Perkutane Nephrolithotomie

The introduction of percutaneous nephrolithotomy (PNL) marked a turning point in the interventional treatment of nephrolithiasis. For the first time, the minimally invasive removal of larger kidney stones, which had previously required open surgery, became possible. With the increasing use of extracorporeal shock wave lithotripsy (SWL) during the 1980s, PNL lost clinical importance. However, since SWL has revealed its limitations, and both the patients’ wishes and economic demand require a fast stone removal, the importance of PNL has risen again. Given the correct indications and performance, PNL is an efficient treatment modality reaching stone free rates of up to 100%. When PNL is performed by an experienced urologist, complications are low and can be managed conservatively in most cases. The most important step in the performance of a PNL is the anatomically correct puncture of the kidney gaining optimal access to the stone. To reach this, a lower calyx is punctured whenever possible, under combined sonographic and fluoroscopic guidance.     

Stone Disease

ObjectivesThe purpose of this review is to discuss the major findings presented at the “New Horizons in Urology” closed expert meeting, held October 2006 in Marbella, Spain, on improving the management of stone disease (renal and ureteral stones), and to summarise the consequences of these findings on improving current practice in managing stone disease.MethodsApproximately 135 European urologists attended the meeting. Data and papers discussed in recent congress meetings in 2006 were considered. Experts in the field of stone disease selected and discussed the most relevant new findings. Furthermore, the delegate's opinion on representative clinical case studies was assessed by interactive voting. An expert panel commented on voting results.ResultsAt the meeting, it was highlighted that stones that fail to pass spontaneously in a reasonable time can be treated by minimally invasive surgical procedures including extracorporeal shock wave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PNL). The choice of treatment largely depends on the size and location of stones. However, treatment with URS is more frequently used for managing stone disease, and the number of SWL therapies is decreasing. Furthermore, the use of α₁-adrenoceptor antagonists as medical expulsive therapy has been shown to increase the expulsion rate and decrease the time until the stone is passed.ConclusionsMinimally invasive surgical procedures such as SWL, URS, and PNL have been widely adopted for stone removal, with each approach having its own advantages and disadvantages.     

The acute and long-term adverse effects of shock wave lithotripsy

Shock wave lithotripsy (SWL) has proven to be a highly effective treatment for the removal of kidney stones. Shock waves (SWs) can be used to break most stone types, and because lithotripsy is the only noninvasive treatment for urinary stones, SWL is particularly attractive. On the downside SWL can cause vascular trauma to the kidney and surrounding organs. This acute SW damage can be severe, can lead to scarring with a permanent loss of functional renal volume, and has been linked to potentially serious long-term adverse effects. A recent retrospective study linking lithotripsy to the development of diabetes mellitus has further focused attention on the possibility that SWL may lead to life-altering chronic effects. Thus, it appears that what was once considered to be an entirely safe means to eliminate renal stones can elicit potentially severe unintended consequences. The purpose of this review is to put these findings in perspective. The goal is to explain the factors that influence the severity of SWL injury, update current understanding of the long-term consequences of SW damage, describe the physical mechanisms thought to cause SWL injury, and introduce treatment protocols to improve stone breakage and reduce tissue damage.     

Percutaneous nephrolithotomy with ultrasonography-guided renal access: experience from over 300 cases

