Biliary cannulation techniques: Optimizing success and minimizing risk

Abstract

Difficult biliary cannulation during endoscopic retrograde cholangiopancreatography (ERCP) increases the risk of post-ERCP pancreatitis and procedural failure. This narrative minireview summarizes cannulation strategies and evidence-based escalation techniques, including needle-knife papillotomy, needle-knife fistulotomy, and transpancreatic sphincterotomy. Early recognition of difficult cannulation, the use of predefined stop criteria to limit papillary trauma, and selection of rescue techniques based on pancreatic duct access and clinical context can maximize outcomes from ERCP.

Key Words: Endoscopic retrograde cholangiopancreatography; Cannulation; Pancreatitis; Sphincterotomy; Needle knife papillotomy; Needle-knife fistulotomy

Core Tip: Biliary cannulation remains a technically demanding but essential component of endoscopic retrograde cholangiopancreatography, with success depending not only on operator expertise but also on careful selection and timely escalation of techniques. Knowledge of the risks and benefits of approaches ranging from wire-guided cannulation to precut and pancreatic duct-assisted methods is critical for minimizing complications such as post-endoscopic retrograde cholangiopancreatography pancreatitis, bleeding, and perforation.

INTRODUCTION

Endoscopic retrograde cholangiopancreatography (ERCP) is a procedure that combines endoscopy using a specialized side-viewing endoscope and fluoroscopy to facilitate access and subsequent maneuvers in the management of biliary and pancreatic ductal (PD) diseases. Biliary cannulation involves advancement of a guidewire or catheter across the papillary orifice and is key to successfully completing ERCP. Most common biliary indications for ERCP include choledocholithiasis, bile leaks (e.g., post-cholecystectomy), malignant conditions resulting in biliary obstruction (pancreatic cancer, cholangiocarcinoma, metastatic disease, extrinsic compression from lymphoma), benign biliary strictures, and functional disease of the biliary system (benign papillary stenosis)[1].

Biliary cannulation success is influenced by many factors, including papillary anatomy, endoscopist technique and experience, patient anatomy, and the underlying disease process. Although biliary cannulation can be accomplished with relative ease in most cases, in approximately 10%-20% of patients’ biliary cannulation can be challenging and is referred to as difficult biliary cannulation[2]. A variety of advanced techniques, including double-guidewire cannulation, pancreatic stent-assisted biliary cannulation, precut access techniques (which involve incision of the overlying mucosa or following PD access), have been developed to improve success rates in these scenarios. Prolonged attempts at cannulation, failed biliary cannulation and the use of modified cannulation techniques have all been shown to be associated with an increased risk of ERCP related adverse events. It is therefore important to think of biliary cannulation as a dynamic process with a constantly evolving, success and adverse event rate, both of which are influenced primarily procedural technique with other factors such as the underlying disease process and patient profile contributing as well. When attempts at biliary cannulation fail, patients may require repeat ERCP, percutaneous transhepatic biliary drainage (PTBD), endoscopic ultrasound (EUS) guided biliary access or drainage or surgical intervention, all of which are associated with increased morbidity and healthcare costs. It is therefore imperative that practicing endoscopists be proficient in different biliary cannulation techniques, anticipate associated intraprocedural and post-procedural adverse events, and employ strategies to minimize the risk of such events. The aim of this narrative minireview is to discuss a contemporary approach to biliary cannulation with an emphasis on procedural considerations to minimize post-ERCP related adverse events.

ERCP RELATED PANCREATITIS

ERCP inherently carries a risk of adverse events that include post-ERCP pancreatitis (PEP), post-sphincterotomy bleeding, infectious complications such as cholangitis and cholecystitis, and perforation. The most common and feared complication associated with ERCP is PEP. Several factors have been identified to play a role in the development of PEP and can be categorized as patient and indication related (e.g., young age, female gender, suspected sphincter of Oddi dysfunction/papillary stenosis), procedure related (papillary anatomy, difficulty of cannulation) and endoscopist related including both procedural technique and volume. A prospective analysis showed that higher annual ERCP case volume per endoscopist correlated with improved cannulation success (P = 0.037) and reduced PEP incidence (P = 0.01), even as case complexity increased[1,3].

