Detection of Residual Stones After Percutaneous Nephrolithotomy: Role of Nonenhanced Spiral Computerized Tomography

Single- versus Multiple-Tract Percutaneous Nephrolithotomy in the Surgical Management of Staghorn Stones or Complex Caliceal Calculi: A Systematic Review and Meta-analysis

Objective

To assess current evidence on the effectiveness and safety of single- versus multiple-tract percutaneous nephrolithotomy in the surgical management of complex caliceal calculi or staghorn stones through a comprehensive literature review.

Methods

A comprehensive literature review of articles investigating the clinical efficacy and safety of single- versus multiple-tract percutaneous nephrolithotomy was performed. Relevant literature was obtained by systematically searching PubMed, EMBASE, and the Cochrane Library through May 2020. We followed the search strategy based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The primary outcomes, including the stone-free rate (SFR), and secondary outcomes (peri- and postoperative complications and operative data) were evaluated using RevMan 5.3 statistical software.

Results

Ten studies involving 1844 patients with complex caliceal calculi or staghorn stones met the inclusion criteria. Single-tract percutaneous nephrolithotomy (STPCNL) had noninferior clinical efficacy with respect to the immediate SFR (odds ratio (OR) = 0.80, 95% confidence interval (CI) (0.46 to 1.38), p = 0.42) and 3-month SFR (OR = 1.22, 95% CI (0.38 to 3.92), p = 0.74) compared with multiple-tract percutaneous nephrolithotomy (MTPCNL). In addition, pooled analyses showed that STPCNL resulted in significantly lower hemoglobin decreases (MD = −0.46, 95% CI (-0.68 to -0.25), p < 0.0001), fewer blood transfusions (OR = 0.48, 95% CI (0.34 to 0.67), p < 0.0001), and fewer pulmonary complications (OR = 0.28, 95% CI (0.09 to 0.83), p = 0.02) than MTPCNL. However, the overall evidence was insufficient to suggest a statistically significant difference for other adverse events.

Conclusion

This meta-analysis indicated that STPCNL is an effective method for treating complex caliceal calculi or staghorn stones. Compared with MTPCNL, STPCNL not only yields similarly high SFRs but also is associated with many advantages, less blood loss, fewer blood transfusions, and fewer pulmonary complications without an increase in other complications. However, the findings of this study should be further confirmed by well-designed prospective randomized controlled trials (RCTs) with a larger patient series.

Clinical application of super-mini PCNL (SMP) in the treatment of upper urinary tract stones under ultrasound guidance

PURPOSE

To present the safety and efficacy of totally ultrasonography-guided Super-mini percutaneous nephrolithotomy (SMP) in the treatment of upper urinary tract stones both in children and adults.

PATIENTS AND METHODS

We carried out SMP in 104 patients (including 48 children and 56 adults) with upper urinary tract stones between June 2015 and February 2017. All steps of renal access were performed by ultrasonography. The lithotripsy was performed using either Holmium laser or pneumatic lithotripter. Perioperative and postoperative parameters along with operative data were recorded in detail.

RESULTS

The mean age of children and adult patients were 4.4 ± 3.6 and 44.3 ± 15.7 years old, respectively. The stone burden was comparable for both groups (1.72 ± 0.66 vs 1.74 ± 0.56 cm, p = 0.852). Mean operation time was not significant different between two groups (p = 0.052), while the mean haemoglobin drop in children was much lower in adult patients (6.3 ± 6.9 vs 10.9 ± 8.69, p = 0.004). Both groups had similar SFRs in postoperative 1 day and at 1-month follow-up (p = 1.000, p = 0.912). Mean hospital stay of children and adult patients was 2.3 ± 0.8 and 2.2 ± 0.76 days (p = 0.484). The total complication rate was significantly lower in two groups (p = 1.000); none of the patients required blood transfusion.

CONCLUSIONS

Ultrasonography-guided SMP was a safe and effective treatment option for moderate-sized upper urinary tract stones, and has the advantage of preventing radiation hazard, especially for pediatric stone patients.

Suctioning Minimally Invasive Percutaneous Nephrolithotomy with a Patented System Is Effective to Treat Renal Staghorn Calculi: A Prospective Multicenter Study

OBJECTIVES

To investigate the safety, efficacy, and practicability of minimally invasive percutaneous nephrolithotomy (MPCNL) with the aid of a patented irrigation clearance system in treating renal staghorn calculi.

METHODS

From August 2009 to July 2014, 4 hospitals had executed a prospective multicenter study with a total of 912 cases. The patients were randomly divided into 3 groups: suctioning MPCNL, standard percutaneous nephrolithotomy (PCNL), and traditional MPCNL groups. Multiple operative and perioperative parameters were compared.

RESULTS

Blood loss and intrapelvic pressure in the suctioning MPCNL group were significantly less than those in the standard PCNL group. The average operation time, intrapelvic pressure, and amount of bleeding in the suctioning MPCNL group were better than those in the traditional MPCNL group. The suctioning MPCNL used one tract more frequently and 2 or 3 tracts less frequently than the standard MPCNL and traditional MPCNL groups. The stone-free rate by one surgery in the suctioning MPCNL group was significantly higher than that in standard PCNL and traditional MPNCL groups.

CONCLUSIONS

Suctioning MPCNL using our patented system shows several advantages in treating renal staghorn calculi, including minimal invasion, shorter operation time, lower intrapelvic pressure, less bleeding and the need for a smaller number of -percutaneous tracts, and higher stone clearance rate by one -surgery.

