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Extracorporeal Shockwave Lithotripsy: Follow-up

Author: Michael Grasso, MD, Chairman, Department of Urology, Saint Vincent's Medical Center; Professor and Vice Chairman, Department of Urology, New York Medical College
Coauthor(s): Josh Hsu, MD, Clinical Fellow in Endourology and Laparoscopic Urologic Surgery, Department of Urology, St Vincent's Catholic Medical Center/New York Medical College; Massimiliano Spaliviero, MD, Clinical Fellow, Department of Urology, St. Vincent's Medical Center
Contributor Information and Disclosures

Updated: Feb 14, 2008

Outcome and Prognosis

In appropriately selected patients, the overall success rate of extracorporeal shockwave lithotripsy (ESWL) is higher than 90% for stone clearance, with patients remaining stone-free for up to 2 years. ESWL is safe and effective. Although small series have shown successful treatment of stones in young children, long-term follow-up of the potential complications, including hypertension and decreased renal function, are not yet mature.

As the degree of stone burden increases and exceeds 2 cm, the stone-free rate drops significantly. In patients with stones sized 2-3 cm, the stone-free rate with ESWL monotherapy is typically 50%. Stone-free rates in patients with larger stones (complete and incomplete staghorn calculi) are correspondingly lower.

The location of the stone also affects the efficacy of ESWL. In a meta-analysis of 2927 patients from 14 centers, Lingeman et al (1996) found that the overall stone-free rate for all lower-pole stones treated with ESWL (59.2%) was lower than the stone-free rate associated with percutaneous nephrolithotomy (90%).1 Some studies have suggested that select patients with appropriate renal collecting system anatomy may see good results with ESWL despite lower-pole stone location. In these studies, the overall stone-free rate was approximately 50%, with a stone-free rate of 85% in patients with favorable anatomy versus 7% in those with unfavorable anatomy.

In a prospective, randomized, multicenter clinical trial performed by the Lower Pole Study Group, patients with lower-pole stones treated with ESWL or percutaneous nephrolithotomy had overall stone-free rates of 37% and 95%, respectively. In contrast, this prospective study did not show any difference in stone-free rates based on renal anatomy, but an inverse relationship was found between stone size and stone-free rate. In patients with stones or stone aggregates measuring larger than 1 cm, percutaneous nephrolithotomy was the most efficacious modality to render patients stone-free.

Sheir et al (2003) evaluated the safety and efficacy of ESWL in patients with an anomalous kidney, including 49 patients with a horseshoe kidney, 120 patients with a malrotated kidney, and 29 patients with a duplex kidney.2 Two second-generation lithotriptors were used. Although the type of renal anomaly and the type of lithotriptor did not affect the stone-free rate, stone length and number (stone burden) significantly influenced the stone-free rate. The prone position facilitated treatment in 38% of the patients with a horseshoe kidney and in 31% of patients with a duplex kidney. The overall retreatment success rate was 64.1%. However, with an overall stone-free rate of 72.2%, Sheir et al deemed ESWL to be safe and reliable in patients with an anomalous kidney and to be considered the primary treatment option for stones smaller than 20 mm.

Early-generation lithotriptors required pushback of stones into the renal pelvis for treatment. With advancements, specifically higher-amplitude waveforms with smaller focal zones, newer lithotriptors are able to treat ureteral stones in situ. Results tend to be better for proximal stones, with stone-free rates of 65-81%, versus 58-67% for distal ureteral stones.

Future and Controversies

Technical improvements, such as synchronous twin-pulse technique with variable angles between the shockwave reflectors, have been attempted to increase the quality and rate of stone disintegration. In a study of 50 patients with renal or ureteral stones (mean size, 12.3 mm; range, 9-18 mm) undergoing the synchronous twin-pulse technique , 17 patients (34%) were stone-free, 20 patients (40%) had less than 5 mm of residual stone, and 13 (26%) patients had 6-9 mm of residual stone 14 days following extracorporeal shockwave lithotripsy (ESWL).3 Thirteen (26%) patients with more than 5 mm of residual stone underwent repeat ESWL. Following treatment, gross hematuria developed in 50% of the patients on the day of treatment and resolved the next day.

Shockwave therapy is efficacious in treating urinary calculi. The mechanism of action is based on pressure waves that, when focused onto a stone, fragment the stone into more easily passable pieces. Success rates, defined as becoming stone-free or having residual fragments less than 4 mm in diameter, are acceptable. However, future improvement of lithotriptor design may increase success rates, decrease renal trauma, and increase patient comfort.

Other groups have attempted to improve the fragmenting capability of the cavitation bubbles created during lithotripsy by forcing their collapse with a second weaker pulse timed immediately after the initial pulse. Using a porcine model with BegoStone phantoms, Young et al (2003) used a 22-kV shock from an HM3 followed with a 4-kV shockwave 500-600 ms later from a separate piezoelectric source. Their initial results showed increased stone comminution rates with reduced renal injury.

