Stone Management


Table 2: Best Practice in Shock Wave Lithotripsy Recommended by the 2nd International Consultation on Stone Disease3


Pre-shock Wave Lithotripsy History


Previous stones and SWL treatment Patient/family Hx of bleeding disorders Patient/family Hx of renal disease Symptoms and signs of recent UTI Physical examination Blood pressure


Pulsating abdominal mass or bruit Investigations Urinalysis


Urine culture


KUB X-ray and abdomen ultrasound Computed tomography scan of the abdomen and pelvis


ECG (male >40 years of age, female > 50 years of age)


CT = computed tomography; D/C = discharged; ECG = electrocardiogram; Hx = history; KUB = kidneys, ureters and bladder; SWL = shock wave lithotripsy; US = ultrasound; UTI = urinary tract infection.


Although it seems logical that the anatomy of the lower pole should influence SWL success, it remains unclear which, if any, of the above-mentioned parameters will be most predictive.9


In practice, SWL is associated with poor clearance of fragments from the lower pole. Early in the 1990s, a meta-analysis showed that for stones in the lower pole, the stone-free rate of SWL was 60% (versus a stone-free rate of 90% for percutaneous nephrolithotripsy [PNL]).12 The analysis also demonstrated an inverse relationship between the burden and the stone-free rates. When stratified by stone size, the meta-analysis showed stone-free rates of 33, 56 and 74% for stones >20mm, between 11 and 20mm and <10mm, respectively. Later on a RCT ( Lower Pole I) comparing SWL and PNL in 128 patients showed similar results, with a stone-free rate of 37% for SWL against 95% for PNL.13


Stone-free rates for SWL were 63, 23 and 14% for stones <10, 11–20 and 21–30mm, respectively.


A randomised controlled trial (Lower Pole II) comparing SWL versus ureteroscopy (URS) for lower calyx stones ≤10mm failed to show any significant difference in stone-free rate although the study was unpowered and prematurely terminated.14


Guidelines Recommendations


SWL in situ is the first treatment option for ureteral stones together with URS for those stones situated in the middle and distal ureter. In the kidney, SWL is the first recommended option for those stones ≤20mm. In case of infectious stones, antibiotics should be added. In both kidney and ureter the acid uric stones are an exception because in both locations oral chemolysis is preferred to other options with the addition of a stent in case the stone is located in the ureter. For partial or complete staghorn calculi, the role of SWL is secondary as an adjuvant after PNL. SWL monotherapy may be an alternative only for a small size staghorn in a non-dilated system.


The European Association of Urology (EAU) guidelines on urolithiasis suggests active treatment for all those urinary stones greater than 6 or 7mm.15


Best Practice in Shock Wave Lithotripsy Table 2 describes the clinical care pathway for best practice in SWL recommended by the 2nd International Consultation on Stone Disease held in Paris in September 2007.3


62


Complications and Adverse Events Immediate complications after SWL are mainly related to residual stone fragments and infectious stones, but also interest those prompted by the tissular effect of the SWs on the kidney and neighbouring organs. SWL treatment can result in renal haematomas and haemorrhages, gastrointestinal injury and acute cardiovascular problems.


Immediate Complications


Complications Related to Residual Stone Fragments The presence of residual fragments after SWL is well-documented even though the treatment may have been successful. Clinically insignificant residual fragments (CIRFs) were defined by Lingeman as residual calculi <5mm in diameter, asymptomatic and not composed of struvite or associated with infection.3


There is no absolute consensus in this


definition as the time elapsed after SWL has to be considered. The definition should be augmented by the addition of: ‘three months after SWL’. Fragments >5mm are generally considered as a short- coming of SWL.9


For others, the size limit to define a CIRF was settled at 4mm. Size choice for the definition of a CIRF has not been chosen based on statistical considerations. CIRF may act as both a nuclei for stone re-growth or dislodgement early after SWL or later.


Residual fragments are of clinical significance in patients with infected stones in whom they may perpetuate infection. Fragment re- growth in this group of patients has been reported ≤75% in comparison with the 10% re-growth rate reported after complete fragment clearance. In patients with metabolic stone disease complete stone clearance does not prevent stone recurrence but may prolong treatment intervals.


The review of the 2nd International Consultation on Stone Disease showed that for a mean follow-up range between 6 and 57 months spontaneous fragment passage occurs in 11–93% of the cases. The likelihood of spontaneous passage is higher for stones situated in the ureter and lower for stones in the lower calyx. The residual fragment remains stable in 11–53% of the cases and re-growth has been described in 2–78%. Wide ranges in these results are explained by the retrospective nature of most of the studies and the different methods of reporting treatment outcomes. However, when the prospective studies on the subject are analysed, the results do not differ from the overall series. From the 463 patients included in four


EUROPEAN UROLOGICAL REVIEW


Intra-shock Wave Lithotripsy Intravenous access for analgesia and appropriate anaesthesia


Monitor for heart rate, blood pressure and oxygen saturation


SW rate 60–90 SW per minute Total SW: few as possible to minimise injury Use pulse progressive fluoroscopy


Optimise coupling using warm gel (large amount container). Do not squeeze bottle.


Post-shock Wave Lithotripsy Observation vitals every 15 minutes x 1 hour


D/C home with instructions Increase fluid intake Analgesics PRN


Strain urine and collect fragments Admit to hospital PRN only


Follow-up Routine imaging at 3 months


(KUB and US or CT scan in radiolucent stones) Early imaging at 2 weeks’ pro re nata


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