Rearrangement of the Guy's stone score improves prediction of stone-free rate after percutaneous nephrolithotomy

Objective

We propose a modification of the original Guy's Stone Score (GSS) to hold on 20 % of prognostic discrimination among groups which makes this score a more reliable resource for risk assessment in patients undergoing percutaneous nephrolithotomy (PCNL).

Material and methods

Historical cohort of 126 patients undergoing PCNL from December 2010 to November 2014 was included in the survey. Every patient was classified according to the original GSS. For the new classification of Guy Stone Score (GSS-M) all of the subgroups included in the scale were analyzed individually and then ranked from better to worst according to the postoperative stone- free rates (SFRs). This ranking led us to reclassify all the original subgroups, clustering them in three new categories according to their SFRs as subgroups of good, intermediate and poor prognosis, trying to achieve at least 20% of prognostic discrimination among the groups.

Results

Hundred and twenty-six PCNL procedures were evaluated, but only 124 were included for statistical analysis and classified based on SFR according to the GSS as follows: 76% for grade 1, 71% for grade 2, 55% for grade 3 and 20% for grade 4. The SFRs were also assessed for the GSS-M obtaining the following predictive values as 93%, 67% and 44% for the good, intermediate and poor prognostic groups, respectively. The prognostic difference among the GSS-M groups was always >20% (p<0.05).

Conclusion

The original GSS has limitations to predict SFR because of its poor discrimination power among prognostic groups. This rearrangement improves prediction of SFR and better discriminates risk groups in PCNL.

Residual stones after percutaneous nephrolithotomy: comparison of intraoperative assessment and postoperative non-contrast computerized tomography

OBJECTIVES

To compare the intraoperative surgeon perspective for detection of residual fragments (RFs) after percutaneous nephrolithotomy (PNL) with postoperative NCCT.

METHODS

A prospective study of adult patients who underwent PNL between March and September 2014 was conducted. Stone complexity was evaluated using the Guy's stone score (GSS). All patients were evaluated by pre- and postoperative NCCT. After the procedure, the surgeon had been asked whether there were residual stones or not. The sensitivity, specificity and predictive values were tested against postoperative NCCT. Predictors of accurate intraoperative assessment were determined using univariate and multivariate statistical analyses.

RESULTS

The study included 306 consecutive patients. The surgeons reported no residual stones in 236 procedures; of whom 170 (72%) were reported stone-free by NCCT. On the other hand, 65 out of 70 procedures (93%) reported with residual stones by the surgeons were true by NCCT. The sensitivity was 50% and the NPV was 72%, while the specificity was 97% and the PPV was 93%. On multivariate analysis, only lower GSS (p < 0.001) was independently associated with true negative surgeon opinion.

CONCLUSIONS

Although there was a high surgeon ability to detect post-PNL residual stones, postoperative imaging is mandatory because of the high false negative rates and low NPV. The surgeon opinions can be judged only in stones with lower GSS. The NPV could be enhanced if a consistent definition of clinically significant RFs is introduced.

Methylene Blue Injection as an Alternative to Antegrade Nephrostography to Assess Urinary Obstruction After Percutaneous Nephrolithotomy

AIMS AND OBJECTIVES

Percutaneous nephrolithotomy (PCNL) remains an effective treatment for large stones. When nephrostomy tube (NT) is left post operation, antegrade urine flow is often confirmed with antegrade nephrostography (ANG) before tube removal. We compare methylene blue (MB) test combined with NT capping trial against ANG to assess antegrade urine flow after PCNL.

MATERIALS AND METHODS

One hundred one consecutive patients undergoing PCNL were prospectively enrolled between 7/2014 and 4/2015. An NT cap was placed the morning of postoperative day 1 (POD1). Failure was defined as need to uncap the NT for any reason. Two hours after capping, 7cc MB was injected into the NT. Positive MB test was defined as presence of blue per bladder Foley. ANG was then performed to assess antegrade urine flow. NTs were removed before discharge home when antegrade flow was documented. Primary outcomes included presence of antegrade flow on ANG and NT removal before discharge home. Receiver operating characteristic (ROC) and areas (Area under the ROC [AUC]), as well as Cohen's kappa coefficient (κ), were calculated comparing agreement of capping trial, MB, and ANG with NT removal.

RESULTS

One hundred one subjects were included in this analysis. 52.9% were left-sided surgeries and 60.4% utilized lower pole punctures. On ROC areas evaluating tests for agreement with NT removal before discharge, MB AUC 0.71 (95% CI 0.60-0.83), capping trial AUC 0.66 (95% CI 0.57-0.75), combed capping trial and MB AUC 0.72 (95% CI 0.61-0.84), and ANG AUC 0.78 (95% CI 0.68-0.88). In predicting NT removal, ANG performed better than capping trial alone (p = 0.042), but no differences were seen between MB and ANG (p = 0.229), combining the capping trial with MB test and ANG (p = 0.266) or combined testing and MB alone (p = 0.972).

CONCLUSIONS

Combining capping trial with MB injection is similarly accurate for predicting NT removal after PCNL compared to ANG. Capping trial and MB may be used in combination to obviate the need for ANG.

Current practice in Latin America of flexible ureterorenoscopy with laser for treating kidney stones

INTRODUCTION

The use of flexible ureterorenoscopy for treating kidney stones has increased in recent years, with considerable worldwide variation in the surgical technique and indications.

OBJECTIVES

To determine the current practice, technique variations, use and indications of flexible ureterorenoscopy for treating kidney stones in Latin American.

METHODS

We sent (by email and web link) an anonymous questionnaire with 30 questions on flexible ureterorenoscopy for treating kidney stones to Latin American urologists from January 2015 to July 2015. We collected the responses through the Survey Monkey system.

