Pancreatoscopy guided lithotripsy for difficult pancreatic duct stones: Evidence and treatment selection in chronic pancreatitis

Abstract

Difficult main pancreatic duct stones in chronic pancreatitis are challenging not only because they are hard to fragment, but because duct clearance does not necessarily translate into durable clinical benefit. Pain relief, freedom from repeated procedures, and avoidance of later surgery should therefore be considered separately from technical clearance. Extracorporeal shock wave lithotripsy (ESWL), usually followed by endoscopic retrograde cholangiopancreatography (ERCP), remains a guideline-supported option for radiopaque stones measuring at least 5 mm in the pancreatic head or body, as well as for large, dense, multiple, or diffuse stone burdens. Digital pancreatoscopy-guided electrohydraulic lithotripsy or laser lithotripsy offers a different advantage: Direct intraductal visualization, targeted fragmentation, and immediate assessment of residual fragments, strictures, and drainage. We reviewed English-language publications available through May 2026. Current data show high technical success in selected patients, and some observational studies suggest fewer treatment sessions than with ESWL. However, randomized comparative data remain limited, and sham controlled and surgery comparison trials show that ductal clearance alone is an incomplete measure of patient benefit. The key question is therefore which patients are most likely to benefit from pancreatoscopy-guided lithotripsy, how it should be sequenced with ESWL and ERCP, how procedural risk and treatment burden should be weighed, and when surgery should be considered earlier. This mini-review presents a practical framework in which pancreatoscopy is used selectively, not as a replacement for ESWL or only as a rescue technique.

Key Words: Chronic pancreatitis; Pancreatic duct stones; Pancreatoscopy guided lithotripsy; Extracorporeal shock wave lithotripsy; Patient selection

Core Tip: Pancreatoscopy-guided lithotripsy has become a useful option for difficult pancreatic duct stones, but the available evidence does not justify replacing extracorporeal shock wave lithotripsy as the default strategy. Its role should be decided case by case. Stone size, computed tomography attenuation, radiopacity, overall stone burden, duct anatomy, downstream strictures, access route, local expertise, and the expected number of procedures all matter. Success should also be measured beyond duct clearance. Pain relief, quality of life, opioid use, hospitalizations, need for repeat intervention, nutritional status, pancreatic function, and timely referral for surgery should all be part of treatment selection. In this setting, duct clearance is only one outcome; the more important question is whether treatment changes the patient’s clinical course.

INTRODUCTION

Chronic pancreatitis (CP) is a progressive fibroinflammatory disease in which pancreatic duct stones, strictures, parenchymal calcifications, recurrent inflammation, pancreatic exocrine insufficiency, diabetes, malnutrition, and chronic pain often coexist[1-4]. Current CP guidelines, including the American College of Gastroenterology guideline and the Japanese evidence-based clinical practice guideline, emphasize that treatment should address the full disease syndrome, including pain, nutritional status, exocrine and endocrine insufficiency, lifestyle modification, complications, and the timing of endoscopic or surgical intervention, rather than isolated ductal morphology alone[3-10].

Obstruction of the main pancreatic duct (MPD) by stones, often together with a dominant stricture, is one of the few anatomic targets in CP that can be treated directly by endoscopic or surgical decompression. However, duct clearance does not always translate into pain relief. In many patients, pain is already sustained by neural injury and sensitization, long-term opioid use, smoking, poor nutrition, and psychological disability, even when the duct appears adequately drained[11-14]. Treatment should therefore focus less on whether the stone can be broken and more on whether the chosen approach is likely to provide durable benefit without exposing the patient to a long sequence of low yield procedures.

Conventional endoscopic retrograde cholangiopancreatography (ERCP) can extract small, mobile stones after pancreatic sphincterotomy, but its efficacy decreases when stones are large, impacted, multiple, upstream to an angulated or strictured duct segment, poorly visible fluoroscopically, or associated with a dominant downstream stricture[5-10]. For decades, extracorporeal shock wave lithotripsy (ESWL) followed by ERCP has been the dominant nonsurgical strategy for obstructing pancreatic duct stones larger than 5 mm, especially when stones are radiopaque and located in the head or body of the pancreas[5,15,16]. However, in a recent sham controlled randomized trial, ESWL followed by ERCP achieved a high rate of ductal clearance, but its clinical benefit was limited[17].

Digital pancreatoscopy has broadened the treatment options by allowing the endoscopist to visualize the stone, duct wall, and lithotripsy probe during electrohydraulic lithotripsy (EHL) or laser lithotripsy (LL)[18-26]. The more relevant question is when direct intraductal lithotripsy should be preferred over ESWL, which patients are likely to benefit, and how well technical success predicts pain control, quality of life (QoL), opioid reduction, fewer admissions, avoidance of reintervention, and timely surgical referral when endoscopic therapy is unlikely to be durable[18-32]. Figure 1 summarizes recent evidence relevant to pancreatic duct stone management. This mini-review summarizes the available evidence and proposes a practical approach to choosing among conventional ERCP, ESWL centered therapy, pancreatoscopy-guided lithotripsy, stricture-directed drainage, and surgery.

Figure 1 Evidence timeline shaping current management of difficult pancreatic duct stones. Chronological overview of key guideline statements, randomized trials, comparative observational studies, meta-analyses, long-term outcome studies, imaging-predictor studies, and training or safety statements relevant to extracorporeal shock wave lithotripsy, pancreatectomy-guided lithotripsy, and the interface with pancreatic surgery. ESGE: European Society of Gastrointestinal Endoscopy; ESWL: Extracorporeal shock wave lithotripsy; DSOP: Digital single-operator pancreatoscopy; AGA: American Gastroenterological Association; ASGE: American Society for Gastrointestinal Endoscopy; CT: Computed tomography; EHL: Electrohydraulic lithotripsy.

