicopathological features of patients who underwent endoscopic snare papillectomy (ESP) and to suggest how to manage patients after the procedure according to the pathological findings. Methodology: Seventy-nine patients underwent ESP for ampullary tumors in 7 tertiary medical centers in...

Background Endoscopic sphincterotomy (EST) combined with large-balloon dilation (LBD) has been proposed as an alternative to manage large bile duct stones. However, recent reports indicate that LBD without EST may be safe and effective in this setting. Methods One hundred thirty-one patients with large common bile duct (CBD) stones 12 mm in size o...

Goals: To identify predictive factors associated with the presence of missed synchronous lesions after endoscopic submucosal dissection (ESD) for gastric adenoma or early gastric cancer (EGC). Background: Secondary gastric neoplasms that develop during follow-up period after ESD for gastric adenoma or EGC are divided into metachronous lesions an...

Biopsy specimens are taken during transnasal esophagogastroduodenoscopy with 1.8 mm forceps. The aims of this study were to compare the concordance of the Campylobacter-like organism (CLO) test and histological diagnoses between biopsies taken with 1.8 mm and 2.2 mm forceps and to determine whether the concordance of the CLO test could be improved...

Endoscopic submucosal dissection (ESD) enables en bloc resection of larger gastric neoplasms. However, the procedure is associated with a high incidence of perforation. Perforations during ESD are divided into macro- and microperforations. Although both types of perforations could cause widespread tissue injury and secondary sepsis, very little is...

The placement of self expandable metal stent (SEMS) is one of the palliative therapeutic options for patients with unresectable malignant biliary obstruction. The aim of this study was to compare the effectiveness of a covered SEMS versus the conventional plastic stent. We retrospectively evaluated 44 patients with unresectable malignant biliary ob...

The aims of this study were to determine the changes in serum histologic surrogate markers and to identify the serum markers predicting treatment response in patients with chronic hepatitis B (CHB) during entecavir treatment. Sixty CHB patients who received entecavir for 12 months were included. We assessed serum markers of liver fibrosis and/or in...

Endoscopic sphincterotomy may be limited in Billroth II gastrectomy because of difficulty in orientating the duodenoscope and sphincterotome as a result of altered anatomy. This study was planned to investigate the efficacy and safety of endoscopic transpapillary large balloon dilation (EPBD) without preceding sphincterotomy for removal of large CB...

Bile leaks remain a significant cause of morbidity for patients undergoing laparoscopic cholecystectomy. Leakage from an injured duct of Luschka (subvesical duct) follows the cystic duct as the most common cause of postcholecystectomy bile leaks. Although endoscopic sphincterotomy, plastic-stent placement, or nasobiliary-drain placement are effecti...

Although still controversial, bilateral stenting may be the best option for palliative drainage of malignant hilar biliary obstruction. The aim of our study was to evaluate the technical and clinical efficacies of endoscopic bilateral metal stenting using a biliary Y-stent for the management of malignant hilar obstruction. This prospective, uncontr...

Although pancreatic stent insertion is recommended for the prevention of post-procedure pancreatitis during endoscopic papillectomy, insertion of the stent after the procedure can be technically difficult. The aim of the present study was to determine the feasibility and safety of inserting a newly developed insulated pancreatic stent before endosc...

Covered metallic or plastic stent placement has become an important treatment for postoperative esophageal leakage; however, fluoroscopic guidance is also required. Here we present a novel stent insertion technique with a newly designed proximal-releasing, self-expanding metallic stent (PR-SEMS) and transnasal endoscope that can enable stent insert...

A study on the application of vinyl radical cyclization via free radical allylation reaction in the synthesis of various carbocyclic compounds is described. In connection with this study, a new allyl transfer reagent, 2-bromo-3-(phenylthio) propene 1 is developed and it was shown that vinyl radical cyclization through free radical allylation reacti...

Bile leaks after laparoscopic cholecystectomy (LC) can be difficult to diagnose early. The aim of this study was to investigate the clinical features of minor bile leaks and to discuss how to manage patients who revisit the hospital with minor bile leaks after LC. From January 2001 to September 2007, 2219 LCs were performed at the Ajou University M...

