What is the management protocol after removing the Lumen-Apposing Metal Stent (LAMS) following Endoscopic Ultrasonography (EUS) with cystogastrostomy and necrosectomy?

Management After LAMS Removal Following EUS-Guided Cystogastrostomy and Necrosectomy

After removing the LAMS following EUS-guided cystogastrostomy and necrosectomy for walled-off pancreatic necrosis, you should exchange it for double pigtail plastic stents to maintain fistula patency long-term, with the LAMS typically removed at 4-6 weeks after initial placement once the collection has resolved. 1, 2

Timing of LAMS Removal

• Remove the LAMS within 4 weeks to avoid food impaction and subsequent complications, as a well-formed fistula develops between the collection and gastrointestinal tract within this timeframe. 1
• The optimal timing is typically 4-6 weeks after initial LAMS placement, allowing adequate time for fistula tract maturation while minimizing stent-related complications. 1
• In the context of walled-off necrosis specifically, LAMS removal should occur once radiographic resolution is achieved (collection ≤3 cm) or after 60 days of indwell time, whichever comes first. 3

Stent Exchange Strategy

At the time of LAMS removal, perform simultaneous exchange to double pigtail plastic stents to maintain the cystogastrostomy tract and prevent fistula closure. 1, 2

Technical Approach:

• Place one or two 7 Fr double pigtail plastic stents through the established fistula tract at the time of LAMS removal. 1, 2
• Plastic stents without intervening side holes between the ends are preferred for optimal drainage outcomes. 2
• The double pigtail configuration provides lower migration rates (9%) compared to straight stents (23%). 2

Follow-Up Endoscopy Protocol

Perform routine follow-up peroral cholecystoscopy/gastroscopy at 4-6 weeks after initial drainage to assess for: 1

• Complete clearance of any residual necrotic debris
• Patency of the fistula tract
• Need for additional interventions
• Stone or debris removal if present

During Follow-Up Endoscopy:

• Assess for spontaneous passage of debris (occurs in approximately 56% of cases). 1
• If residual solid material persists, perform direct endoscopic debridement using stone-retrieval baskets or other extraction devices. 1
• Overall clearance rates of 88% are achieved after a mean of 1.25 endoscopy sessions. 1

Plastic Stent Management

Maintain plastic stents with routine exchanges every 2-4 weeks until the cavity has contracted to <2 cm in size. 2

• Continue prophylactic antibiotics covering enteric gram-negative organisms and enterococci (second-generation cephalosporin or quinolone) during the post-removal period. 1
• Monitor with regular imaging (CT or MRI) to assess cavity size reduction and ensure no recurrence. 2

Alternative Approach for High-Risk Patients

In frail patients or those refusing a second procedure, the LAMS may be left in place permanently with acceptable long-term outcomes: 1

• 3-year stent patency of 86% with this approach
• Delayed adverse events occur in only 7.1% of cases
• Median follow-up data shows this is safe for very-high-risk patients who cannot tolerate stent exchange

Critical Caveat:

Long-term LAMS placement carries risk of food impaction, which can impair drainage and induce recurrence. 1 This approach should be reserved only for patients with prohibitive surgical risk and inability to undergo repeat endoscopy.

Monitoring for Complications

Actively surveil for delayed adverse events during the post-removal period:

Early Complications (First 30 Days):

• Bleeding (including delayed pseudoaneurysm formation, which can present up to 3 weeks post-procedure) 4
• Stent migration (occurs in 5.6% of cases) 5
• Infection/sepsis 3
• Bile or pancreatic fluid leak 1

Late Complications:

• Recurrent collection formation (occurs in 2.6% with proper stent maintenance vs 20% without) 1
• Buried stent syndrome if LAMS left too long 1
• Fistula closure if plastic stents not maintained 1

Common Pitfalls to Avoid

• Do not remove LAMS without establishing alternative drainage unless the collection has completely resolved and the fistula tract is no longer needed. 1, 2
• Avoid leaving LAMS in place beyond 4-6 weeks in patients who can tolerate stent exchange, as this increases risk of food impaction and tissue overgrowth. 1
• Do not discontinue antibiotics prematurely during the post-removal period, as the cystogastrostomy creates a clean-contaminated environment. 1
• Ensure multidisciplinary support availability (interventional radiology, surgery) for managing potential complications like bleeding or perforation. 1

Special Considerations

If the patient becomes a surgical candidate after LAMS removal, be aware that: 1

• Cholecystectomy or surgical intervention may be more complicated due to the transmural fistula
• Fistula repair will be required at the time of surgery to prevent postoperative leak
• Surgical consultation before LAMS placement is ideal to clarify future surgical plans

Stent location influences tissue reaction: Duodenal locations result in more stable tracts than gastric locations due to peristaltic movements in the stomach causing more pronounced tissue reaction. 1