LITERATURE REVIEW

This narrative mini-review summarizes English-language literature available through May 2026. We searched PubMed, society guidelines, and selected regulatory or manufacturer documents for studies on CP, pancreatic duct stones, ESWL, ERCP, pancreatoscopy guided lithotripsy, pain outcomes, CT based stone assessment, adverse events (AEs), endoscopic ultrasound (EUS) guided pancreatic duct drainage, and pancreatoscopy training.

Guidelines, randomized and sham controlled trials, comparative studies, systematic reviews, imaging-predictor studies, long-term outcome reports, safety statements, and training or consensus documents were prioritized. Case reports and early device reports were used only when they clarified unusual access routes or emerging platforms. Because most available data are observational and clinically heterogeneous, this mini-review focused on patient selection, stone characteristics, generalizability, and clinically meaningful outcomes rather than duct clearance alone.

DEFINITION AND PHENOTYPING OF DIFFICULT PANCREATIC DUCT STONES

“Difficult pancreatic duct stones” is a useful clinical word, although it is not defined formally. In this review, the term refers to symptomatic obstructing MPD stones that are unlikely to be cleared by standard ERCP extraction alone, or stones that have already failed conventional endoscopic therapy (Table 1). Ideally, this judgment should be made before repeated unsuccessful extraction attempts. In an unfavorable duct, repeated balloon or basket sweeps often add edema, trauma, fluoroscopy time, and another procedure without addressing the underlying mechanical problem.

Table 1 Phenotype-driven features that define difficult pancreatic duct stones.

Domain	High-yield features	Clinical implication	Preferred action/caveat
Stone phenotype	> 5 mm size, impaction, multiple or chain-like burden, radiolucency, high CT attenuation, poor fluoroscopic target	Predicts failure of simple ERCP extraction and informs selection between intraductal and extracorporeal fragmentation	Classify size, density, location, burden, and radiopacity before ERCP; avoid repeated extraction attempts when mechanical failure is predictable
Duct anatomy	MPD diameter, downstream dominant stricture, tortuosity, angulation, side-branch disease, inflammatory head mass	Determines pancreatoscope passage, fragment clearance, drainage durability, and need for stricture therapy	Treat drainage and stricture control as part of the same obstruction syndrome, not secondary details
Access route	Major papilla, minor papilla, pancreas divisum, surgically reconstructed anatomy, EUS-guided access route	May favor conventional ERCP, pancreatoscopy, ESWL, surgery, or expert-center antegrade salvage	Avoid intraductal lithotripsy when safe access and drainage are not achievable
Pain and patient phenotype	Intermittent vs constant pain, opioid use, admissions, malnutrition, diabetes, exocrine insufficiency, central sensitization	Determines probability that ductal clearance will translate into durable clinical benefit	Assess pain and QoL before committing to repeated endotherapy; involve pain, nutrition, and diabetes care early
System factors	ESWL availability, pancreatoscopy expertise, anesthesia, trained assistants, quality monitoring, pancreatic surgery backup	A technically attractive modality may be locally unsafe, unavailable, or inefficient	Use local capability honestly; refer when required expertise or backup is not available

CT: Computed tomography; ERCP: Endoscopic retrograde cholangiopancreatography; MPD: Main pancreatic duct; EUS: Endoscopic ultrasound; ESWL: Extracorporeal shock wave lithotripsy; QoL: Quality of life.

A difficult stone is not defined by size alone. A 6 mm stone may be straightforward if it is mobile, visible, and downstream in a dilated duct. The same-sized stone can be much more challenging if it is impacted, radiolucent, located beyond an angulated segment, or sitting above a tight stricture. Conversely, a larger stone may still be approachable if ESWL is readily available and fragments are likely to drain. Important features include stone size, impaction, number and distribution of stones, computed tomography (CT) attenuation, fluoroscopic visibility, duct caliber, downstream strictures, ductal angulation, side-branch disease, and diffuse calcification[5,15,33-36].

Access also shapes the treatment plan. Standard major papilla access is different from minor papilla access, pancreas divisum, surgically altered anatomy, or cases in which EUS-guided pancreatic duct access is considered[37-41]. The patient’s clinical phenotype is equally important. Intermittent obstructive-type pain, repeated admissions, opioid dependence, malnutrition, diabetes, exocrine insufficiency, and prior failed procedures all affect whether another endoscopic attempt is likely to help[11-14,42-45]. Local resources are also important. A center with reliable ESWL, pancreatoscopy experience, trained assistants, anesthesia support, quality monitoring, and surgical backup will make different choices from a center without these options[37,46-50].

For this reason, the same stone diameter may lead to different treatment choices. A single 7 mm radiolucent or poorly targeted impacted stone in a dilated head duct may be well suited to upfront pancreatoscopy guided lithotripsy. By contrast, a 14 mm high-density stone burden extending through the head and body, especially when strictures are present, may be better managed with ESWL based therapy, staged drainage, or early surgical evaluation. In practice, “difficult” should not simply mean technically hard. It should signal the need to choose deliberately among competing decompression strategies before the patient is exposed to a long sequence of low yield procedures.

CURRENT ROLE AND LIMITATIONS OF ESWL

ESWL remains a central treatment platform for pancreatic duct stones. The European Society of Gastrointestinal Endoscopy recommends ESWL for radiopaque obstructive MPD stones measuring at least 5 mm in the head or body of the pancreas[5]. The American Gastroenterological Association states that larger stones may require ESWL and/or pancreatoscopy guided intraductal lithotripsy[6]. The American Society for Gastrointestinal Endoscopy guideline recognizes both ESWL- and ERCP-based approaches with or without pancreatoscopy for larger radiopaque stones while emphasizing early surgical evaluation in appropriate candidates[7,8]. These recommendations support coexistence and selective use rather than replacement.

