Extracorporeal shock wave lithotripsy for lower pole nephrolithiasis: efficacy and variables that influence treatment outcome.

OBJECTIVES

Extracorporeal shock wave lithotripsy (ESWL) for the treatment of lower caliceal stones (LCS) tends to have a poor success rate, prompting many urologists to advocate alternative treatment modalities. This study attempts to identify variables that may influence the outcome of ESWL treatment for LCS to help in selecting patients that are likely to benefit from the treatment.

METHODS

One hundred forty-two patients with isolated LCS treated with the Dornier HM3 lithotriptor were reviewed. The study data include characteristics of patients, stones, urinary tract treated, previous treatment of stones in the same kidney, and details of the ESWL treatment.

RESULTS

Eighty patients (56%) were stone free 3 months after ESWL. Multivariate analysis with logistic regression identified six independent and significant variables that influenced treatment outcome: these included number of stones (P = 0.001), previous percutaneous nephrostolithotomy (PNL) treatment (P = 0.001), side of the stone (P = 0.002), presenting stone type (P = 0.004), number of ESWL sessions (P = 0.01), and maximum kilovoltage setting of ESWL at treatment (P = 0.02). Stone size did not influence the treatment outcome in this study.

CONCLUSIONS

ESWL provides an acceptable first line treatment for patients with LCS. Patients who fail ESWL and have poor prognostic features (ie, multiple LCS, hard stones requiring high voltage and multiple ESWL sessions, lower caliceal stone formation secondary to ESWL treatment of stones in other locations of the renal unit, or previous treatment with PNL) should be counseled for alternative treatment modalities.