RESULTS

A total of 283 urologists in 15 Latin American countries participated (response rate, 10.8%); 254 answered the questionnaire completely; 52.8% were urologists from Mexico and 11% were from Argentina; 11.8% of the responders stated that they performed >100 cases per year; 15.2% considered ureterorenoscopy as the treatment of choice for stones >2cm, and 19.6% performed ureterorenoscopy in single stages for calculi measuring >2.5cm. Some 78.4% use fluoroscopy, 69.1% use a ureteral sheath in all cases, 55.8% place double-J catheters at the end of surgery, 37.3% considered a stone-free state to be 0 fragments, and 41.2% use plain radiography to assess the stone-free condition.

CONCLUSIONS

Most participating urologists consider flexible ureterorenoscopy as the first-choice treatment for stones <2cm; a small percentage of these urologists perform >100 ureterorenoscopies per year. More than half of the urologists routinely used fluoroscopy and ureteral access sheath; the most common method for determining the stone-free state is plain abdominal radiography.

Clinical significance of residual fragments in 2015: impact, detection, and how to avoid them

PURPOSE

Residual fragments are common after stone treatment. Little is known about clinical outcomes relevant to the patient. This comprehensive review of the literature highlights the impact of residual fragments, modes of detection, and treatment strategies to avoid residual fragments in shock wave therapy, ureteroscopy, and percutaneous nephrolithotomy.

METHODS

A comprehensive review of current literature was performed using PubMed(®), MEDLINE(®), Embase™, Ovid(®), Google Scholar™, and the Cochrane Library. Publications relevant to the subject were retrieved and critically appraised.

RESULTS

Residual fragments after treatment for urinary stones have a significant impact on a patient's well-being and future course. (Ultra-) low-dose non-contrast computed tomography detects small residuals most reliably. In shock wave lithotripsy, adherence to basic principles helps to improve results. Various techniques and devices facilitate complete stone clearance in conventional and miniaturized percutaneous nephrolithotomy and (flexible) ureteroscopy. Promising new technologies in shock waves, lasers, and robotics (and potentially microrobotics) are on the horizon.

CONCLUSIONS

Residual fragments are relevant to patients. Contemporary treatment of urolithiasis should aim at complete stone clearance.

Comparison of imaging modalities for detection of residual fragments and prediction of stone related events following percutaneous nephrolitotomy

Introduction

Achieving stone free status (SFS) is the goal of stone surgery. In this study it is aimed to compare effectiveness of unenhanced helical computerized tomography (UHCT), KUB and ultrasonography (US) for detection of residual RFs and predicition of stone releated events following percutaneous nephrolitotomy (PNL).

Materials and Methods

Patients underwent PNL for radiopaque stones between November 2007 and February 2010 were followed. Patients were examined within 24-48 hours after the procedure by KUB, US and UHCT. For stone size 4 mm was accepted as cut off level of significance.Sensitivity and specificity of KUB and US for detection of RFs and value of them for prediction of stone related events were calculated.

Results

SFS was achieved in 95 patients (54.9%) and when cut off value of 4 mm for RFs was employed, SFS was achieved in 131 patients (75.7%). Sensitivity was 70.5% for KUB, and 52.5% for US. UHCT was shown to be significantly more efficient for detection of RFs compared to both KUB (p=0.01) and US (p=0.001). When cut off level of 4 mm employed, sensitivity of KUB and US increased to 85.7% and 57.1%. Statistical significant superiority of UHCT still remained (p value vs. KUB: 0.03 and p value vs. US: 0.008).

Conclusion

UHCT is the most sensitive diagnostic tool for detecting RFs after PNL. It has higher sensitivity regardless of stone size compared to KUB and US. Additionally UHCT has higher capability of predicting occurrence of stone related events.

Advances in CT imaging for urolithiasis

Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice.

Percutaneous nephrolithotomy versus open surgery for treatment of staghorn stones in pediatric patients

INTRODUCTION

We compare percutaneous nephrolithotomy (PCNL) and open surgery in the treatment of staghorn stones in children.

METHODS

We retrospectively reviewed the electronic records of children who underwent treatment for staghorn stones between September 2000 and August 2013. They were divided between Group 1 (patients who underwent PCNL) and Group 2 (patients who underwent open surgery). We compared stone-free and complications rates, need for multiple procedures, and hospital stay.

RESULTS

The study included 41 patients (35 boys and 6 girls), with mean age 7.4 ± 3.1 years (range: 2-15). Of these 41 patients, 26 had unilateral renal stone and 15 had bilateral renal stones. The total number of treated renal units was 56: 28 underwent PCNL and 28 underwent open surgery. The complication rate was comparable for both groups (32% for open surgery vs. 28.6%, p = 0.771). Multiple procedures were more needed in PCNL group (60.7% vs. 32% in open surgery, p = 0.032). The stone-free rate was 71.4% after PCNL and 78.6% after open surgery (p = 0.537). A significant difference was observed in shorter hospital stay after PCNL (5 vs. 8.8 days, p < 0.001). Our study's limitations include its retrospective design and relatively small sample size.

CONCLUSIONS

For the treatment of staghorn stones in children, PCNL was comparable to open surgery in complication and stone-free rates. PCNL had the advantage of a shorter hospital stay and open surgery showed a decreased need for multiple procedures.

Minimally invasive percutaneous nephrolithotomy for simple and complex renal caliceal stones: a comparative analysis of more than 10,000 cases

PURPOSE

To determine whether minimally invasive PCNL (MPCNL) is as safe and effective in the management of complex renal caliceal stones as it is for simple renal stones.

