Logistic regression model for predicting stone-free rate after minimally invasive percutaneous nephrolithotomy

Effects of hydronephrosis on the surgical outcomes of fluoroscopically guided supine percutaneous nephrolithotomy

PURPOSE

To evaluate the effect of hydronephrosis on operation success and the development of complications in supine percutaneous nephrolithotomy (PCNL).

METHODS

A total 259 patients were included in the study who underwent supine PCNL in our clinic between September 2019 and November 2023. The patients were divided into four groups: normal, mild, moderate and severe, according to their preoperative hydronephrosis degrees. Demographic data, kidney stone characteristics, clinical aspects, surgical findings, and postoperative complications were compared across groups.

RESULTS

In terms of American Society of Anesthesiologists score, stone-free rate, operation time, fluoroscopy time, and Clavien-Dindo classification grades, a statistically significant difference was found between the hydronephrosis groups. The stone-free rate in the normal, mild, moderate, and severe groups was 86.6, 82.5, 76.0, and 61.5, respectively. The severe hydronephrosis group varied statistically substantially from the other hydronephrosis groups in terms of stone-free rate, according to the post-hoc analysis. In terms of Clavien-Dindo classification grades, the severe hydronephrosis group varied statistically significantly from the normal and mild hydronephrosis groups (p values 0.04, 0.02, respectively). In terms of Clavien-Dindo classification grades, no statistically significant difference was seen between the severe and moderate hydronephrosis groups (p = 0.085).

CONCLUSION

The findings of this study demonstrated that the existence of hydronephrosis was a predictive factor for the occurrence of complications and decreased the success rate of supine PCNL. Furthermore, univariate and multivariate analyses showed that the presence of hydronephrosis was a predictive factor for PCNL success and the development of complications.

Risk factors of stone residual after retrograde intrarenal surgery: A prospective cohort study

BACKGROUND

Complete removal of renal stones is crucial for optimal patient outcomes, but recent studies have reported residual stones after retrograde intrarenal surgery (RIRS). This study aimed to identify the associated risk factors to improve patient management and treatment selection.

METHODS

This cohort study was conducted over 18 months at two hospitals and recruited adult patients with renal stones less than 3 cm. Preoperative assessment included medical history, physical examination, laboratory tests, and radiological imaging. Intraoperative and postoperative data collection and follow-up were conducted to evaluate surgical success and potential complications.

RESULTS

A total of 100 patients were included, with a mean age of 45.3 ± 10.7 years and a mean BMI of 26.2 ± 1.4 kg/m2. Approximately 19% of the patients had residual stones after the RIRS procedure. The RUSS score showed good diagnostic performance with an AUC of 0.843, and the optimal cut point was ⩾2.0 with a sensitivity of 52.6% and specificity of 95.1%. Independent predictors of residual stones were multiple sites (OR = 24.98; p = 0.002), multiple stones (OR = 13.62, p = 0.002), stone size of 21-30 mm (OR = 4.91, p = 0.038), lower calyx site (OR = 4.85, p = 0.033), and surgeon experience of fewer than 50 cases (OR = 6.82, p = 0.020).

CONCLUSIONS

This study identifies several factors associated with residual stones after RIRS for renal stones, including stone size, location, number, and surgeon experience. The study suggests that the RUSS score can be used as a reliable tool for predicting the likelihood of residual stones, which can help clinicians in patient selection and treatment planning.

In Vivo Prediction of Kidney Stone Fragility Using Radiomics-Based Regression Models

Introduction: The surgical technique for urinary stone removal is partly influenced by its fragility, as prognosticated by the clinician. This feasibility study aims to develop a linear regression model from CT-based radiomic markers to predict kidney stone comminution time in vivo with two ultrasonic lithotrites. Materials and Methods: Patients identified by urologists at our institution as eligible candidates for percutaneous nephrolithotomy were prospectively enrolled. The active engagement time of the lithotrite in breaking the stone during surgery denoted the comminution time of each stone. The comminution rate was computed as the stone volume disintegrated per minute. Stones were grouped into three fragility classes (fragile, moderate, hard), based on inverse of the comminution rates with respect to the mean. Multivariable linear regression models were trained with radiomic features extracted from clinical CT images to predict comminution times in vivo. The model with the least root mean squared error (RMSE) on comminution times and the fewest misclassification of fragility was finally selected. Results: Twenty-eight patients with 31 stones in total were included in this study. Stones in the cohort averaged 1557 (±2472) mm3 in volume and 5.3 (±7.4) minutes in comminution time. Ten stones had nonmoderate fragility. Linear regression of stone volume alone predicted comminution time with an RMSE of 6.8 minutes and missed all 10 stones with nonmoderate fragility. A fragility model that included stone volume, internal morphology, shape-based radiomics, and device type improved RMSE to below 3.3 minutes and correctly classified 20/21 moderate and 6/10 nonmoderate stones. Conclusions: CT metrics-based fragility models may provide information to surgeons regarding kidney stone fragility and facilitate the selection of stone removal procedures.