ESWL remains valuable because it is familiar, widely studied, and practical for large, radiopaque, high-density, multiple, or diffuse pancreatic duct stones. In a systematic review and meta-analysis, complete ductal clearance was achieved in about 70% of patients, and more than half reported complete pain relief during follow-up. However, the included studies were heterogeneous and largely observational[15]. Large cohort studies also support durable benefit when ESWL is combined with ERCP for fragment extraction, duct drainage, and treatment of associated strictures[16].

The drawbacks are mainly practical, but they are essential. ESWL requires coordination of equipment, anesthesia, radiographic targeting, and usually ERCP, often over more than one session. Access to ESWL is uneven, and radiolucent or poorly targeted stones can be difficult to treat. The more important limitation is clinical. As one sham controlled randomized trial showed, ESWL plus endoscopy may produce only modest short term pain relief despite targeting ductal obstruction[17]. This finding does not mean that duct decompression is ineffective. It does mean that stone clearance should not be treated as a stand-in for meaningful patient benefit. Pain phenotype and patient-reported outcomes should be part of treatment selection from the beginning.

PANCREATOSCOPY GUIDED LITHOTRIPSY

Modern pancreatoscopy uses digital single operator scopes with improved image quality, irrigation, and accessory compatibility[33]. In peroral pancreatoscopy (POP) guided lithotripsy, the stone is treated under direct vision. An EHL or laser probe is advanced to the stone, fragmentation is performed under irrigation, and the duct is inspected again to confirm whether the fragments are small enough to clear (Figure 2). It replaces indirect fluoroscopic targeting with visual intraductal targeting.

Figure 2 Representative pancreatoscopy-guided lithotripsy workflow. A: Direct pancreatoscopy shows an obstructing pancreatic duct stone within the main pancreatic duct; B: A laser fiber or electrohydraulic lithotripsy probe is positioned against the stone under direct visualization; C: Controlled intraductal lithotripsy achieves progressive stone fragmentation; D: Residual fragments are cleared, and associated downstream ductal stricture is managed with dilation and/or temporary pancreatic stenting when required.

EHL produces localized hydraulic shock waves at the probe tip inside a fluid filled duct. It works best when the probe can be held steadily against or near the stone and the field is kept clear with irrigation. Visibility may quickly worsen when there is bleeding, debris, or inadequate flushing. LL, most often holmium based in pancreatic applications, allows focused energy delivery but requires dedicated equipment and strict safety precautions. According to available literatures, pancreatic data do not show a consistent advantage of LL over EHL. In practice, the choice depends on local experience, available equipment, stone characteristics, duct anatomy, and the route of access[18-32].

The procedure also has limitations that should be recognized before starting. POP requires reliable duct access and enough duct caliber to pass the scope. If there is a dominant downstream stricture, treating the stone alone is usually incomplete and drainage has to be restored as well. Fragmentation should be gradual, with repeated checks for fragment size, duct-wall injury, bleeding, irrigation pressure, and downstream drainage. Temporary pancreatic stenting may be needed to maintain drainage, prevent obstruction from residual fragments, or allow staged therapy. After each session, the endoscopist should reconsider whether further endoscopic treatment is still likely to help. A difficult stone should not justify open-ended ERCP. Table 2 summarizes currently available pancreatoscopy and pancreaticobiliary scope platforms, including access diameter, working channel, working length, processor compatibility, and practical limitations in pancreatic use.

Table 2 Current cholangiopancreatoscopy/pancreaticobiliary scope platforms relevant to pancreatic duct therapy.

Manufacturer	Platform/processor	Reusable or single-use	Typical access route	Approximate outer diameter/working length	Working channel	Diagnostic/therapeutic versions or accessories	Pancreatic relevance/caveat
Boston Scientific	SpyGlass DS/DS II Digital Controller with SpyScope DS II catheter	Single-use digital catheter-based cholangiopancreatoscope	Duodenoscope-assisted transpapillary access	Approximate distal tip 10.5 Fr/3.5 mm; working length approximately 214 cm; requires large duodenoscope channel	Approximately 1.2 mm channel	Diagnostic visualization; compatible with EHL and LL fibers/probes within channel constraints	Most commonly reported modern platform; duct caliber and downstream stricture can limit passage
Boston Scientific	SpyGlass Discover Digital Catheter	Single-use digital catheter designed for surgical/endoscopic pancreaticobiliary use	Short-access or operative access routes depending on setup	Approximate distal tip 10.5 Fr/3.5 mm; working length approximately 65 cm	Approximately 1.2 mm channel	Diagnostic and therapeutic pancreaticobiliary visualization with compatible accessories	May be relevant to altered access or operative settings; pancreatic duct use depends on local indication and equipment
Micro-Tech	eyeMAX cholangiopancreatoscopy platform	Single-use digital scopes in different outer-diameter/channel configurations	Duodenoscope-assisted transpapillary access	Reported configurations include approximately 3.2-3.9 mm outer diameter; working length depends on model	Reported channels approximately 1.2-2.0 mm depending on model	Diagnostic and therapeutic versions/accessory compatibility varies by region	Larger channel may aid accessory passage but may require larger duct/access; verify local regulatory availability
Olympus	CHF-B260/CHF-B290 mother-baby pancreatocholangioscopes	Reusable fiber/video cholangiopancreatoscopes	Mother-baby system through duodenoscope	Approximate outer diameter around 3.4 mm for older systems; working length/model-specific	Approximately 1.2-1.3 mm channel depending on model	Diagnostic visualization and selected therapy with compatible accessories	Reusable mother-baby systems require two operators and are less widely used than single-operator platforms
Olympus	CHF-BP260 ultra-slim pancreatocholangioscope	Reusable ultra-slim fiber/video scope	Mother-baby or special access routes	Approximate outer diameter around 2.8 mm; working length/model-specific	Approximately 0.8 mm channel	Primarily diagnostic or limited therapy due small channel	Smaller diameter may help narrow ducts but restricts lithotripsy accessories
CenterPoint Systems	Dragonfly Pancreaticobiliary Scope and Digital Controller	Single-use digital catheter and controller	Duodenoscope-assisted transpapillary access	FDA-cleared specifications report approximately 3.6 mm outer diameter and 139 cm working length	Working channel approximately 5.1 Fr	Diagnostic and therapeutic pancreaticobiliary endoscopy with compatible accessories	Newer platform; published pancreatic stone outcome data remain limited
Tangent Endoscopy	Tangent Single-Use Digital System	Single-use digital catheter and controller	Pancreaticobiliary endoscopy via compatible endoscope/access route	FDA-cleared specifications report approximately 3.3 mm shaft outer diameter and 650 mm working length	Approximately 1.6 mm channel	Diagnostic and therapeutic pancreaticobiliary use with compatible accessories	Newer platform; real-world pancreatic lithotripsy evidence is limited

