Version July 2025
INTRODUCTION —
Electrohydraulic lithotripsy (EHL) is a method for performing endoscopy-guided fragmentation of bile and pancreatic duct stones. EHL systems are portable, efficient, and relatively inexpensive. EHL is typically used under direct visualization during peroral cholangioscopy or pancreatoscopy. (See "Cholangioscopy and pancreatoscopy".)
Historically, EHL was used for treating urinary tract stones, but it has largely been replaced by other methods for urinary tract stone fragmentation (eg, laser lithotripsy, extracorporeal shock wave lithotripsy). However, laser lithotripsy for bile duct stones has not been widely adopted because its use is limited by cost and the need for specialized equipment.
This topic will focus on the technical aspects, efficacy, and safety of EHL in managing bile duct and pancreatic duct stones.
Clinical features, diagnosis, and management of bile duct and pancreatic duct stones are discussed in more detail separately:
●(See "Choledocholithiasis: Clinical manifestations, diagnosis, and management".)
●(See "Chronic pancreatitis: Clinical manifestations and diagnosis in adults" and "Chronic pancreatitis: Management".)
Other lithotripsy methods are discussed separately:
For bile duct stones:
●Mechanical lithotripsy – (See "Endoscopic management of bile duct stones", section on 'Mechanical lithotripsy'.)
●Laser lithotripsy – (See "Laser lithotripsy for the treatment of bile duct stones".)
For pancreatic duct stones:
●Extracorporeal shock wave lithotripsy – (See "Extracorporeal shock wave lithotripsy for pancreatic stones".)
Clinical applications and technical aspects of ERCP-guided cholangioscopy and pancreatoscopy are discussed separately. (See "Cholangioscopy and pancreatoscopy".)
Percutaneous cholangioscopy is discussed separately. (See "Percutaneous transhepatic cholangioscopy".)
PATIENT SELECTION
Clinical applications — We use EHL to fragment difficult bile duct stones when mechanical lithotripsy has been or is unlikely to be successful for facilitating stone extraction (picture 1 and picture 2) [1]. As examples, we may use EHL for patients with any of the following (see "Choledocholithiasis: Clinical manifestations, diagnosis, and management"):
●Very large bile duct stones (eg, >2 cm, unlikely to fit in the basket).
●Stone impacted in bile duct.
●Stone-basket complex impacted in the bile duct – When using a basket to retrieve a bile duct stone or stone fragments, the basket-stone complex may become impacted in the distal bile duct and cannot be removed or dislodged (image 1).
●Bile duct stone in a difficult anatomic location (eg, Mirizzi syndrome, proximal to biliary stricture). (See "Mirizzi syndrome".)
We also use EHL to fragment pancreatic duct stones that are causing obstruction. Completely or partially obstructing pancreatic duct stones may increase intraductal pressure that contributes to abdominal pain in patients with chronic pancreatitis. The pancreatic duct is typically smaller than the bile duct but is usually dilated in patients with obstructing pancreatic stones. Thus, the pancreatic duct can accommodate the pancreatoscope and instruments related to EHL. (See "Chronic pancreatitis: Management", section on 'Patients with dilated pancreatic duct'.)
Other less common applications of EHL include relieving gastrointestinal obstruction (eg, small bowel, colon) related to a gallstone or biliary stone [2-4]. Gallstone ileus infrequently causes mechanical bowel obstruction, and this is discussed separately. (See "Gallstone ileus".)
Contraindications — We typically perform EHL during endoscopic retrograde cholangiopancreatography (ERCP), and contraindications to ERCP are discussed separately. (See "Overview of endoscopic retrograde cholangiopancreatography (ERCP) in adults", section on 'Contraindications'.)
