What are the methods for stone fragmentation in the common bile duct (CBD)?

Methods for Stone Fragmentation in the Common Bile Duct

For difficult CBD stones that cannot be removed by standard techniques, cholangioscopy-guided lithotripsy using either electrohydraulic lithotripsy (EHL) or laser lithotripsy (LL) achieves stone clearance rates of 73-97% and represents the most effective fragmentation approach when mechanical lithotripsy fails. 1

Primary Fragmentation Techniques

Mechanical Lithotripsy

• Standard first-line fragmentation method after conventional basket/balloon extraction fails during ERCP 1
• Used in conjunction with endoscopic papillary large balloon dilation (EPLBD) and prior sphincterotomy for large stones 1
• Lower success rates (63%) compared to laser lithotripsy for very large stones or stones floating above a tapering CBD 2

Electrohydraulic Lithotripsy (EHL)

• Mechanism: Generates shock waves through rapid thermal expansion of fluid caused by high-voltage spark, creating hydraulic pressure waves that fragment stones 1
• Must be performed under direct cholangioscopic visualization to ensure safety and precise targeting 1
• Achieves 73-97% stone clearance rates when used with single-operator cholangioscopy (SOC) guidance 1
• Final stone clearance achieved in 77% of patients in long-term Swedish experience, with 52% requiring only one session 3

Laser Lithotripsy (LL)

• Mechanism: Pulsed laser energy focused on stone causes thermal absorption by water in stones, creating expansion and shock waves that fragment calculi 1
• Requires direct visualization through cholangioscopy for safe delivery 1
• Superior to mechanical lithotripsy with 100% vs 63% first-session clearance rate for very large CBD stones after failed EPLBD 2
• Significantly lower radiation exposure (20,989 vs 40,745 mGycm²) compared to mechanical lithotripsy 2
• Can rescue 60% of failed mechanical lithotripsy cases within the same session 2

Extracorporeal Shock Wave Lithotripsy (ESWL)

• Highly effective for stones >5mm with >90% fragmentation success rates 1
• Complete duct clearance by subsequent ERCP achievable in more than two-thirds of patients 1
• Total CBD clearance achieved in 84.4% of patients with large stones, with 74.6% requiring ≤3 sessions 4
• Major limitation: Not widely available in the United States, restricting generalizability 1
• More than half of patients remain pain-free over 2-year follow-up 1

Technical Considerations for Cholangioscopy-Guided Lithotripsy

Platform Technology

• SpyGlass Legacy system introduced in 2006 allows single-operator cholangioscopy through duodenoscope 1
• SpyGlass DS digital platform (2015) addresses earlier concerns about fiber optic visualization and accessory insertion 1

Safety Profile

• Cholangitis occurs in up to 9% of patients, necessitating prophylactic antibiotics 1
• Other complications comparable to conventional ERCP 1
• Minor complications in 15.9% with ESWL, with no procedure-related mortality 4
• Post-ERCP pancreatitis and cholangitis remain potential risks 3

Clinical Algorithm for Stone Fragmentation

When Standard Extraction Fails

1. First attempt: Mechanical lithotripsy with EPLBD and prior sphincterotomy 1
2. Second-line: Cholangioscopy-guided EHL or LL for stones refractory to mechanical lithotripsy 1
3. Alternative (if available): ESWL for stones >5mm, particularly when intraductal access is difficult 1, 4
4. Complementary approach: ESWL and pancreatoscopy-directed lithotripsy often work together for large/complex stones 1

Factors Favoring Successful Fragmentation

• For ESWL: Radiolucent calculi, presence of fluid around calculus, shock frequency of 90/min, and epidural anesthesia improve fragmentation 4
• Technical success with intraductal lithotripsy: 88% overall, but lower with pancreatic duct strictures, multiple stones, or upstream location 1

Critical Pitfalls to Avoid

• Never perform blind instrumentation of the bile duct without choledochoscope due to perforation risk and increased stricture development 1
• Do not proceed to bypass surgery without attempting cholangioscopy-guided lithotripsy, which has 73-97% clearance rates 5, 6
• Recognize that multiple sessions may be required - 52% achieve clearance in one session, but additional attempts often succeed 3
• Consider percutaneous or surgical extraction only after all endoscopic techniques (including cholangioscopy-guided lithotripsy) have failed 1