Specifications are manufacturer- or regulator-reported approximations and may vary by model, catalog number, region, and date of procurement. This table is intended for clinical orientation and should not substitute for local device verification. EHL: Electrohydraulic lithotripsy; LL: Laser lithotripsy; FDA: United States Food and Drug Administration.

QUANTITATIVE EVIDENCE FOR PANCREATOSCOPY GUIDED LITHOTRIPSY

The clinical literature on POP guided lithotripsy has grown, but it is still less established than the ESWL evidence base. The main studies are summarized in Table 3. In an early multicenter retrospective series of 109 patients from 17 tertiary centers, complete ductal clearance was achieved in 89.9%, single session success in 73.5%, and AEs occurred in 10.1%. Having more than three ductal stones was associated with the need for more than one pancreatoscopy session[18]. In a prospective single center EHL series, complete or partial clearance was achieved in 24 of 34 patients (70.6%). Among patients in whom pancreatic duct cannulation was successful, technical success was 92.3%, complete clearance was achieved in 80% of treated patients, and the Izbicki pain score improved from 62.3 to 27.5 at 6 months. Post-procedure pancreatitis occurred in seven patients, all mild[20].

Table 3 Primary pancreatoscopy guided lithotripsy studies and clinically relevant quantitative endpoints.

Ref.	Design/population	Sample size	Lithotripsy modality	Technical/clearance result	Clinical result	AEs/follow-up	Major limitation/practical inference
Attwell et al[19], 2015	Multicenter United States retrospective/prospective follow-up experience in calcific CP	28	LL	Successful stone fragmentation/clearance in most patients; early evidence that LL could be performed during ERCP with POP	Pain improvement reported during follow-up	AEs occurred but were generally manageable; follow-up heterogeneous	Small nonrandomized cohort; older platforms; limited phenotype stratification
Brewer Gutierrez et al[18], 2019	International multicenter retrospective study at 17 tertiary centers	109	EHL 59; LL 50	Complete ductal clearance 899%; single-session success 73.5%; > 3 stones predicted repeat sessions	Clinical endpoints less standardized than technical endpoints	AEs 10.1%; median follow-up 210 days	Expert-center retrospective design; no randomized comparator
van der Wiel et al[20], 2022	Prospective single-center consecutive case series of first-line EHL in obstructive CP stones > 5 mm	34 included; 26 with successful duct cannulation	EHL	Complete or partial clearance in 24/34; technical success after duct cannulation 92.3%; complete clearance 80% of treated patients	Izbicki pain score improved from 62.3 to 27.5 at 6 months	Acute pancreatitis in 7 patients, all mild; median 2 ERP and 1 EHL procedure	Duct cannulation failure excluded from technical denominator; single-center expertise
Bick et al[21], 2022	Comparative retrospective cohort: Single-operator pancreatoscopy-guided intraductal lithotripsy vs ESWL	18 POP; 240 ESWL	EHL/LL	Clearance 889% vs 86.7% with ESWL	Clinical response not uniformly patient-reported	Complications 5.6% vs 6.3%; fewer total procedures and shorter cumulative procedure time with POP	Selection bias; small POP group; historical/Local practice effects
Gerges et al[22], 2023	Prospective multicenter cohort of digital single-operator pancreatoscopy for symptomatic pancreatic duct stones	40 enrolled	EHL and/or LL	High complete clearance in selected patients with limited head/body stone burden	Overall pain relief reported in most evaluable patients at 6 months	Serious AEs 12.5%, conservatively managed	Highly selected anatomy; moderate sample size; no randomized comparator
de Rijk et al[23], 2023	Long-term observational follow-up of first-line EHL compared with historical ESWL cohort	19 EHL; 18 ESWL	EHL	Long-term treatment success at least comparable to historical ESWL; recurrence 37% vs 61%	Sustained clinical success 58% in EHL group	Median follow-up 35.0 months EHL and 76.5 months ESWL; QoL not significantly different	Historical comparison; small cohorts; follow-up duration imbalance
Iwata et al[24], 2024	Multicenter retrospective cohort: Disposable POP-guided lithotripsy vs ESWL	19 POP; 47 ESWL	EHL 13; LL 4; mixed or failed in some	Treatment success 78.9% vs 70.2%; median sessions 1 vs 5	Clinical symptoms heterogeneous	Complications 21.0% vs 6.3%; POP complications included hyperamylasemia and MPD perforation	Small POP group; nonrandomized treatment assignment; era and technology effects
Conrad et al[25], 2025	Retrospective multicenter long-term study after successful digital single-operator video pancreatoscopy-guided lithotripsy	58	EHL	Sustained ductal and clinical outcomes in selected patients with initial success	Pain relief 70.7% at month 3, persisting through 24 months; QoL not consistently improved	AEs 26%, mostly mild/moderate pancreatitis	Enriched for initial technical/clinical success; limited generalizability
Yoshida et al[26], 2026	Retrospective predictor study of POP-guided EHL without ESWL	Noted in article; cohort focused on pancreatic duct stones treated with EHL	EHL	CT attenuation > 2050 HU and diameter > 12.8 mm predicted incomplete EHL	Clinical outcomes linked to clearance predictors	AE details center-specific	Thresholds require external validation before universal use