PEP remains the most common and clinically significant adverse event following ERCP. Conceptually, it is important to understand that PEP is more likely to occur in the setting of a patient with an otherwise healthy pancreas and repeated manipulation of the pancreatic orifice and PD. Risk factors for PEP can broadly be categorized into patient-related, procedure-related, and operator-related factors. Patient- and indication-related factors include younger age, female sex, and suspected sphincter of Oddi dysfunction or papillary stenosis. In addition, patients with a prior history of PEP or undergoing ERCP for recurrent acute pancreatitis are at an increased risk of developing PEP[1,3].

Procedure-related factors associated with PEP include difficult cannulation, prolonged cannulation time, repeated PD access, and papillary trauma. Pancreatic guidewire passage has in general been shown to be associated with an increased risk of PEP with the risk potentially being higher in the setting of multiple pancreatic guidewire passages[4,5]. Pancreatic sphincterotomy introduces hydrostatic, mechanical, and thermal injury, while PD opacification may cause contrast-related irritation. Prolonged procedure duration (≥ 45 minutes) and difficult or prolonged cannulation (> 10 minutes) further increase PEP risk, likely due to cumulative papillary trauma and edema[6,7]. Anatomical challenges, such as the presence of periampullary diverticulum and distal bile duct and/or ampullary pathology increase the risk of a difficult biliary cannulation and PEP[8].

Aside from procedural techniques, a higher annual ERCP volume per endoscopist has been associated with improved cannulation success and reduced PEP incidence, even as procedural complexity increases. Failure rates are also lower in high-volume centers, likely reflecting greater operator experience and the availability of a second endoscopist when initial cannulation attempts are unsuccessful[9].

Three adjunctive measures have been shown to reduce the risk of PEP, particularly in high-risk patients. Prophylactic PD stent placement lowers PEP incidence by improving ductal drainage and reducing PD hypertension[10]. Combined rectal indomethacin and prophylactic PD stenting is more effective than indomethacin alone in high-risk patients[11]. As the primary focus of this review is cannulation technique and escalation strategy, pharmacologic prophylaxis is referenced here but not discussed in further detail.

Multiple pancreatic guidewire passes [odds ratio (OR) = 2.84; P < 0.001] and brush cytology (OR = 6.37) increase incidence, likely due to ductal trauma and manipulation[4,5]. Pancreatic sphincterotomy (OR = 2.39) introduces hydrostatic, mechanical, and thermal injury, while PD imaging/opacification (OR = 4.43) may cause contrast-related irritation. Longer procedure duration (≥ 45 minutes) and difficult or prolonged cannulation (> 10 minutes; OR: 2.33-2.42) also increase the risk of PEP likely due to repeated manipulation and edema[6,7]. Anatomical challenges such as juxtapapillary duodenal diverticula (OR = 2.00) also predispose to ductal trauma[8]. Collectively, these findings underscore the importance of minimizing pancreatic manipulation, optimizing technical efficiency, and developing strategies to reduce PEP risk. In addition, failure rate has also been shown to be lower in high volume centers likely due to overall higher volume and the ability to utilize the expertise of a second endoscopist if cannulation is not successful by initial treating endoscopist[9].

ADJUNCTIVE STRATEGIES TO REDUCE PEP

Three important adjunctive strategies have been identified to reduce the risk of PEP, in both high and moderate risk patients. These include prophylactic PD stent placement, periprocedural rectal non-steroidal anti-inflammatory drug administration, and adequate periprocedural intravenous fluid. PD stent placement is a well-established prophylactic measure for reducing the overall risk of PEP and in high-risk patients, the risk of severe PEP. The technique involves placement of a temporary plastic stent into the PD to maintain ductal drainage, thereby reducing intraductal hypertension and minimizing pancreatic injury[10]. A recent randomized trial further showed that a combination of rectal indomethacin and PD stenting was more effective than indomethacin alone in high-risk patients[11]. It is therefore important for endoscopists to be proficient in PD stent placement. This narrative minireview focuses on technical aspects of cannulation and escalation pathways. Hence, pharmacologic prophylaxis (e.g., non-steroidal anti-inflammatory drugs, hydration) is referenced but not detailed.

