5-year-follow-up of Patients with Clinically Insignificant Residual Fragments after Extracorporeal Shockwave Lithotripsy

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1 European Urology European Urology 47 (2005) year-follow-up of Patients with Clinically Insignificant Residual Fragments after Extracorporeal Shockwave Lithotripsy Mahmoud M. Osman, Yvonne Alfano, Stefan Kamp, Axel Haecker, Peter Alken, Maurice Stephan Michel, Thomas Knoll* Department of Urology, Mannheim University Hospital, Theodor-Kutzer-Ufer 1 3, Mannheim, Germany Accepted 6 January 2005 Available online 19 January 2005 Abstract Objectives: After SWL treatment, many patients have residual fragments in the kidney or ureter. Fragments 4 mm have high probability to pass spontaneously and are normally not further treated. The term clinically insignificant residual fragment (CIRF) has been established for these stones. However, this term is still controversial, as persisting fragments might be important risk factors for stone growth and recurrence. Aim of this study was to evaluate the impact of CIRF on stone recurrence. Methods: We evaluated 173 patients (age 3 89 years) who have been treated by SWL and released with CIRF. Mean follow up was 4.9 years ( ). 78% of the patients were recurrent stone formers with >2 stones episodes. These patients and their referring urologist received follow-up questionnaires which contained questions about stone clearance, late complications, auxillary measures and dietary or drug metaphylaxis. Results: Most residual stone fragments were located within the lower calyx (17%) and the renal pyelon (14%). Stone analysis was available in 142 patients with CIRF and revealed calciumoxalate calculi in 93.6% of the cases. In 78.6%, CIRF cleared spontaneously within few weeks and did not recur within 5 years. However, residual stones led to stone recurrence and need of re-treatment in 21.4%. Renal pyelon (23%) and calices showed comparable growth of former CIRF (lower calices 26.5%, middle calices 27%, upper calices 26%). Only 48% of the patients with recurrent stone formation followed dietary metaphylaxis. However, a significant correlation between a general or specific metaphylaxis and stone growth of CIRF could not be demonstrated. Conclusions: Most of the CIRF after SWL pass spontaneously without any complications. But considering that one fifth of the patients developed new stones at the side of residual fragments, it is obvious that close follow-up is required. Although we could not demonstrate a relation between metaphylaxis and stone re-growth, it is conceivable that adequate metaphylaxis can reduce stone recurrences. # 2005 Elsevier B.V. All rights reserved. Keywords: Shockwave lithotripsy; Urinary calculi; Treatment failure 1. Introduction Extracorporeal shockwave lithotripsy (SWL) is still the treatment of choice for most upper urinary tract calculi. However, only a little percentage of patients is immediately stone free after SWL treatment. 85% of * Corresponding author. Tel ; Fax: address: thomas.knoll@uro.ma.uni-heidelberg.de (T. Knoll). patients have been reported having residual fragments when discharged from hospital [1]. Fragments 4 mm are expected to pass spontaneously without further treatment, leading to the definition of clinically insignificant residual fragements (CIRF). However, it has been demonstrated, that stone passage often takes several weeks [1]. In case of persistance within the upper urinary tract, these fragments may grow and gain clinical relevance again [2]. The term CIRF is therefore /$ see front matter # 2005 Elsevier B.V. All rights reserved. doi: /j.eururo

2 still controversial, long-term data about stone recurrences from such fragment is rare. This study was carried out to evaluate the significance of CIRF on stone recurrence. M.M. Osman et al. / European Urology 47 (2005) Methods We evaluated 173 patients (3 89 years), who have been treated by SWL for urolithiasis from 01/1997 and 12/1998 at Mannheim University Hospital. Mean follow up was 4.9 years ( ). 90/ 173 (52.0%) of the patients were recurrent stone formers with 2 stones episodes. All patients had clinically insignficant residual fragments when discharged from hospital. CIRF were defined as post-swl, nonobstructive, noninfectious, asymptomatic (absence of pain, hematuria and pyuria), residual fragments of 4 mm or less in size [3]. All patients were treated using Modulith SLX or Modulith SLK electromagnetic lithotripters (Storz Medical, Kreuzlingen, Switzerland). Primary diagnostic procedures included intravenous or retrograde pyelography and ultrasound. The initial stone locations were lower calices in 27.6%, middle calices in 11.6%, upper calices in 9.1%, the renal pelvis in 17.6%, the upper ureter in 19.9%, the middle ureter in 3.4% and the distal ureter in 7.4% in the distal ureter. 