Pancreatitis, Acute Necrotizing

Pancreatic necrosis complicates approximately 20-30% of severe acute pancreatitis cases. While many collections resolve without intervention, persistent symptomatic collections-particularly when infected-are associated with significant morbidity and mortality and frequently require procedural management. Current guidelines recommend delaying intervention until collections are fully walled off, typically around four weeks. However, in clinical practice, many patients deteriorate before this window is reached. Prospective data from our institution, supported by recent meta-analyses, suggest that early intervention using modern endoscopic techniques can be performed safely, even when undertaken within the first four weeks of disease onset. We believe that, in appropriately selected patients, early endoscopic intervention may prevent clinical deterioration, reduce complications, shorten hospital stay, and decrease overall healthcare utilization compared with a delayed approach. To formally evaluate this strategy, an international, multicenter randomized trial is being conducted, entitled Strategic Timing of Endoscopic Procedural Interventions in Infected Necrotizing Pancreatitis (STEP-IN Trial).

This multicenter, randomized controlled trial (WONDER-03 study) investigates the optimal timing for endoscopic ultrasound (EUS)-guided drainage in patients with necrotizing pancreatitis. Although current guidelines recommend delaying drainage until at least four weeks after the onset of acute pancreatitis to allow for encapsulation of necrosis, recent observational data suggest that the degree of encapsulation itself may more strongly influence treatment success and safety. In this trial, patients are randomly assigned to one of two groups: an encapsulation-oriented group, in which EUS-guided drainage is performed when imaging confirms ≥80% encapsulation of the necrotic collection with symptoms, and a timing-oriented group, in which drainage is performed at four to five weeks after disease onset, regardless of encapsulation status. The primary endpoint is clinical success within 180 days, defined as both radiologic resolution of necrosis and improvement in symptoms. Secondary endpoints include adverse event rates, recurrence of fluid collections, technical and clinical success rates, and healthcare resource use. This study aims to determine whether a strategy based on encapsulation leads to better clinical outcomes than the conventional time-based approach and may help establish a new evidence-based treatment algorithm for necrotizing pancreatitis.

Walled-off necrosis (WON) is a pancreatic fluid collection, which contains necrotic tissue after four weeks of the onset of acute pancreatitis. Interventions are required to manage patients with infected WON, for which endoscopic ultrasonography (EUS)-guided drainage has become a first-line treatment modality. For patients who are refractory to EUS-guided drainage, the step-up treatment including endoscopic necrosectomy (EN) and/or additional drainage is considered to subside the infection. Recent evidence suggests that EN immediately after EUS-guided drainage may shorten treatment duration without increasing adverse events. In this randomized trial, the investigators will compare treatment duration between EN immediately after EUS-guided drainage versus the step-up approach in patients with symptomatic WON.