Predicting the outcome of mini percutaneous nephrolithotomy using STONE nephrolithometry score-a single-center experience

To predict stone-free and complication rates following mini-percutaneous nephrolithotomy (m-PCNL) using STONE nephrolithometry score, this prospective observational study was conducted in the Department of Surgery, Urology Unit, Patan Hospital. All the patients undergoing m-PCNL were included. The cases were performed in the prone position, a single tract less than 18 French was made, and pneumatic lithotripsy was done. Stone-free rates were assessed with plain X-ray kidney, ureter, and bladder (X-ray KUB) on the first post-operative day or at 15 days follow-up. Complications within 30 days were graded using modified Clavien grading. A total of 106 patients were included in the final analysis. The overall stone-free rate was 83%. Among the individual variables, only staghorn calculus was associated with residual stone (p = 0.007). Patients who were rendered stone-free had statistically significantly lower STONE scores than those with residual stone (p < 0.001). The complication rate was 23%, and the majority were Clavien grade I complications. A higher STONE score had a greater risk of having complications but was not statistically significant (p = 0.11). STONE nephrolithometry score can predict stone complexity pre-operatively and subsequent stone-free status and thus, helps in pre-operative surgical planning and counseling for possible outcomes following m-PCNL.

Factors Affecting Residual Stone Rate, Operative Duration, and Complications in Patients Undergoing Minimally Invasive Percutaneous Nephrolithotomy

Background and objectives: Although minimally invasive percutaneous nephrolithotomy (MPCNL) has demonstrated its efficacy, complete stone clearance was not always achieved, necessitating a second procedure. The purpose of this study was to evaluate factors associated with residual stone rate, operative duration, complications, and hospital stay, in order to develop algorithms for pre-operative prognosis and planning. Materials and Methods: This retrospective study involved 163 Bulgarian patients who underwent MPCNL with Holmium: YAG lithotripsy for the treatment of kidney stones. Patients were considered stone-free if no visible fragments (<3 mm) were found on nephroscopy at the end of the procedure, as well as on postoperative X-ray and abdominal ultrasound on the first postoperative day. Results: Immediate postoperative stone-free outcome was attained for 83.43% of the patients (136/163). Residuals were associated with staghorn stones (OR = 72.48, 95% CI: 5.76 to 91.81); stones in two locations (OR = 21.91, 95% CI: 4.15 to 137.56); larger stone size (OR = 1.12, 95% CI: 1.006 to 1.25); and higher density (OR = 1.03, 95% CI:1.005 to 1.06). The overall categorization accuracy for these factors was 93.80%, AUC = 0.971 (95% CI: 0.932 to 0.991), 89.71% sensitivity, and 96.30% specificity. Predictors of prolonged operative duration were staghorn stones and volume, R-square (adj.) = 39.00%, p < 0.001. Longer hospitalization was predicted for patients with hydronephrosis and staghorn stones, R-square (adj.) = 6.82%, p = 0.003. Post-operative complications were rare, predominantly of Clavien-Dindo Grade 1, and were more frequent in patients with hydronephrosis. We did not find a link between their occurrence and the outcome of MPCNL. Conclusions: Staghorn stones and stones in more than one location showed the strongest association with residual stone rate. Staghorn stones and larger volume were linked with a longer operative duration. Hydronephrosis increased the risk of complications and longer hospitalization.

Application of S.T.O.N.E. Nephrolithometry Score for Prediction of Stone-Free Status and Complication Rates in Patients Who Underwent Percutaneous Nephrolitotomy for Renal Stone

Background: Renal stone disease is a common disorder in urology practice. Kidney stone has various treatment methods such as extracorporeal shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy (PCNL). In this study, we aimed to determine the value of S.T.O.N.E. nephrolithometry score, which is considered as a new scoring system for predicting residual stone rate and complications in patients undergoing PCNL due to renal calculi. Materials and Methods: A total of 120 patients >18 years old who underwent PCNL were evaluated prospectively. Five parameters available from preoperative noncontrast-enhanced computed tomography were measured: stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence or stone density (E) and then S.T.O.N.E. nephrolithometry score was calculated. The prediction of the stone-free rates and complication rates of this scoring was evaluated statistically. Results: When the age, gender, body mass index, comorbidities, and American Society of Anesthesiologists scores of the patients were evaluated according to the patients' postoperative stone-free status, no statistical difference was found between the groups. Patients had a stone-free rate of 78%. Patients' mean neuropilitometry score was calculated to be 7.75 S.T.O.N.E. nephrolithometry score statistically significant (P = .001) for prediction of stone-free status. S.T.O.N.E. nephrolithometry score was significantly correlated with operation time, estimated blood loss, duration of fluoroscopy, duration of hospital stay, and number of punctures. Complications were seen in 13 patients. Conclusions: S.T.O.N.E. nephrolithometry score can be used as an objective criterion for predicting the complexity of the PCNL process. In addition, this scoring system is expected to provide more objective preoperative counseling and can provide standardization in academic studies.

Reliability and validity of "S.T.O.N.E" nephrolithometry scoring system to predict the stone-free rate after percutaneous nephrolithotomy

Objective:

The objective was to assess the reliability and validity of “S.T.O.N.E” nephrolithometry scoring system to predict the stone-free rate (SFR) after percutaneous nephrolithotomy (PNL).

Methods:

A total of 123 patients with unilateral radiopaque stones ≥2 cm were included in the study. According to S.T.O.N.E score, five parameters available from preoperative computed tomography (CT) without contrast were measured: stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence of stone (E). The Stone free rates evaluated within one month postoperatively by plain X-ray and/or CT scan without contrast.

Results:

The mean S.T.O.N.E. score in this study was 7.4 in stone-free (SF) group and 9.3 in residual stone group (P = 0.0001). Patients with SF comprised 82.1% after the first PNL, whereas 17.9% had significant residual stones >4 mm. Postoperative complications were 8%. The most common complications were bleeding requiring transfusion. The size of stone (P = 0.002) and number of calices involved (P = 0.001) had a statistically significant difference between patients with residual stones, other components were not. There was a statistically significant difference between non-SF and SF according to the hospital stay (P = 0.002).