CP: Chronic pancreatitis; LL: Laser lithotripsy; ERCP: Endoscopic retrograde cholangiopancreatography; POP: Per-oral pancreatoscopy; AE: Adverse event; EHL: Electrohydraulic lithotripsy; ERP: Endoscopic retrograde pancreatography; ESWL: Extracorporeal shock wave lithotripsy; QoL: Quality of life; MPD: Main pancreatic duct; CT: Computed tomography; HU: Hounsfield units.

Prospective multicenter data are also encouraging, although still limited to selected patients. In a digital single-operator pancreatoscopy cohort, clearance and pain-response rates were high among patients with symptomatic CP and limited stone burden in the pancreatic head or body; serious AEs occurred in 12.5% and were managed conservatively[22]. Longer term multicenter follow-up suggests that pain relief can persist in some patients. In one study, 70.7% of patients reported pain relief at 3 months, and this benefit was maintained through 24 months. However, AEs occurred in 26%, mostly mild or moderate pancreatitis, and improvement in QoL was not consistently shown[25]. Taken together, these studies support pancreatoscopy guided lithotripsy in selected patients, but they also show that it should not be viewed as a low risk extension of routine ERCP.

The comparative data point in the same direction. Bick et al[21] reported similar stone clearance with single operator pancreatoscopy guided intraductal lithotripsy and ESWL (88.9% vs 86.7%), but the pancreatoscopy group required fewer total procedures and had shorter cumulative procedure time. A Japanese group compared disposable POP-guided lithotripsy with ESWL in 66 patients and found treatment success rates of 78.9% and 70.2%, respectively. The median number of sessions was lower with POP-guided lithotripsy (1 vs 5), although complications were numerically more frequent in the POP-guided group (21.0% vs 6.3%)[24]. A long term comparison between EHL and a historical ESWL cohort found recurrent symptomatic stones in 37% and 61%, respectively, but the study was small and nonrandomized[23].

Metanalyses are useful, but they should be read with the underlying study designs in mind. Early systematic reviews reported pooled technical or clinical success rates of approximately 90%, but most included studies were retrospective and heterogeneous[27-29]. A 2024 meta-analysis of 17 studies including 441 patients reported complete stone clearance in 81%, clinical success in 90%, and an AE rate of 12%[30]. A 2025 meta-analysis comparing POP guided lithotripsy with ESWL found no significant difference in technical success, clinical success, or overall AEs[31]. These data support pancreatoscopy guided lithotripsy as an important option, but not as a universal replacement for ESWL. A recent Pancreas meta-analysis comparing LL with EHL adds to the available evidence, although device level conclusions remain limited by nonrandomized designs and heterogeneous stone phenotypes[32].

TREATMENT SELECTION

The treatment plan should be shaped before cannulation, not after a difficult extraction has already begun. Cross-sectional imaging is central to this step. The key findings include stone size, number, location, radiopacity, CT attenuation, MPD diameter, downstream strictures, ductal angulation, side-branch disease, inflammatory head mass, and postsurgical anatomy. Non-contrast CT is particularly useful for assessing stone attenuation and estimating how readily the stone may fragment. Magnetic resonance cholangiopancreatography adds complementary information by defining duct anatomy, strictures, disconnected segments, and postoperative access routes.

Recent studies support this more quantitative approach to imaging. Bush et al[34] developed a CT-based pancreatic duct stone index using stone density and size to estimate the likely number of ESWL sessions. Dalal et al[35] showed that stone density on noncontrast CT may help predict ESWL outcomes. Lozova et al[36] also found that stone density was associated with the number of ESWL treatments required. For pancreatoscopy guided therapy, Yoshida et al[26] reported that CT attenuation greater than 2050 hounsfield units and stone diameter greater than 12.8 mm independently predicted incomplete EHL when ESWL was not used. These cutoffs should not be treated as universal rules, but they highlight a practical point that the first treatment choice should be based on the imaging phenotype, not simply on stone diameter.

A practical algorithm is best framed around common clinical scenarios (Figure 3 and Table 4). Conventional ERCP remains reasonable for small, mobile stones when there is no major downstream stricture. Upfront POP-guided lithotripsy is most appealing when the stone burden is limited, duct access is favorable, fluoroscopic targeting is poor, the stone is radiolucent or impacted, and same-session clearance is realistic. ESWL remains well suited to very large, dense, radiopaque, multiple, chain-like, or diffuse stone burdens, particularly when POP access is unfavorable. When the main problem is downstream outflow obstruction, treatment should focus on stricture directed drainage rather than stone fragmentation alone. Early surgical consultation is appropriate when there is head-dominant inflammatory disease, complex strictures, repeated endoscopic failure, escalating opioid use, concern for malignancy, or a low likelihood of durable endoscopic decompression[37-42].