OBJECTIVE: To report our experience with over 300 patients treated with percutaneous nephrolithotomy (PNL), for although PNL was established as a treatment in the 1970s, its use diminished with the introduction of extracorporeal shockwave lithotripsy (ESWL); clinical experience with ESWL showed its limitations, and the role of PNL for treating urolithiasis was redefined, which with improvements in instruments and lithotripsy technology has expanded the capability of percutaneous stone disintegration. PATIENTS AND METHODS: The study included 315 patients (156 males, 159 females, aged 13-85 years) treated with PNL in our department between 1987 and 2002. The mean (range) stone diameter was 27 (7-52) mm. The kidney was punctured under ultrasonography guidance via a lower-pole calyx whenever possible. The working channel was dilated using an Alken dilator under X-ray control. If necessary, a flexible renoscope was used. Ultrasonic, pneumatic and laser probes were used for lithotripsy. RESULTS: Four weeks after treatment the total stone-free rate was 96.5%; 45.7% of all patients were primarily stone-free, 21.3% had clinically insignificant residual stones that passed spontaneously within 4 weeks after PNL, and 33% of the patients needed auxiliary measures (a second PNL, ESWL, ureterorenoscopy). Overall, the early complication rate was 50.8%, the most common complications being transient fever (27.6%), clinically insignificant bleeding (7.6%) or both (3.2%); 3.5% of the patients developed urinary tract infections (with no signs of urosepsis), 3.2% had renal colic and 2.9% upper urinary tract obstruction. One patient (0.3%) developed acute pancreatitis after PNL; one died from urosepsis and one needed selective angiographic embolization of the punctured kidney due to bleeding. No patient required transfusions and there were no injuries to neighbouring organs. CONCLUSIONS: These results show that PNL causes no significant blood loss or major complications in almost all patients. Two aspects may especially reduce the potential complications: ultrasonography-guided renal puncture and using PNL in an experienced centre. PNL is a highly efficient procedure that provides fast and safe stone removal.     

Is measurement of stone surface area necessary for SWL treatment of nonstaghorn calculi?

BACKGROUND AND PURPOSE: The size of urinary tract stones is usually assessed by the longest diameter (LD) alone. Logically, however, two-dimensional measurement of the stone surface area (SSA) susceptible to shockwaves would give more useful information for the planning of treatment by extracorporeal shockwave lithotripsy (SWL). This has been shown for staghorn calculi. The aim of this study was to determine for nonstaghorn kidney and ureter stones whether the LD alone identifies as reliably a subgroup of patients with a stone of a certain size as does the SSA. Furthermore, we sought to determine whether the LD alone indicates as reliably the number of patients who would be rendered stone free after one SWL session within a certain subgroup as would the SSA. PATIENTS AND METHODS: Retrospectively, SWL treatment and radiographic data of 330 patients who had undergone SWL for a single stone were analyzed. RESULTS: Ureteral stones were significantly smaller on average, and ureteral stone patients needed fewer SWL treatment sessions and fewer shockwaves to become stone free. Stratification of both kidney and ureteral stones by either LD or SSA resulted in comparable groups of patients. There were no significant differences in patient, stone, or treatment data. More importantly, the stone-free rates after one treatment did not differ significantly. CONCLUSION: The LD does accurately reflect the size of a nonstaghorn kidney or ureteral stones. Therefore, the measurement of LD, as generally practiced, appears clinically sufficient and appropriate for the assessment of stone size prior to SWL in both kidney and ureteral stones.     

Direct pelvic access percutaneous nephrolithotomy in management of ectopic kidney stone: a case report and literature review

Abstract

Percutaneous nephrolithotomy (PNL) is an effective procedure for the treatment of patients with large or complex stones. PNL is challenging in anomalous kidneys, certain patients, such as those with renal ectopia. It is unable to undergo PNL in conventional technique safely in these cases. We presented a case report of laparoscopic-assisted PNL via direct pelvic puncture in a pelvic kidney stone and discussed previous published literature. A 49-year-old man presented with right lower quadrant pain and hematuria. Intravenous pyelography and three-dimensional computerized tomography revealed an opaque 2.7?×?1.7?cm pelvis renalis stone in a right side ectopic pelvic kidney with grade III hydronephrosis. Laparoscopic-assisted tubeless PNL was performed to remove the calculus. Laparoscopic-assisted PNL as a minimally invasive therapy in ectopic kidney has many advantages. Our case showed that, in pelvic ectopic kidney with pelvic stones greater than 1.5?cm in size, laparoscopic-assisted PNL via direct pelvis puncture is a safe and effective technique.     

