Abstract
Keywords
Introduction
Peri-pancreatic fluid collections (PFCs)—notably pancreatic pseudocysts and walled-off necrosis (WON)—represent one of the most challenging complications following acute or chronic pancreatitis. As per the revised Atlanta classification, these fluid collections range from acute peripancreatic fluid accumulations to pseudocysts and WON, depending on the timing of evolution and the presence of necrotic debris. 1 Historically, their management has been driven by clinical severity, radiologic characteristics, and local expertise, with surgical and percutaneous approaches forming the cornerstone of intervention. However, these traditional modalities are associated with significant morbidity, prolonged hospitalization, and, in many cases, suboptimal long-term outcomes.
In recent years, the emergence of endoscopic ultrasound (EUS)-guided techniques has fundamentally changed this paradigm and has largely supplanted open surgery for mature PFCs. 2 The incorporation of lumen-apposing metal stents (LAMS) into the endoscopist’s armamentarium has provided a platform for both efficient drainage and direct access for endoscopic necrosectomy (DEN; Table 1 and Figure 1). These innovations offer the potential for minimally invasive, effective, and safer treatment of WON, especially in centers with multidisciplinary experience. The strength of these techniques lies not only in their technical feasibility but also in the increasingly favorable safety profile and clinical efficacy reported across both randomized and real-world studies. Notably, our prospective and retrospective analyses in adult and pediatric populations affirm this trend and serve as pivotal contributions toward establishing LAMS as a frontline tool in WON management.3,4
Milestones in the evolution of EUS-guided LAMS in the management of NOS.
CT, computed tomography; DEN, direct endoscopic necrosectomy; EUS, endoscopic ultrasound; LAMS, lumen-apposing metal stent; LOS, length of stay; USG, ultrasonography; WON, walled-off necrosis.
Management of severe acute pancreatitis with PFC via EUS-guided LAMS placement. This flowchart illustrates the management of severe acute pancreatitis with PFC. After imaging confirmation (CECT/EUS >4 weeks), drainage is indicated for infection, persistent symptoms, or gastric outlet obstruction. EUS-guided LAMS placement achieves 100% technical success, with adjunctive strategies like lavage and saline irrigation. The outcomes show >90% clinical success, low reinvention rates, and no mortality.
Evolution of EUS-guided management
Conventional endoscopic drainage methods initially relied on blind or fluoroscopic techniques using double-pigtail plastic stents (DPPS), which were limited by small luminal diameters, susceptibility to occlusion, and a lack of structural anchoring. These limitations became especially problematic in infected WON with high solid content. The development of EUS guidance enabled safer, more precise puncture of fluid collections by visualizing vascular structures and ensuring appropriate wall apposition. Despite these advances, Plastic Stent (PS) remained inadequate in terms of debris evacuation and durability of drainage. 5
The advent of LAMS, such as the AXIOS (Boston Scientific, Boston, USA) and EGIS S-PD (S&G Biotech, Yongin-si, South Korea), overcame many of these challenges. These stents offer a large-diameter conduit (typically 10–20 mm), with dual-flanged designs providing luminal apposition that minimizes migration and leakage. The short length and electrocautery-enhanced delivery systems further allow single-step placement under EUS guidance. These features have transformed the management of WON, facilitating not only effective drainage but also safe access for repeated DEN sessions where necessary.6,7
Clinical evidence and outcomes from real-world studies
In our recent adult cohort study involving 95 patients undergoing EUS-guided LAMS placement for WON, we observed a 100% technical success rate and a 92.6% clinical success rate, defined by radiological resolution and symptomatic improvement at 12 weeks. The mean diameter of collections was 13.8 ± 5.1 cm, with an average solid component of 27%, and the intervention was typically performed around the 44th day post-onset of pancreatitis. Importantly, no mortality or major procedural adverse events (AEs) were reported. Stent occlusion occurred in only 7.3% of patients, all of whom were managed conservatively or with DEN. Notably, 89% of patients required no further interventions beyond initial stent placement, and median hospitalization was limited to 5 days. 3 This might be attributed to “On-site active drainage” during stent placement, which not only accelerated clinical improvement but also mitigated the risk of sepsis and reduced procedural complications, emphasizing its critical role in optimizing LAMS deployment.
Parallel results emerged from our pediatric prospective study of 11 patients aged 5–18 years with WON. In this cohort, the technical success rate was again 100%, with clinical success achieved in 90.9%. Stent occlusion occurred in 18%, a slightly higher proportion than in adults, but only one patient required escalation to video-assisted retroperitoneal debridement. These results reinforce the cross-population applicability of LAMS and demonstrate that with appropriately sized equipment and experienced operators, EUS-guided drainage is not only feasible but preferable even in pediatric age groups. 4
Other studies, including a meta-analysis by Chen et al., have similarly shown superior outcomes for LAMS compared to PS in drainage of WON. In their pooled analysis of 189 patients, clinical success was significantly higher with LAMS (80.4% vs 57.5%, p < 0.01; pooled odds ratio (OR) ≈ 2.26), with fewer repeat interventions. 8 The same conclusion was echoed in randomized controlled trials such as the one by Bang et al., 7 where LAMS showed comparable or improved results relative to PS with shorter procedure times and better safety profiles.
