Percutanous nephrolithotomy effective, safe in small lower-pole stones

October 1, 2009

Percutaneous nephrolithotomy, with or without a tube, offers a high success rate in treating small or asymptomatic lower-pole stones.

Key Points

Providence, RI-Percutaneous nephrolithotomy (PNL), with or without a tube, offers a high success rate in treating small or asymptomatic lower-pole stones, results from two comparative studies suggest.

In their retrospective review, urologists from the Warren Alpert Medical School of Brown University in Providence, RI, determined outcomes of 45 consecutive patients assigned to one of three groups, who were treated for solitary lower-pole calculi ranging in size from 0.5 to 1.5 cm by tubeless PNL, shock wave lithotripsy (SWL), or ureteroscopy (URS). All procedures were performed by a single surgeon (Gyan Pareek, MD). The 15-patient cohorts were similar with respect to mean age, stone size, infundibulopelvic angle, skin-to-stone distance, and body mass index.

Stone clearance was achieved with a single procedure in all patients undergoing tubeless PNL, whereas a secondary procedure was needed in seven SWL patients and two URS patients.

No major complications were encountered, and the only two minor complications were in patients treated by SWL, reported first author Sutchin R. Patel, MD, a urology resident working with Dr. Pareek and colleagues.

"URS and SWL are used as primary treatment modalities for lower-pole stones <1.5 cm, due to their minimally invasive nature," Dr. Patel said in his presentation at the AUA annual meeting in Chicago. "However, efficacy of SWL has diminished with newer-generation lithotripters, and despite technological advances in URS, access to lower-pole calices remains challenging with URS.

"While this is a retrospective study, we still believe the results support offering tubeless PNL as first-line treatment for small lower-pole stones. However, per our hospital pathway, an overnight stay is required after tubeless PNL, and an internal ureteral stent is placed after all URS and tubeless PNL procedures. Therefore, further studies comparing cost-benefit and quality of life associated with these three techniques are also important."

Treatment of asymptomatic stones

At the Haseki Training and Research Hospital, Istanbul, Turkey, Murat Binbay, MD, and colleagues undertook a prospective, randomized trial analyzing outcomes in 52 patients with asymptomatic lower-pole calculi assigned to PNL (15 patients), SWL (19 patients), or observation (18 patients). The groups were matched in gender, age, and stone size, all had a mean follow-up of about 13 months, and single surgeons each performed all PNL or all SWL procedures.

Among the PNL procedures, all were single access and six were tubeless.

Treated patients were evaluated at 3 and 12 months with noncontrast helical CT scan to determine stone-free status and with DMSA scintigraphy at 6 weeks and 12 months to identify scarring. Patients in the observation group were evaluated every 3 months for signs of progression and underwent DMSA scintigraphy at 12 months.

All patients treated with PNL became stone free after a single session, while the stone-free rate was 57.8% for SWL, with only four patients achieving clearance after a single session and 10 patients undergoing three SWL sessions each.

Evidence of renal scarring was present in one PNL patient (6.6%) and three SWL patients (15.7%), although the higher rate for SWL was not statistically significant. There were no stone-related events in the intervention groups compared with four (22.2%) in the observation group.

During follow-up, three observation patients (16.6%) required intervention, one (5.2%) developed steinstrasse after SWL and was successfully treated with SWL, and lower-pole hematuria developed in one SWL patient (5.2%).

"Based on these results, we believe all patients with asymptomatic lower-pole caliceal stones are better off treated," Dr. Binbay said. "PNL has efficacy and safety advantages compared with SWL, but if SWL is performed as primary treatment, patients should be referred to PNL if they are not stone free after two sessions."