The argument against the routine use of ureteral access sheaths

The current authors' experience with thousands of ureteroscopic procedures has led them to believe that ureteral access sheaths are seldom necessary. No study to date has accurately determined an advantage of using these sheaths for routine ureteroscopy. The current authors have outlined their alternative methods that eliminate the reported advantages of the sheaths. Their philosophy of stone treatment uses laser lithotripsy for small stone burdens and SWL or PNL for larger stone burdens and eliminates the need for prolonged ureteroscopic procedures. Several disadvantages of access sheaths are evident. When this information is taken into account, the routine use of a ureteral access sheath becomes unnecessary. It is only in unusual cases that ureteral access sheaths are of any utility.     

Cystinuria in childhood and adolescence: recommendations for diagnosis, treatment, and follow-up

Cystinuria, an autosomal-recessive disorder of a renal tubular amino acid transporter, is the cause of about 10% of all kidney stones observed in children. Different genetic characteristics are not represented by different phenotypes. The stones are formed of cystine, which is relatively insoluble at the physiological pH of urine. Without any preventive measures, the patients will suffer from recurrent stone formation throughout their life. Even with medical management, long-term outcome is poor due to insufficient efficacy and low patient compliance. Many patients suffer from renal insufficiency as a result of recurrent stone formation and repeated interventions. However, regular follow-up and optimal pharmacotherapy significantly increase stone-free intervals. Medical management is mainly based on hyperhydration and urine alkalinization. Sulfhydryl agents such as tiopronin can be added. Recurrent stone formation necessitates repeated urological interventions. These mostly minimally invasive procedures carry the risk of impairment of renal function. In adults, extracorporeal shockwave lithotripsy (SWL) as well as intracorporeal lithotripsy is often unsuccessful. However, in children SWL shows excellent results for cystine stones. In cases with large stone burden, percutaneous nephrolithotripsy (PNL) or even open surgical nephrolithotomy are preferred. This review discusses the underlying pathogenetic mechanisms and provides guidance for the diagnosis, therapy, and management of cystinuria following the recommendations of the International Cystinuria Consortium and the European Association of Urology.     

Percutaneous Nephrolithotomy in Autosomal Dominant Polycystic Kidney Disease: Is it Different from Percutaneous Nephrolithotomy in Normal Kidney?

Objectives

Nephrolithiasis has been reported in 20-28% of patients, of whom 50% are symptomatic for stone disease and 20% require definite urologic intervention. The management of nephrolithiasis includes oral alkali dissolution therapy, extracorporeal shock wave lithotripsy and surgical treatment. In such patients, percutaneous nephrolithotomy (PNL) as a method of stone treatment has been reported in few cases with limited experience. The aim of this study is to present our experience of PNL in autosomal dominant polycystic kidney disease (ADPKD) and assessing the outcome results.

Material and Methods

From 2002 to 2011, 22 patients (26 renal units) suffering from ADPKD with stone were managed by PNL. Demographic characteristics, operative parameters and postoperative complications were recorded and analysed.

Result

The overall success rate of PNL was 82.1% and PNL with extracorporeal shock wave lithotripsy for clinically significant residual fragments was 92.85% respectively. The hematuria required blood transfusion (n = 9), postoperative fever due to cyst infection (n = 4) and paralytic ileus (n = 3) were recorded.

Conclusion

The PNL in ADPKD PNL is safe and effective but have more postoperative complications such as bleeding requiring transfusions, fever due to cyst infection and paralytic ileus.Key Words: Percutaneous nephrolithotomy, Nephrolithiasis, Autosomal dominant polycystic kidney disease     

Prognostic variables for shockwave lithotripsy (SWL) treatment success: no impact of body mass index (BMI) using a third generation lithotripter

Study Type – Therapy (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? Therapy success in SWL treatment differs between individuals. According to recent studies done with first and second generation lithotripters, different prognostic variables like stone size, stone location, stone composition, age of patient and BMI have been shown to have prognostic relevance for outcome after SWL treatment. This study has been performed with a newer, third generation lithotripter. According to this study, BMI has no impact on SWL treatment success. Therefore, SWL treatment with newer generation lithotripters should be considered for the treatment of kidney stones in overweight and obese patients.