Conclusion:

This score predicted the clearance after PNL. The size of calculi and number of calices involved statistically affected the stone clearance, whereas other S.T.O.N.E scoring parameters were not. There was a statistically significant difference between SF and residual stones groups according to the hospital stay (P = 0.0001).

Effects of severe hydronephrosis on the outcomes of percutaneous nephrolithotomy with one-shot dilation method

OBJECTIVE

To investigate the effect of the presence of severe hydronephrosis on percutaneous nephrolithotomy (PNL) outcome in patients who underwent PNL operation with one-shot dilatation technique.

MATERIALS AND METHODS

Medical data of 989 patients underwent PNL operation in our clinic between 2012 and 2018 were retrospectively reviewed. We included 373 of the patients underwent PNL operation due to renal pelvic stone, who were older than 18 years of age, who did not have any urinary tract abnormality, and had no previous history of open renal stone operation. Patients were divided into two groups according to the presence of severe hydronephrosis and absence of hydronephrosis. These two groups were compared in terms of age, gender, body mass index (BMI), number of stones, stone burden, operation duration, fluoroscopy time, hospitalization time, hemoglobin and creatinine change, complications, and stone free rate.

RESULTS

There was no statistically significant difference between the groups in terms of age, gender, BMI, stone number, stone size, stone density, operation duration, fluoroscopy time, and hospitalization duration. The mean change in hemoglobin was 1.5 g/dL in group 1 and 1.1 g/dL in group 2. This difference was statistically significant (p = 0.006). Postoperative blood transfusion was required for 3 patients (2.1%) in group 1 and 12 patients (5.1%) in group 2. This difference was statistically significant (p < 0.001).

CONCLUSION

Only the presence of severe hydronephrosis was found to be associated with the change in hemoglobin and postoperative blood transfusion.

Critical Application of Adult Nephrolithometric Scoring Systems to Children Undergoing Mini-Percutaneous Nephrolithotomy

Objective: To evaluate and compare the ability of the Guy's stone score (GSS), the S.T.O.N.E. nephrolithometry, and the Clinical Research Office of the Endourology Society (CROES) nomogram to predict the outcome of mini-percutaneous nephrolithotomy (MPNL) in children, and to identify which of the predictors involved in these scoring systems can separately affect this outcome. Patients and Methods: All children younger than 14 years who had MPNL in our center over a period of 3 years were included prospectively. Bivariate analyses were done to evaluate the associations of the three scoring systems and the predictors composing them with single-session stone clearance and complications. Receiver operating characteristic (ROC) curve analyses of the three scoring systems were conducted to evaluate and compare their abilities to predict the outcomes. Decision curve analyses for the three scoring systems were conducted to evaluate the clinical benefit of using each of them to predict stone clearance. Results: We consecutively enrolled 92 renal units in 89 children with a median age of 9.5 years. Single-session stone clearance was achieved in 76 (82.6%) renal units. Complications occurred with 19 (20.7%) procedures. Stone multiplicity (p = 0.043), staghorn stone (p = 0.007), prior stone treatment (p < 0.001), number of calices involved (p = 0.006), stone burden (p = 0.003), GSS (p < 0.001), S.T.O.N.E. nephrolithometry (p = 0.012), and CROES nomogram (p < 0.001) had significant associations with stone clearance. Only stone attenuation was significantly associated with complications (p = 0.031). For prediction of stone clearance, CROES nomogram demonstrated the greatest area under the ROC curve and the greatest net benefit on decision curve analyses. Conclusions: For children undergoing MPNL, CROES nomogram is the best to predict stone clearance. However, none of the studied scoring systems predicted complications efficiently.

Predictability and Practicality of Image-Based Scoring Systems for Patient Assessment and Outcome Stratification During Percutaneous Nephrolithotomy: a Contemporary Update

Preoperative nomograms offer systematic and quantitative methods to assess patient- and stone-related characteristics and their impact on successful treatment and potential risk of complication. Discrepancies in the correlation of perioperative variables to patient outcomes have led to the individual development, validation, and application of four independent scoring systems for the percutaneous nephrolithotomy: Guy's stone score, S.T.O.N.E. nephrolithometry, Clinical Research Office of the Endourology Society nomogram, and Seoul National University Renal Stone Complexity. The optimal nomogram should have high predictive ability, be practically integrated into clinical use, and be widely applicable to urinary stone disease. Herein, we seek to provide a contemporary evaluation of the advantages, disadvantages, and commonalities of each scoring system. While the current data is insufficient to conclude which scoring system is destined to become the gold standard, it is crucial that a nephrolithometric scoring system be incorporated into common practice to improve surgical planning, patient counseling, and outcome assessment.