3.4% of the patients presented with staghorn stones (Fig. 1). Initial stone size was 2 21 mm (Fig. 2). Patients developing complications during clinical follow-up were treated conservatively or received appropriate ancillary treatment (DJ-catheter, percutaneous nephrostomy, percutaneous nephrolithotomy (PNL), ureteroscopy (URS) or open surgery; Table 1). All hospital files on these patients were reviewed. The patients and their referring urologist received follow-up questionnaires which contained questions about stone clearance or stone recurrence, late complications, auxillary measures and dietary or drug metaphylaxis. Only patients with complete follow-up were included. Statistical analysis was performed with SAS software package using the Mann-Whitney test and ANOVA. Data are expressed as mean. A p value <0.05 was considered to be statistical significant. Fig. 1. Stone location before shockwave therapy in patients with later clinically insignificant fragments. Fig. 2. Initial size of stones treated by shockwave lithotripsy in patients with later clinically insignificant residual fragments. Table 1 Auxiliary measures after shockwave therapy with respect to stone localization Localisation DJ URS Nephrostomy PNL Open surgery 3. Results None Pelvis 27.4% 9.7% 3.2% 4.8% 0.0% 69.4% Calices lower 13.4% 5.2% 2.1% 1.0% 0.0% 83.5% Calices middle 12.2% 7.3% 0.0% 0.0% 0.0% 85.4% Calices upper 15.6% 12.5% 0.0% 0.0% 0.0% 81.3% Staghorn 75.0% 0.0% 8.3% 25.0% 2.1% 16.7% Ureter distal 36.0% 12.0% 4.0% 4.0% 0.0% 64.0% Ureter middle 58.3% 50.0% 8.3% 0.0% 0.0% 41.7% Ureter proximal 38.6% 21.4% 4.3% 2.9% 1.4% 52.9% DJ: Double-J-catheter, URS: Ureterorenoscopy, PNL: Percutaneous nephrolithotomy. Most residual stone fragments of all CIRF were located within the lower calyx (16.8%) followed by the renal pelvis (13.9%). Stone analysis was available in 142/173 (82.1%) patients with CIRF and revealed 93.6% calcium oxalate calculi. Ancillary procedures were required for 76 patients (Table 1). Patients with caliceal stones needed significantly less interventions (p < 0.05), however, no difference could be found between distinct calices. Stones within the middle and proximal ureter required ureteroscopy in 50% and 21.4%, respectively. Virtually all staghorn stones needed additional treatment. In 78.6% (136/173) of the patients, CIRF cleared spontaneously within few weeks and did not recur within 5 years. In 97/173 patients, fragments cleared spontaneously within 4 weeks, further 39 patients lost

3 862 M.M. Osman et al. / European Urology 47 (2005) Discussion Fig. 3. Time curse of spontaneous clearance of residual fragments. their stones within 6 months (Fig. 3). Highest clearance rate was found for ureteric stones, the lowest for the lower pole (93.0% vs. 75.9%; p < 0.05). If fragments persisted inside the renal collecting system, the residual stones led to stone growth and the need of retreatment within follow-up in 37/173 (21.4%) patients. These new stones were located within renal pelvis in 23.0%, lower calices in 26.5%, middle calices 27.0% and upper calices in 27.0% (not significant, Fig. 4). Stone recurrence from ureteric stones were rare (proximal ureter 13.5%; p < 0.05, distal ureter 2.7%, p < 0.01). According to the questionnaires, only 43/90 (47.7%) of the patients with recurrent stone formation followed dietary or medical metaphylaxis. Most common prophylaxis were increased fluid intake to >2 L (55.6%) and weight reduction >2 kg (50%). Only 11.1% took specific medication (alkalicitrates, L-methionine and low-dose antibiotics). However, we could not demonstrate a significant correlation between stone metaphylaxis and stone recurrence from CIRF. Fig. 4. Localication of recurrent stone formation from residual stones after former shockwave therapy. * p < 0.05, p < Residual fragments represent a common and still controversial problem after SWL. Although efficient fragmentation of stones with SWL into fragments less than 5 mm has been described in 85% to 96% of cases [4,5], residual fragments are still present in 24% to 36% of cases 3 months after SWL treatment [3 6]. Asymptomatic fragments smaller than 5 mm and without associated infection or obstruction were defined as CIRF, although several groups have reported stone recurrence from such fragments in varying percentages [2,3,7 9]. In our study, re-growth was seen in 21.4% of cases. In contrast, Buchholz et al. reported a very low 2% re-growth rate of residual fragments at a mean follow-up of 2.5 years [9], while a far higher 59% regrowth rate at a follow up of 15 