OBJECTIVE

? To investigate the effect of different variables including body mass index (BMI) on therapy outcome in patients with upper urinary tract stones treated with a third generation lithotripter, as BMI has been reported to be an independent predictor for stone‐free status after extracorporeal shockwave lithotripsy (SWL) performed with first or second generation lithotripters.

PATIENTS AND METHODS

? In all, 172 patients with kidney stones with a mean (range) size of 9.2 (3.0–32.0) mm were included in the study. ? In all, 91 patients (52.9%) were treated with a ureteric stent in situ. ? For SWL therapy a third generation, electromagnetic lithotripter (Siemens Lithoskop^TM) was used. Stone‐free status was reached, when no more treatable stones were present (no stone or stone < 3 mm). ? BMI, stone size and localization, age, gender, treatment parameters and ureteric stent in situ were evaluated for their prognostic relevance on therapy success.

RESULTS

? The mean (range) BMI of all patients was 27.8 (19.0–58.6) kg/m². ? Patients were categorized into two groups: A) patients that were stone free after one treatment; B) patients with residual stones. The mean (sd ) BMI was 27.4 (4.6) kg/m² and 28.4 (6.1) kg/m² for A and B, respectively. ? Univariate and multivariate analysis for freedom of stones showed that only stone size (P < 0.01) and presence of a ureteric stent (P= 0.01) were independent prognostic variables. ? BMI had no significant influence on therapy outcome (P= 0.51).

CONCLUSIONS

? Using a third generation lithotripter, BMI was not an independent predictor of stone‐free rate after SWL therapy of kidney stones. ? This effect might be attributed to a greater penetration depth of the shockwave energy. Stone size and a ureteric stent in situ were the only variables with prognostic significance.     

Bilateral percutaneous nephrolithotomy in a patient with hemophilia A disorder

A 50-year-old man with hemophilia A presented with recurrent hematuria due to renal stone disease. He was receiving approximately 50,000 units of recombinant factor (rF) VIII concentrate every year due to hematuria. Between 1996 and 2002, his serum creatinine level increased from 0.7 to 1.2 ng/ml. In an effort to resolve the problems of excessive blood loss with transfusions, recurrent rF VIII replacements and deteriorating renal function, he was offered treatment with percutaneous nephrolithotomy (PNL) in conjunction with rF VIII administration. He underwent left PNL for left staghorn calculi in November 2002 with administration of 52,000 units rF VIII, and another PNL for the right kidney in April 2004 with the administration of 90,500 units rF VIII. A pneumatic lithotriptor was used in both operations. The serum creatinine level was 0.8 ng/ml upon completion of treatment and the patient was symptom and stone free at 10-month follow-up. He has not suffered from hematuria since that time. We conclude that bleeding disorders may not be a contraindication for PNL if corrected and monitored appropriately.     

Benefits of ureteroscopic pneumatic lithotripsy for the treatment of impacted ureteral stones.