External validation and comparison of the scoring systems (S.T.O.N.E, GUY, CROES, S-ReSC) for predicting percutaneous nephrolithotomy outcomes for staghorn stones: A single center experience with 160 cases

The aim of this study was validation and comparison of stone scoring systems (S.T.O.N.E, GUY, CROES, S-ReSC) used to predict postoperative stone-free status and complications after percutaneous nephrolithotomy (PCNL) for staghorn stones. A total of 160 patients who had staghorn renal stones and underwent PCNL between January 2012 and August 2015 were included in the current retrospective study. Guy, S.T.O.N.E., S-ReSC (Seoul National University Renal Stone Complexity) and CROES (Clinical Research Office of the Endourological Society) nephrolithometry scores were calculated for each patient, and their potential association with stone-free status, operative and fluoroscopy time, and length of hospital stay (LOS) were evaluated. Postoperative complications were graded according to the modified Clavien classification, and the correlation of scoring systems with postoperative complications was also investigated. The mean CROES, S.T.O.N.E, Guy and S-ReSC scores were 143.5 ± 33.6, 9.7 ± 1.6, 3.5 ± 0.5 and 6.2 ± 2.0 respectively. The overall stone-free rate was 59%. All scoring systems were significantly correlated with stone-free status in univariate analysis. However, Guy and S-ReSC scores were the only significant independent predictor in multivariate analysis. And all four nomograms failed to predict complication rates. Current study demonstrated that Guy and S-ReSC scoring systems could effectively predict postoperative stone-free status for staghorn stones. However all four scoring systems failed to predict complication rates.

External Validation and Comparisons of the Scoring Systems for Predicting Percutaneous Nephrolithotomy Outcomes: A Single Center Experience with 506 Cases

BACKGROUND

To validate and compare the stone scoring systems (stone size [S], tract length [T], obstruction [O], number of involved calices [N], and essence or stone density [E] [S.T.O.N.E.], Guy's Stone Score [GSS], Clinical Research Office of the Endourological Society [CROES], and Seoul National University Renal Stone Complexity [S-ReSC]) used to predict postoperative stone-free status and complications after percutaneous nephrolithotomy (PCNL).

METHODS

A total of 567 patients who underwent PCNL for renal stones between January 2012 and August 2015 were included in the recent retrospective study. Sixty-one patients who had not done preoperative CT were excluded from the study. GSS, S.T.O.N.E., S-ReSC, and CROES nephrolithometry scores were calculated for each patient, and their potential association with stone-free status, operative and fluoroscopy time, and length of stay (LOS) was evaluated. Postoperative complications were graded according to the modified Clavien classification, and the correlation of scoring systems with postoperative complications was also investigated.

RESULTS

The mean CROES, S.T.O.N.E., GSS, and S-ReSC scores were 203.7 ± 59.8, 7.52 ± 1.8, 2.08 ± 0.9, and 3.35 ± 2.2, respectively. The overall stone-free rate was 77.9%. All scoring systems were significantly correlated with stone-free status and operation time. While GSS, S.T.O.N.E., and CROES systems were significantly correlated with complication rates (CR), S-ReSC score failed to predict CR. All scoring systems except S.T.O.N.E. were significantly correlated with LOS. CROES and S-ReSC scores were predictive of estimated blood loss (EBL), while GSS and S.T.O.N.E. failed to predict EBL.

CONCLUSIONS

Recent study demonstrated that S.T.O.N.E., GSS, CROES, and S-ReSC scoring systems could effectively predict postoperative stone-free status. Although S-ReSC scoring system failed to predict CR, the rest three scoring systems were significantly correlated with postoperative CR.

Evaluation of stone volume distribution in renal collecting system as a predictor of stone-free rate after percutaneous nephrolithotomy: a retrospective single-center study

We analyzed our stone-free rates of PNL with regard to stone burden and its ratio to the renal collecting system volume. Data of 164 patients who underwent PNL were analyzed retrospectively. Volume segmentation of renal collecting system and stones were done using 3D segmentation software with the images obtained from CT data. Analyzed stone volume (ASV) and renal collecting system volume (RCSV) were measured and the ASV-to-RCSV ratio was calculated after the creation of a 3D surface volume rendering of renal stones and the collecting system. Univariate and multivariate statistical analyses were performed to determine factors affecting stone-free rates; also we assessed the predictive accuracy of the ASV-to-RCSV ratio using the receiving operating curve (ROC) and AUC. The stone-free rate of PNL monotherapy was 53% (164 procedures).The ASV-to-RCSV ratio and calyx number with stones were the most influential predictors of stone-free status (OR 4.15, 95% CI 2.24-7.24, <0.001, OR 2.62, 95% CI 1.38-4.97, p < 0.001, respectively). Other factors associated with the stone-free rate were maximum stone size (p < 0.029), stone surface area (p < 0.010), and stone burden volume (p < 0.001). Predictive accuracy of the ASV-to-RCSV ratio was AUC 0.76. Stone burden volume distribution in the renal collecting system, which is calculated using the 3D volume segmentation method, is a significant determinant of the stone-free rate before PCNL surgery. It could be used as a single guide variable by the clinician before renal stone surgery to predict extra requirements for stone clearance.

Mini PCNL for renal calculi: does size matter?

OBJECTIVE

To evaluate the minimally invasive percutaneous nephrolithotomy (MIP) system for renal calculi.

PATIENTS AND METHODS

Consecutive patients undergoing mini-percutaneous nephrolithotomy (mPCNL) procedures with the MIP system were enrolled. Patient position, American Society of Anesthesiologists classification, puncture location, stone clearance, postoperative drainage and complications were recorded, and features unique to MIP were noted.

RESULTS

In all, 30 patients underwent 32 mPCNL procedures. The mean stone size was 17 (10.75-21.25) mm and the mean number of stones was 1 (1-2). The median stone clearance rate was 96.5 (95-100)%. The complication rate was 9.3%. No patient required a transfusion. In addition to these outcomes, we noted that the MIP system has many advantages over conventional PCNL (cPCNL). It is easy to learn and can be performed in both supine and prone positions. It is safe for supracostal puncture, provides excellent access to nearly all calyces and upper ureter, has multiple stone treatment options, can be used as an adjunct to cPCNL, and can be performed as a tubeless procedure.

