Outcomes for percutaneous stone removal have been shown to be less dependent on stone size, complexity, and other factors than SWL, with most patients achieving stone-free status with a single procedure.
However, as researchers and clinicians have gained experience with both procedures, we are finding that SWL has significant limitations in certain stone types and patient populations. At the same time, outcomes for percutaneous stone removal have been shown to be less dependent on stone size, complexity, and other factors, with most patients achieving stone-free status with a single procedure. These findings were evident in a number of papers presented at the 2007 AUA annual meeting.
In one study from the Albert Einstein College of Medicine, researchers found that patients' body mass index and stone burden did not affect PCNL outcomes, including stone-free rates, postoperative fever, or changes in hemoglobin (see, "PCNL outcome may be unrelated to BMI, stone burden"). The majority of study patients were either obese or morbidly obese, and more than one-third had a stone burden >300 mm2.
Long-term results for PCNL in renal transplant patients were similarly positive, according to a group from the University of Alabama. Of 16 renal allograft patients who received PCNL, 13 were stone free after 7 years, and none of these 13 patients required additional treatment for calculi during this follow-up period.
Perhaps of greatest significance are the findings from the Mayo Clinic group, which reported long-term (up to 20-year) data on both PCNL and SWL (see, "20-year study confirms safety, efficacy of PCNL"). The data show that stone recurrence is lower among PCNL patients than among those undergoing SWL: 40% versus 53.5%, respectively. PCNL was not associated with the development of adverse medical conditions. However, research reported by this group last year suggested that new-onset hypertension and diabetes mellitus were more prevalent among SWL patients than among conservatively treated patients at a follow-up of 19 years (J Urol 2006; 175:1742-7).
It is clear from these data that urologists need to be selective in deciding the optimum treatment for renal stone removal. In many patients, a slightly more invasive procedure may be associated with considerably less morbidity in the long term than if the patient were treated with SWL. Further enhancements in endoscopic instrumentation and percutaneous nephrolithotomy technique will continue to benefit patients with large or complex renal calculi.