PATIENTS AND METHODS

We retrospectively reviewed 5761(41.2%) simple caliceal stones (isolated renal pelvis including isolated calix) and 8223 (58.8%) complex caliceal stones (renal pelvis accompanying two calices at least) that were managed by MPCNL between 1992 nd 2011. The safety, efficacy, and outcome were compared and analyzed.

RESULTS

Stone burden was larger in complex caliceal stones (1763.0 vs 1018.6 mm(2), P<0.05). Patients with simple stones had significantly shorter operative time, less frequency of multiple percutaneous accesses, and less hemoglobin drop. They also had a higher initial stone-free rate (SFR) (77.6% vs 66.4%) after a single session of MPCNL (P<0.05). The differences diminished in the final SFR (86.7% vs 86.1%) after relook and/or auxiliary procedures (P>0.05). The complication rate (17.9% vs 19.0%) and blood transfusion rate (grade II) (2.2% vs 3.2%) were similar in both groups (P>0.05). Both groups had a low rate of high Clavien grade complications. Renal vascular embolizations (grade III), however, were significantly higher in patients with complex caliceal stones (P<0.05).

CONCLUSIONS

MPCNL is a safe and effective treatment option for patients with complex caliceal stones except there is a slightly higher frequency rate of embolization. There was a higher initial SFR in simple stones, but this difference diminished with secondary procedures.

Percutaneous nephrolithotomy guided solely by ultrasonography: a 5-year study of >700 cases

OBJECTIVE

To evaluate the safety and efficacy of percutaneous nephrolithotomy (PCNL) solely guided by ultrasonography (US).

PATIENTS AND METHODS

From May 2007 to July 2012, 705 24-F-tract PCNL procedures were performed (679 patients, of whom 26 had bilateral stones). Calyceal puncture and dilatation were performed under US guidance in all cases. The procedure was evaluated for access success, length of postoperative hospital stay, complications (modified Clavien system), stone clearance and the need for auxiliary treatments.

RESULTS

The mean (sd) operating time was 66 (25) min, with a mean (sd) postoperative hospital stay of 3.98 (1.34) days. The patients experienced a mean (sd) haemoglobin level decrease of 2.24 (2.02) g/day and the overall stone-free rate at 4 weeks after surgery was 92.6% in patients with a single calculus and 82.9% in patients with staghorn or multiple calculi. Auxiliary treatments, including shockwave lithotripsy in 52 patients, re-PCNL in 41 patients and ureteroscopy in 18 patients, were performed 1 week after the primary procedure in 111 (15.7%) cases for residual stones >4 mm in size. The sensitivities of intra-operative US-guidance and flexible nephroscopy for detecting significant residual stones and clinically insignificant residual fragments were 95.3 and 89.1%, respectively. There were 94 grade 1 (13.3%), 17 grade 2 (2.4%), and two grade 3 (0.3%) complications, but there were no grade 4 or 5 complications.

CONCLUSION

Total US-guided PCNL is safe and convenient, and may be performed without any major complications and with the advantage of preventing radiation hazards and damage to adjacent organs.

Is computed tomography mandatory for the detection of residual stone fragments after percutaneous nephrolithotomy?

The introduction of minimally invasive endourologic procedures for upper urinary stone disintegration has closed the curtain on the era of open surgery for upper urinary tract stones in which complete stone eradication was the rule. This shift to minimally invasive procedures has led to the introduction of new terminology, such as stone-free rates and residual stone fragments, the presence of which after treatment was considered an acceptable therapeutic end point. Percutaneous nephrolithotomy (PCNL) is currently considered the procedure of choice for large renal stones. Its use has been greatly facilitated by the favorable profile of multidetector CT with regard to its sensitivity in detecting small stones. Despite the fact that CT is considered essential for the diagnosis and exact localization of stones and has been used for the creation of percutaneous tracts in PCNL, however, its routine use for the post-PCNL detection of residual stones has not been established. There is evidence that routine application of post-PCNL CT provides additional advantages compared with other imaging modalities-namely, the identification of the presence and location of even small residual fragments, which has been shown to cause significant trouble and necessitate secondary procedures in a significant cohort of patients after PCNL. On the other hand, the issues of cost, availability of CT scanners, and radiation exposure along with the acceptable sensitivity, cost, and availability of other imaging studies has raised doubts as to whether CT should be the routine imaging study after PCNL. The present review will discuss the concept of clinically significant residual fragments and comment on the advantages and drawbacks of different imaging studies used for the detection of residual stones after PCNL. This review also aims to clarify the indications in which CT should routinely be performed or could be omitted in the follow-up after PCNL.

Combined semirigid and flexible ureterorenoscopy via a large ureteral access sheath for kidney stones >2 cm: a bicentric prospective assessment

PURPOSE

The international guidelines on urolithiasis state that the percutaneous approach is superior for kidney stones ≥20 mm. Nevertheless, several groups have reported high stone-free rates (SFRs) with low morbidity for ureteroscopic treatment of calculi >15 mm. We hereby describe a new technique including the combined use of semirigid and flexible ureteroscopy via a large ureteral access sheath (UAS).

METHODS

The proposed technique includes (a) preoperative ureteral stenting, (b) use of a large lumen UAS (14/16F, 35 cm), (c) use of a semirigid ureteroscope, (d) holmium laser lithotripsy, (e) passive and (f) active fragment extraction, and finally, the removal of caliceal stones (g) using a flexible scope. We conducted a prospective outcome analysis for 38 patients treated at two tertiary university centers.