CONCLUSION

Our experience with the MIP system has shown several advantages over cPCNL. mPCNL with the MIP system has several features that suggest it should be considered as an alternative or adjunct to cPCNL, ureteroscopy and extracorporeal shockwave lithotripsy.

How practical is the application of percutaneous nephrolithotomy scoring systems? Prospective study comparing Guy's Stone Score, S.T.O.N.E. score and the Clinical Research Office of the Endourological Society (CROES) nomogram

Objective

To prospectively compare the Guy’s Stone Score (GSS), S.T.O.N.E. [stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence or stone density (E)] score and the Clinical Research Office of the Endourological Society (CROES) nephrolithometric nomogram to predict percutaneous nephrolithotomy (PCNL) success rate and assess the correlation with perioperative complications.

Patients and methods

We prospectively evaluated all consecutive PCNL patients at our institute between 1 November 2013 and 31 May 2015. The above scoring systems were applied to preoperative non-contrast computed tomography and the practical difficulties in such applications were noted. Perioperative complications and the stone-free rate (SFR) were also recorded. Receiver operating characteristic curves were drawn and the areas under curves were compared and appropriate statistical analysis done.

Results

In all, 48 renal units were included in the study. The overall SFR was 62.2%. The presence of staghorn stones (β = 27.285, 95% confidence interval 1.19–625.35; P = 0.039) was the only significant variable associated with the residual stones on multivariate analysis. Stone-free patients had significantly lower median GSS (2 vs 4) and S.T.O.N.E. scores (6 vs 10) and higher median CROES scores (83% vs 63%) (all P < 0.001) compared to residual-stone patients. All scoring systems were significantly associated with SFR (all P < 0.001). There was no significant difference in the areas under curves of the scoring systems (0.858, 0.923, and 0.931, respectively). Furthermore, all scoring systems had weak correlations with Clavien–Dindo classified complications (r = 0.29, P = 0.045; r = 0.40, P = 0.005 and r = −0.295, P = 0.04, respectively). We found no standardisation for the measurement of stone dimensions, tract length, Hounsfield units, and staghorn definition.

Conclusions

All scoring systems equally predicted SFR and had a weak correlation with Clavien–Dindo complications. Standardisation is needed for the variables in which they have been found deficient.

Comparison of S.T.O.N.E and CROES nephrolithometry scoring systems for predicting stone-free status and complication rates after percutaneous nephrolithotomy: a single center study with 262 cases

The aim of this study was to compare the accuracy of the CROES nephrolithometric nomogram and S.T.O.N.E. scoring system in predicting PCNL outcomes in terms of stone-free rate, estimated blood loss (EBL), operative time (OR), length of hospital stay (LOS), and complications. Patients who underwent PCNL for renal stones between May 2012 and January 2015 were analyzed retrospectively. The patients' demographic characteristics and operational features were recorded prospectively in all patients postoperatively. S.T.O.N.E. and CROES nephrolithometry scores' correlation with stone-free status, operation and fluoroscopy time, length of hospital stay (LOS) and blood loss (BL) was evaluated. Patients were categorized according to S.T.O.N.E. nephrolithometry and CROES nephrolithometry scores. Postoperative complications were graded according to modified Clavien classification (Dindo et al. in Ann Surg 240:205-213, 2004) and the correlation of both scoring systems with postoperative complications was also evaluated. We identified 437 patients who underwent PCNL between May 2012 and January 2015. A total of 262 patients who are available data for the CROES and S.T.O.N.E. scoring systems were included in the recent study. The mean S.T.O.N.E score was 7.65 ± 1.56 and the mean CROES score was 191.13 ± 64.39. The overall stone-free rate was 71.4%. Of the 262 patients, 89 experienced postoperative complications. Stone-free patients had significantly lower BMI (<0.001) and stone burden (p < 0.001). Regression analysis showed that both scoring systems were significantly associated with stone-free rates and operation time. We demonstrated that S.T.O.N.E. and CROES scoring systems were useful for predicting post-PCNL stone-free status. But both scoring systems were not useful for predicting post-PCNL complications.

Effects of Parenchymal Thickness and Stone Density Values on Percutaneous Nephrolithotomy Outcomes

BACKGROUND It is unclear whether parenchymal thickness (PT), in combination with stone density measured by Hounsfield Units (HU), affects stone-free rates after PCNL. The aim of the present study was to investigate the relationship between PT in combination with stone density values and the outcomes of PCNL. MATERIAL AND METHODS From 2009 to 2014, data from 216 PCNL patients were prospectively analyzed. In total, 120 patients were included in the study. Using NCCT images, stone burden, stone localization, stone density as HU values, PT, and operative-postoperative parameters were recorded. RESULTS Stone localization, stone type, stone burden, and presence of hydronephrosis were statistically significant factors affecting stone-free status (p<0.001, p<0.001, p<0.01, and p<0.01, respectively). The stone-free rate in patients with thicker renal parenchyma was higher than in patients with lower parenchymal thickness (p<0.01). No correlation was detected between stone density and success rate (p>0.05). Drop in Hb (%) was only correlated with parenchymal thickness (p<0.01). In univariate analyses, factors that affected blood transfusion requirement were PT, BMI, and operative times (p<0.01, p<0.05, and p<0.05, respectively). CONCLUSIONS Stone location, stone burden, and presence of hydronephrosis detected with NCCT were factors affecting PCNL outcome. Stone density values did not correlate with the rate of bleeding or success of PCNL. PT measured by NCCT may predict bleeding and may guide surgeons in determining preoperative blood requirements. The outcome of PCNL appeared to be better in patients with thicker renal parenchyma and should be taken into consideration in the clinical evaluation of patients undergoing PCNL.

