(Peri)pancreatic necrosis is nonviable tissue located in the pancreas alone, or in the pancreas and peripancreatic tissues, or in peripancreatic tissues alone. It can be solid or semisolid (partially liquefied) and is without a radiologically defined wall. Sterile (peri)pancreatic necrosis is the absence of proven infection in necrosis. Infected (peri)pancreatic necrosis is defined when at least one of the following is present: gas bubbles within (peri)pancreatic necrosis on computed tomography; a positive culture of (peri)pancreatic necrosis obtained by image guided fine-needle aspiration; a positive culture of (peri)pancreatic necrosis obtained during the first drainage and/or necrosectomy. Organ failure is defined for three organ systems (cardiovascular, renal, and respiratory) on the basis of the worst measurement over a 24-hour period. In patients without pre-existing organ dysfunction, organ failure is defined as either a score of 2 or more in the assessed organ system using the SOFA (Sepsis-related Organ Failure Assessment) score or when the relevant threshold is breached, as shown: Cardiovascular, need for inotropic agent; Renal, creatinine ≥171 μmol/L (≥2.0 mg/dl); Respiratory, PaO2/FiO2 (partial pressure of oxygen/fractional inspired oxygen concentration) ≤300 mmHg (≤40 kPa). Persistent organ failure is the evidence of organ failure in the same organ system for 48 hours or more. Transient organ failure is the evidence of organ failure in the same organ system for less than 48 hours.