What are potential complications of shock wave lithotripsy in a patient with nephrolithiasis?

Potential Complications of Shock Wave Lithotripsy in Nephrolithiasis

Ureter obstruction is the most likely potential complication of shock wave lithotripsy (SWL) in a patient with nephrolithiasis. 1

Mechanism of Complications

SWL works by generating high-pressure shock waves that release energy when passing through areas of different acoustic impedance, fragmenting kidney stones. However, this process can lead to several complications:

1. Ureter Obstruction (Steinstrasse)

   • When SWL fragments stones, the resulting pieces must pass through the urinary tract
   • These fragments can accumulate in the ureter, creating a "stone street" (steinstrasse) that obstructs urine flow
   • This is particularly common with larger stones or when multiple fragments attempt to pass simultaneously

2. Other Potential Complications

   • Renal hemorrhage - potentially serious but less common than obstruction 2, 3
   • Perinephric hematoma - can occur in rare cases 4
   • Infection - possible but typically requires pre-existing infected stones or UTI
   • Tissue injury - acute renal effects have been documented in treated kidneys 5

Why Ureter Obstruction Is Most Likely

The 2007 AUA Guideline for Management of Ureteral Calculi specifically addresses complications of SWL and notes that ureter obstruction is a common issue that may require additional procedures 1. The guideline states that additional procedures are frequently necessary (0.62 procedures per patient for proximal ureteral stones, 0.52 for mid-ureteral stones, and 0.37 for distal ureteral stones), primarily due to obstruction from stone fragments.

Comparison with Other Options

• Erectile dysfunction - Not a recognized direct complication of SWL in the guidelines or research evidence
• Urinary tract infection - While possible, this is less common than obstruction and typically requires pre-existing infection
• Urinary incontinence - Not a recognized direct complication of SWL in the guidelines or research evidence

Clinical Implications

When performing SWL:

• Patients should be counseled about the possibility of ureter obstruction from stone fragments
• Close follow-up is essential to monitor for signs of obstruction (persistent pain, worsening hydronephrosis)
• Additional procedures may be necessary to address obstruction, including:
  • Repeat SWL
  • Ureteroscopy
  • Placement of ureteral stents
  • Percutaneous nephrostomy in severe cases

Prevention and Management

To minimize the risk of ureter obstruction:

• Appropriate patient selection (smaller stone burden has lower risk)
• Adequate hydration post-procedure to facilitate fragment passage
• Consider prophylactic stenting for larger stones
• Use of medical expulsive therapy (alpha blockers) may help facilitate fragment passage

If obstruction occurs, prompt intervention is necessary to prevent complications such as infection, renal damage, or sepsis.