eMedicine Specialties > Urology > Stones
Extracorporeal Shockwave Lithotripsy: Treatment
Updated: Feb 14, 2008
Treatment
Preoperative Details
Several factors related to the stone, including stone burden (size and number), composition, and location, affect the outcome of extracorporeal shockwave lithotripsy (ESWL).Stone size
As stone size approaches 2 cm, the likelihood of success with ESWL decreases, and the need for retreatment and adjunctive therapy increases. ESWL has also been found to be most efficacious in treating nonobstructing renal calculi. In patients with a large stone burden, pre-ESWL stenting may secure drainage and prevent obstructive urosepsis.
Stone composition
The density and ability of a stone to resist ESWL is based in part on the composition of the stone. Stones composed of calcium oxalate dihydrate, magnesium ammonium phosphate, or uric acid tend to be softer and to fragment more easily with ESWL. Stones composed of calcium oxalate monohydrate or cystine, on the other hand, are less susceptible to ESWL. To a degree, this can be predicted with CT scanning by measuring the radio-opacity of stones. A recent retrospective study showed that ESWL monotherapy is more likely to be effective against stones with a lower radio-opacity (551 Hounsfield units [HU]) than those with a higher radio-opacity (926 HU).
In addition, certain radiolucent stones (uric acid, indinavir [Crixivan]) are difficult to visualize on fluoroscopy and therefore require either ultrasonography-guided localization or the addition of retrograde or intravenous contrast to localize a calculus.Stone location
- Lower-pole calculi: Although ESWL can fragment stones in the lower pole of the kidney, the resulting stone-free rate is decreased because of the difficulty in passing stones from this location. Recent studies have delineated renal morphology associated with improved stone-free rates (eg, lower infundibular length–to–diameter ratio of <7, lower-pole infundibular diameter of >4 mm, single minor calyx), as well as factors associated with decreased stone-free rates (infundibulopelvic angle of <70°, an infundibular length of >3 cm, an infundibular width of <5 mm). Regardless of anatomy, ESWL tends to yield better results in patients with smaller stone burdens.
- Calyceal diverticula with infundibular stenosis: In patients with diverticula caused by or related to infundibular stenosis, fragmented stones cannot easily bypass the obstruction, with resultant retained stone fragments. These patients are best served by more invasive techniques that allow the surgeon to address the obstruction and the stones simultaneously, either with retrograde ureteroscopy or in an antegrade percutaneous fashion.
- Ureteral calculi: Fragmentation of proximal stones is more effective than mid or distal stones. In addition, when associated with hydronephrosis, ureteroscopy yields better stone-free rates for stones larger than 15 mm.
Preoperative and intraoperative stenting
In the modern setting, where access to ESWL and ureteroscopy is readily available, the indications for stenting prior to definitive treatment are much fewer. These indications include (1) obstructed pyelonephritis or pyelitis and (2) newly onset renal insufficiency or renal failure. In these situations, the stent helps to ensure internal drainage and allows passive dilatation of the ureter, facilitating future endoscopic evaluation and treatment. With the advent of newer and smaller ureteroscopic equipment, the rates of endoscopic complications (ie, strictures) have subsequently declined. When preoperative stenting is required, the authors believe that ureteroscopy, especially for ureteral stones, may yield higher stone-free rates without a significant increase in morbidity, time, or cost.
The need for intraoperative manipulation of stones for ESWL (eg, stone pushback) or placement of a ureteral catheter to assist with stone visualization has decreased, as newer machines are capable of treating proximal ureteral stones or visualizing radiolucent stones with ultrasonography. That said, intraoperative ureteral stents should be considered in patients with larger stones, as the rate of steinstrasse (German for “stone street”) increases with stone burden (1-4% in general vs 10% for stones >2 cm).Intraoperative Details
The optimal shockwave lithotripsy treatment is thought to be about 80-90 shocks per minute. Faster rates have been shown to be associated with decreased stone-free rates, especially for larger stones (11-20 mm). The difference in stone-free rates is less significant for smaller stones. Conversely, slower rates obviously increase the total operative time.
