Presentation Authors: Ravin J. Bastiampillai*, Shuang Li, Kristina L. Penniston, Sara L. Best, Sean P. Hedican, Stephen Y. Nakada, Madison, WI
Introduction: Percutaneous nephrolithotomy (PCNL) is the surgical modality of choice for larger renal stones. However, post-surgical residual fragments (RF) are common. Although the clinical impact of RF size has been studied, few reports have examined re-operation as a metric for success. We characterized the incidence of subsequent stone surgery at our institution based on RF size after initial PCNL.
Methods: From our institutional HIPPA-certified surgical stone database, we identified patients who underwent PCNL between 2009-2017. They were followed up for at least 12 months, and had a computerized tomography (CT) scan within 3 months after PCNL. Repeat surgery was defined as a surgical procedure beyond the 90 day perioperative period. CT was not performed in some cases where the surgeon deemed the patient both endoscopically and fluoroscopically stone-free.
Results: Of 2,762 patients (58% female), 140 (154 renal units) were identified. Patients were predominantly calcium stone formers (70.7%), were 54 Â± 15 years of age, and had a BMI at the time of PCNL of 32.2 Â± 10.0. The mean post-surgical followup time was 57 Â± 29 months. Following PCNL, 52 renal units (33.8%) were deemed stone free; 50 renal units (32.4%) had RF 1-4mm, and 52 renal units (33.8%) had RF >4mm. After PCNL, 58 renal units (37.7%) required unplanned repeat stone surgery of any kind. Of these, 33 renal units (56.9%) had RF >4mm. Hazard ratios for the need for repeat surgery were significantly higher for RF size >4mm (see table).
Conclusions: The need for repeat stone surgery increases as post-PCNL RF size increases. Specifically, RFs >4mm are predictive of the need for repeat surgery. Surgeons should aim to minimize RF size during PCNL to < 4mm in order to avoid the need for re-operation.