What is the role of extracorporeal shockwave lithotripsy in the treatment of struvite and staghorn calculi?

Updated: Jan 02, 2019
  • Author: Maxwell Meng, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

SWL was introduced in 1982 and is used to fragment urinary stones in a variety of locations without requiring an incision or instrumentation of the urinary tract.

Struvite calculi are effectively broken by SWL because of the multiple laminations within the stones. However, even with excellent stone fragmentation by primary SWL, repeat therapy via SWL must be performed in 50% of patients because of a large stone burden. If multiple sessions are anticipated, the renal pelvis should be treated first. Real-time monitoring of stone fragmentation using fluoroscopy is important to target and shock all areas of the stone.

In addition, the potential for urinary obstruction during spontaneous stone passage usually requires the placement of an indwelling ureteral stent. In up to 40% of patients, a percutaneous nephrostomy (PCN) tube is subsequently required to allow adequate renal drainage. [17]

If the renal infundibula are narrow, stone fragments that stem from SWL are unlikely to pass and remain in the calyces. Percutaneous nephrolithotomy (PNL) is the preferred surgical therapy in these cases. Large, wide infundibula that permit easy passage of fragments increase the stone-free rate and overall success of SWL treatment for staghorn calculi.


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