During shockwave lithotripsy, tracking the stone burden becomes an important issue, in part because of the natural movement of the kidney during respiration, with subsequent movement of the stone burden in and out of the focal zone. The smaller focal zone of the newest devices necessitates less anesthesia, but the patient’s increased ability and susceptibility to cough, shift, or otherwise move requires vigilance to ensure the appropriate targeting accuracy in the application of energy to the stone. This means that the targeting of the machine needs to be adjusted more often.
Postoperative Details
Common adverse effects associated with ESWL include flank petechiae, hematuria, and passage of stone fragments with associated renal colic. Many patients are issued a urine strainer to help collect stone fragments, which can later be chemically analyzed to assist with prevention of future stones. Hydration and analgesia alleviate most flank discomfort and symptoms caused by the passage of fragments. Some groups have initiated trials of pharmacologic aids similar to those involved in medical stone-passage protocols to facilitate stone passage. In the treatment arm, pharmacologic aids (stone-free rate of 86% with nifedipine and 82% with tamsulosin) were superior to placebo (stone-free rate of 52-57%).
Quantification of residual stone burden and resolution of hydronephrosis was defined with postoperative radiography or ultrasonography. Postoperative imaging is usually obtained within 6 weeks following the procedure or sooner if the patient is symptomatic.
Follow-up
Stone-prevention strategies
All patients who undergo surgery for stones should be given information about kidney-stone prevention. General measures include increased fluid intake and restriction of dietary sodium and purine. In patients with calcium oxalate stones, intake of foods high in oxalate (eg, spinach, nuts, beer, chocolate, rhubarb, green leafy vegetables) should be discouraged. Calcium intake should be moderated; extremely high or low levels of calcium can increase stone production.
Blood work and 24-hour urine collections measuring for pH, urinary volume, citrate, calcium, oxalate, uric acid, sodium, magnesium, phosphates, and electrolytes can assist in identifying and alleviating risk factors for future stone production. Following treatment of the initial stone event, testing should be performed in all children and in patients with solitary kidneys, chronic diarrhea, a history of bariatric surgery, renal failure, and nephrocalcinosis, as well as in any patient with kidney stones who has sufficient motivation to follow long-term treatment recommendations to prevent future stones. Twenty-four–hour urine-testing protocols are available from a number of sources, including Mission, Dianon, UroCor, Quest, LabCorp, and Litholink.
The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC), which is part of the National Institutes of Health (NIH), is a good general patient information Web site.
The NIH has also recommended The Kidney Stones Handbook (Savitz and Leslie, 2000). This award-winning patient guide to kidney stones can be ordered directly from the publisher (Grant Gibbs) by email (gsavitz@earthlink.net) or by telephone (530-889-1727).
Complications
Renal complications
Bacteriuria develops in 7.7-23.5% of patients undergoing extracorporeal shockwave lithotripsy (ESWL) and is more likely to develop in patients with infection-related stones. Bacteremia is less common, developing in up to 14% of patients, with fewer than 1% developing clinical sepsis (although this number increases to 2.7% in patients with staghorn calculi). Although preoperative antibiotic coverage remains controversial, antibiotics may be recommended in patients with infection-related stones, positive urine cultures results, or recurrent urinary tract infections.
Post-ESWL hematuria is usually mild and transient. In the event of significant hematuria with clots or frank clot retention, imaging the kidneys should be considered to identify a perinephric hematoma. Perinephric, subcapsular, or intranephric hematomas may be associated with severe pain, ileus, and, infrequently, shock or hypotension. Unexplained or unusually severe pain or any unusual drop in blood pressure may suggest a hematoma. Subcapsular hematoma following ESWL usually responds to bedrest, transfusions, and supportive care. If the patient requires multiple transfusions, arteriography and selective embolization should be considered.
Stone fragments may pass with a minimal amount of discomfort. In some patients, the comminuted stone fragments pile up in the ureter, creating a virtual column of stone called steinstrasse. The overall rate of steinstrasse is 1-4%, with the rate progressively increasing for greater stone burdens (10% for stone burdens >2 cm2) and approximately 40% for complete staghorn calculi. Patients with asymptomatic nonobstructing steinstrasse can be monitored closely with serial imaging.