Figure 3 Phenotype-driven treatment algorithm for difficult main pancreatic duct stones. Proposed clinical algorithm for difficult pancreatic duct stones, incorporating patient symptoms, stone and duct features, access anatomy, local expertise, and expected treatment burden to guide selection among endoscopic retrograde cholangiopancreatography extraction, pancreatoscopy-guided lithotripsy, extracorporeal shock wave lithotripsy-centered therapy, stricture-focused decompression, and early surgical consultation. MPD: Main pancreatic duct; CT: Computed tomography; ERCP: Endoscopic retrograde cholangiopancreatography; ESWL: Extracorporeal shock wave lithotripsy.

Table 4 Extracorporeal shock wave lithotripsy centered therapy vs pancreatoscopy guided lithotripsy.

Domain	ESWL-centered therapy	Pancreatoscopy-guided lithotripsy	Clinical interpretation
Evidence maturity	Longer experience base, guideline-supported for radiopaque obstructive MPD stones ≥ 5 mm in pancreatic head/body	Growing evidence base with prospective and multicenter cohorts but fewer randomized data	Treat as complementary modalities; avoid claims of routine replacement
Best-fit stone phenotype	Large, dense, multiple, chain-like, radiopaque, or diffuse burden; favorable radiographic targeting	Limited stone burden; impacted or radiolucent/poorly fluoroscopic target; favorable duct access; realistic same-session clearance	Stone size alone is insufficient; CT attenuation, radiopacity, duct caliber, and strictures matter
Procedure burden	Often staged; may require multiple ESWL and ERCP sessions	May reduce total sessions in selected cohorts but can increase single-session complexity	Discuss expected session burden and anesthesia exposure before treatment
Advantages	Nonintraductal fragmentation; broad historical evidence; useful for large radiopaque burdens	Direct visualization, targeted fragmentation, immediate reassessment of fragments/strictures, potential same-session clearance	Choose by phenotype and local capability
Limitations	Availability, targeting of radiolucent stones, multiple sessions, modest link between clearance and durable pain benefit	Requires advanced pancreatic ERCP, adequate duct caliber/access, irrigation control, expertise, device cost, AE monitoring	Referral is preferable to low-volume improvisation
Safety profile	Pancreatitis, bleeding, pain flare, steinstrasse/fragment obstruction, need for staged ERCP; pooled AE rates generally around 10% in meta-analyses	PEP, hyperamylasemia, bleeding, infection, ductal trauma/perforation, stent-related events; cohort AE rates range from below 10% to > 20% depending on definitions and follow-up	Use standardized AE definitions and PEP prevention bundle
Patient-centered endpoints	Pain relief may occur but sham-controlled data show only modest short-term benefit in some populations	Pain improvement reported in selected cohorts; QoL improvement inconsistent	Clearance is a technical endpoint; pain, QoL, opioids, admissions, nutrition, and later surgery must be tracked
When surgery should enter	Early when head-dominant inflammatory disease, complex strictures, repeated ESWL/ERCP failure, opioid escalation, or low chance of durable drainage	Early when POP would require repeated high-risk sessions, access is unsafe, or ductal clearance is unlikely to reverse pain biology	Surgery should be parallel-consulted in red-flag phenotypes, not delayed until all endoscopy fails

ESWL: Extracorporeal shock wave lithotripsy; MPD: Main pancreatic duct; CT: Computed tomography; ERCP: Endoscopic retrograde cholangiopancreatography; AE: Adverse event; PEP: Post-endoscopic retrograde cholangiopancreatography pancreatitis; QoL: Quality of life.

PATIENT CENTERED OUTCOMES BEYOND DUCTAL CLEARANCE

The most important conceptual correction is to separate technical success from clinical success. Complete ductal clearance is important because residual obstructing fragments can perpetuate ductal hypertension, recurrent pancreatitis, and the need for additional intervention. However, durable patient benefit is better assessed by pain trajectory, QoL, opioid use, hospital admissions, nutrition, pancreatic exocrine and endocrine function, reintervention-free survival, and need for later surgery[11-14,43-46].

Outcome data remain incomplete, but several clinically relevant patterns are apparent. In the prospective EHL series by van der Wiel et al[20], the Izbicki pain score decreased from 62.3 to 27.5 at 6 months. In the multicenter prospective cohort by Gerges et al[22], pain scores also improved substantially at 6 months, and most treated patients reported pain relief, although serious AEs were not rare. In the long-term cohort by de Rijk et al[23], sustained clinical success was seen in 58% of EHL-treated patients, but QoL did not differ significantly from baseline or from 6-month follow-up. In the long-term study by Conrad et al[25], pain relief persisted in selected patients, but consistent major improvement in QoL was not shown. These studies show why clearance and fragmentation alone are not enough. Pain, QoL, and the burden of repeated treatment need to be reported with the same care as technical success.

The broader CP literature points in the same direction. In a multicenter United States cohort, pancreatic endotherapy was commonly used, but patient selection and outcomes varied widely[43]. A prospective QoL study suggested that pancreatic endotherapy can improve QoL for up to 1 year, whereas pain relief may be less durable[44]. A systematic review of QoL after pancreatic endotherapy found that many studies still focus mainly on technical outcomes and use inconsistent patient-reported endpoints[45]. In a large CP cohort, constant pain, disability or unemployment, current smoking, and comorbidities were major determinants of QoL[46]. Procedural success should therefore be interpreted in this broader clinical context, not as a fluoroscopic endpoint alone (Figure 4).