Supracostal Punctures for PCNL: Factors that Predict Safety, Success and Stone Free Rate in Stag Horn and Non-Stag Horn Stones: A Single Centre Experience and Review of Literature

INTRODUCTION

Supra-costal Percutaneous Nephrolithotomy (PCNL) procedure has now become an established standard of care in patients with renal stone disease, in terms of morbidity, stone clearance, duration of stay and shorter convalescence period. Gone are the days when supracostal punctures were considered to be associated with a high morbidity. With increased expertise gained in performing multiple punctures and further refinements in focusing techniques, more and more of these procedures are being performed with an intention to achieve a maximum stone clearance with least morbidity.

AIM

To prospectively analyze the various factors that predict the safety, efficacy and stone clearance rate in patients who have undergo supracostal punctures for PCNL procedures.

MATERIALS AND METHODS

Three hundred seventy six patients underwent PCNL for renal stones. Ninety two (n=92) of them needed supra-costal puncture. All patients were subdivided into groups 1 and 2 based on the size, location of the stone and the stone burden. In all, 132 tracts were established.

RESULTS

About 83% of patients achieved a complete stone free rate after initial PCNL. Stones more than 3 centimeters were found to be associated with significant residual stones. Radio opacity under image intensifier also had a significant impact on the ultimate stone free status. About 23% of those (n=5/22) who needed longer duration of surgery had a clinically significant residual stones, needing ancillary procedures. Fifteen patients (16%) had complications related to the procedure, of which 13 were in group 1 (87%). High percentage of complications in patients with larger stone burden was found to be statistically significant. In about 76% (n=70), the procedure required only less than 90 minutes. Also, in those 22 patients in whom the duration of procedure exceeded 90 minutes, 12 of them had complications, with a p-value of <0.0001.

CONCLUSION

Supra-costal punctures are safe and effective options in a selected group of patients. The overall results are almost on par with that of the infra costal punctures, with an acceptable morbidity.

Comparison of minimally invasive percutaneous nephrolithotomy and flexible ureteroscopy for the treatment of intermediate proximal ureteral and renal stones in the elderly

The aim of this study is to compare the outcomes of flexible ureteroscopy (fURS) and minimally invasive percutaneous nephrolithotomy (mPNL) for the treatment of renal and/or proximal ureteral stones sized 1-2 cm in the elderly (≥60 years). Between January 2010 and March 2015, 184 consecutive mPNL and fURS were performed to treat intermediate renal and/or proximal ureteral stones in geriatric patients. The records were retrospectively reviewed and outcomes were compared. Although no significant difference was found in the complication rate between two groups, a statistical trend (p = 0.059) in favor of fURS was observed. In addition, multivariate analysis demonstrated that mPNL, preoperative positive urine culture and lower hemoglobin were independent risk factors for postoperative complication (p = 0.016, p = 0.021, p = 0.001, respectively). And fURS was significantly associated with less hemoglobin drop, red blood cell transfusion, analgesics requirement, postoperative hospital duration, and charges of laboratory tests, medical examinations and medications (p = 0.019, p = 0.037, p = 0.006, p = 0.000 and p = 0.007, p = 0.000, p = 0.000, p = 0.001, respectively), while higher costs of operations (p = 0.008). Receiver operating characteristic curve suggested a preoperative hemoglobin of 106.5 g/L as the threshold for predicting red blood cell transfusion after mPNL. The overall one-session stone-free rate of fURS at 1 month was lower (p = 0.006), while it was similar for solitary stone between two groups. Comorbidity and previous stone surgery did not affect postoperative complication and stone-free rate. This study shows that mPNL is more effective for multiple stones, but fURS is associated with potentially less complications and postoperative hospital stay. Furthermore, preoperative hemoglobin level and urine culture can be used to predict postoperative complication risk and they may be helpful in choosing treatment methods for the elderly.

Prospective evaluation of outcome of percutaneous nephrolithotomy using the 'STONE' nephrolithometry score: A single-centre experience

Objective

To assess the prediction of stone clearance and complications of percutaneous nephrolithotomy (PCNL) using the ‘STONE’ nephrolithometry score, assessing stone size, tract length (skin-to-stone distance), degree of obstruction, number of calyces involved and stone essence (density).

Patients and methods

This was a prospective study of patients undergoing single-tract PCNL while prone, conducted at a university hospital. All patients had non-contrast-enhanced computed tomography within 3 weeks of the procedure. Only patients with a unilateral procedure and radio-opaque stones were included. The five variables of the STONE nephrolithometry score were calculated before the procedure. The stone-free rates were assessed with a plain abdominal film at 4 weeks and complications were graded using the modified Clavien system.

Results

In all, 107 patients were included in the final analysis. Overall, 80% of patients were rendered stone-free. Among the individual variables, a larger stone (P = 0.002) and the involvement of multiple calyces (P = 0.04) were associated with residual stones, while tract length (skin-to-stone distance), stone density and presence of hydronephrosis were not. Patients who were rendered stone-free had a statistically significant lower overall STONE score than those with residual stones, at 7.24 vs. 8.14 (P = 0.02). The score also correlated with operative duration, which was significantly longer with a higher STONE score (P = 0.03). The complication rate was 18% and most complications were Clavien grade 2, with bleeding requiring a blood transfusion (11 patients) being the commonest. There were no deaths within 30 days of surgery, but there was no correlation between the STONE score and complications.

