Encapsulation-oriented vs. Timing-oriented Strategies for Necrotizing Pancreatitis

Summary

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.

Conditions

• Walled Off Necrosis
• Pancreatitis
• Acute Necrotic Collection
• Necrotizing Pancreatitis
• Pancreatitis, Acute Necrotizing

Interventions

PROCEDURE

The timing of endoscopic intervention for necrotizing pancreatitis is determined based on the degree of encapsulation

In the encapsulation-oriented group, participants undergo EUS-guided drainage of necrotizing pancreatitis when the degree of encapsulation reaches ≥80%, as confirmed by cross-sectional imaging (preferably contrast-enhanced CT). Imaging is repeated every 7-10 days after enrollment to assess encapsulation. Once sufficient encapsulation is observed and the patient presents with symptoms such as infection, abdominal pain, GOO or biliary obstruction, endoscopic drainage is performed. Drainage is typically performed using a lumen-apposing metal stent (LAMS) placed under EUS guidance, often accompanied by placement of an external drain. Step-up therapy, including endoscopic necrosectomy or additional drainage procedures, may be used if symptoms do not improve. If the patient improves with conservative therapy before encapsulation is achieved, drainage may be deferred. Endoscopic/percutaneous interventions should, in principle, be discussed with the expert panel beforehand.

PROCEDURE

EUS-guided drainage based on the interval from the onset of acute pancreatitis

In the timing-oriented group, participants undergo EUS-guided drainage of necrotizing pancreatitis at 4 to 5 weeks after the onset of acute pancreatitis, regardless of the degree of encapsulation. Drainage is performed only in symptomatic patients who meet predefined clinical criteria, such as signs of infection, significant pain, GOO, or biliary obstruction. Imaging is performed before the procedure. The standard approach involves placing a LAMS under EUS guidance, optionally supplemented by external drains. If symptoms do not improve, step-up interventions such as endoscopic necrosectomy, percutaneous drainage may be considered. If inflammation and symptoms improve with conservative treatment (e.g., antibiotics), EUS-guided drainage may be omitted. Conversely, even before 4-5 weeks from onset, early drainage is allowed if conservative treatment is deemed insufficient by the attending physician. In principle, intervention decisions should be discussed with the expert panel.

Sponsors & Collaborators

• Tokyo Women's Medical University

  collaborator OTHER

• Tokyo University

  lead OTHER

Principal Investigators

• Yousuke Nakai · Department of Gastroenterology, Tokyo Women's Medical University

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2025-08-05

Primary Completion

2028-07-31

Completion

2028-07-31

Countries

• Japan

Study Locations