GUIDELINE CONTEXT FOR BILIARY CANNULATION

Society recommendations and competence benchmarks

Major gastroenterology societies, the European Society of Gastrointestinal Endoscopy (ESGE) and the American Society of Gastrointestinal Endoscopy (ASGE) have established competence benchmarks for biliary cannulation and to define difficult cannulation to limit papillary trauma and PEP. The ASGE recommends a deep biliary cannulation success rate exceeding 90% as a competency benchmark whereas the ESGE suggests a selective biliary cannulation success rate greater than 80% prior to performing precut techniques[12].

Definitions of difficult cannulation and escalation pathways

Both the ASGE and ESGE recommend the use of a wire-guided cannulation (WGC) technique using a hydrophilic-tipped wire as the first line approach for biliary cannulation. ESGE defines difficult biliary cannulation when one or more of the following criteria are met: More than 5 contacts with the papilla, more than 5 minutes of cannulation time, or more than one unintended PD cannulation or opacification[2].

For escalation, ESGE supports pancreatic guidewire-assisted techniques with prophylactic PD stenting and precut sphincterotomy. When ERCP fails and PTBD is not feasible, EUS-guided biliary drainage or single-operator cholangioscopy are acceptable rescue options[2,13,14]. Though these guidelines provide effective management algorithms, many are based on older research and may require re-evaluation based on evolving techniques and technologies. Although the two societies broadly agree on cannulation strategy, ESGE provides more explicit procedural thresholds for defining difficult cannulation and guiding escalation strategies. Thus, the ESGE definition of difficult cannulation is used throughout this minireview. Table 1 outlines ASGE and ESGE criteria and their differences.

Table 1 Comparison of American Society of Gastrointestinal Endoscopy and European Society of Gastrointestinal Endoscopy criteria for difficult cannulation.

Parameter	ASGE	ESGE
Competence benchmark	≥ 90% selective cannulation success rate	> 80% selective cannulation success rate for precutting
Definition of difficult cannulation	Not explicitly defined in ASGE guidelines; ACG 2026 quality indicators discuss difficult cannulation but without specific criteria	> 5 contacts with papilla OR > 5 minutes cannulation time OR > 1 unintended; pancreatic duct cannulation (5-5-2 criteria)
First-line technique	Guidewire-assisted technique recommended	Guidewire-assisted technique (strong recommendation, moderate quality evidence)
Escalation strategy	Advanced techniques include double-guidewire, needle-knife sphincterotomy, transpancreatic sphincterotomy; endoscopists should be familiar with ≥ 1 advanced technique	Pancreatic guidewire-assisted cannulation with prophylactic pancreatic stenting; needle-knife fistulotomy preferred for precutting; transpancreatic sphincterotomy for small papilla with inadvertent pancreatic access
Rescue after failed ERCP	EUS-guided biliary drainage as alternative; percutaneous transhepatic biliary drainage; interval ERCP	Anterograde guidewire insertion via percutaneous or EUS-guided approach; EUS-rendezvous technique

ERCP: Endoscopic retrograde cholangiopancreatography; ACG: American College of Gastroenterology; EUS: Endoscopic ultrasound; OR: Odds ratio; ASGE: American Society of Gastrointestinal Endoscopy; ESGE: European Society of Gastrointestinal Endoscopy.

DETERMINANTS OF CANNULATION SUCCESS

Anatomical variation between patients is an important contributing factor that determines the technical difficulty of biliary cannulation[15-17]. Correct positioning of the duodenoscope and cannulation device is important, as the tip of the scope should be situated below the major duodenal papilla to approach the biliary orifice. Duodenoscope positioning may be suboptimal due to upper gastrointestinal tract anatomy, e.g., a duodenal narrowing or sharp angulation, the natural location of the papilla in the duodenum and the morphology of the papilla. Cannulation can be more difficult in small or pleated papillae and may be associated with a higher chance of complications as they may require the use of escalation techniques. In the setting of a periampullary diverticulum the major papilla may be within the diverticulum or on the rim of a diverticulum. This can result in difficulty in aligning the duodenoscope and cannulation device to gain access and advancement of the cannulation wire into the bile duct[3,17]. Distal biliary malignant strictures, for example related to pancreatic or ampullary cancer or malignant retroperitoneal lymphadenopathy, are associated with direct tumor infiltration and difficult cannulation[2].