Asymptomatic or mildly symptomatic steinstrasse with mild dilatation of the upper urinary tract can be managed conservatively. If fragments fail to progress within 3-4 weeks or if patients develop significant symptoms or obstruction, endoscopic lithotripsy or percutaneous drainage should be performed. Patients with high-grade obstruction and concomitant pyelonephritis require prompt percutaneous nephrostomy drainage with appropriate antibiotic coverage, followed by staged endoscopic removal of stone fragments.
Renal atrophy, although uncommon, can result from renal vascular or severe atherosclerotic disease. Patients with underlying renal parenchymal disease are at a higher risk of renal atrophy. However, studies of ESWL in patients with a solitary kidney have shown no statistical evidence of renal function deterioration secondary to shockwave lithotripsy.
Hypertension is an unusual complication of ESWL but may occur as a sequela of a large perinephric hematoma (ie, page kidney). Older patients with abnormal renal perfusion may develop hypertension within 26 months after the ESWL session.
Patients who undergo ESWL may have a slightly higher likelihood of eventually developing hypertension and diabetes than patients who undergo other therapies for stone removal. The evidence, however, may be biased because of the high usage of first-generation ESWL machines in the study group and other problems, but it still suggests a possible connection. In addition, alternative therapies may not be as effective or may carry higher initial morbidity and complication rates. For now, the authors continue to use ESWL, when appropriate. Hopefully, further studies will better delineate the actual risks involved and provide solutions to eliminate or minimize them.
Other possible complications
Less-common complications may include (1) pulmonary contusion, (2) pancreatitis, (3) splenic hematoma, (4) elevated liver functions (transient), and (5) biliary colic with inadvertent fragmentation of adjacent biliary stones.
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 |
| « Previous Page | Next Page » |
References
Lingeman JE, Zafar FS. Lithotripsy systems. In: Smith AD, Badlani GH, Bagley DH, et al. Smith's Textbook of Endourology. St Louis, Mo: Quality Medical Publishing; 1996:553-89.
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].
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].
Abe T, Akakura K, Kawaguchi M, Ueda T, Ichikawa T, Ito H, et al. Outcomes of shockwave lithotripsy for upper urinary-tract stones: a large-scale study at a single institution. J Endourol. Sep 2005;19(7):768-73. [Medline].
Albala DM, Assimos DG, Clayman RV, Denstedt JD, Grasso M, Gutierrez-Aceves J, et al. Lower pole I: a prospective randomized trial of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy for lower pole nephrolithiasis-initial results. J Urol. Dec 2001;166(6):2072-80. [Medline].
Anagnostou T, Tolley D. Management of ureteric stones. Eur Urol. Jun 2004;45(6):714-21. [Medline].
Auge BK, Preminger GM. Update on shock wave lithotripsy technology. Curr Opin Urol. Jul 2002;12(4):287-90. [Medline].
Chacko J, Moore M, Sankey N, Chandhoke PS. Does a slower treatment rate impact the efficacy of extracorporeal shock wave lithotripsy for solitary kidney or ureteral stones?. J Urol. Apr 2006;175(4):1370-3; discussion 1373-4. [Medline].
Chaussy CG, Fuchs GJ. Current state and future developments of noninvasive treatment of human urinary stones with extracorporeal shock wave lithotripsy. J Urol. Mar 1989;141(3 Pt 2):782-9. [Medline].
Collins JW, Keeley FX. Is there a role for prophylactic shock wave lithotripsy for asymptomatic calyceal stones?. Curr Opin Urol. Jul 2002;12(4):281-6. [Medline].
Delius M. This month in Investigative Urology: effect of extracorporeal shock waves on the kidney. J Urol. Aug 1988;140(2):390. [Medline].
Joshi HB, Obadeyi OO, Rao PN. A comparative analysis of nephrostomy, JJ stent and urgent in situ extracorporeal shock wave lithotripsy for obstructing ureteric stones. BJU Int. Aug 1999;84(3):264-9. [Medline].
