What is the treatment for walled-off necrosis (WON)?

Treatment of Walled-Off Necrosis (WON)

For walled-off necrosis requiring intervention, initiate a step-up approach starting with endoscopic ultrasound-guided transmural drainage (preferably using lumen-apposing metal stents), followed by endoscopic necrosectomy if drainage alone fails, with surgery reserved only for failures of less invasive approaches. 1, 2, 3

When to Intervene

Not all WON requires intervention. Treat WON when any of the following are present:

• Infected necrosis (confirmed by positive cultures, gas in collection on CT, bacteremia, sepsis, or clinical deterioration) 2, 4, 3
• Persistent organ failure after 4 weeks without signs of infection 2, 4
• Mechanical complications: gastric outlet obstruction, biliary obstruction, or intestinal obstruction from large collections 2, 4
• Disconnected pancreatic duct syndrome 2, 4
• Persistent symptoms (pain, nausea, vomiting, nutritional failure) after 8 weeks despite conservative management 2, 3

Small (<5 cm), stable, asymptomatic, and sterile collections can be managed conservatively with observation. 4

The Step-Up Treatment Algorithm

Step 1: Initial Drainage

Begin with EUS-guided transmural drainage as the preferred first-line approach. 2, 3

• Lumen-apposing metal stents (LAMS) are superior to plastic stents for initial drainage, as they reduce technical difficulty and may eliminate the need for subsequent necrosectomy 3, 5
• EUS-guided drainage is optimal for central collections abutting the stomach 2
• This approach provides shorter hospital stays and better patient-reported mental and physical outcomes compared to surgical approaches 2
• Critical timing consideration: Delay intervention until >4 weeks after disease onset whenever possible, as earlier intervention (<4 weeks) significantly increases mortality 1, 2, 4

Alternative: Percutaneous catheter drainage (PCD) should be considered for:

• Collections in the early acute period (<2 weeks) when patient is too unstable for endoscopy 3
• Large, complex collections involving the pancreatic tail 2
• Collections with deep extension into paracolic gutters and pelvis (often as adjunct to endoscopic drainage) 3
• Patients who are poor surgical candidates 2

However, recognize that PCD alone has limited success (14-32% cure rate) and typically requires prolonged drainage with higher reintervention rates. 2, 4

Step 2: Direct Endoscopic Necrosectomy (if drainage fails)

If transmural drainage with LAMS alone does not achieve adequate clinical response:

• Proceed to direct endoscopic necrosectomy to actively debride solid necrotic debris 3, 5, 6
• This is particularly needed when WON contains substantial solid necrotic material that cannot drain passively 7
• Approximately 60-77% of patients requiring intervention will need necrosectomy in addition to drainage 6, 7
• This step should only be performed at referral centers with appropriate expertise and surgical backup 3

Step 3: Surgical Intervention (for failures)

Surgery is reserved for cases where endoscopic and percutaneous approaches fail. 1, 2, 3

Surgical indications include:

• Failure of percutaneous/endoscopic procedures 2
• Abdominal compartment syndrome 2, 3
• Acute ongoing bleeding when endovascular approach fails 2
• Bowel complications or fistula extending into collection 2

Surgical approach options:

• Minimally invasive techniques are preferred over open necrosectomy when feasible, including video-assisted retroperitoneal debridement (VARD), laparoscopic transgastric necrosectomy, or open transgastric necrosectomy 1, 3
• For selected cases with WON and disconnected pancreatic duct, single-stage surgical transgastric necrosectomy is an option with reported mortality of 2% and morbidity of 38% 1
• Minimally invasive approaches result in less new-onset organ failure but require more interventions compared to open surgery, though mortality rates are similar 1

Adjunctive Management

Antibiotics

• Use antibiotics only for proven or strongly suspected infection, not prophylactically 4, 3
• When infection is suspected, use broad-spectrum IV antibiotics with good pancreatic penetration: carbapenems, quinolones, or metronidazole 3
• Limit prophylactic antibiotics to patients with >30% pancreatic necrosis and continue for no more than 14 days 4
• Routine antifungal prophylaxis is not recommended 3

Nutrition

• Initiate enteral feeding early to decrease risk of infected necrosis 4, 3
• Trial oral nutrition immediately if patient has no nausea, vomiting, or severe ileus 3
• If oral feeding not feasible, use nasogastric/duodenal or nasojejunal tube feeding 4, 3
• Reserve total parenteral nutrition only for patients unable to tolerate enteral nutrition 4, 3

Critical Pitfalls to Avoid

• Never intervene before 4 weeks unless absolutely necessary (abdominal compartment syndrome, bowel necrosis), as early surgery dramatically increases mortality 1, 2, 4
• Remove LAMS by 3 weeks if WON is resolved on CT to avoid stent-related complications including bleeding (14% risk) and buried stent syndrome 5
• Evaluate the main pancreatic duct status before choosing drainage approach, as complete central occlusion may lead to PCD failure and require endoscopic or surgical management 2, 4
• Don't use simple drainage without debridement when significant solid necrotic debris is present, as this predisposes to persistent infection 4
• Avoid relying on size alone as an indication for intervention; symptomatic status and infection are more important than collection size 2

Special Consideration: Disconnected Pancreatic Duct

For patients with disconnected left pancreatic remnant after mid-body necrosis who are reasonable operative candidates, definitive surgical management with distal pancreatectomy should be undertaken, as insufficient evidence supports long-term endoscopic stenting alone. 3