Operator experience and referral considerations

Operator experience and procedural volume are critical determinants of cannulation success. Precise scope positioning, refined guidewire manipulation, and early recognition of difficult cannulation are essential technical skills[3,15,16]. When biliary access cannot be achieved despite appropriate technique and escalation, several options can be considered to reduce the risk of complications. During the same procedure cannulation may be attempted by a second endoscopist or EUS guided biliary access techniques can be considered. Alternatively, the procedure can be stopped, and the patient referred to a tertiary referral center for a repeat ERCP or interventional radiology for percutaneous drainage. If a precut technique has been used, the procedure may be repeated 48 to 72 hours later during which time papillary edema often resolves, and the biliary orifice becomes easier to identify.

One technical adaptation that may improve outcomes is physician-controlled WGC. While guidewire-based techniques reduce PEP risk compared with contrast-based methods, assistant-related inexperience in wire handling may contribute to cannulation failure. Advances in device design allow endoscopists to control the guidewire directly, potentially enabling faster cannulation and improved torque and directional control[18]. It should be noted however that adjunctive techniques require assistant-controlled wire manipulation. It is therefore important for endoscopy assistants to be trained in device and wire handling techniques.

STANDARD BILIARY CANNULATION TECHNIQUES

Contrast-assisted cannulation

In contrast-assisted cannulation, a sphincterotome or cannula is advanced into the papillary orifice in the orientation of the bile duct. Once the device is engaged in the papilla, small volumes of radiopaque iodinated contrast dye are injected to identify the bile duct, following which a guidewire is advanced into the duct. Limitations of this technique include inadvertent contrast injection of the PD, potential need for multiple attempts to cannulate the bile duct, injection of contrast in the submucosal space if deep biliary cannulation has not been achieved successfully and papillary edema in the setting of repeated attempts and contrast injection[19].

WGC

WGC involves advancing a hydrophilic wire into the papillary orifice in the anticipated direction of the bile duct before advancing the sphincterotome or cannula. In pure WGC fluoroscopic wire orientation is used to aid ductal identification, with a superior and a right to leftward trajectory (the 11 o’clock position) suggesting biliary access and an oblique and left to rightward trajectory (the 1 o’clock position) suggesting PD access (Video 1). Once cannulation has been achieved, contrast injected to obtain a biliary cholangiogram.

Advantages include more controlled duct entry and easier navigation through narrow distal common bile duct segments[20]. Contemporary practice favors WGC as it has been shown to be associated shorter time to accomplish biliary cannulation, a lower rate of contrast injection into the PD and an overall lower rate of PEP compared to contrast-assisted cannulation[2,13,21]. According to recent surveys of biliary cannulation practices, WGC approach has become the preferred approach for biliary cannulation for most endoscopists, increasing from 70%-85% to 95% more recently[12,22-24]. Meta-analyses demonstrate modest improvements in primary cannulation success and reduced need for precut sphincterotomy without increased bleeding or perforation risk[21,25]. It is important to note that overall clinical success and risk mitigation are dependent on careful operator technique to limit trauma and employment of appropriate prophylactic measures to reduce complications irrespective of which cannulation approach is pursued[12,25].

Hybrid cannulation techniques

Hybrid techniques combine WGC with minimal contrast injection to confirm duct orientation before or after wire passage. In situations where the wire is minimally engaged in the papillary orifice, gentle back traction of the wire can be used to guide the cannulation device into the orifice. This maneuver allows the sphincterotome or cannula to be seated in the papilla following which may become easier to advance the wire into the bile duct. A hybrid approach preserves the low PEP rate associated with WGC while reducing blind wire probing, combining the advantage of WGC-while reducing the risk of PEP associated with inadvertent wire passage into the PD. The hybrid technique has been associated with faster deep biliary cannulation and shorter procedure time, and a reduced rates of wire passage into the PD and need for pre-cut techniques as[26].