Conclusion

The STONE nephrolithometry score is a simple and easy to apply system for predicting complexity in stone clearance with PCNL.

Simultaneous ureteroscopic lithotripsy and contralateral percutaneous nephrolithotomy for ureteral calculi combined with renal staghorn calculi

OBJECTIVES

To investigate the efficacy, safety, and cost-effectiveness of simultaneous ureteroscopic lithotripsy and contralateral percutaneous nephrolithotomy for ureteral calculi combined with contralateral renal staghorn calculi.

METHODS

The present prospective controlled trial had been registered with the Chinese Clinical Trial Registry (Registration number: ChiCTR-ONRC-13004146). Patients with ureteral calculi and contralateral renal staghorn calculi were enrolled into the staged (ureteroscopic lithotripsy first followed by a staged percutaneous nephrolithotomy) or the simultaneous (synchronous ureteroscopic lithotripsy and contralateral percutaneous nephrolithotomy) treatment group according to the odd or even number of the last hospitalization number. All patients signed informed consent. The primary outcomes were the stone-free rate and total hospital costs. The second outcomes were the operative and anesthesia times, the complication rate, and hospital stay.

RESULTS

A total of 51 patients were enrolled into the staged group and 52 patients were enrolled into the simultaneous group. There were no statistically significant differences in patients' characteristics. The overall stone-free rate was 94.1% in the staged group and 92.3% in the simultaneous group. No severe complication was observed. The total hospital stay of the staged group was longer, and it was negatively correlated to different procedures. The cost in the staged group was higher, and it was correlated with total operation time and postoperative hospital stay.

CONCLUSIONS

Simultaneous ureteroscopic lithotripsy and contralateral percutaneous nephrolithotomy represent safe and effective procedures, and they can be considered as a first-line treatment for selected patients presenting with ureteral calculi combined with contralateral renal calculi.

Does the presence of hydronephrosis have effects on micropercutaneous nephrolithotomy?

PURPOSE

To evaluate the effects of presence of hydronephrosis on micropercutaneous nephrolithotomy (micro-PNL) surgery.

PATIENTS AND METHODS

A retrospective analysis of 112 patients who underwent microperc surgery between December 2012 and April 2014 was performed. Patients were evaluated in two groups according to whether the presence of hydronephrosis. Stone size and location, fluoroscopy and operation time, stone-free rates and patient-related parameters were prospectively recorded into a centralized computer-generated system.

RESULTS

A total of 58 patients in Group 1 with hydronephrosis and 54 patients in Group 2 with no hydronephrosis were analyzed. There was no statistically significant difference in terms of stone sizes and body mass indexes (BMI) in comparison of groups (155.2 ± 93.06 vs. 143.70 ± 70.77 mm(2), p = 0.856 and 27.6 ± 4.2 vs. 26.7 ± 3.2 kg/m(2), p = 0.625). The success rates were similar (91.3 vs. 92.5%, p = 0.341). While the mean operation time and fluoroscopy time in Group 1 were 44.2 ± 23.62 min and 105.3 ± 47 s, it was 38.8 ± 26.4 min and 112.53 ± 68.3 s in Group 2, but there was no statistical difference in comparison of both groups. The mean attempts of percutan puncture were 1.35 ± 0.47 in Group 1 and 1.76 ± 0.31 in Group 2 (p = 0.185). We also found no statistical differences regarding mean hemoglobin change and hospitalization time, respectively (p = 0.685 and p = 0753). In comparison of grades of hydronephrosis, there was no statistically significant difference in subgroups analysis.

CONCLUSIONS

The presence of hydronephrosis does not affect success rates and operative time in micro-PNL procedures significantly. Micropercutaneous nephrolithotomy is technically feasible and efficacious both in hydronephrotic and non-hydronephrotic kidneys.

Pyelocaliceal Distribution of Kidney Stones Used as an Outcome Predictor in Percutaneous Nephrolithotomy After Being Evaluated with Preoperative and Postoperative CT Scan

OBJECTIVE

To identify kidney stone characteristics that will determine either success or failure of a percutaneous nephrolithotomy (PCNL) and design a classification system to predict results according to these characteristics.

MATERIALS AND METHODS

One hundred thirty-eight patients were assessed with multislice abdominal and pelvic CT before and after PCNL. With regard to pyelocaliceal stone distribution, we classified our patients in two groups that we called "no extra stone in middle calix" (NESMC) and "extra stone in middle calix" (ESMC), according to the difficulty in reaching the stones. We did a univariate and a multivariate analysis, as well as a receiving operating curve (ROC) of the proposed classification, based on the foreseen probabilities, to determine the diagnostic yield.

RESULTS

Global residual lithiasis (RL) was 26.08%. The proportion of patients with RL according to classification was NESMC 11.5% and ESMC 59.5%. In the univariate logistic regression analysis of the distribution, number, total volumetry, side, type, radio-opacity of stones, and the presence or not of preoperatory urinary tract infection, the variables related to RL were the distribution (11.3; 95% confidence interval [95% CI] 4.7, 27.4), volumetry (odds ratio [OR] 1.01; 95% CI 1.004, 1.014), and the presence of staghorn stones (OR 6.64; 95% CI 2.463, 17.905). In the multivariate analysis, distribution was statistically significant (OR 8.687; 95% CI 2.69, 28.06), whereas total volumetry and the presence of staghorn stones were not (OR 1; 95% CI 1.000, 1.000 and OR 2.7; 95% CI 0.35, 20.57, respectively). The ROC showed an area under the curve of 0.77.