PURPOSE: Although new forms of lithotripsy, such as new-generation shockwave and laser lithotripsies, have recently been developed, the optimal treatment for impacted ureteral stones (IUS) remains controversial. We investigated, retrospectively, the outcome of IUS treated with ureteroscopic pneumatic lithotripsy. PATIENTS AND METHODS: Twenty-two IUS cases were treated using ureteroscopic pneumatic lithotripsy. Of 22 stones, 8 (36%) were treated by ureteroscopic pneumatic lithotripsy as initial treatment and 14 (64%) with pneumatic lithotripsy as an auxiliary treatment after SWL. The stone sizes ranged from 7 to 16 mm with 14 located in the proximal, 3 in the middle, and 5 in the distal ureter. RESULTS: Twenty stones (91%) were effectively fragmented by ureteroscopic pneumatic lithotripsy and eliminated within 1 month after treatment. One stone could not be observed with the ureteroscope secondary to the kinking and stricture of the ureter under the stone, and the stone moved into the kidney during the procedure. The stone was subsequently treated successfully with SWL. One other stone was first fragmented into two pieces; and one big piece, which migrated into the kidney, was treated successfully with SWL. Complications such as bleeding, ureteral injury, and perforation did not occur. Although a few small fragments migrated into the kidney during the procedure in three cases, the overall stone-free rate at 1 month after a one-session treatment with pneumatic lithotripsy was 91%. CONCLUSION: Impacted ureteral stones can be treated effectively with ureteroscopic pneumatic lithotripsy in both the short and the long term.     

Extracorporeal shockwave lithotripsy compared with ureteroscopy for the removal of small distal ureteral stones

INTRODUCTION: The treatment of small distal ureteral stones smaller or equal to 5 mm in size is still highly controversial. In distal ureteral stones larger than 5 mm in size, ureteroscopy (URS) has been shown in many studies to be superior to shockwave lithotripsy (SWL). The objective was to analyze the stone-free rate after treatment of distal ureteral stones with in situ SWL or URS. MATERIALS AND METHODS: A total of 3,857 SWL treatments were performed at our institution between 1996 and 2001. During this period 45 in situ SWL procedures were performed with the Dornier MFL 5000 lithotripter on distal ureteral stones regardless of the stone size. A total of 262 URS treatments were performed on distal ureteral stones. URS for small (5 mm or less) distal ureteral stones was performed in 110 cases. RESULTS: Distal ureteral stones smaller or equal to 5 mm in size were treated successfully stone free in 78% in one SWL session. Patients required a second SWL in 14% of the cases and 8% of the patients required a third SWL session. URS patients were successfully stone free after the procedure in 97% of the cases. Failed URS that needed an additional URS were performed in 2 and 1% of the patients had one SWL in situ treatment. CONCLUSIONS: URS treatment has shown to be the therapy of choice for distal ureteral stones. It is more effective than SWL treatment in this stone location. In experienced hands URS is a safe though even more invasive procedure than SWL. This can be expected as urologists perform more than 40 URS procedures per year.     

Management of lower pole renal calculi: shock wave lithotripsy versus percutaneous nephrolithotomy versus flexible ureteroscopy

Current ureteroscopic intracorporeal lithotripsy devices and stone retrieval technology allow for the treatment of calculi located throughout the intra-renal collecting system. Difficulty accessing lower pole calculi, especially when the holmium laser fiber is utilized, is often encountered. Herein we review our experience where lower pole renal calculi were ureteroscopically managed by holmium laser fragmentation, either in situ, or by first displacing the stone into a less dependent position with the aid of a nitinol stone retrieval device. Lower pole stones less than 20 mm can be primarily treated by ureteroscopic means in patients: that are obese; have a bleeding diathesis; with stones resistant to shockwave lithotripsy (SWL); with complicated intra-renal anatomy; or as a salvage procedure after failed SWL. Lower pole calculi are fragmented with a 200 μm holmium laser fiber via a 7.5 F flexible ureteroscope. For those patients where the laser fiber reduced ureteroscopic deflection, precluding re-entry into the lower pole calyx, a 1.9 F nitinol basket is used to displace the lower pole calculus into a more favorable position, thus allowing for easier fragmentation. A nitinol device passed into the lower pole, through the ureteroscope, for stone displacement cause only a minimal loss of deflection and no significant impact on irrigation. Eighty-five percent of patients were stone free by IVP or CT scan performed at 3 months. Ureteroscopic management of lower pole calculi is a reasonable alternative to SWL or percutaneous nephrolithotomy (PNL) in patients with low volume stone disease. If the stone cannot be fragmented in situ, nitinol basket or grasper retrieval, through a fully deflected ureteroscope, allows for repositioning of the stone into a less dependant position, thus facilitating stone fragmentation.     