ALTERNATIVE TECHNIQUES FOR DIFFICULT CANNULATION

When standard biliary cannulation techniques fail several advanced techniques may be employed to achieve ductal access while minimizing the risk of adverse events. Figure 1 details a stepwise clinical algorithm for determining the order of selecting advanced techniques in the setting of difficult cannulation.

Figure 1 A stepwise clinical algorithm for determining the order of selecting advanced techniques in the setting of difficult cannulation. PD: Pancreatic ductal; CBD: Common bile duct; ERCP: Endoscopic retrograde cholangiopancreatography; EUS: Endoscopic ultrasound; CDS: Choledochoduodenostomy; HGS: Hepaticogastrostomy; PTBD: Percutaneous transhepatic biliary drainage.

Double-guidewire cannulation

The double guidewire technique (DGW) is a common salvage strategy for difficult biliary cannulation. Andis typically used in the setting of inadvertent guidewire passage into the PD during biliary cannulation. The pancreatic guidewire helps to stabilize the papilla and adjust the duodenoscope axis. In addition, the PD wire can be advanced gently into the duodenal lumen to separate the pancreatic and biliary orifices. A second wire can then be advanced int the orientation of the bile orifice to facilitate cannulation[2,27] (Video 2). The technique can also facilitate contrast drainage from the PD and be used to place a PD stent for PEP prophylaxis. According to the ESGE guidelines, the DGW technique is the preferred secondary approach for biliary cannulation if the PD is accessed inadvertently during initial biliary cannulation. Given that repeated guidewire cannulation of the PD increases the risk of PEP, it is generally recommended to leave the guidewire in the PD early and consider a DGW technique rather than repeatedly passing a guidewire into the PD. The technique can be especially helpful in the anatomically complex cases, such as intradiverticular papillae when conventional biliary access may not be feasible due to the periampullary anatomy and approach to the papilla.

Early meta-analysis suggested an increased risk of PEP without higher cannulation success, likely reflecting its use after multiple failed attempts. More recent randomized data indicate that early DGW, initiated after the first unintended PD cannulation, is associated with improved cannulation success without significantly increasing PEP rates[28,29]. Observational studies similarly suggest that excess PEP risk may reflect repeated failed cannulation attempts rather than the technique itself[30,31].

Precut access techniques

Precut access techniques, also referred to as precut sphincterotomy, refer to several techniques in which bile duct access is accomplished after performing an incision of the mucosal surface of the papilla to expose the biliary orifice and access to the bile duct. Precut access techniques are the most established salvage techniques for difficult biliary access. Evidence supports a strategy of switching to precut techniques early rather than prolonged cannulation attempts as the latter may lead to edema and reduced success with precut techniques. In one study of 70 patients, early precut sphincterotomy (≤ 10 minutes) achieved higher first-attempt success (95% vs 73%) as compared to delayed precut (> 10 minutes) technique. Additionally, significantly higher rates of prophylactic pancreatic stents were described in the delayed compared to early precut group (36.7% vs 12.5%; P = 0.009)[32]. However, precut techniques are considered to be an independent risk factor for PEP, even after controlling for other procedural variables. Precut access techniques carry additional procedural risks, including bleeding and periampullary perforation due to loss of anatomical landmarks which can result in in the incision being made in wrong plane. These risks can complicate subsequent cannulation and increase post-ERCP morbidity. Precut techniques may be performed freehand or after guidewire access into the PD, with PD-assisted precut generally offering greater stability and lower complication rates compared with freehand incision techniques[33,34].

