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.
Patients diagnosed with necrotizing pancreatitis according to the revised Atlanta classification, confirmed by contrast-enhanced CT (plain CT or MRI may be substituted if contrast-enhanced CT is not feasible).
Within 28 days of onset of acute pancreatitis.
Age ≥ 18 years at the time of consent, regardless of sex.
Provided written informed consent from the patient or a legally authorized representative after sufficient explanation.
Unknown date of onset of acute pancreatitis.
Patients who have already undergone transluminal drainage with stent placement for necrotizing pancreatitis.
Diagnosis of chronic pancreatitis.
Patients for whom endoscopic treatment is deemed unsafe.
Parallel
The timing of endoscopic intervention for necrotizing pancreatitis is determined based on the degree of encapsulation
Procedure/SurgeryIn 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.
EUS-guided drainage based on the interval from the onset of acute pancreatitis
Procedure/SurgeryIn 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.
Clinical success rate within 180 days after randomization
Defined as reduction of necrotic collection to ≤2 cm on imaging and resolution of symptoms that required intervention (infection: at least two out of the following inflammatory indicators: body temperature, white blood cell count, and C-reactive protein, pain, GI obstruction, or jaundice).
Rate of procedure-related adverse events
Adverse events will be classified according to the ASGE lexicon and AGREE classification.
All-cause mortality
Includes any death occurring during the study period.
Time to clinical success
Defined as the number of days between randomization and the achievement of both imaging and symptom resolution criteria.
Technical success of initial EUS-guided drainage
Defined as successful drainage of necrotizing pancreatitis
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Tokyo University
Lead sponsor
Tokyo Women's Medical University
Sponsor institution
Tokyo Women's Medical University
Collaborator
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