months was published by Khaitan et al. [2]. In our study, 78.6% of fragments passed spontaneously within few weeks and did not recur during the follow-up period of 5 years. These findings are comparable with other series reporting clearance rates from 30 to 87% [7 9]. In our patients, more than 98% of spontaneous cleared stones passed within the first 12 weeks. Shigeta et al. examined patients with CIRF 3 month after SWL and could show that only 14.3% of patients reached a stone free state during a further 20 month follow-up [23]. However, some studies have shown that the duration of follow up does not significantly affect the stone-free rate after SWL for caliceal calculi [14,15]. With increasing renal persistence of residual fragments the probability of stone clearance seem to decrease. Reports on fragment clearance of distinct anatomic locations are inhomogeneous and contradictory: Although some groups reported better clearance of the residual fragments in the upper calyx than in the lower calyx [4,11], others found poorest clearance rate for the superior calices and highest for the renal pelvis which was attributed to the gravity effect [1,2,13]. Fialkov et al. [10] found that the likelihood of a secondary procedure was only increased in middle calices. The spontaneous clearance rate in our study was highest in the ureter and lowest for the lower pole. In our study, the possibility of CIRF becoming clinically significant increased as their size and number increased. This finding is in accordance with most previous reports [1,2,6 8,10], however, Candau et al. [1] and Zanetti et al. [6] failed to demonstrate any significant difference in outcome depending on the size of the CIRF. Although lower pole stones showed significant lower clearance, in our study, re-growth of stones was comparable in renal pyelon and calices. These

4 M.M. Osman et al. / European Urology 47 (2005) oberservations are in accordance to data published by Zanetti et al. [12] and Moon et al. [13] found that the location of residual fragments did not significantly influence the clearance rate. With the aim of improving the clearance of the residual fragments, various investigators have proposed early re-treatment and achieved additional success in 40% to 83% [16,17]. However, systematic SWL re-treatment of all asymptomatic patients was not justified by others [9,12,17,18]. A significant improvement of stone clearance has been demonstrated for vibration massage [19]. Only 48% of our patients with recurrent stone formation followed dietary metaphylaxis. However, we could not demonstrate a significant correlation between a general or specific metaphylaxis and stone growth of CIRF, while several other studies indicate a beneficial effect of medical treatment on stone clearance and stone prevention. Cicerello et al. [20] demonstrated that administration of citrate resulted in clearance of residual fragments at 12 months, increasing the stone-free rate from 32% to 74% in cases of sterile calcium oxalate stones and from 40% to 86% for infectious stones. In another study on this topic, Soyguer et al. [22], showed that patients with calcium oxalate urolithiasis treated with potassium citrate had a significant remission rate 44.5% vs. 12.5% compared to untreated patients with residual fragments after SWL treatment during 12 months follow-up. Moreover, Fine et al. could also demonstrate medical stone prophylaxis being capable to decrease the re-growth of residual fragments significantly [21]. All of our patients were treated by their office urologists, therefore treatment modalities were inhomogeneous and quality of prophylactic measures was difficult to assess. The special patient care characteristics in the German health system might be an explanation why we could not demonstrate a relation between medical treatment and stone recurrence. However, this topic needs additional investigation. 5. Conclusions Most of the CIRF after SWL pass spontaneously shortly after treatment without any complications. But considering that one fifth of the patients developed new stones at the side of residual fragments, it is obvious that close follow-up is required. The value of medical treatment for optimizing fragment clearance has yet to be determined. Acknowledgements This study was supported by a grant to M. Osman from the German Acadmic Exchange Service (DAAD). It has been highlighted at the XVIV EAU Annual Meeting 2004, Vienna, Austria. Dr. Osman is a fellow of Department of Urology, Assiut University, Egypt. References [1] Candau C, Saussine C, Lang H, Roy C, Faure F, Jacqmin D. Natural history of residual renal stone fragments after SWL. 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