Renal calculi. Percutaneous management

Percutaneous nephrolithotomy has established indications and is performed with high success and minimal morbidity. Patients who have large or hard stones or stones associated with urinary obstruction are candidates for a percutaneous procedure. When the certainty of the final result is important, the patient should have a PNL. In general, the best treatment for SWL failure is not more SWL; such patients usually should have an endoscopic procedure.     

Comparison of retrograde intrarenal surgery, shockwave lithotripsy, and percutaneous nephrolithotomy for treatment of medium-sized radiolucent renal stones

Objectives

To compare the outcomes of shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PNL), and retrograde intrarenal surgery (RIRS) for 10–20 mm radiolucent renal calculi by evaluating stone-free rates and associated complications.

Patients and methods

A total of 437 patients at 7 institutions who underwent SWL (n = 251), PNL (n = 140), or RIRS (n = 46) were enrolled in our study. Clinical success was defined as stone-free status or asymptomatic insignificant residual fragments <3 mm. The success rates, auxiliary procedures, and complications were compared in each group.

Results

Success rates were 66.5, 91.4, and 87 % for SWL, PNL, and RIRS (p < 0.001). The need for auxiliary procedures was more common after SWL than PNL and RIRS (21.9 vs 5.7 vs 8.7 %, respectively; p < 0.001). The overall complication rates for the SWL, PNL, and RIRS were 7.6, 22.1, and 10.9 %, respectively (p < 0.001). Thirteen patients in PNL group received blood transfusions, while none of the patients in RIRS and SWL groups transfused. Hospitalization time per patient was 1.3 ± 0.5 days in the RIRS group, while it was 2.6 ± 0.9 days in the PNL group (p < 0.001). Fluoroscopy and operation time were significantly longer in the PNL group compared to RIRS (145.7 ± 101.7 vs 28.7 ± 18.7 s, and 57.5 ± 22.1 vs 43.1 ± 17 min, respectively).

Conclusions

For treatment of moderate-sized radiolucent renal stones, RIRS and PNL provide significantly higher success and lower retreatment rate compared with SWL. Although PNL is effective, its biggest drawback is its invasiveness. Blood loss, radiation exposure, hospital stay, and morbidities of PNL can be significantly reduced with RIRS technique.     

Comparing non contrast computerized tomography criteria versus dual X-ray absorptiometry as predictors of radio-opaque upper urinary tract stone fragmentation after electromagnetic shockwave lithotripsy

The objective of this study was to assess the value of dual X-ray absorptiometry (DXA) in comparison to non contrast computed tomography (NCCT) density as possible predictors of upper urinary tract stone disintegration by shock wave lithotripsy (SWL). This study included 100 consecutive patients, with solitary renal stone 0.5–2 cm or upper ureteral stone up to 1 cm. DXA to calculate stone mineral density (SMD) and stone mineral content (SMC) was done. NCCT was performed to measure Hounsfield units (HU). SWL was performed with an electromagnetic lithotripsy, plain X-ray documented disintegration after SWL. Successful treatment was defined as stone free or complete fragmentation after 1 or 2 sessions of SWL. The impact of patients age, sex, body mass index, stone laterality, location, volume, length, mean SMC and SMD, HU and Hounsfield density (HD), skin to stone distance (SSD) and number of shock waves were evaluated by univariate and multivariate analysis. Only 76 patients were available for follow-up. Success of disintegration was observed in 50 out of 76 patients (65.8 %). On multivariate analysis, SMC and number of shock wave were the significant independent factors affecting SWL outcome (p = 0.04 and p = 0.000, respectively). SMC as detected by DXA is a significant predictor of success of stone disintegration by SWL. SMC measured by DXA is more accurate than HU measured by CT. Patients with high stone mineral content (SMC greater than 0.65 g) should be directly offered another treatment option.     