Several clinical conditions require special consideration before performing EHL, although there are no consensus-based contraindications specific to EHL:
●Use of anticoagulants or antiplatelet agents – Performing EHL in patients who are taking an anticoagulant or antiplatelet agent may increase the risk of bleeding due to intraductal manipulation of the EHL probe and removal of sharp stone fragments. Management of anticoagulants and antiplatelet agents in patients undergoing endoscopy is discussed separately. (See "Management of anticoagulants in patients undergoing endoscopic procedures" and "Management of antiplatelet agents in patients undergoing endoscopic procedures".)
●Acute pancreatitis – For patients with acute pancreatitis, fragmenting bile or pancreatic duct stones may escalate the severity of pancreatitis due to mechanical trauma.
●Acute cholangitis – For patients with acute cholangitis, intraductal instrumentation and insufflation of fluid may raise intraductal pressures and lead to bacterial translocation and worsening of acute cholangitis. (See "Infectious adverse events related to endoscopic retrograde cholangiopancreatography (ERCP)".)
PATIENT PREPARATION —
The preprocedure preparation for patients undergoing EHL is similar to that described for patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) (See "Overview of endoscopic retrograde cholangiopancreatography (ERCP) in adults", section on 'Patient preparation'.)
●Antibiotic prophylaxis – We use antibiotic prophylaxis for patients undergoing peroral EHL during ERCP with cholangioscopy or pancreatoscopy. Options for antibiotic regimens in this setting are similar to those used for patients undergoing ERCP with other indications for antibiotic prophylaxis (eg, incomplete biliary drainage) (table 1) [5]. (See "Antibiotic prophylaxis for gastrointestinal endoscopic procedures" and "Cholangioscopy and pancreatoscopy", section on 'Patient preparation'.)
●Sedation/anesthesia – We typically perform peroral ERCP-guided EHL with general anesthesia, although the approach to anesthetic management may vary among advanced endoscopists and institutions. Aspiration is a risk during any endoscopic procedure. With cholangiopancreatoscopy, there is a mildly increased risk because the bile or pancreatic duct is irrigated with saline that may reflux into the duodenum and the stomach. Anesthetic management for advanced endoscopic procedures is discussed separately. (See "Anesthesia for gastrointestinal endoscopy in adults", section on 'Advanced endoscopic procedures'.)
●Adjusting medications – The management of antiplatelet and anticoagulant therapy in patients undergoing ERCP is typically individualized, managed in conjunction with the prescribing specialist, and is discussed separately. (See "Management of anticoagulants in patients undergoing endoscopic procedures" and "Management of antiplatelet agents in patients undergoing endoscopic procedures".)
EQUIPMENT
Cholangiopancreatoscope — We use a small diameter, flexible endoscope (10.5 French) to access the common bile or pancreatic duct, and this small endoscope may be collectively referred to as a cholangiopancreatoscope. In addition, the small endoscope may be referred to as a cholangioscope when examining the common bile duct and as a pancreatoscope when examining the pancreatic duct.
We use a digital, single-operator cholangiopancreatoscope (eg, SpyGlass DS) and advance it through the accessory channel of a therapeutic duodenoscope. Features of the digital, small caliber scope include (see "Cholangioscopy and pancreatoscopy"):
●Working channel diameter of 1.2 mm that allows for introducing accessories needed for therapeutic intervention
●Separate irrigation channel
●Four-way endoscope tip deflection
EHL probe and charge generator — Systems for EHL consist of a bipolar probe and a charge generator, and such systems are generally compact and easily mobile [6]. The EHL probe contains two coaxially insulated electrodes ending at an open tip. The EHL probe measures approximately 1.9 to 3.3 French (0.66 to 1.1 mm). Transmitting a charge across the electrodes creates a spark that induces expansion of the surrounding fluid, as discussed below. (See 'Principles of generating electrical current' below.)
TECHNICAL ASPECTS
Principles of generating electrical current — EHL involves creating an electric spark between two electrodes located at the tip of the EHL probe [1]. The spark induces expansion of the surrounding fluid (ie, saline) resulting in a spherical shock wave. The shock wave oscillates, generating sufficient hydraulic pressure to fragment the stone [6]. Saline irrigation into the bile or pancreatic duct provides a medium for shock wave transmission. We typically use EHL under direct visualization (ie, cholangiopancreatoscopy) because misguided shock waves may cause ductal injury and perforation. (See 'Adverse events' below.)
