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Glenn M. Premingerallow complete removal of a staghorn stone through onesite. However, two or more access sites may be requiredwhen the collecting system anatomy is complex.Once access is achieved, the tract is dilated to 24 to 30French with a balloon or coaxial dilators. Initial fragmentationis performed with a rigid nephroscope usingan ultrasonic or pneumatic lithotrite, or with a lithotritethat combines both modalities. Sterile saline is used forirrigation. Flexible nephroscopy then is used to accessstones that cannot be reached with the rigid nephroscope.Stone fragmentation is undertaken with aHolmium:yttrium-aluminum-garnet (YAG) laser or electrohydrauliclithotripsy, and fragments can be removedwith flexible instruments. Historically, a 20 to 24 Frenchnephrostomy tube has been placed at the end of the procedure.Some investigators have used smaller nephrostomytubes in an attempt to reduce postoperative morbiditywhile others have advocated placing an internalizedureteral stent and not using a nephrostomy tube, socalled “tubeless PNL”.Hospitalization is usually 1 to 4 days, and most patientsresume normal activities 2 weeks after stone removal.Post-procedure tube management varies amongst urologists,with some removing all tubes within 24 to 48hours and others discharging the patient from the hospitalwith a percutaneous tube that is removed 5 to 7 dayslater. Transfusion rates for PNL in treating staghorn calculivary from 5 to 25%. Secondary procedure rates, ie,rates at which an instrument must be reinserted throughthe tract to remove residual stones, vary from 10% insimple situations to 40 to 50% for more complicatedproblems. Stone-free rates of 60 to 90% are achievableusing PNL.Combination percutaneous nephrolithotomy and shock wavelithotripsyAlternatively, one can utilize both PNL and SWL formanaging staghorn calcluli. This approach combines themain advantages of the two techniques by using PNL torapidly remove large volumes of stone and by using SWLto fragment stones that are difficult to access with PNL.PNL is undertaken initially, and every effort is made toremove as much stone as possible before proceedingwith SWL. Experience has demonstrated that passage ofall fragments does not occur following SWL. Therefore,most studies recommend that the final procedure incombination therapy should be percutaneousnephroscopy. Yet, it is apparent that combination therapyis being used less frequently as a result of improvementsin endoscopic and intracorporeal lithotripsy technology.Studies suggest that repeat PNL, or second-looknephroscopy through an established tract, may provemore efficient for complete stone removal than the combinationapproach. Some of the recent series have omittedthe second-look PNL, and this change in techniquelikely accounts for the lower current stone-free rate comparedto that reported in the original staghorn guidelinedocument.Shock wave lithotripsy monotherapySWL is commonly used to treat many patients withnephrolithiasis. The original lithotripter, the DornierHM-3, still is utilized, but newer, second- and third-generationdevices have been designed with variable powercapabilities as well as tighter focal regions, which haveresulted in less need for general or regional anesthesiaduring SWL administration. Yet, these smaller focalzones have resulted in inferior stone fragmentation ascompared to the Dornier HM3 device. Moreover, thehigher power density created by some of the second- andthird-generation machines have been reported toincrease the potential for postoperative complicationsincluding the incidence of clinically significant perinephrichematoma and need for transfusion.SWL is widely available, and its noninvasive nature hasmuch appeal. SWL monotherapy has disadvantages,however, in the management of patients with staghornstones. In these patients, numerous studies have foundthat SWL is associated with a higher risk of residual fragmentsand a higher probability of unplanned proceduresthan PNL. In patients with staghorn calculi, such additionalinterventions as well as the need for multiple SWLprocedures may make this approach more expensivethan the other alternatives.Recent in vitro animal and clinical studies suggest thatthe rate of shock-wave administration can influencestone fragmentation and resultant clearance of stonefragments. These studies have demonstrated that a slowershock-wave rate can significantly improve stone-freerates and may have application for SWL monotherapy inpatients with staghorn calculi.RESULTSAs noted previously, most urologists would agree that thestone-free rate is the most meaningful determinate of thesuccessful treatment of patients with staghorn stones.Using this criterion, results of meta-analyses demonstratethat, among the four treatments analyzed, an optimaloutcome is most likely to be achieved with endoscopic orPNL-based therapy and least likely with SWL-monotherapy.Combination therapy yields intermediate stone-freerates, and most studies conclude that percutaneousnephroscopy should be the last part of any combinationsequence as it allows for better assessment of stone-freestatus and a greater chance of achieving this state.Meta-analytic estimates of stone-free rates (95% confidenceintervals) from multiple studies are 78% (74-83%)for PNL, 66% (60-72%) for combination therapy, 54%(45-64%) for SWL, and 71% (56-84%) for open surgery.The fact that the 95% confidence interval for PNL doesnot overlap with those of either combination therapy orSWL supports recommendations that PNL should be theinitial treatment utilized for most patients.DISCUSSIONPNL has emerged as the treatment of choice for the managementof patients with staghorn calculi based on superioroutcomes and acceptably low morbidity. Recentadvances in instrumentation and technique haveimproved stone-free rates, increased treatment efficiency,and reduced morbidity thereby favoring PNL monotherapy.38Archivio Italiano di Urologia e Andrologia 2010; 82, 1