Figure 4 Mechanistic framework linking ductal stone therapy to patient-important outcomes. Schematic overview of how protein plugs and calcification may lead to main pancreatic duct obstruction, ductal hypertension, recurrent inflammation, neural remodeling, and peripheral or central sensitization. The figure illustrates why ductal clearance can help selected patients with obstructive disease, but may not consistently improve pain, quality of life, opioid use, or the need for later surgery. ERCP: Endoscopic retrograde cholangiopancreatography; ESWL: Extracorporeal shock wave lithotripsy.

SAFETY, AES, AND PREVENTION OF POST ERCP PANCREATITIS

POP-guided pancreatic lithotripsy should be regarded as an advanced pancreatic intervention, not as a minor extension of diagnostic endoscopy. Reported AE rates differ across studies, depending on study design, definitions, patient selection, and how closely events were captured. In systematic reviews, overall AE rates are often approximately 5%-15%, and a recent pancreatoscopy review estimated the complication risk at less than 5%-10% in selected settings[27-31,47]. Prospective and long-term cohorts, however, show that higher rates may be seen when events are collected more actively, particularly pancreatitis and post-procedure pain flares[20,22,25].

In the 109-patient multicenter digital single operator study, AEs occurred in 10.1% of patients[18]. In the prospective consecutive EHL series, seven patients developed acute pancreatitis, all mild[20]. In the multicenter prospective cohort by Gerges et al[22], serious AEs occurred in 12.5% and were managed conservatively. In the comparative cohort by Iwata et al[24], complications after POP guided lithotripsy included hyperamylasemia and MPD perforation, whereas complications after ESWL included pancreatitis and bleeding. Overall complications were numerically more frequent in the POP group (21.0% vs 6.3%). In the long-term multicenter cohort by Conrad et al[25], AEs occurred in 26%, mostly mild or moderate pancreatitis. These figures are important to state plainly, because high clearance rates do not make the procedure benign.

Because POP guided lithotripsy is usually performed as part of ERCP, post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) prevention needs to be built into the procedure. This includes risk stratification, rectal nonsteroidal anti-inflammatory drugs when not contraindicated, wire-guided cannulation when appropriate, minimizing unnecessary pancreatic duct trauma, selective prophylactic pancreatic stenting in high-risk cases, and appropriate periprocedural hydration[48]. AEs should also be reported using standardized definitions, including PEP, pain flare, fever or infection, bleeding, ductal trauma, perforation, stent-related complications, unplanned admission, and need for rescue intervention[49,50].

TRAINING, EXPERTISE, AND GENERALIZABILITY

Favorable outcomes with POP guided lithotripsy have mainly been reported from expert centers, which limits generalizability. The procedure requires advanced pancreatic ERCP skills, reliable duct access, experience with intraductal EHL or LL, and the ability to manage associated strictures, residual fragments, stents, and procedure-related AEs. Recent European quality standards and consensus recommendations describe cholangiopancreatoscopy as an advanced procedure requiring structured training, appropriate case selection, quality monitoring, and competence assessment[51,52]. These requirements are particularly relevant for difficult pancreatic duct stones, where therapeutic pancreatic ERCP is combined with intraductal energy delivery.

INTERFACE WITH SURGERY AND MULTIDISCIPLINARY DECISION-MAKING

Surgery should not be treated as the final option only after all endoscopic approaches have failed. In randomized trials of painful obstructive CP, surgical drainage provided better pain outcomes and required fewer procedures than endoscopic therapy in selected patients with dilated ducts or advanced obstructive disease[37-39]. The ESCAPE trial also supported earlier surgical consideration in patients with painful CP, a dilated pancreatic duct, and recent opioid use[40]. On long term follow-up, early surgery was associated with lower pain scores than an endoscopy first strategy and a higher rate of complete pain relief (45% vs 20%); about half of the patients initially assigned to endoscopy ultimately underwent surgery[41]. In the same phenotype, early surgery was also more cost effective[42].

These data matter when discussing difficult pancreatic duct stones. POP-guided lithotripsy should not be presented simply as a way to avoid surgery. It is most useful when it can provide efficient and durable duct decompression in a patient whose anatomy and pain pattern make endoscopic benefit likely. By contrast, early surgical discussion is appropriate when there is an inflammatory head mass, complex stricturing, repeated failed endotherapy, escalating opioid use, diffuse calcific disease, concern for malignancy, or a low likelihood of durable endoscopic drainage.

For these patients, multidisciplinary review should include pancreatobiliary endoscopy, pancreatic surgery, radiology, pain medicine, nutrition, diabetes care, and, when relevant, psychology or addiction medicine. The purpose is not to make the plan more complicated, but to avoid a common mistake: Assuming that a technically possible procedure is also the right procedure for the patient. In difficult MPD stones, the key question is not just which device can break the stone, but whether the chosen pathway is likely to change the patient’s course.

EMERGING PLATFORMS AND FUTURE DIRECTIONS

The field needs consistent definitions of difficult MPD stones, technical fragmentation, complete ductal clearance, clinical success, reintervention, and AEs. Imaging should also be built into study design from the outset. CT attenuation, stone size, number of stones, radiopacity, duct diameter, and downstream strictures should be evaluated prospectively as factors that may influence treatment response, not reported only as baseline characteristics[26,34-36]. Comparative trials should also avoid a simple device vs device design. A trial comparing POP guided lithotripsy with ESWL would be more informative if it prespecified subgroups by stone density, stone size, duct diameter, stricture, access anatomy, and prior intervention[31]. Patient centered outcomes should be included as major endpoints, including pain, QoL, opioid use, admissions, work disability, nutritional status, pancreatic function, number of sessions, cumulative anesthesia exposure, and later surgery[11-14,43-46].