RESULTS

Perioperative data were as follows: median cumulative stone size 24.5 mm (20-60), median operating time 95 min (50-205), post-operative ureteral stenting (2-35 days) in 33 patients (86.8 %), Clavien complications 2 and 3 in 7.9 %, primary SFR 63.2 %, and overall computed tomography (CT) controlled SFR after 3 months 81.8 % (including staged procedures). No late complications were observed.

CONCLUSIONS

The combined use of semirigid ureteroscopy and an UAS further develops the endoscopic treatment of kidney stones. This is the first series of this kind that confirms high SFRs by CT. The approach has significant advantages: Superior irrigation and outflow enhance both vision and stone clearance, and multiple ureteral passages without putting the ureter at injury risk. These encouraging results make this modality an appealing alternative to percutaneous nephrolithotomy.

Residual fragments after percutaneous nephrolithotomy

Clinically insignificant residual fragments (CIRFs) are described as asymptomatic, noninfectious and nonobstructive stone fragments (≤4 mm) remaining in the urinary system after the last session of any intervention (ESWL, URS or PCNL) for urinary stones. Their insignificance is questionable since CIRFs could eventually become significant, as their presence may result in recurrent stone growth and they may cause pain and infection due to urinary obstruction. They may become the source of persistent infections and a significant portion of the patients will have a stone-related event, requiring auxilliary interventions. CT seems to be the ultimate choice of assessment. Although there is no concensus about the timing, recent data suggests that it may be performed one month after the procedure. However, imaging can be done in the immediate postoperative period, if there are no tubes blurring the assessment. There is some evidence indicating that selective medical therapy may have an impact on decreasing stone formation rates. Retrograde intrarenal surgery, with its minimally invasive nature, seems to be the best way to deal with residual fragments.

Place of non contrast thin-slice spiral computed tomography in evaluation of stone-free ratio after percutaneous nephrolithotomy

PURPOSE

To search the place of non contrast abdominal computed tomography to detect the stone-free rate after percutaneous nephrolithotomy (PNL) and the clinical importance of its superiority against to plain film radiography (KUB).

MATERIALS AND METHODS

Between February 2006 and July 2010, 62 patients including 27 women had no stone detected peroperative fluoroscopy and nephroscopy during PNL were included. Patients whom stone was not detected under 5 mm section upper abdomen non contrast spiral CT and KUB control in postoperative day 3 were defined as Group 1; patients whom stone was detected in a single slice CT were defined as clinically insignificant fragment (CIF)(Group 2) and patients whom stone was detected at least in two slice were defined as rest fragment (Group 3).

RESULTS

Median stone size were 22.3 mm (19-37 mm). Preoperative stone localization of groups were upper calyx, middle calyx, pelvis, lower calyx and 2.1, 14.9, 25.5 and 57.4%, respectively. CIF was detected in postoperative CT control of 12 (25.5%) patients whom stone was not followed in KUB and rest fragment was detected in 6 (12.8%) patients. Three of patients whom rest fragment was detected required an additional intervention for stone.

CONCLUSION

KUB which is routinely used to determine stone-free ratio after PNL operation is not sufficient to detect rest calculi and/or CIF existence in 38.3% patients. But when it is considered that most of rest stones detected were CIF and only 6.3% patients had additional intervention required rest calculi. We can think that CT follow-up is not absolutely required.

Management of Clinically Insignificant Residual Fragments following Shock Wave Lithotripsy

Clinically insignificant residual fragments (CIRFs) are small fragments (less than 5 mm) that are present in upper urinary tract at the time of regular post-SWL followup. The term is controversial because they may remain silent and asymptomatic or become a risk factor for stone growth and recurrence, leading to symptomatic events, and need further urologic treatment. Although a stone-free state is the desired outcome of surgical treatment of urolithiasis, the authors believe that the presence of noninfected, nonobstructive, asymptomatic residual fragments can be managed metabolically in order to prevent stone growth and recurrence. Further urologic intervention is warranted if clinical indications for stone removal are present.

Prospective comparison of outcomes of percutaneous nephrolithotomy in elderly patients versus younger patients

PURPOSE

The purpose of the study was to prospectively compare operative and postoperative characteristics and outcomes in elderly patients undergoing percutaneous nephrolithotomy (PCNL) compared with younger patients.

PATIENTS AND METHODS

Prospectively collected data from the Clinical Research Office of the Endourological Society (CROES) Global PCNL Study database were used. Elderly patients were defined as those aged 70 years and above, while younger patients were those between 18 and 70 years of age. Matched and unmatched group comparisons were performed based on imaging modality used for assessing stone-free status. Patient characteristics, operative data, and postoperative outcomes were compared.

RESULTS

The median age of the elderly group vs the young group was 74 years (range 70-93 years) vs 49 years. In the unmatched analysis, staghorn stones were seen at higher rates in the elderly group (27.8% vs 21.8%, P=0.014); however, the mean stone size was not significantly different (465.0 vs 422.8, P=0.063). The length of hospitalization was significantly longer in the elderly group compared with the young group in the unmatched analysis (5 days vs 4.1 days, P<0.001). The same difference was not apparent in the matched analysis (5.0 days vs 4.4 days, P=0.288). Overall complication rates were not significantly different in the unmatched analysis. In the matched analysis, however, a statistically significant higher rate of overall complications was seen. Stone-free rates were similar among all groups.

CONCLUSION

PCNL in elderly patients over the age of 70 years produces results comparable to those seen in younger patients. With only a slightly higher-be it statistically significant-complication rate, the stone-free rate in older patients was the same as in the younger group.

Percutaneous nephrolithotomy for treating staghorn stones: 10 years of experience of a tertiary-care centre

Objective

To present the results of percutaneous nephrolithotomy (PCNL) for treating staghorn stones.