Comparison of success rates and financial cost of extracorporeal shock-wave lithotripsy in situ and after manipulation for proximal ureteral stones

Our aim was to compare the stone free rate and the financial cost between in situ and after manipulation shock wave lithotripsy (SWL) for proximal ureteral stones. A total of 130 patients with proximal ureteral stones were prospectively randomized into two groups. Sixty-five patients (group 1) underwent SWL in situ and 65 patients (group 2) underwent SWL after an attempt was made to push back the stone into the kidney with the help of a ureteral catheter. The mean per person financial cost of both techniques was estimated after a follow up period of 3 months. The stone free rate 1 month post treatment was 83% (54/65 patients) for group 1 and 95% (62/65) for group 2. The higher success rate at 1 month for the pushback group was statistically significant (P=0.04) but was correlated with a higher cost (€852 vs €1,008.5). Fifteen additional sessions of SWL and follow up visits were needed in group 1, therefore making the final costs of the two therapeutic pathways almost equal (€1,050.9 vs €1,088.9), with no great difference in the overall fragmentation rates at 3 months between groups (94% and 97%, respectively). Stone manipulation offers higher stone free rates faster than in situ extracorporeal SWL, but is more expensive. This disparity in cost is diminished when costs are corrected for follow-ups and treatment of complications.     

In-Vivo relation between CT attenuation value and shockwave fragmentation

PURPOSE: To use CT attenuation numbers as a means of determining the susceptibility of an artificial stone to in-vivo fragmentation with extracorporeal shockwave lithotripsy (SWL). MATERIALS AND METHODS: Four types of artificial kidney stones having different CT attenuation values were used. One randomly selected stone was implanted in the renal pelvis of a kidney of 12 young pigs and exposed in vivo to 2500 shockwaves (21 kV) using an electrohydraulic lithotripter. Bilateral nephrectomy was performed after SWL. Fragments were strained through a mesh with a 3.1-mm grid, and the debris left on the mesh was dried and weighed. Fragmentation coefficients (FCs) were associated with CT attenuation values using a statistical model. RESULTS: The relation between FC and CT number was significant, indicating that as CT attenuation increases, FC is reduced. Larger stone fragments were obtained from stones with higher CT numbers. Initial stone weight was not a significant explanation for variations in FC. CONCLUSION: The CT values could be helpful in selecting patients for SWL in the future. However, other parameters such as stone porosity, shape, and roughness also will have to be considered.     

Percutaneous nephrolithotomy in pediatric patients: is computerized tomography a must?

The aim of this study was to retrospectively evaluate the results of pediatric percutaneous nephrolithotomy (PNL) cases, and discuss the results and necessity of non-contrast computerized tomography (CT) in these cases. In all, 48 pediatric patients who underwent PNL were retrospectively evaluated. Before PNL, either intravenous urography or CT was performed. In all patients, we evaluated the PNL time, scopy time with stone burden, and complications. During the PNL procedure, we switched to open surgery in two cases: in one because of renal pelvis perforation and in the other because of transcolonic access. In one patient who was scheduled to undergo PNL, we performed open surgery, primarily because we detected a retrorenal colon with CT. The stone burden in 45 patients who underwent PNL was 445 ± 225 mm², the PNL time was 51 ± 23 min, and the scopy time was 6.1 ± 2.7 min. We removed nephrostomy tubes 1–4 days after the procedure. In two patients, 24 h after removal of nephrostomy tubes, we inserted double J stents because of prolonged urine extravasation from the tract. In all, 34 of the 45 patients were stone-free, 5 patients had clinically insignificant stone fragments, and 6 patients had residual stones. PNL is a safe and effective method in the treatment of pediatric patients with kidney stones. Clinical experience is the most important factor in obtaining stone-free results. CT should be performed in all pediatric patients in order to prevent colon perforation.