Summary - Salute per tutti

A. Skolarikos, H. Mitsogiannis, C. DeliveliotisToday, most authors consider a largest renal stone diameterof 20 mm as a practical upper limit for SWL, butlarger stones are also successfully treated with SWL insome centres and other limits for SWL have been suggested(4,22). In general, SWL shows stone-free rates aslow as 41-54% for large stones. In the treatment ofstones with an area up to 40x30 mm the combination ofPNL and SWL has emerged as a solution, with successrates of 71-96% and acceptable morbidity and complications(9, 23). Regarding staghorn stones, a recent metaanalysisshowed that the overall stone-free rates for PNL,the combination of PNL and SWL and SWL asmonotherapy were 78%, 66% and 54%, respectively.When PNL is the terminal procedure in the combinedtherapy and “second look” nephroscopy is performed,stone-free rates may rise to 81% (24). The only randomized,prospective trial comparing PNL to SWL forstaghorn stone management demonstrated stone-freerates with PNL-based therapy to be more than threetimes greater than with SWL monotherapy (25).Combining primary procedures, secondary proceduresto completely remove stones and adjunctive proceduresto correct complications, PNL required 1.9, combinationtherapy 3.3 and SWL 3.6 total procedures, respectively.In the SWL group, stone-free rates and total proceduresneeded were higher for complete staghorn calculi comparedto partial staghorn calculi. Although, transfusionneed was lower for SWL the overall significant complicationrate was similar for all treatment modalities, rangingbetween 13% and 19% (24).Composition and hardness of the stoneVarious investigators have demonstrated the relative susceptibilitiesof different stone compositions to SWL.When adjusted for stone size, cystine, brushite and calciumoxalate stones are more resistant to SWL comparedto uric acid and calcium oxalate dehydrate stones (26,27). Success rates for these two groups of stones wereshown to be 60-63% and 38-81%, respectively (28).More specifically, stone-free rates of 71% for rough cystinestones with a diameter of less than 15 mm have beenreported. When the diameter exceeds 20 mm the successrate for these stones drops to 40% (29).Stone locationStones < 20 mm in diameter, located in the renal pelvisare the most amenable to SWL, with stone-free rates of56% to 80% (23). Similarly, for stones < 20 mm in theupper and middle calyces, SWL stone-free rates rangefrom 57.4% to 76.5%, supporting this approach in mostupper-tract stones of these characteristics (23). Lowerpole stones treated with SWL are less likely to clear thanstones in other regions of the collecting system. Morethan one decade ago, a metaanalysis of 2927 patientswith lower pole stones treated with SWL or PNL showedstone-free rates of 53% and 90%, respectively. Further, itwas determined that the stone-free rates for SWLdecreased compared with PNL according to the stoneburden, with a stone-free rate of 74 versus 100%, 68.2versus 89%, and 32.6 versus 93.7% for stones < 10 mm,11-20 mm, and > 20 mm for SWL and PNL, respectively(30). These results were recently reinforced by the outcomeof two prospective randomized trials comparingdifferent treatment modalities for lower pole stones. Thefirst Lower Pole Study compared SWL with PNL forsymptomatic lower pole only calculi < 30 mm. The overallstone-free rates were 37% and 95%, respectively.Stone-free rates for SWL and PNL in the 1-10, 11-20 and21-30 mm groups were 63 versus 100%, 23 versus 93%and 14 versus 86%, respectively. No significant differencein complications rates was noted (31). A subsequentstudy from the same group compared SWL andureteroscopy for the treatment of lower pole stones≤ 10 mm. There was no statistically significant differencein stone-free rates between the two treatments (35 versus50%) (32). Anatomy of the lower pole in the form oflower pole dependency, infundibulopelvic angle,infundibular width, length and diameter, lowerinfundibular length to diameter ratio and the number ofcalyces may affect stone clearance (33). However, it is notalways predictive of stone clearance (34).Collectively, the above data suggest that SWL constitutes areasonable first-line treatment for lower pole stones< 10 mm in diameter, based mainly on acceptable stonefreerates, low morbidity and high patient preference (35).Finally, a recent comprehensive review showed that thesuccess rates of SWL for stones located in diverticula arerather poor, since urine drainage is usually hindered.Therefore, an endoscopic, percutaneous, laparoscopic ora combined approach for treatment of both stone andstenotic infundibulum is recommended (36).Congenitally abnormal and transplanted kidneysStone-free rates with SWL alone in anatomically anomalouskidneys range between 28 and 80%. Repeat SWLsessions are common for the majority of these patients.The major predisposing factor to success is stone burden.In general, stones < 10-15 mm in size can reasonably bemanaged with SWL or flexible ureteroscopy. PNL is preferredfor larger stones (37).Despite the risk of requiring multiple procedures, SWLcan been performed safely in transplant patients withcalculi < 15 mm. Although data are limited, high successrates of 100% have been reported. Patients are treated inthe prone position and when there is a high probabilityfor obstruction, placement of a stent or percutaneousnephrostomy tube is recommended (38,39).Patient related factorsDespite initial fears of significant renal damage secondaryto SWL in children, recent reports indicate that SWL issafe and effective for the paediatric stone population,attaining stone-free rates for renal and proximal ureteralstones in excess of 80% without significant sequelae torenal function or growth (40, 41). Similar to children,SWL is an option for old and fragile patients sufferingfrom small renal stones. Advanced age is not a seriousissue in PNL outcomes in terms of stone-free status andcomplications. As a consequence indications for this categoryof patients are similar to other adults (9). SWL inobese and morbidly obese patient has been consideredfrom some authors as a contraindication because the lowstone-free rates reported and because technically is difficultto match F2 with renal stone and the likelihood of58Archivio Italiano di Urologia e Andrologia 2010; 82, 1