Patient description: The patient is a 57-year-old man with abdominal pain and vomiting. The pain started gradually about 20 hours ago in the epigastric and periumbilical regions, radiating to his back. He drinks around 60 units of alcohol per week and smokes 22 cigarettes per day. He is healthy with no history of allergies or using any medications. His family history is positive for type 2 diabetes (his father and sister). He lives alone and has no children. The abdomen is tender and soft. His bowel sounds are normal. His heart rate is 115/min and blood pressure 110/75 mmHg. The lab results are remarkable for leukocytosis (19.5), urea of 8.5, high CRP (145), high amylase (1200) and Glc level of 15. Cross-sectional imaging was negative for obstructive pancreatitis.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Walled-off Necrosis WON diagnosed on contrast-enhanced dual phase CT abdomen/pelvis (CECT) or MRI with gadolinium (seen as a fluid collection in the setting of documented pancreatic necrosis that contains necrotic material and encased within a well-defined tissue layer) 2. All WON centered within the pancreatic/peri-pancreatic space not requiring percutaneous drainage, ≥ 6cm, located within 2cm of the enteric wall, not extending into the flanks or pelvis 3. WON with single loculation, with no extension into the flanks, pelvis or into the root of the small bowel mesentery. Collections should have an estimated solid component of = or >25% based on cross sectional imaging and/or endosonographic evaluation of the collection at the time of study procedure. 4. Suspected/confirmed infected WON (defined as temp ≥ 100.5°F, serum WBC ≥ 15x199/L, positive blood cultures or positive Gram stain/culture of aspirated necrotic material) and/or 5. Symptomatic WON (defined as abdominal pain, gastric/intestinal/biliary outlet obstruction resulting in nausea, vomiting, early satiety, jaundice, or persistent malaise) at a time interval of ≥ 4 weeks from attack of acute pancreatitis complicated by pancreatic necrosis 6. Documented history of acute or chronic pancreatitis a) Acute pancreatitis is diagnosed if 2 of the following 3 are met: i) Abdominal pain characteristic of acute pancreatitis ii) Serum lipase/amylase ≥ x3 upper limit of normal iii) Characteristic radiological findings of acute pancreatitis on CECT/MRI/US abdomen, such as homogeneous enhancement of pancreatic parenchyma, standing of peripancreatic fat (1) b) Chronic pancreatitis is diagnosed if characteristic radiological changes are seen on CT/MRI with MRCP (such as pancreatic atrophy, dilated pancreatic duct, pancreatic calcification) (11) or EUS (≥5/9 of Rosement criteria) (12) 7. Able to undergo general anesthesia  Age < 18 years 2. Unable to obtain consent for the procedure 3. Pregnancy 4. Irreversible coagulopathy: INR > 1.5, platelets < 50 x 109/L 5. Use of anticoagulants that cannot be discontinued for the procedure 6. Unable to tolerate general anesthesia 7. WON with ≥ 3 loculations 8. WON that is not accessible for EUS-guided drainage 9. Percutaneous drainage of WON is required or performed prior to EUS-guided drainage 10. Prior endoscopic, percutaneous or surgical drainage procedure(s) for pancreatic/peri-pancreatic fluid collections. 11. Contraindication to endoscopic drainage: Gastrectomy with Billroth II, gastric bariatric surgery, prior pancreatic surgery, prior esophagectomy, cirrhosis