Needle-knife papillotomy/papillotomy at the orifice

Needle-knife papillotomy (NKP) involves freehand incision at the papillary orifice and is commonly performed after a failed wire-guided or contrast-guided cannulation approach. The cutting needle is advanced into the papillary orifice and oriented towards the bile duct (11 o’clock position of the papillary mound and towards the midline of the mound). The mucosa is then cut using short, sequential incisions to expose the sphincter muscle underlying the mucosal surface (Video 3). The incisions are continued at the sphincter level carefully until bile drainage is the catheter or wire can be advanced into the bile duct to achieve biliary cannulation. The major challenging aspect of this technique is the risk of losing orientation when performing a precut incision, which can result in the incision being extended away from the biliary sphincter resulting in bleeding and retroperitoneal perforation. On the other hand, in experienced hands and with careful technique, these complications can be minimized. Retrospective and prospective studies demonstrate biliary cannulation success rates of 76%-96% with acceptable adverse event rates when performed by experienced endoscopists[35]. Importantly, early NKP does not appear to increase PEP risk compared with delayed use, given it is performed in high-volume centers[36].

If PD access has been achieved, the technique can be modified by placing a pancreatic stent prior to performing a NKP or by performing it over the pancreatic wire (Video 4). These techniques are described as NKP over a PD stent and NK over PD wire respectively. The former has the advantage of minimizing the risk of PEP by early PD stent placement and reducing the risk of losing wire access to the PD during NKP. Adjunctive pancreatic stent placement has been shown to improve outcomes. In a 190-patient cohort, pre-NKP stent placement increased cannulation success (94% vs 83%) without increasing adverse events and was an independent predictor of success[37]. A head-to-head comparison of pancreatic stent-assisted NKP and stent-assisted WGC found that pancreatic stent-assisted NKP yielded higher success (97% vs 90%) and lower PEP rates (3% vs 11%), supporting its role as a safe and effective early rescue technique[38].

Needle-knife fistulotomy

Needle-knife fistulotomy (NKF), in contrast to NKP, creates an incision above the papillary orifice to avoid direct trauma to the PD (Video 5). Several comparative studies and meta-analyses suggest NKF provides similar cannulation success to NKP and may reduce overall adverse events, including PEP[39]. In one study, in patients with a long papilla, primary NKF achieved higher success (96% vs 88%), required fewer attempts, and was associated with lower PEP incidence (2% vs 10%) compared with standard transpapillary approaches[40]. Morphology-specific studies further support primary NKF’s safety and efficacy across regular, long, and bulging papillae, with uniformly high success[41].

Transpancreatic precut sphincterotomy

Transpancreatic precut sphincterotomy (TPS) exploits unintentional PD access by incising the septum between the pancreatic and bile ducts. Following PD cannulation, a sphincterotome is introduced into the pancreatic orifice, oriented towards the bile duct, and a pancreatic sphincterotomy is performed with the aim of cutting the papillary septum to facilitate biliary access (Video 6). Care must be taken not to insert the cutting wire of the sphincterotome too deep into the pancreatic orifice to minimize the risk of acute PD injury and edema, and development of a delayed stricture of the PD. Following the cut, a DGW or sphincterotome/cannula guided approach can be used to attempt biliary cannulation, and a PD stent can be placed to minimize the risk of PEP. In situations where biliary cannulation is not possible despite TPS, an NKP can be performed after initial TPS. TPS has been shown to be associated with a higher cannulation success than NKP (97% vs 71%), though with a somewhat higher risk of pancreatitis and perforation and similar outcomes for expert and non-expert endoscopists, with cannulation a success rate 85% and PEP rate of approximately 9% in both groups[42-44].

DGW vs TPS

Both DGW and precut techniques, like TPS, leverage unintentional PD access. ESGE guidelines recommend DGW as the initial strategy, reserving TPS for failed cases[2]. Critics argue TPS offers higher success and that avoiding DGW delays may reduce PEP risk[45-47]. A recent comparative study found no significant differences in cannulation success, PEP incidence, or severity between sequential DGW followed by TPS and primary TPS when prophylactic PD stenting was used[48]. Given a higher risk of long-term complications with TPS, DGW remains a reasonable first-line salvage technique, with TPS as a secondary option. Table 2 provides a comparison of precut and pancreatic duct-assisted salvage techniques for difficult biliary cannulation.

Table 2 Comparison of precut and pancreatic duct-assisted salvage techniques for difficult biliary cannulation.