CONCLUSION

In our experience, the distribution of kidney stones is the most important predictor of RL after PCNL. The results also suggest that the presence of stones in the middle calix has a direct impact on the stone-free rate. We put forward a simple and reproducible classification, easy to apply, and useful to estimate the chances of success of the procedure using preoperatory CT scans.

Clinical efficacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy for large impacted proximal ureteral calculi: a prospective, randomized study

PURPOSE

To evaluate the clinical efficacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy (POBC-URSL) for large impacted proximal ureteral calculi.

PATIENTS AND METHODS

156 patients with impacted proximal ureteral stones ≥1.5 cm in size were randomized to ureteroscopic lithotripsy (URSL), POBC-URSL, and percutaneous nephrolithotomy (PNL) group between May 2010 and May 2013. For URSL, the calculi were disintegrated with the assistance of anti-retropulsion devices. POBC-URSL was performed with the assistance of an 8F percutaneous occlusive balloon catheter. PNL was finished with the combination of an ultrasonic and a pneumatic lithotripter. A flexible ureteroscope and a 200 μm laser fiber were used to achieve stone-free status to a large extent for each group. Variables studied were mean operative time, auxiliary procedure, postoperative hospital stay, operation-related complications, stone clearance rate, and treatment costs.

RESULTS

The mean lithotripsy time for POBC-URSL was shorter than URSL, but longer than PNL (42.6±8.9 minutes vs 66.7±15.3 minutes vs 28.1±6.3 minutes, p=0.014). The auxiliary procedure rate and postoperative fever rate for POBC-URSL were significantly lower than URSL and comparable to PNL (p<0.01, p=0.034). POBC-URSL was superior to URSL with regard to the stone clearance rate at 3 days postoperatively, and as good as PNL (98.1% vs 75.0% vs 96.2%, p<0.01). The postoperative hospital stay and hematuria rate were lower in POBC-URSL group than PNL group and similar to URSL group (p=0.016, p<0.01). The treatment costs were lowest in POBC-URSL group ($1205.0±$113.9 vs $1731.7±$208.1 vs $2446.4±$166.4, p=0.004).

CONCLUSIONS

For large impacted proximal ureteral calculi, POBC-URSL was associated with a higher stone clearance rate, fewer complications and costs. POBC-URSL combined the advantages of URSL and PNL.

Tubeless percutaneous nephrolithotomy: yes but when? A multicentre retrospective cohort study

The aim of our study is to determine the predictive factors for placement of percutaneous nephrostomy tube (PNT) in percutaneous nephrolithotomy (PCNL) procedure and to evaluate the optimal cutoff points of the predictive factors. 229 patients, who had undergone percutaneous nephrolithotomy operation between February 2009 and February 2013 were reviewed retrospectively. Five patients were excluded from the study because of solitary kidney. All characteristics of 224 patients, stones and operative data were investigated. Patient and stone-related factors, such as age, BMI, history of previous surgery or SWL, characteristics of the stone, renal parenchymal thickness (RPT), as well as procedural factors, such as percutaneous access number and location were analyzed by univariate and multivariate tests. The continuous variables were analyzed using Receiver operating characteristic curve analysis. There were no differences in sex, age, BMI and hemoglobin decrease between the groups. Previous operation status, RPT, stone size, multiplicity of the stone, stone localization, blood transfusion presence, access points, access number and operation time were found statistically different according to univariate analysis. Multivariate analysis showed that RPT, operation time and stone size were the independent factors that affected the PNT insertion. For RPT, operation time and stone size, the optimal cutoff points for insertion PNT were 13.75 mm, 75.5 min and 890 mm(2), respectively. Tubeless PCNL should be chosen in patients with stone area less than 890 mm(2), and parenchymal thickness thicker than 13.75 mm and procedure with operation period <75.5 min.

A supracostal approach for percutaneous nephrolithotomy of staghorn calculi: A prospective study and review of previous reports

OBJECTIVES

To evaluate a supracostal approach for percutaneous nephrolithotomy (PCNL) of staghorn calculi through a prospective study and review of previously reported cases.

METHODS

From June 2009 to November 2011, 40 patients with staghorn calculi were scheduled for supracostal S-PCNL in a prospective study. Of the 40 renal units, 16 (40%) had a complete staghorn and 24 (60%) had a partial staghorn calculus. Perioperative complications were stratified according to the modified Clavien system. Univariate and multiple logistic regression analyses were used to determine statistically significant variables affecting the stone-free rate and development of complications.

RESULTS

In all, 57 tracts were established in the 40 renal units; 23 (58%) renal units were approached through one supracostal upper pole calyx, while 13 (33%) and four (10%) required a second middle- or lower-pole puncture, respectively. Overall, 78% of patients were rendered stone-free or had clinically insignificant residual fragments with PCNL monotherapy, and this increased to 88% with auxiliary procedures. In the logistic regression analysis, a complete staghorn stone was the only independent variable for residual stones (P = 0.005). There was an overall complication rate of 38%. Independent variables with an influence on complications were staghorn stone burden (P = 0.007), and operative duration (P = 0.045).

CONCLUSIONS

The supracostal upper calyceal approach provides optimum access for the percutaneous removal of staghorn stones. Appropriate attention to the technique and to monitoring before and after surgery can detect thoracic complications, and these can be managed easily with intercostal chest tube drainage, with no serious morbidity.