Procedure technique (peroral EHL)
Initial steps (establishing duct access) — The initial steps during ERCP involve gaining access to the common bile or pancreatic duct with guidewire-facilitated ductal cannulation and performing sphincterotomy.
After ductal cannulation, we obtain a cholangiogram (or pancreatogram) by injecting contrast into the duct of clinical interest to visualize the obstruction and duct characteristics (eg, diameter, contour). After assessing the duct diameter and stone size, we create an exit path for the stone by enlarging the ampullary orifice (or pancreatic orifice) by incising the sphincter (ie, sphincterotomy) [7]. (See "Endoscopic biliary sphincterotomy".)
After sphincterotomy is performed, the sphincterotome is removed and the guidewire is left in place within the bile or pancreatic duct. (See 'Direct visualization (cholangiopancreatoscopy)' below.)
Direct visualization (cholangiopancreatoscopy) — Cholangiopancreatoscopy provides direct visualization of the bile or pancreatic duct and the stone(s), and the technique is summarized as follows:
●Advance the cholangiopancreatoscope over the guidewire and into the duct using a combination of endoscopic and fluoroscopic guidance (image 2).
●After advancing the cholangiopancreatoscope to the target location, remove the guidewire to permit use of the accessory channel and to enhance visualization. Technical aspects of cholangiopancreatoscopy are discussed in more detail separately. (See "Cholangioscopy and pancreatoscopy".)
Inserting the EHL probe — The technique for inserting the EHL probe into the common bile or pancreatic duct is summarized as follows [8]:
●Flush the accessory channel of the cholangiopancreatoscope with liquid silicone to lubricate the channel.
●Slowly advance the EHL probe through the accessory channel. We typically try to straighten the cholangiopancreatoscope while advancing the EHL probe because the probe is rigid and may easily damage the scope's channel if it is angulated.
●To straighten the cholangiopancreatoscope, we usually push it forward to achieve a "long" position.
Flushing water through the accessory channel may facilitate advancing the EHL probe. If placing the EHL probe into the bile duct is difficult, we may advance the cholangioscope into the proximal bile duct and then try to advance the EHL probe.
Fragmenting the stone(s) — After advancing the EHL probe through the cholangiopancreatoscope, we fragment the stone using the following steps [6]:
●Visualize the tip of the probe endoscopically and with fluoroscopy (figure 1).
●Irrigate the duct with saline.
●Advance the EHL probe to the stone's center and position it approximately 1 to 2 cm from the stone. The stone can be touched if needed. However, touching the stone may reduce the functional lifespan of the probe itself.
If we cannot place the probe at the stone's center, we may fire the EHL probe tangentially while avoiding contact with the duct wall. Electric sparks delivered tangentially may chip the stone without fragmenting it. Thus, chipping the stone may allow for better placement of the probe against the stone.
●Deliver electrical current while continuously irrigating the duct with saline. Saline irrigation generates a fluid medium and increases the electrical power (by approximately 10-fold). Successful stone fragmentation requires a fluid environment for both the probe's tip and the stone surface. Saline irrigation also clears debris within the duct and facilitates visualization.
When delivering electrical current, we usually use a computer-controlled generator that simplifies the power settings such that watts are adjusted to preset power settings. If such a generator is not available, electrical current can be delivered by starting with 70 watts and increasing it by 10 watts as needed to a maximum of 100 watts via 1- to 2-second pulsations or continuous pulsations. Some generators have a preset power wattage (usually in the range of 70 to 100 watts).
Extracting the stone(s) — Following stone fragmentation, we withdraw the EHL probe and cholangiopancreatoscope from the duodenoscope. Some stones will exit the bile duct without further intervention, while other stones will require additional extraction methods. Commonly used extraction devices include balloon or basket catheters (figure 1). Methods for extracting stone fragments are discussed separately. (See "Endoscopic management of bile duct stones", section on 'ERCP-guided stone removal'.)