Feature	Needle-knife papillotomy	Needle-knife fistulotomy	Transpancreatic sphincterotomy
Approach	Freehand incision at papillary orifice	Freehand incision above papillary orifice	Incision of septum following pancreatic duct wire access
Best clinical scenario	Failed standard cannulation without stable PD access	Long or bulging papilla; when avoiding pancreatic duct trauma is desirable	Repeated unintended PD cannulation or stable PD wire access
Key prerequisites	Experienced endoscopist; ability to maintain orientation of papillary anatomy	Clear papillary anatomy; endoscopist expertise with needle-knife techniques	Pancreatic duct cannulation; ability to place PD stent
Adjuncts	Rectal NSAIDs; prophylactic PD stent if PD manipulated	Rectal NSAIDs; PD stent rarely required	PD stent placement strongly recommended; rectal NSAIDs
Advantages	Widely used; effective in experienced hands	Avoids PD trauma; high success in long papilla; effective in experienced hands	Stable access; high success when PD access is obtained
Risks/limitations	Loss of landmarks; higher risk of PEP; bleeding; perforation	Requires skill; risk of bleeding or perforation	Higher pancreatitis risk; perforation; difficult with complex morphologies; risk of pancreatic duct injury or stricturing

PD: Pancreatic ductal; NSAIDs: Nonsteroidal anti-inflammatory drug; PEP: Post-endoscopic retrograde cholangiopancreatography pancreatitis.

EUS-guided bile duct access and drainage offer the advantage of biliary access to facilitate ERCP or placement of a transgastric or transduodenal stent directly into the biliary tree to achieve biliary drainage. EUS-guided rendezvous (EUS-RV) involves accessing the biliary tree via a transduodenal approach (extrahepatic bile duct access) or transgastric approach (transhepatic access), following which a wire is advanced into the biliary system and across the papillary orifice. The wire is left in the duodenum and the EUS scope is exchanged for a duodenoscope to either cannulate the bile duct alongside the rendezvous wire or by pulling the wire out of the patient’s mouth and loading it into the duodenoscope channel, following which a catheter or sphincterotome can be advanced into the bile duct.

EUS guided transmural drainage techniques involve creating a choledochoduodenal, hepaticogastric and less commonly a hepaticoduodenal or choledochogastric fistula using a multi-step technique or a cautery assisted catheter and stent system. These approaches have gained significant popularity over the last 20 years, particularly in challenging settings such as intradiverticular papillae, malignant obstruction, or altered anatomy where the papilla is either inaccessible or cannot be cannulated. A meta-analysis of the EUS-RV technique reported a pooled technical success of approximately 86% and clinical success of approximately 81%, with an overall adverse event rate of approximately 14% of EUS[49]. Comparative studies suggest EUS-RV is associated with similar outcomes for percutaneous rendezvous and precut sphincterotomy techniques[50-53]. Meta-analyses comparing EUS-guided biliary access drainage techniques with percutaneous biliary drainage demonstrate higher clinical success, fewer post procedure adverse events, and lower rates of reintervention for EUS-guided biliary access and drainage techniques. Importantly, since EUS-guided biliary drainage avoids the need for percutaneous drains, this approach is associated with better quality of life for patients.

Benign disease

In benign biliary disease, the primary goal of salvage cannulation is to achieve ductal access while minimizing trauma to the papilla and surrounding structures and compromising natural biliary drainage via the papilla. EUS-RV is therefore widely considered the preferred rescue strategy in this setting, as evidenced by a recent meta-analysis and a recent randomized controlled trial that compared EUS-RV with precut sphincterotomy in cannulation for benign biliary disease[54,55].

