Do renal stones that fail lithotripsy require treatment?

The rates of extracorporeal shock wave lithotripsy (SWL) appear stable in the UK. However, there is little evidence on the natural history of these calculi if SWL fails. We set to look at the effectiveness of SWL in patients with a single, previously untreated renal stone and the natural history of those stones that failed treatment. We retrospectively reviewed all data from our prospectively collected database of patients undergoing a first treatment for a single renal stone between October 2010 and November 2013. Outcomes after SWL were categorised as success, subsequent intervention needed or conservative management. The medical records of patients managed conservatively were reviewed to determine whether further intervention was required and why. We further sought to define, in those patients where SWL failed, whether subsequent active intervention was needed. For the remainder, we examined whether conservative management was a reasonable management option. 313 patients fitted the inclusion criteria. Of these, 144 were treated successfully. Of the 170 patients with a residual stone, 51 went on to flexible ureteroscopy directly at their next clinical review mainly due to persistent symptoms. 79 patients were managed conservatively, and for 39 follow-up data were unavailable as their follow-up was at a different hospital. 63 patients (80%) were successfully managed conservatively with no recurrence of symptoms over the follow-up period (mean 2 years 4 months). 16 (20%) patients that were initially managed conservatively required subsequent intervention. Of these, 87% had a stone in an upper pole calyx. Conservative management of renal stones after failed SWL is a suitable option for asymptomatic patients with stones not located in the upper pole. For patients with upper pole stones, early intervention is warranted due to the high risk of requiring intervention.