The aim of this study was to analyze the clinical/pathological outcomes of patients that underwent surgery for gallbladder adenomyomatosis, to clarify the characteristics of the type and pathogenesis of adenomyomatosis. From May 1997 to March 2008, 4704 consecutive patients underwent cholecystectomy at Ajou University Medical Center. Among them, 11...

Cannulation of the pancreatic duct (PD) during endoscopic retrograde pancreatography (ERP) can fail even in experienced hands. A technique for therapeutic EUS-assisted rendezvous ERP has been described in a few case reports. To investigate the efficacy and safety of therapeutic EUS-assisted ERP. Retrospective study. Tertiary-care medical center. Th...

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Background: The aim of the present study was to investigate clinicopathological features of patients who were diagnosed with unsuspected gallbladder cancer (UGC) after laparoscopic cholecystectomy (LC) and to clarify the relationship between acute cholecystitis (AC) and unsuspected gallbladder cancer. Methods: From June 1997 to March 2008, a tot...

Gastric adenoma with low-grade dysplasia (LGD) is a less progressive disease than with high-grade dysplasia; nevertheless, a certain portion of lesions can progress. The purpose of this study was to evaluate the effectiveness of argon plasma coagulation (APC) with submucosa saline injections (APC–SSI) for gastric adenoma with LGD on an outpatient d...

Endoscopic therapy has been increasingly recognized as the effective therapy in selected patients with chronic pancreatitis. Utility of endotherapy in various conditions occurring in chronic pancreatitis is discussed. Its efficacy, limitations, and alternatives are addressed. For the best management of these complex entities, a multidisciplinary ap...

Objectives This study was designed to provide safe management guidelines for ampullary adenoma by analysis of clinicopathological features. Background The treatment of ampullary cancer has been established; however, the indications for treatment of ampullary adenoma remain controversial. Methods Between July 1997 and July 2008, a total of 33 patien...

Endoscopic resection for pathologic diagnosis and complete eradication of subepithelial tumors (SETs) has offered less invasive alternatives to surgical resection. The aim of this study is to evaluate feasibility of endoscopic resection for the treatment of gastric SETs originated from the muscularis propria layer and to determine related factors i...

Porcelain gallbladder has generally been regarded as a risk factor for gallbladder cancer. This study was designed to clarify the association between porcelain gallbladder and cancer by analysis of clinicopathological features of patients who underwent surgery for suspected porcelain gallbladder. From January 2002 to December 2008, 3159 cholecystec...

The placement of self-expandable metallic stents (SEMS) is known to be effective palliative treatment of malignant gastroduodenal obstruction. There are two types of SEMS--covered and uncovered--each with its own advantages and disadvantages. This study was conducted to compare between the clinical outcomes of covered and uncovered stents in patien...

Xanthogranulomatous cholecystitis (XGC) is a rare disease of the gallbladder, showing high conversion rate and complications. However, it has been reported as collected data or as a case review. Therefore, we compared surgical outcomes of laparoscopic cholecystectomy (LC) in patients who were diagnosed with XGC with that of other cholecystitis. Fro...

IntroductionThe aim of this study was to analyze clinicoradiologic findings and treatment outcomes of patients with endoscopic retrograde cholangiopancreatography (ERCP)-related perforations. Between May 2003 and November 2007, 2,247 ERCP procedures with or without sphincterotomy were performed at Ajou University Medical Center, Suwon, Korea, and 2...

Background: This study was designed to compare surgical, morphological, and functional outcomes of pancreaticoduodenectomy (PD) according to the types of pancreaticoenterostomy performed and to suggest a proper anastomotic method after PD. Methods: From January 2001 to December 2006, 147 PDs were performed at Ajou University Medical Center. Surg...

To investigate prevalence of Clonorchis sinensis in patients with gastrointestinal symptoms, and the relation of the infection to hepatobiliary diseases in 26 hospitals in Korea. Consecutive patients who had been admitted to the Division of Gastroenterology with gastrointestinal symptoms were enrolled from March to April 2005. Of those who had been...

There are various causes of splenic infarction. Antiphospholipid antibody is associated with numerous thromboembolic phenomena. We report a case of young male who presented with acute abdominal pain and was diagnosed as a case of splenic infarction and acute pancreatitis with antiphospholipid syndrome. He was positive for anticardiolipin antibody,...