Addressing technical andprocedural considerations
One of the primary concerns in LAMS use is the timing of drainage. The timing of endoscopic intervention in necrotic pancreatic fluid collection remains a critical determinant of clinical outcomes. By consensus, drainage is generally deferred until 4 weeks after onset of pancreatitis to allow the collection wall to mature and necrotic debris to liquefy, thereby facilitating safer and more effective intervention. This distinction underlies the definitions of “early drainage” (ED; <4 weeks of onset of pancreatitis) and “late drainage” (LD; >4 weeks), with the latter traditionally favored in practice to allow for maturation of the collection wall and liquefaction of necrotic debris. This approach is supported by data from the POINTER trial, which showed no significant benefit in ED (within 72 h) compared to a delayed strategy, with a greater number of interventions required in the early group. 9 Similarly, a meta-analysis encompassing 855 patients (320 ED, 535 LD) found that while complication and necrosectomy rates were comparable, mortality was marginally higher in the ED group (OR ≈ 1.94). 10 Our studies adhered to the delayed drainage principle, with most interventions occurring between 40 and 45 days post-onset, aligning with current international recommendations.1,9 Nonetheless, when clinically indicated—such as in the presence of sepsis, organ dysfunction, or gastric outlet obstruction—ED may be safely undertaken by multidisciplinary teams in high-acuity settings. 10
Moreover, stent management is critical after PFC treatment. Current consensus recommendations suggest removing LAMS after roughly 3–5 weeks to minimize stent-related complications. 11 For example, Korean guidelines advise follow-up imaging at 4–8 weeks, with routine removal of the transluminal stent (LAMS or plastic) at about 4 weeks post-drainage. 12 The European and American literature similarly advocate a ~4-week limit based on retrospective studies showing late removal can lead to bleeding or “buried stent” overgrowth. 13 Major risks of prolonged LAMS dwell include erosion into adjacent vessels (causing delayed hemorrhage, often from pseudoaneurysm) and mucosal overgrowth that embeds the flange (“buried stent syndrome”).
Clinical data on removal timing are mixed. A large retrospective series found that stent removal at <4 weeks was an independent predictor of persistent or recurrent fluid collections, with clinical success achieved in only 70% if removed early versus 96% if removed later. 11 This study reported similar delayed-AE rates in both early and late removal groups, suggesting benefit to leaving LAMS longer in many cases. Moreover, a UK registry of over 1000 patients showed no significant increase in complications with prolonged stent indwelling. 14 In practice, timing decisions are individualized: many centers perform interval imaging at 3–4 weeks, and remove the stent if the collection has resolved or shrunk substantially. If significant necrotic debris or symptoms persist, the stent may be left longer with plans for additional necrosectomy. Real-world practice varies; for instance, one series reported a median dwell time of 48 days (range 2–950) and >80% of stents left beyond 4 weeks, often due to ongoing necrosectomy needs or follow-up delays. 11 Ultimately, the optimal timing balances the risks of residual fluid/sepsis from premature removal against stent-related harms from over-retention, and must be tailored to each patient’s imaging and clinical course.
Another important factor is stent size. In a study by Parsa et al., 15 the use of 20-mm LAMS (n = 306, 102 vs 204 matched patients of WON) was associated with fewer necrosectomy sessions compared to 15-mm stents (1.3 vs 2.1, respectively), suggesting better initial drainage and cavity decompression. In our adult and pediatric studies, we used 16-mm EGIS S-PD stents, achieving high rates of spontaneous cavity collapse and low need for DEN. These data undercut the notion that a “mid-sized” stent is optimal; in fact, larger 20-mm stents resolved collections with fewer necrosectomies, at no cost in safety. Therefore, the size of stent may be decided from case to case basis.
Coaxial DPPS appear to mitigate certain complications of LAMS drainage but do not eliminate overall risk. For example, AbiMansour et al.’s 2024 meta-analysis (9 studies, 709 patients) found that adding DPPS significantly lowered stent occlusion (OR ≈ 0.53) and infection (OR ≈ 0.55) rates, yet had no significant effect on the composite AE rate (OR ≈ 0.57, p = 0.06) or bleeding (OR ≈ 0.61, p = 0.12). 16 Notably, reported AE frequencies in the literature vary widely: some series observed only ~12%–15% overall AEs, whereas others—especially in complex or necrotic collections—report complication rates on the order of 40%–50%.17 –19 Such heterogeneity likely reflects differences in study design and practice (retrospective vs prospective, single- vs multi-center), inconsistent AE definitions, and variable management protocols (e.g., timing of LAMS removal and debridement schedules). 16 For instance, earlier cohorts often kept LAMS in situ until complete resolution (with bleeding rates up to 25%), whereas more recent practice favors prompt stent removal, which can blunt the apparent impact of DPPS on bleeding. 16 In sum, DPPS use seems to reduce specific issues like occlusion and infection, but it does not eliminate bleeding risk or the marked variability in AE rates. Our own series did not employ coaxial stents; nevertheless, these data suggest that selective use of DPPS—in patients at high risk for stent clogging or infection—may confer benefit without adding a clear bleeding advantage. 3 Further study is needed to identify which PFC cases may derive the greatest incremental value from adjunctive DPPS.