Other methods for EHL — Alternatives to peroral endoscopy-guided EHL include (see "Cholangioscopy and pancreatoscopy"):
●Percutaneous cholangioscopy with EHL – We reserve the percutaneous approach for peripheral or intrahepatic stones proximal to biliary strictures. Percutaneous cholangioscopy with EHL can be used in patients with postsurgical anatomy that impacts access to the bile duct via ERCP (ie, peroral route). As an example, we have performed percutaneous cholangioscopy in patients after pancreatoduodenectomy who developed a biliojejunal anastomotic stricture and formed a stone proximal to it.
●Intraoperative EHL – An intraoperative approach has been described for fragmenting refractory pancreatic duct stones [9,10]. In addition, intracorporeal lithotripsy can be used in conjunction with extracorporeal lithotripsy in patients with stones that are difficult to remove. (See "Percutaneous transhepatic cholangioscopy".)
POSTPROCEDURE CARE —
Postprocedure care following endoscopic retrograde cholangiopancreatography includes monitoring patients as they recover from anesthesia. Peroral EHL is generally performed on an outpatient basis. Post-anesthesia care and other postprocedure issues are discussed in more detail separately. (See "Overview of endoscopic retrograde cholangiopancreatography (ERCP) in adults", section on 'Post-procedure care' and "Anesthesia for gastrointestinal endoscopy in adults", section on 'Post-anesthesia care'.)
EFFICACY
Bile duct stones — Reported rates for complete clearance of the common bile duct with EHL have approached or exceeded 90 percent [11-15]. In a study of 407 patients with bile duct stones who underwent cholangioscopy-guided lithotripsy (EHL or laser lithotripsy), overall rates of ductal clearance were 97 and 99 percent, respectively [13]. In an earlier systematic review including 32 studies and 1969 patients, laser lithotripsy was associated with higher rates of complete ductal clearance compared with EHL and with extracorporeal shock wave lithotripsy (ESWL) (95 versus 88 and 85 percent, respectively) [12]. However, this review included studies using older EHL generators, and in our experience, the automated EHL generators perform better than older models and are comparable to holmium laser lithotripters.
Pancreatic stones — Studies suggested that pancreatoscopy-guided EHL was effective for clearing pancreatic stones and improving symptoms related to ductal obstruction (eg, abdominal pain) [16-20]. In a retrospective study including 109 patients with pancreatic duct stones, rates of ductal clearance were not significantly different for EHL compared with laser lithotripsy (94 versus 100 percent) [16]. In addition, adverse event rates were not significantly different between groups. In a study including 25 patients with obstructive chronic calcific pancreatitis who underwent pancreatoscopy with stone visualization, EHL was associated with complete ductal clearance in 20 patients (80 percent) and partial clearance in five patients (20 percent) [17]. In addition, treatment with EHL was associated with lower pain scores after six months of follow-up.
ADVERSE EVENTS —
Reported rates of adverse events related to endoscopic retrograde cholangiopancreatography (ERCP) with EHL have ranged from 3 to 13 percent, and events include bleeding, perforation, pancreatitis, and cholangitis [13,16,17,21-23]. However, adverse events reported in patients who undergo peroral, endoscopy-guided EHL may have been related to other interventions performed during ERCP (eg, sphincterotomy) or to cholangiopancreatoscopy. (See "Adverse events related to endoscopic retrograde cholangiopancreatography (ERCP) in adults" and "Cholangioscopy and pancreatoscopy", section on 'Adverse Events'.)
