These include the following:

I find it easiest to define the stones most appropriately treated by PCNL as those that cannot be removed by ESWL, retrograde ureteroscopy, other forms of nephrolithotomy, or when these procedures have failed.

Historically, ESWL was described in 1980 by Chaussey and PCNL in 1981 by Alken and Wickham. Initially, ESWL was expensive and limited to specific sites in West Germany. It was not until 1984 that ESWL was performed outside Germany by Wickham et al.

As a result, PCNL, which required far less sophisticated and less expensive instrumentation, developed rapidly as the primary management for the majority of renal calculi, except for very large branched calculi, between 1981 and 1985.

When ESWL readily became available, it appeared that PCNL may become extinct.

However, it soon became clear that ESWL had its limitations. Experience demonstrated that the most appropriate calculi that could be safely treated by ESWL should be less than 2.5 cm in diameter, contained within a collecting system that drained freely and able to be completely fragmented by externally generated shockwaves. Cystine, brushite and calcium oxalate monohydrate calculi were refractory to ESWL. Generally, the higher the Hounsfield Unit (HU) of a calculus, the more refractory it is to ESWL. With PCNL, all calculi no matter what their HU measures are, can be fragmented by intracorporeal lithotripsy. Also, 30 % of patients retained residual stone fragments in the kidney following ESWL. This was obviously significant in relation to infection-related calculi and stone recurrence. Notwithstanding these indications and limitations, the majority of stones in developed countries were suitable for primary monotherapy by ESWL, as they were small and in normally draining collecting systems.

As PCNL removed calculi by a nephrocutaneous conduit, free distal drainage was not a prerequisite. Also, as all calculi, including those refractory to ESWL, could be broken by powerful lithotrites through a nephroscope, neither size nor composition presented a problem for PCNL. Anatomical access was the limiting factor.

PCNL became logical treatment for stones that were not suitable for ESWL or that had failed ESWL.

It was then a rational extension to combine the therapies so that a large stone obstructing a kidney could be debulked to leave an unobstructed system and the small peripheral fragments in difficult-to-access calyces could be cleared by subsequent ESWL.

Today, these smaller stones and fragments can be treated by ureteroscopy and laser FURS, as can calculi in obese patients in whom the distance from the skin to the kidney is too long for ESWL focus or the length of the nephroscope.