Patients and methods

A database was compiled from the computerised files of patients who underwent PCNL for staghorn stones between 1999 and 2009. The study included 238 patients (128 males and 110 females) with a mean (SD) age of 48.9 (14) years, who underwent 242 PCNLs, and included staghorn stones that were present in the renal pelvis and branched into two or more major calyces. PCNL was performed or supervised by an experienced endourologist. All perioperative complications were recorded. The stone-free status was evaluated after PCNL and again after 3 months.

Results

Multiple tracts were needed in 35.5% of the procedures, and several sessions of PCNL were needed in 30% of patients. There were perioperative complications in 54 procedures (22%); blood transfusion was needed in 34 patients (14%). The stone-free rate for PCNL monotherapy was 56.6% (137 patients). Secondary procedures were required for 51 patients (21%), and included shock-wave lithotripsy for 49 and ureteroscopy for two. The 3-month stone-free rate was 72.7% (176 patients). Multiple tracts resulted in an insignificantly higher overall complication rate than with a single tract (P = 0.219), but the reduction in the haemoglobin level was statistically significant with multiple tracts (P = 0.001).

Conclusions

PCNL for staghorn stones must be done by an experienced endourologist in a specialised centre with all the facilities for stone management and treatment of possible complications. The patients must be informed about the range of stone-free and complication rates, and the possibility of multiple sessions or secondary procedures.

A 970 Hounsfield units (HU) threshold of kidney stone density on non-contrast computed tomography (NCCT) improves patients' selection for extracorporeal shockwave lithotripsy (ESWL): evidence from a prospective study

What's known on the subject? and What does the study add? Stone density on non-contrast computed tomography (NCCT) is reported to be a prognosis factor for extracorporeal shockwave lithotripsy (ESWL). In this prospective study, we determined that a 970 HU threshold of stone density is a very specific and sensitive threshold beyond which the likelihood to be rendered stone free is poor. Thus, NCCT evaluation of stone density before ESWL may useful to identify which patients should be offered alternative treatment to optimise their outcome.

OBJECTIVE

• To evaluate the usefulness of measuring urinary calculi attenuation values by non-contrast computed tomography (NCCT) for predicting the outcome of treatment by extracorporeal shockwave lithotripsy (ESWL).

PATIENTS AND METHODS

• We prospectively evaluated 50 patients with urinary calculi of 5-22 mm undergoing ESWL. • All patients had NCCT at 120 kV and 100 mA on a spiral CT scanner. Patient age, sex, body mass index, stone laterality, stone size, stone attenuation values (Hounsfield units [HU]), stone location, and presence of JJ stent were studied as potential predictors. • The outcome was evaluated 4 weeks after the ESWL session by NCCT. • ESWL success was defined as patients being stone-free (SF) or with remaining stone fragments of <4 mm, which were considered as clinically insignificant residual fragments (CIRF).

RESULTS

• Our survey concluded that 26 patients (52%) were SF, 12 (24%) had CIRF and 12 (24%) had residual fragment on NCCT after a one ESWL treatment. • Stones of patients who became SF or had CIRF had a lower density compared with stones in patients with residual fragments [mean (sd) 715 (260) vs 1196 (171) HU, P < 0.001]. • The Youden Index showed that a stone density of 970 HU represented the most sensitive (100%) and specific (81%) point on the receiver-operating characteristic curve. • The stone-free rate for stones of <970 HU was 96% vs 38% for stones of ≥ 970 HU (P < 0.001). A linear relationship between the calculus density and the success rate of ESWL was identified.

CONCLUSION

• The use of NCCT to determine the attenuation values of urinary calculi before ESWL helps to predict treatment outcome, and, consequently, could be helpful in planning alternative treatment for patients with a likelihood of a poor outcome from ESWL.

Computed tomography versus ureteroscopy in identification of renal tract stone with ureteral stent in situ

INTRODUCTION

The aim of this study was to validate the use of non-contrast computed tomography (CT) with a ureteral stent in situ instead of ureteroscopy for identification of renal tract stones.

METHODS

All patients who had stents inserted for renal tract stones and underwent non-contrast CT with the stent in situ followed by ureteroscopy between May 2008 and October 2009 at The Canberra hospital, Australia, were analysed retrospectively. Statistical analysis was performed to compare any differences between CT and ureteroscopy in the identification of stones.

RESULTS

Overall, 57 patients were included in the study. The difference between CT and ureteroscopy findings was statistically significant. CT identification of stones with a stent in situ had a sensitivity of 86%, a specificity of 46%, a positive predictive value of 63%, a negative predictive value of 76% and an accuracy of 67%.

CONCLUSIONS

Our study suggests that non-contrast CT is inferior to the 'gold standard' of ureteroscopy. It lacks sensitivity, specificity, positive predictive value, negative predictive value and accuracy. Therefore, we cannot recommend using non-contrast CT to replace ureteroscopy.

Impact of radiological technologists on the outcome of shock wave lithotripsy

OBJECTIVE

To evaluate the correlation of radiological technologists (RTs) and the outcome of shock wave lithotripsy (SWL) in terms of fluoroscopy time, fragmentation rate, and stone-free rate.

MATERIAL AND METHODS

A retrospective review of a prospectively collected database of 601 SWL treatments between June 2009 and March 2010 was performed. Patients with radiolucent stones were excluded. SWL was done by 6 RTs with different levels of experience. Follow up was available for 534 treatments. Multivariate analysis was performed.