Kim FJ, Rice KR. Prediction of shockwave failure in patients with urinary tract stones. Curr Opin Urol. Mar 2006;16(2):88-92. [Medline].
Krambeck AE, Gettman MT, Rohlinger AL, Lohse CM, Patterson DE, Segura JW. Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of followup. J Urol. May 2006;175(5):1742-7. [Medline].
Lee C, Ugarte R, Best S, Monga M. Impact of renal function on efficacy of extracorporeal shockwave lithotripsy. J Endourol. May 2007;21(5):490-3. [Medline].
Lee YH, Tsai JY, Jiaan BP, Wu T, Yu CC. Prospective randomized trial comparing shock wave lithotripsy and ureteroscopic lithotripsy for management of large upper third ureteral stones. Urology. Mar 2006;67(3):480-4; discussion 484. [Medline].
Lindqvist K, Holmberg G, Peeker R, Grenabo L. Extracorporeal shock-wave lithotripsy or ureteroscopy as primary treatment for ureteric stones: a retrospective study comparing two different treatment strategies. Scand J Urol Nephrol. 2006;40(2):113-8. [Medline].
Lingeman JE, Kim SC, Kuo RL, McAteer JA, Evan AP. Shockwave lithotripsy: anecdotes and insights. J Endourol. Nov 2003;17(9):687-93. [Medline].
Liou LS, Streem SB. Long-term renal functional effects of shock wave lithotripsy, percutaneous nephrolithotomy and combination therapy: a comparative study of patients with solitary kidney. J Urol. Jul 2001;166(1):36; discussion 36-7. [Medline].
Madaan S, Joyce AD. Limitations of extracorporeal shock wave lithotripsy. Curr Opin Urol. Mar 2007;17(2):109-13. [Medline].
Martin TV, Sosa RE. Shock-wave lithotripsy. In: Walsh PC, Retik AB, Vaughan ED, Wein AJ. Campbell's Urology. Vol 3. 7th ed. Philadelphia, Pa: WB Saunders; 1998:2735-52.
Micali S, Grande M, Sighinolfi MC, De Stefani S, Bianchi G. Efficacy of expulsive therapy using nifedipine or tamsulosin, both associated with ketoprofene, after shock wave lithotripsy of ureteral stones. Urol Res. Jun 2007;35(3):133-7. [Medline].
Moody JA, Evans AP, Lingeman JE. Extracorporeal shockwave lithotripsy. In: Weiss RM, George NJR, O'Reilly PH, eds. Comprehensive Urology. Mosby International Limited; 2001:623-36.
Pareek G, Armenakas NA, Fracchia JA. Hounsfield units on computerized tomography predict stone-free rates after extracorporeal shock wave lithotripsy. J Urol. May 2003;169(5):1679-81. [Medline].
Putman SS, Hamilton BD, Johnson DB. The use of shock wave lithotripsy for renal calculi. Curr Opin Urol. Mar 2004;14(2):117-21. [Medline].
Sayed MA, el-Taher AM, Aboul-Ella HA, Shaker SE. Steinstrasse after extracorporeal shockwave lithotripsy: aetiology, prevention and management. BJU Int. Nov 2001;88(7):675-8. [Medline].
Segura JW, Preminger GM, Assimos DG, Dretler SP, Kahn RI, Lingeman JE, et al. Nephrolithiasis Clinical Guidelines Panel summary report on the management of staghorn calculi. The American Urological Association Nephrolithiasis Clinical Guidelines Panel. J Urol. Jun 1994;151(6):1648-51. [Medline].
Skolarikos A, Alivizatos G, de la Rosette J. Extracorporeal shock wave lithotripsy 25 years later: complications and their prevention. Eur Urol. Nov 2006;50(5):981-90; discussion 990. [Medline].
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].
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].
Weiland D, Lee C, Ugarte R, Monga M. Impact of shockwave coupling on efficacy of extracorporeal shockwave lithotripsy. J Endourol. Feb 2007;21(2):137-40. [Medline].
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