Controversy exists with some of the newer shockwave generators. The smaller focal zone and newer tabletop designs increase the indications for treatment and lower the anesthetic requirements, but they may decrease overall efficacy of the treatment. Many newer generators require precise localization, with little margin for error in light of the greatly reduced focal zones. The focal zone of the original Dornier HM3 exceeded 2 cm, but most new electromagnetic generators have focal zones averaging only 6 mm. As a result, the operator must be more attentive and must actively compensate for respiratory movements during treatment. On a positive note, however, less renal parenchyma is affected or damaged during treatment.

 


More on Extracorporeal Shockwave Lithotripsy

Overview: Extracorporeal Shockwave Lithotripsy
Workup: Extracorporeal Shockwave Lithotripsy
Treatment: Extracorporeal Shockwave Lithotripsy
Follow-up: Extracorporeal Shockwave Lithotripsy
References
Further Reading
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References

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  2. Sheir KZ, Madbouly K, Elsobky E, Abdelkhalek M. Extracorporeal shock wave lithotripsy in anomalous kidneys: 11-year experience with two second-generation lithotripters. Urology. Jul 2003;62(1):10-5; discussion 15-6. [Medline].

  3. Sheir KZ, El-Diasty TA, Ismail AM. Evaluation of a synchronous twin-pulse technique for shock wave lithotripsy: the first prospective clinical study. BJU Int. Feb 2005;95(3):389-93. [Medline].

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  29. Tan EC, Tung KH, Foo KT. Comparative studies of extracorporeal shock wave lithotripsy by Dornier HM3, EDAP LT 01 and Sonolith 2000 devices. J Urol. Aug 1991;146(2):294-7. [Medline].

  30. Unal B, Kara S, Bilgili Y, Basar H, Yilmaz E, Batislam E. Giant abdominal wall abscess dissecting into thorax as a complication of ESWL. Urology. Feb 2005;65(2):389. [Medline].

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Further Reading

For additional information, see Medscape’s Stone Disease Resource Center.

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Keywords

extracorporeal shockwave lithotripsy, extracorporeal shock wave lithotripsy, extracorporeal shock-wave lithotripsy, ESWL, shockwave lithotripsy, shock wave lithotripsy, shock-wave lithotripsy, stone removal, stone fragmenting, calculus removal, kidney stone, renal calculi, renal stones, ureteral calculi, ureteric calculi, ureteral stones, electrohydraulic energy, piezoelectric energy, electromagnetic energy, shockwave generation, electromagnetic generators, Dornier HM3, lithotriptor, ureteral stenting, steinstrasse, lithotripsy, Siemens system, Storz system, shockwave lithotriptor

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Contributor Information and Disclosures

Author

Michael Grasso, MD, Chairman, Department of Urology, Saint Vincent's Medical Center; Professor and Vice Chairman, Department of Urology, New York Medical College
Michael Grasso, MD is a member of the following medical societies: American Medical Association, American Urological Association, California Medical Association, and Endourological Society
Disclosure: Nothing to disclose.

Coauthor(s)

Josh Hsu, MD, Clinical Fellow in Endourology and Laparoscopic Urologic Surgery, Department of Urology, St Vincent's Catholic Medical Center/New York Medical College
Josh Hsu, MD is a member of the following medical societies: American Urological Association and Endourological Society
Disclosure: Nothing to disclose.

Massimiliano Spaliviero, MD, Clinical Fellow, Department of Urology, St. Vincent's Medical Center
Disclosure: Nothing to disclose.

Medical Editor

Daniel B Rukstalis, MD, Chief, Associate Professor, Department of Surgery, Division of Urology, Medical College of Pennsylvania-Hahnemann University
Daniel B Rukstalis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Surgeons, American Urological Association, New York Academy of Sciences, and Society of Laparoendoscopic Surgeons
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

CME Editor

J Stuart Wolf, Jr, MD, FACS, David A Bloom Professor of Urology, Director, Division of Minimally Invasive Urology, Department of Urology, University of Michigan Medical Center
J Stuart Wolf, Jr, MD, FACS is a member of the following medical societies: American College of Surgeons, American Medical Association, American Urological Association, Catholic Medical Association, Endourological Society, Society for Urology and Engineering, Society of Laparoendoscopic Surgeons, and Society of University Urologists
Disclosure: Terumo Corporation Consulting fee Consulting; Omeros Corporation Consulting fee Consulting

Chief Editor

Stephen W Leslie, MD, FACS, Founder and Medical Director of the Lorain Kidney Stone Research Center, Clinical Assistant Professor, Department of Urology, Medical College of Ohio
Stephen W Leslie, MD, FACS is a member of the following medical societies: American College of Surgeons, American Urological Association, National Kidney Foundation, and Ohio State Medical Association
Disclosure: Nothing to disclose.

 
 
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