RESULTS

RTs (A-F) performed 144, 109, 118, 58, 57, and 48 SWL sessions, respectively. There was no statistical difference among RTs in terms of mean stone size or stone location. Compared with other RTs, RT A had a significantly lower mean fluoroscopy time of 129 seconds (95% CI 120.8-137.3) (P <.001), higher stone-free rate (75.7%; P = .035), and stone fragmentation rate after a single SWL session (82.6%; P = .004). After correcting for stone size and location, fluoroscopy time (P <.001), fragmentation rate (P = .002), and stone-free rate (P = .04) maintained their significance. When comparing the top 3 RTs performing >100 SWL sessions, RTs B and C had significantly higher fluoroscopy time compared with RT A (OR [95% CI] 1.84 [1.38-2.45]; P <.001 and 2.67 [2.00-3.57]; P <.001), respectively. After correcting for stone size and location, RT B had significantly lower fragmentation rate when compared with RT A (OR [95% CI] 0.21 [0.05-0.86], P = .03]. However, there were no significant differences among the top 3 RTs in terms of stone-free rates.

CONCLUSION

RTs significantly differ in fluoroscopy usage in addition to stone fragmentation and stone-free rates.

Percutaneous nephrolithotomy for 1-2 cm lower-pole renal calculi

Objectives:

The most appropriate management of patients with lower-pole calyceal (LC) stones remains controversial. In this review we discuss the role of percutaneous nephrolithotomy (PCNL) in the management of LC stones 1–2 cm in maximum dimension.

Materials and Methods:

A detailed literature review was performed to summarize the recent technical developments and controversies in PCNL. The results of PCNL for 1-2 cm LC calculi were reviewed.

Results:

PCNL is increasingly employed as a primary modality in the treatment of LC calculi. It has a high success rate and acceptably low percentage of major complications in experienced hands. Supine position is found to be as safe and effective as prone position. Urologist-acquired access is associated with fewer access-related complications and better stone-free rates. Ultrasound is increasingly employed as an imaging modality for obtaining access. There have been increasing reports of tubeless PCNL in the literature. Most patients undergoing tubeless PCNL do not need hemostatic agents as an adjuvant for hemostasis. Non-contrast computed tomography does not yield statistically valuable increase in the diagnosis of significant residual stones compared with that of plain X-ray and linear tomography. Comprehensive metabolic evaluation and aggressive medical management can control new stone recurrences and growth of residual fragments following PCNL.

Conclusions:

PCNL is a highly effective procedure with consistently high stone-free rates when compared with extracorporeal shockwave lithotripsy or retrograde intrarenal surgery. The results also do not depend on anatomic factors and stone size. It is associated with low morbidity in experienced hands.

Factors determining stone-free rate in shock wave lithotripsy using standard focus of Storz Modulith SLX-F2 lithotripter

OBJECTIVES

To calculate the efficiency quotient (EQ) of the latest mobile Storz Modulith SLX-F2 lithotripter and to identify the factors determining the stone-free rate.

METHODS

A retrospective review of a prospectively collected database of the first consecutive 533 patients undergoing shock wave lithotripsy (SWL) from June 2009 to February 2010 was performed. A total of 16 patients with radiolucent stones and 43 patients with incomplete follow-up were excluded. The patients were followed up with plain radiography to assess the stone-free status. Univariate and multivariate analyses were performed to identify the factors determining the stone-free rates.

RESULTS

Follow-up was complete for 474 patients, with a mean age of 54.2 ± 14.5 years. The success rate after a single SWL session was 82.7% (renal 82.2% and ureteral 83.3%; P = .81). The retreatment rate was 14.7% (renal 15.2% and ureteral 14.2%; P = .79). The stone-free rate was 77% (renal 74.1% and ureteral 80.9%; P = .10). Of the 474 patients, 43 had pre-SWL ureteral stents, and 13 required post-SWL ureteral stenting; 35 patients required post-SWL curative procedures. The EQ was 0.66, and the modified EQ was 0.62. On multivariate analysis, the stone-free patients had a smaller stone size (9.5 vs 10.3 mm, P = .02), younger age (53.1 vs 58.0 years, P = .002), right-sided stones (83.6% vs 71.0% P = .001), and the absence of a ureteral stent (78.7% vs 64.3%; P = .001).

CONCLUSIONS

The mobile Storz Modulith SLX-F2 lithotripter has an acceptable EQ of 0.66. In the present study, smaller stones (<10 mm), younger age, right-sided stones, and the absence of ureteral stents were associated with significantly greater stone-free rates.

Multicenter analysis of postoperative CT findings after percutaneous nephrolithotomy: defining complication rates

OBJECTIVES

To perform a multi-institutional study to characterize CT-detected complications after PNL. Computed tomography (CT) is commonly performed after percutaneous nephrolithotomy (PNL). One benefit of this imaging modality is the detection of procedure-related complications. Presently, the incidence of such complications is not well-defined.

PATIENTS AND METHODS

PNL procedures performed at 5 stone referral centers between July 2007 and June 2008 were reviewed. All patients undergoing CT within 24 hours after surgery were selected for further analysis. All CT studies were reviewed by a staff radiologist.

RESULTS

One-hundred ninety-seven patients satisfied the study inclusion criteria. A body mass index >30 was present in 27.5% of patients. Treated stone burden was staghorn in 70 (35.5%), >2 cm in 72 (36.5%), and <2 cm in 55 (28%). Six treated renal units (3%) were ectopic; 45.4% of calculi were predominantly lower pole. Thoracic complications encountered were atelectasis in 88 (44.7%), pleural effusion in 17 (8.6%), pneumothorax in 3 (1.5%), hemothorax in 2 (1%), and hydrothorax in 1 (0.5%). Renal complications were perinephric hematoma in 15 (7.6%), collecting system perforation in 4 (2%), subcapsular hematoma in 3 (1.5%), urinoma in 2 (1%), and pseudoaneurysm in 1 (0.5%). There was 1 trans-splenic nephrostomy without splenic hematoma. No injuries to hollow viscera were detected. Two patients (1%) were found to have ascites.