Adverse events attributed specifically to endoscopy-guided lithotripsy are uncommon and include:
●Ductal perforation – Direct contact of the EHL probe with the duct wall increases the risk of perforation of the common bile or pancreatic duct. Perforation can also occur due to extreme elevation of the surface temperature of the stone and surrounding ductal tissues, which is usually caused by prolonged application of EHL. In a study of 407 patients who underwent cholangioscopy-guided lithotripsy for difficult biliary stones, bile duct perforation occurred in one patient (<1 percent) and was treated endoscopically with a fully covered, self-expandable metal stent [13]. In a study of 109 patients who underwent pancreatoscopy-guided lithotripsy for pancreatic duct stones, perforation of the main pancreatic duct occurred in one patient (1 percent) [16]. (See 'Principles of generating electrical current' above.)
●Bleeding – Bleeding may result from trauma induced by the EHL probe against the wall of the bile or pancreatic duct. In a study of 407 patients who underwent cholangioscopy-guided lithotripsy for difficult biliary stones, bleeding occurred in one patient (<1 percent) [13]. In a study of 109 patients who underwent pancreatoscopy-guided lithotripsy for pancreatic duct stones, bleeding occurred in two patients (2 percent) [16].
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Biliary infection and obstruction" and "Society guideline links: Chronic pancreatitis and pancreatic exocrine insufficiency".)
SUMMARY AND RECOMMENDATIONS
●Background – Electrohydraulic lithotripsy (EHL) is a method for performing endoscopy-guided fragmentation of bile duct and pancreatic duct stones. EHL is typically used under direct visualization during peroral cholangioscopy or pancreatoscopy. (See "Cholangioscopy and pancreatoscopy".)
EHL involves creating an electric spark between two electrodes located at the tip of the EHL probe. The spark induces expansion of the surrounding fluid resulting in a spherical shock wave. The shock wave oscillates, generating sufficient hydraulic pressure to fragment the stone. Saline irrigation into the bile or pancreatic duct provides a medium for shock wave transmission.
●Clinical applications – We may use EHL to fragment bile duct or pancreatic duct stones in patients with any of the following (see 'Clinical applications' above and "Choledocholithiasis: Clinical manifestations, diagnosis, and management"):
•Very large (>2 cm) bile duct stones (picture 1 and picture 2)
•Stone or stone-basket complex that is impacted in the common bile duct (image 1)
•Bile duct stone in a difficult anatomic location (eg, Mirizzi syndrome, proximal to biliary stricture) (see "Mirizzi syndrome")
•Pancreatic duct stones that are causing obstruction (see "Chronic pancreatitis: Management", section on 'Patients with dilated pancreatic duct')
●Preprocedure preparation
•The preprocedure preparation for patients undergoing EHL is similar to that described for patients undergoing endoscopic retrograde cholangiopancreatography (ERCP). (See "Overview of endoscopic retrograde cholangiopancreatography (ERCP) in adults", section on 'Patient preparation'.)
•We use antibiotic prophylaxis for patients undergoing EHL during ERCP with cholangioscopy or pancreatotoscopy. Options for antibiotic regimens in this setting are similar to those used for patients with other indications for antibiotic prophylaxis (eg, ERCP with incomplete biliary drainage) (table 1) [5]. (See "Cholangioscopy and pancreatoscopy", section on 'Patient preparation'.)
●Equipment – Equipment for EHL includes a flexible, small caliber endoscope (cholangiopancreatoscope) for direct ductal visualization in addition to the EHL probe and charge generator. (See 'Equipment' above.)
●Postprocedure care – Postprocedure care following ERCP includes monitoring patients as they recover from anesthesia. (See 'Postprocedure care' above and "Anesthesia for gastrointestinal endoscopy in adults", section on 'Post-anesthesia care'.)
●Efficacy and safety – Reported rates for stone clearance of the common bile duct or pancreatic duct with EHL have approached or exceeded 90 percent.
Adverse events attributed to endoscopy-guided lithotripsy are uncommon and include ductal perforation and bleeding. (See 'Adverse events' above.)
ACKNOWLEDGMENT —
The UpToDate editorial staff acknowledges Susana Escalante-Glorsky, MD, and Isaac Raijman, MD, who contributed to earlier versions of this topic review.
