ENDoscopic Assessment in Acute PANcreatitis Study (ENDOPAN Study)

Inclusion Criteria: * Age 18 years or older. * Diagnosis of acute pancreatitis according to the revised Atlanta criteria, defined by the presence of at least two of the following three features: typical abdominal pain consistent with acute pancreatitis; serum amylase and/or lipase activity at least three times the upper limit of normal; imaging findings consistent with acute pancreatitis. * Hospital admission due to acute pancreatitis to the study center. * Admission during the early phase of acute pancreatitis, allowing planned upper gastrointestinal endoscopy within 24-48 hours from hospital admission. * Ability to undergo diagnostic upper gastrointestinal endoscopy according to the investigator's and treating physician's assessment. * Ability to provide written informed consent before enrollment and before any study-specific procedure. Exclusion Criteria: * Age below 18 years. * Lack of written informed consent. * Inability to provide informed consent before enrollment. * Clinical condition precluding safe diagnostic upper gastrointestinal endoscopy, including hemodynamic instability, severe respiratory failure, or other unstable life-threatening condition. * Need for emergency therapeutic upper gastrointestinal endoscopy before planned study endoscopy, for example due to active upper gastrointestinal bleeding. * Known or suspected gastrointestinal perforation. * Previous gastric or duodenal surgery significantly altering upper gastrointestinal anatomy and preventing reliable assessment of gastric or duodenal mucosa. * Known advanced upper gastrointestinal malignancy affecting the stomach or duodenum. * Pregnancy. * Contraindication to upper gastrointestinal endoscopy or sedation according to the treating physician's or investigator's assessment. * Any condition that, in the investigator's opinion, would make participation unsafe or would prevent completion of study procedures.