Pediatric applications: A new frontier
Although LAMS has become a mainstay in adult WON management, its pediatric application remains underexplored, largely due to anatomical constraints, concerns about procedural safety, and the lack of pediatric-specific endoscopic accessories. Unlike in adults, where EUS-guided interventions are now standard of care, pediatric guidelines—such as those from the NASPGHAN Pancreas Committee—have traditionally refrained from recommending LAMS for WON, citing insufficient data and advocating case-by-case discretion. 20
Our prospective study, the largest to date focusing exclusively on pediatric WON, challenges this conservative dogma by demonstrating that trans-gastric LAMS placement can achieve high efficacy with minimal morbidity in children. With a clinical success rate of 90.9% and a 100% technical success rate, our cohort exhibited outcomes comparable to adult series. 4 Importantly, over 90% of children avoided surgery altogether, and the mean hospitalization was markedly short (5.36 ± 3.32 days), underscoring the minimally invasive advantage. Previous pediatric reports using LAMS or plastic stents—such as those by Kim and Trevino, 21 Ramesh et al., 22 and Trevino et al. 23 —were limited to isolated cases or small series, often requiring multiple interventions and facing complications like stent migration or occlusion. By contrast, our study employed procedural refinements such as on-site drainage and targeted antibiotic therapy, resulting in a lower rate of AEs. These findings not only advocate for broader adoption of LAMS in well-equipped pediatric centers but also set the stage for regulatory reconsideration and the development of future pediatric-specific endoscopic protocols.
Long-term outcomes and future considerations
Beyond short-term resolution, the long-term sequelae of necrotizing pancreatitis—such as disconnected pancreatic duct syndrome (DPDS) and new-onset diabetes—require structured monitoring. Although our studies followed patients for 48 weeks without recurrence, prior literature suggests that DPDS is associated with a six-fold increased risk of recurrence and may benefit from long-term transmural stenting. 22 However, stent retention beyond 4 weeks increases the risk of delayed bleeding and migration, as shown in studies by Yang et al. 24 and Nakai et al. 25 Thus, optimal timing for stent removal and strategies to bridge disconnected ducts remain pressing clinical challenges.
Further innovations, such as the EndoRotor device for automated necrosectomy and flexible-flanged LAMS, offer additional avenues to improve outcomes. In a recent meta-analysis encompassing 7 studies with 79 patients, EndoRotor demonstrated a pooled technical and clinical success rate of 96%, with an average of 2.2 sessions per patient and a low incidence of AEs (8%), including minor bleeding, pneumoperitoneum, and pleural effusion. 26 These data suggest that EndoRotor is not only safe but also potentially superior to conventional debridement tools in reducing the number of required necrosectomy sessions. Furthermore, cost-effectiveness analyses are warranted, particularly in low-resource settings, to determine whether such technologies—despite their upfront expense—can reduce overall healthcare burden by minimizing surgical intervention, shortening hospital stay, and expediting recovery.
Lastly, electrocautery-enhanced LAMS (e.g., Hot AXIOS) further streamline placement by enabling single-step puncture and deployment. 27 Compared to conventional DPPS, LAMS placement is technically easier and much faster (median procedure time ~8.5 vs 25 min for plastic). 28 Clinical success rates of LAMS (and other covered metal stents) for drainage are high (typically 88%–100% resolution of PFCs), with pooled technical success >95%. 29 Reported AEs include bleeding (1%–7%), perforation, stent migration (1%–6%), and infection. In comparative series, LAMS often match plastic stents in overall efficacy, but LAMS generally require fewer interventions and less procedure time. However, a recent randomized trial in very large WON (>15 cm) found no clear advantage of a 20 mm LAMS over dual 7 Fr plastic stents in terms of clinical success or complication rates, underscoring that selection should be individualized. 30
Conclusion
EUS-guided techniques, particularly the use of LAMS, have transformed the management landscape for PFCs. Our adult and pediatric studies add to a growing body of literature confirming their efficacy, safety, and potential as a first-line therapeutic option in appropriately selected patients. LAMS not only enable efficient drainage of complex collections but also facilitate step-up management strategies, minimize hospital stay, and reduce the need for invasive surgery.
Although questions remain regarding optimal timing, stent design, and long-term strategies—particularly in the context of DPDS and pediatric use—there is little doubt that EUS-guided LAMS represent a major step forward in pancreatology. With continued innovation and standardized multicenter trials, LAMS may soon become the default choice for managing WON across all age groups.
Footnotes
Acknowledgements
The authors would like to thank the Department of Gastroenterology at Dayanand Medical College & Hospital, Ludhiana, and the Department of Anaesthesia at AIIMS, New Delhi, for their continuous support and collaboration during the development of this editorial. We also acknowledge the contributions of the data management team and radiology department in supporting our clinical studies that informed this work.