Malignant biliary obstruction

For patients with malignant biliary obstruction, the optimal rescue strategy has shifted towards establishing transmural biliary drainage that bypasses the tumor. While EUS-RV remains a valid option, it is a multistep procedure and requires traversing the malignant stricture which can be technically challenging and time consuming. Due to these challenges, EUS-guided transmural approaches, specifically EUS-guided choledochoduodenostomy (CDS) and hepaticogastrostomy (HGS), are increasingly being used[56-59] as an alternative to EUS-RV. EUS-CDS has the advantage that it can be performed using dedicated cautery assisted catheter and stent systems and is therefore associated with a short procedure time and can be performed with relatively limited experience[60]. Recent systematic reviews have demonstrated that EUS-HGS has higher clinical success rates, fewer adverse events, and fewer reinterventions compared to traditional methods such as PTBD[61,62]. When comparing transmural techniques (HGS/CDS) with recent guidelines suggest that for distal malignant obstruction, EUS-CDS provides comparable safety to ERCP but with a significantly lower risk of pancreatitis[63,64]. Unlike the rendezvous technique, which still relies on transpapillary access, HGS and CDS create a new outflow tract away from the tumor, potentially offering longer-lasting patency. Thus, in cases of malignant obstruction where standard cannulation fails, shifting directly to HGS or CDS is often preferred over persistent attempts at rendezvous or percutaneous drainage. In addition, in randomized trials, comparing EUS-BD to ERCP, transmural approaches have also been shown to be associated with a reduced risk of pancreatitis attributed to lack of manipulation of the papillary orifice[65]. Although this concept is appealing and requires further study, ERCP remains the first-line approach for biliary drainage for malignant distal biliary obstruction. Limitations of EUS-BD include a lack of large studies to assess efficacy and safety, the logistical challenges of training providers to safely perform these procedures, and widespread implementation of EUS-BD.

Figure 1 displays the step-by-step clinical escalation algorithm for difficult biliary cannulation during ERCP. Initial biliary access should be attempted using WGC. Escalation is recommended when predefined stop criteria are reached (≥ 5 papillary contacts, ≥ 5 minutes cannulation time, or > 1 unintended PD cannulation, as per ESGE criteria). When unintended PD access occurs, pancreatic guidewire-assisted strategies such as the DGW or PD stent-assisted cannulation are recommended, followed by transpancreatic sphincterotomy if necessary. In the absence of PD access, early precut techniques including NKF or papillotomy (NKF/NKP) may be performed. If ERCP cannulation ultimately fails, rescue strategies should be selected based on clinical context, with EUS-RV preferred in benign disease and EUS-guided transmural drainage favored in malignant obstruction.

INNOVATIVE TECHNIQUES

Several innovative approaches have been described to achieve biliary access, however, remain investigational. Partial ampullary EMR involves limited resection of the papillary mucosa to expose and enlarge the biliary orifice, thereby facilitating cannulation. Small case series report greater than 95% technical success with acceptable complication rates[66]. In patients with periampullary or intradiverticular papillae, clip-assisted cannulation is a technique that can be used. In this technique, a hemostatic clip is used to apply traction to the duodenal mucosa to change the orientation of the papilla and facilitate cannulation.

Submucosal injection before precut has also been described as a technique to facilitate biliary access. By injecting saline or dye into the submucosal layer beneath the papilla, the mucosa is lifted away from the underlying sphincter complex. This theoretically reduces the risk of perforation and provides a clearer dissection plane for needle-knife incision. Early case reports and small series suggest the approach may improve safety by maintaining landmarks and minimizing deep mural injury[65,66].

Machine learning (ML) approaches have also been used to explore predict difficult biliary cannulation and the risk of PEP. It is anticipated that ML and artificial intelligence technologies will help predict challenges associated with biliary cannulation based on papillary morphology and ampullary anatomy, provide guidance to optimize biliary cannulation and predict the risk of complications and mitigate these risks.

CONCLUSION

Biliary cannulation remains a technically demanding but essential component of ERCP, with success depending not only on operator expertise but also on careful selection and timely escalation of techniques. Knowledge of the risks and benefits of approaches ranging from WGC to precut and PD-assisted methods is critical for minimizing complications such as PEP, bleeding, and perforation. As this minireview highlights, both traditional and emerging strategies have unique advantages and limitations, underscoring the importance of tailoring cannulation approaches to patient anatomy and procedural context. Importantly, the field continues to evolve with novel endoscopic techniques, adjunctive measures such as PD stenting, and even ML-based risk prediction. Looking ahead, changes in devices, training, and evidence-based algorithms will further enhance the safety and efficacy of cannulation. A balanced understanding of current methods, along with openness to innovation, will remain central to optimizing patient outcomes in therapeutic ERCP.