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Clinical significance of residual stone fragments following stone removal

Glenn M Preminger, MD
Section Editor
Stanley Goldfarb, MD
Deputy Editor
Albert Q Lam, MD


Before the advent of shock wave lithotripsy (SWL) and percutaneous nephrolithotomy (PNL), patients underwent open surgical procedures for stone removal. A successful open surgical procedure was defined as complete removal of all stones without leaving any residual stone fragments. Patients with residual calculi were considered a treatment failure.

However, the introduction of less invasive procedures for the management of nephrolithiasis has resulted in a change in treatment goals. With these modalities, residual stone material is often present post-procedure, particularly if the pre-procedure stone was larger than 5 mm in diameter, and minimal emphasis is often placed on the presence of these residual fragments. Instead, success, as currently defined by some investigators, is determined by fragmentation rates and the size of remaining stone fragments. As an example, small stone fragments, such as those less than 5 mm in size, are considered by some clinicians to be "clinically insignificant."

Several studies, however, have noted a dramatic increase in stone formation with the presence of residual calculi following SWL or PNL [1-4]. As a result, it is not acceptable to use the term "clinically insignificant stone fragments," since residual fragments may act as a nidus for further stone formation.

The clinical significance of residual fragments following stone removal will be reviewed here. Detailed discussions of the methods and indications for stone removal are presented separately. (See "Options in the management of renal and ureteral stones in adults".)


A high incidence of stone growth has been found among patients with residual calculi after shock wave lithotripsy (SWL) or other treatment modalities [1-6]. Based upon this observation, various algorithms and neural networks have been created to help predict the incidence of residual stones following lithotripsy treatment [7,8].

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Literature review current through: Nov 2017. | This topic last updated: Apr 08, 2016.
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