What is laser lithotripsy?

What is Laser Lithotripsy

Laser lithotripsy is an intracorporeal stone fragmentation technique that uses laser energy—most commonly the Holmium:YAG laser—to break kidney or ureteral stones into smaller fragments that can either be extracted with baskets or left to pass spontaneously through the urinary tract. 1

Mechanism of Action

• Laser lithotripsy delivers focused laser energy through a flexible fiber (typically 200-365 microns) that is passed through a ureteroscope to directly contact the stone 1, 2
• The laser energy creates a photothermal and photomechanical effect that fragments the stone into smaller pieces 3
• The Holmium:YAG laser is considered the gold standard for intracorporeal lithotripsy due to its effectiveness across all stone compositions 1
• The thulium fiber laser offers comparable efficacy as an alternative technology 1

Clinical Applications

Stone Location and Size

• Laser lithotripsy is used during ureteroscopy (URS) for stones throughout the urinary tract—in the kidney, ureter, and bladder 1
• It is particularly effective for stones less than 20 mm in the renal pelvis, upper and middle calyces 1
• For stones 2-3 cm, flexible ureteroscopy with laser lithotripsy can achieve 63-93% stone-free rates (0-2 mm residual fragments), though percutaneous nephrolithotomy remains superior for complete clearance 4, 2
• Laser lithotripsy is increasingly used with flexible nephroscopy during percutaneous nephrolithotomy to reduce the number of access tracts needed for staghorn stones 1

Advantages Over Other Modalities

• Unlike extracorporeal shock wave lithotripsy (ESWL), laser lithotripsy allows direct visualization and treatment of the stone under endoscopic guidance 1
• Laser lithotripsy is effective regardless of stone composition, whereas ESWL has reduced efficacy for hard stones like calcium oxalate monohydrate or cystine 1, 5
• The procedure can be performed with minimal anesthesia (intravenous sedation) in many cases 1

Technical Approaches

Dusting vs. Fragmentation with Extraction

• Dusting uses low energy and high frequency settings to create very small stone fragments (dust) that can pass spontaneously, resulting in shorter procedure times and lower risk of ureteral injury 3
• Fragmentation with extraction uses high energy and low frequency settings to create larger fragments that are actively removed with baskets, potentially providing more complete initial stone clearance 3
• High-power laser settings reduce lasering time but have no proven clinical advantage over standard settings 1
• Complete stone removal is the goal; "dust and go" should be limited to large renal stones 1

Procedural Considerations

Equipment and Access

• Laser lithotripsy can be performed with either semirigid ureteroscopes (for ureteral stones) or flexible ureteroscopes (for intrarenal stones) 1, 2
• A ureteral access sheath is commonly used (in approximately 67% of cases) to facilitate repeated passage of the ureteroscope 4
• Ultrasonic, pneumatic, and combined lithotripsy systems are alternatives for rigid nephroscopy, but lasers are increasingly preferred for flexible instruments 1

Stenting Practices

• Routine prestenting before ureteroscopy is not recommended but may improve treatment outcomes for renal stones 1
• Routine post-procedure stenting is unnecessary after uncomplicated procedures and may increase morbidity 1
• Stenting is advised when there is ureteral trauma, residual fragments, bleeding, perforation, urinary tract infection, or pregnancy 1
• Alpha-blockers improve stent tolerability when stenting is necessary 1

Outcomes and Efficacy

Success Rates by Location

• For proximal ureteral stones: 81% stone-free rate with ureteroscopic laser lithotripsy 1
• For mid-ureteral stones: 86.1% immediate success rate 6
• For distal ureteral stones: 94.5% immediate success rate 6
• For renal stones in children: 94.4% stone-free rate with laser lithotripsy compared to 62.5% with pneumatic lithotripsy 7

Procedural Characteristics

• Most procedures (84%) can be completed in a single stage for stones 2-3 cm 4
• The mean number of procedures for stones 2-3 cm is 2.3 (range 2-4) 2
• Medical expulsive therapy (alpha-blockers) after laser lithotripsy aids stone passage and reduces colic 1

Safety Profile

Complication Rates

• Ureteral perforation occurs in less than 5% of cases, with long-term complications like stricture formation occurring in 2% or less 1
• Minor complications in pediatric patients include perirenal hematoma, urinoma, and minimal ureteral perforation, all significantly lower with laser compared to pneumatic lithotripsy 7
• Major complications are rare, with one study reporting only one ureteral perforation in 232 patients (0.9%) 6
• The reoperation rate through 18-month follow-up is approximately 2.5% 4

Contraindications

• Ureteroscopy with laser lithotripsy has no specific contraindications aside from general anesthesia risks and untreated urinary tract infections 1
• Flexible ureteroscopy is recommended when antithrombotic therapy cannot be stopped 1

Clinical Pitfalls to Avoid

• Residual fragments: The dusting technique may leave small fragments that could lead to stone regrowth (21-59% regrowth rate for residual fragments), so consider active extraction for complete clearance when feasible 8, 3
• Lower pole stones: Laser lithotripsy effectiveness is partially limited for stones in lower pole calyces due to gravity-dependent drainage 7
• Incomplete treatment: Always perform follow-up imaging to confirm stone clearance, as residual fragments may not be apparent during the procedure 5
• Infection risk: Obtain urine culture before the procedure and treat bacteriuria; administer antimicrobial prophylaxis based on local antibiogram 5