What is lithotripsy?

What is Lithotripsy

Lithotripsy is a medical procedure that uses shock waves generated outside the body to break kidney stones or ureteral stones into smaller fragments that can pass through the urine. 1

Mechanism of Action

• Shock waves are generated externally and focused onto the stone using specialized equipment, releasing energy when passing through areas of different acoustic impedance. 1
• Hundreds to thousands of shock waves are typically delivered to adequately fragment the stones into passable pieces. 1
• Most modern lithotripters have variable power capabilities, starting with lower energy levels and gradually increasing as needed. 1
• The stone fragments typically pass through the urine within days to weeks after the procedure. 1

Types of Lithotripsy

Extracorporeal Shock Wave Lithotripsy (ESWL)

• ESWL is the only noninvasive method for stone removal and was once considered the primary option for treating virtually all stones. 2
• It revolutionized kidney stone treatment when introduced in 1980 by offering patients a non-invasive procedure. 3
• ESWL is currently the preferred initial treatment for approximately 80-85% of calculi. 4

Other Lithotripsy Modalities

• Electrohydraulic lithotripsy (EHL) should not be utilized as first-line modality for intra-ureteral lithotripsy due to its propensity to damage ureteral mucosa, resulting in ureteral perforation. 5
• Lithotripsy can be performed through ureteroscopy (URS) or percutaneous nephrolithotomy (PCNL) using various energy sources. 4

Clinical Indications and Success Rates

Stone Size Considerations

• For symptomatic patients with total non-lower pole renal stones ≤20 mm, ESWL or URS may be offered. 5
• For stones >20 mm, PCNL should be offered as first-line therapy due to higher stone-free rates. 5, 6
• ESWL has good success rates particularly for stones less than 2 cm in size. 1
• Stone-free rates for ESWL vary by size: 90% for stones <1 cm, 80% for 1-2 cm stones, and 60% for stones >2 cm. 5

Pediatric Considerations

• In pediatric patients with renal stones <2 cm, ESWL remains first-line per European Association of Urology guidelines, though flexible ureteroscopy shows higher stone-free rates. 5
• Meta-analysis of randomized controlled trials demonstrated flexible ureteroscopy has significantly higher stone-free rates than ESWL (RR=1.17,95% CI: 1.04-1.33, P=0.01) with no difference in complication rates. 5

Common Side Effects and Complications

Expected Side Effects

• Blood in the urine (hematuria) occurs in approximately 17% of patients. 1
• Mild pain or discomfort during fragment passage occurs in about 12% of patients. 1
• Steinstrasse (a line of stone fragments in the ureter) occurs in approximately 4% of patients. 1

Serious Complications

• Symptomatic hematoma occurs in 0.21% of cases. 1
• Infection or sepsis occurs in 0.15% of cases. 1
• ESWL can cause vascular trauma to the kidney and surrounding organs, potentially leading to scarring with permanent loss of functional renal volume. 7
• Recent evidence suggests potential long-term adverse effects including new onset hypertension and possible links to diabetes mellitus development. 7

Absolute Contraindications

Lithotripsy should not be performed in the following situations: 1

• Pregnancy
• Uncontrolled urinary tract infections
• Bleeding disorders
• Severe obesity or skeletal malformations preventing proper positioning
• Arterial aneurysm near the stone

Special Precautions

Cardiac Device Patients

• Patients with cardiac pacemakers or implantable cardioverter-defibrillators require special precautions, including keeping the lithotripsy beam away from the cardiac device. 1
• For patients with atrial pacing when the lithotripsy system triggers on the R-wave, atrial pacing may need to be disabled before the procedure. 1

Infection Management

• In patients with obstructing stones and suspected infection, urgent drainage of the collecting system with a stent or other means must be performed. 5
• Proper antibiotic prophylaxis before lithotripsy procedures and treatment of pre-existing urinary tract infections help prevent complications. 8

Post-Procedure Management

• Patients are encouraged to drink plenty of fluids to help pass stone fragments. 1
• Alpha-blockers may be prescribed to facilitate stone passage. 1
• Gas in the renal collecting system is a common finding post-lithotripsy and alone is not necessarily indicative of infection. 8
• Close monitoring for fever, leukocytosis, or signs of systemic inflammatory response is crucial to distinguish benign post-procedural findings from infectious complications. 8

Current Treatment Landscape

• Lithotripsy use is waning, particularly with the advent of minimally invasive ureteroscopic approaches. 3
• In adults, ureteroscopy has overtaken ESWL as the most performed treatment modality for kidney stones. 5
• Recent studies show lithotripsy remains effective as first-line therapy for reno-ureteral lithiasis with a low percentage of complications (8.8%). 9
• Stone size, ureteral location, and number of waves used are factors associated with successful stone size reduction. 9