CONCLUSIONS

Major post-PNL complications detected by CT are uncommon, and when encountered, they are generally amenable to conservative management.

Diagnostic utility and clinical value of postpercutaneous nephrolithotomy nephrostogram

BACKGROUND AND PURPOSE

After percutaneous nephrolithotomy (PCNL), the current standard of care is to obtain a nephrostogram before removal of the nephrostomy tube to rule out distal ureteral obstruction. The aim of this study was to determine whether nephrostogram findings predict prolonged urinary drainage and postoperative ureteral stent insertion.

PATIENTS AND METHODS

Data for all patients who had nephrostomy tubes inserted post-PCNL between January and December 2006 were retrospectively reviewed. Patients with radiolucent stones, concomitant procedures, or caliceal diverticula were excluded. All nephrostograms were reviewed to identify distal ureteral obstruction without evidence of residual fragments. The Fisher's exact test was used.

RESULTS

Fifty patients who underwent 51 PCNLs were included in the study (one patient had bilateral PCNLs). Nephrostograms were performed on median postoperative day (POD) 2 (range POD 2-8), and tubes were removed on median POD 2 (range POD 2-10). In 14 (27%) patients who had distal ureteral obstruction without ureteral stones, the nephrostomy tube was removed on the same day of nephrostography. Eight (16%) patients experienced a prolonged urinary leak (>24 hours). While obstruction on the nephrostogram predicted prolonged urinary leak (36% vs 8%; P = 0.02), none of these obstructed patients needed postoperative ureteral stent placement. A patient with a horseshoe kidney without distal ureteral obstruction had his nephrostomy removed on POD 2. He presented on POD 7 with prolonged urinary leakage and needed readmission with ureteral stent placement and Foley catheterization.

CONCLUSION

While distal obstruction seems to predict prolonged urinary leakage (more than 24 hours), it may not necessitate ureteral stent placement or prolonged nephrostomy drainage because blood clot or ureterovesical junction edema resolve spontaneously with expectant management.

Ultrasound-guided X-ray free percutaneous nephrolithotomy for treatment of simple stones in the flank position

The purpose of this study was to examine the effectiveness and safety of percutaneous nephrolithotomy with ultrasonography-guided renal access in the flank position without the use of fluoroscopy in any stage of the procedure. Percutaneous nephrolithotomy was performed in flank position under the guidance of ultrasound (USG) without the use of fluoroscopy between December 2008 and January 2010 on 43 patients who had kidney stones bigger than 20 mm. Access to the kidney's proper calyx was achieved by dilatation through the guide wire placed after insertion of the needle through the needle director under the guidance of transrectal ultrasound probe placed on the patient's flank area. A convex USG probe was used for imaging during dilatation and lithotripsy instead of fluoroscopy. Access to the targeted calyx was achieved successfully in all patients (100%). The percentage stone free rate was 86.1% (37 patients). Residual stones were detected in six patients. Their dimensions ranged from 5 to 12 mm. The mean stone diameter was 29 (20-41) mm, duration of surgery was 87.1 ± 43.2 (55-210) min and duration of hospital stay was 3.1 (2-8) days. Blood transfusions were given to two patients; none of the patients had major intraoperative or postoperative complications. In comparison with standard percutaneous nephrolithotomy, percutaneous nephrolithotomy in flank position under ultrasonographic imaging instead of using fluoroscopy seems to be safe and effective. This procedure has to be limited to selected cases with one or maximum two big stones in the pelvis or in a single calyx in absence of complex intrarenal anatomy. Both surgical team and the patients were protected from the harmful effects of radiation. Regarding anesthesia, flank position is more comfortable for the patient than prone position.

Diagnosis and management of postpercutaneous nephrolithotomy residual stone fragments

Residual stone fragments can occur in up to 8% of patients who are treated with percutaneous nephrolithotomy (PCNL). When left untreated, approximately half of these patients will experience a stone-related event, for which more than half will need a secondary surgical intervention. Predictors of adverse events are a residual fragment larger than 2 mm that is located in the pelvis or ureter. Preventive measures for the creation of residual fragments include a carefully selected access giving exposure to the bulk of the stone, the creation of multiple tracts, the use of single pulse pneumatic lithotripsy, the prevention of stone migration with ureteral balloons or stone cones, and careful flushing of the stones from the collecting system. Plain radiography of the kidneys, ureters, and bladder, linear tomography, and ultrasonography have all been used to judge the result of PCNL and to detect the presence of residual fragments. Thin-slice, unenhanced helical CT, however, is more sensitive and should be performed at 1 month after surgery. While medical therapy and shockwave lithotripsy possess a minor role, second-look flexible nephroscopy and/or flexible ureterorenoscopy seem to be the treatments of choice for residual stone fragments after PCNL.

Computed tomography for percutaneous renal access

Abstract Successful percutaneous nephrolithotomy (PCNL) relies on appropriate preoperative planning and optimal percutaneous access. CT has now become the standard imaging tool for PCNL. For percutaneous renal access, CT may be used for planning access, guiding access, and in the follow-up after access. In this review, we discuss the role of each aspect for percutaneous access in PCNL. In particular, we describe the technique for gaining access using CT, a valuable method in the difficult collecting system.