Alternative access routes and new scope designs may broaden the options for selected salvage cases. When transpapillary access fails, the papilla is inaccessible, anatomy is surgically altered, or the duct is completely obstructed, EUS guided pancreatic duct drainage or rendezvous techniques may provide another route. These procedures, however, are technically demanding and carry meaningful AE risk[53,54]. Ultra-slim or modified-channel cholangiopancreatoscopes may also improve access through narrow ducts, the minor papilla, or transluminal antegrade tracts. Recent proof-of-concept reports have described LL for an impacted pancreatic duct stone through the minor papilla and lithotripsy across a pancreaticojejunostomy stricture through an EUS guided pancreatogastrostomy route[55,56]. These cases are important, but they should be viewed as early experience until larger studies define their impact on clearance, procedure time, safety, cost, learning curve, and long term outcomes.

LIMITATIONS

The main limitation of this mini-review is its narrative design. It was not registered as a systematic review and did not include duplicate screening, formal risk-of-bias assessment, or meta-analytic pooling. The pancreatoscopy literature itself remains limited by retrospective study designs, expert-center experience, variable definitions of ductal clearance and clinical success, and highly selected patients. Technical outcomes are reported more consistently than clinically important outcomes such as pain, QoL, opioid use, hospitalizations, nutritional status, pancreatic function, cost, and later surgery.

Comparisons between ESWL and POP-guided lithotripsy are also difficult to interpret. Most are observational, and treatment assignment is strongly influenced by stone density, radiopacity, duct caliber, strictures, local expertise, and access to equipment. Device specifications and availability vary by region and continue to change. For these reasons, the algorithm proposed in this review should be viewed as a practical guide for decision-making, not as a validated predictive model.

CONCLUSION

The management of difficult pancreatic duct stones is evolving, but the change should not be framed as pancreatoscopy replacing ESWL. POP-guided EHL or LL is a credible and often efficient option in selected patients, particularly when stone burden is limited, duct access is favorable, fluoroscopic targeting is poor, the stone is radiolucent or impacted, and same session targeted fragmentation is realistic[18-32]. ESWL remains guideline supported and clinically important for larger, denser, multiple, radiopaque, or diffuse stone burdens, especially when staged fragmentation and subsequent ERCP are practical[5,15,16,34-36].

Treatment selection should begin with careful review of the stone and duct phenotype, including CT attenuation, radiopacity, stone size, stone number, MPD caliber, downstream strictures, and access anatomy (Table 5). Conventional ERCP remains appropriate for small mobile stones. Upfront POP guided lithotripsy is best reserved for selected cases with limited stone burden and favorable access. ESWL-centered therapy remains better suited to large, dense, radiopaque, multiple, or diffuse stones, whereas stricture-directed drainage should be prioritized when downstream obstruction is the main problem. Early surgical consultation should not be delayed when there are concerning features or repeated endoscopic failure.

Table 5 Scenario-based treatment selection.

Clinical scenario	Preferred initial strategy	Rationale	Caveat
Small, mobile stone(s) without major downstream stricture	Conventional ERCP extraction	Fragmentation may be unnecessary when balloon or basket extraction is likely to succeed	Proceed if duct access is safe and drainage is achievable; avoid over-escalation
Limited 5-10 mm burden, favorable duct caliber, impacted or poorly fluoroscopic/radiolucent stone	Selective upfront POP-guided EHL or LL	Direct visualization can reduce targeting uncertainty and allow same-session reassessment	Best in expert centers with clear stopping rules and stent/drainage plan
Very large, high-density, radiopaque, multiple, chain-like, or diffuse burden	ESWL-centered pathway plus ERCP	Extracorporeal fragmentation may be more efficient than prolonged intraductal therapy	Consider CT attenuation and expected sessions; POP can be adjunct or rescue
Dominant downstream stricture with obstructing stone	Stricture-focused drainage strategy with dilation/stenting plus definitive fragmentation	Fragmentation without outflow correction often fails clinically	Stage therapy if necessary; reassess duct caliber and fragment clearance before repeating lithotripsy
Inflammatory head-dominant disease, complex strictures, repeated failed endotherapy, persistent opioid escalation	Early pancreatic surgery consultation	Randomized and health-economic evidence supports early surgery in selected painful obstructive CP	Do not use pancreatoscopy to postpone indicated surgery
Minor papilla access, postsurgical reconstruction, failed transpapillary access, or EUS-guided antegrade route	Individualized expert-center salvage strategy	Alternative access may enable therapy but evidence is limited and AE risk is meaningful	Reserve for high-volume centers with multidisciplinary backup

ERCP: Endoscopic retrograde cholangiopancreatography; POP: Per-oral pancreatoscopy; EHL: Electrohydraulic lithotripsy; LL: Laser lithotripsy; ESWL: Extracorporeal shock wave lithotripsy; CT: Computed tomography; CP: Chronic pancreatitis; AE: Adverse event; EUS: Endoscopic ultrasound.

Success should be judged by outcomes that matter to patients, not by duct clearance alone. Pain relief, QoL, opioid use, admissions, procedure burden, nutritional status, pancreatic function, and need for later surgery should be considered alongside technical success. POP guided lithotripsy should also be performed only in settings with appropriate expertise, systematic PEP prevention, AE monitoring, and multidisciplinary support. The real advance is not a new device hierarchy, but better selection of the patient, the stone, and the treatment pathway most likely to provide durable benefit.