Skin-to-stone distance has no impact on outcomes of percutaneous nephrolithotomy

[How quickly can a complex stone be treated in percutaneous mini-nephrolithotomy?]

OBJECTIVES

Knowing the treatment's time of a complex stone is important for operating programming. It depends on the installation time, renal access time and the rate of fragmentation. The main objective of the study is to calculate the processing speed of complex stones by the percutaneous mini-nephrolithotomy (mini-NLPC) technique.

POPULATION AND METHODS

A prospective single-center study was carried out between November 2019 and October 2020. Patients treated with mini-NLPC and with a result without fragment were included. The stone volume was measured using 3D reconstruction software and the operating time was differentiated into installation time, renal access time and fragmentation time.

RESULTS

Of the 36 patients treated by the percutaneous technique, 20 patients were included. The median 3D volume of the stones was 4145 mm³ (2211-6998). The median duration of the intervention time was 104.5min (80-125). The fragmentation speed was 48.2 mm³min^-1 (30.2-62.5) taking into account the total duration of the intervention and 110.4 mm³min^-1 (85.3-126.5) in taking into account only the duration of fragmentation.

CONCLUSION

The fragmentation speed for complex stones was 48.2 mm³min^-1 (30.2-62.5) taking into account all the different operating times. It would be interesting to compare these results with that of ureteroscopy with the same methodology.

LEVEL OF PROOF

C.

Comparing different kidney stone scoring systems for predicting percutaneous nephrolithotomy outcomes: A multicenter retrospective cohort study

OBJECTIVE

To compare the predictive performance of five previously described scoring systems (i.e., S.T.O.N.E., Guy's, Clinical Research Office of the Endourological Society (CROES), the Seoul National University Renal Stone Complexity (S-RESC) and the new Stone Kidney Size (SKS) score) for postoperative outcomes regarding stone-free rate (SFR) and complications in adult patients.

METHODS

Data from 349 patients who underwent percutaneous nephrolithotomy (PCNL) in three urology departments were analyzed. SKS, S.T.O.N.E., S-ReSC, CROES and Guy's nephrolithometry scoring systems were used to retrospectively calculate predictions for each patient. Univariate and multivariate analyses were performed to evaluate factors associated with SFR and complication rates. Receiver operating characteristic (ROC) curves were generated and areas under curves (AUC) were compared to identify the method with the highest predictive value.

RESULTS

Median SKS, S.T.O.N.E., S-ReSC, CROES and Guy's scores were 4, 7, 3, 170.8 and 2, respectively. Overall, SFR was 67.0% (234/349) with a complications rate of 36.7% (128/349). AUCs of each method for predicting stone-free status, highlighted reasonable predictive capabilities with 0.709, 0.806, 0 0.869, 0.207, and 0.735, respectively; however, the S-ReSC scoring system had the best discriminative performance. According to multivariate logistic regression and AUC results, none were effectively capable of predicting complications.

CONCLUSIONS

All scoring systems correlated significantly with stone-free status; although, S-ReSC appears to have the greatest predictive ability. This method is also relatively easy to implement and highly reproducible. However, none of the methods analyzed are able to accurately predict postoperative complications.

Noncontrast computed tomography factors predictive of extracorporeal shock wave lithotripsy outcomes in patients with pancreatic duct stones

Purpose

To assess the usefulness of factors unique to NCCT for the prediction of ESWL outcomes in patients with pancreatic duct stones.

Materials and methods

We retrospectively evaluated 148 patients with multiple PDS who had undergone ESWL therapy. All patients received an examination for NCCT both before and after ESWL. The following parameters were measured and recorded: patient characteristics including sex and age; NCCT parameters including mean stone length, mean stone volumes before and after ESWL, mean value of CT attenuation, standard deviation of CT attenuation, variation coefficient of CT attenuation, skin-to-stone distance, and pancreatic duct diameter; ESWL outcome indexes including stone clearance rate calculated using the formula \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{V0 - V1}{V0} \times 100\%$$\end{document}V0-V1V0×100%, and the number of ESWL sessions. All patients were divided into groups based on their SCR: A group (SCR ≥ 90%), B group (SCR between 50% and 90%), and C group (SCR < 50%). Analysis of variance was used among the three groups to evaluate the potential predictors of SCR, and a receiver-operating curve was established to determine the optimal cutoff value.

Results

ANOVA analysis revealed that MSD was the only significant predictor for SCR (p < 0.05), and ROC indicated an optimal cutoff value of +1000.45 HU, with a sensitivity up to 78.0% and specificity of 48.6%. Stones with MSD lower than +1000.45 HU had higher SCR (69.3%) than that of higher-density ones (59.6%). Pearson correlation analysis and histogram indicated a significant positive correlation between ESWL No. and MSL (r = 0.536), MSD (r = 0.250), SDSD (r = 0.247), and PDD (r = 0.227), all values being p < 0.01.

Conclusion

MSD is the optimal predictor of ESWL efficacy, and PDS with lower MSD had a better clearance rate with fewer fragmentation sessions.

Skin to calyx distance is not a predictive factor for miniaturized percutaneous nephrolithotomy outcomes

Objective

To evaluate the predictive value of the distance from skin to calyx (SCD) on the outcome and complication rates of patients undergoing mPNL.

Materials and Methods

Patient’s charts, who had undergone mPNL between June 2012 and June 2015, were analyzed retrospectively. Patients who had a preoperative computerized tomography (CT) were enrolled into the study. Two separateurologists evaluated the CT scans and calculated the SCD defined as the distance between the skin and surface/lateral edge of the calyx, which was the preferred site of entry for percutaneous access. The average value of the two measurements was included inthe final analysis to avoid bias. The mean SCD was 75mm. According to the median SCD value, patients were divided into two groups: group 1 (SCD ≤75) and group 2 (SCD >75).

Results

A total of 140 patients and 130 patients were enrolled in groups 1 and 2, respectively. The mean operation time and the mean fluoroscopy time was significantly longer in group 2 (p:0.004 vs. p:0.021). The rate of blood transfusion was significantly higher in group 1 (6 patients). None of patientsin group 2required blood transfusion (p:0.017). Stone-free status after a single session of mPNL was 67.1% in group 1 and 75.4% in group 2 (p:0.112). After additional procedures, stone-free rates increased to 84.3% and 85.4% in group 1 and group 2, respectively (p:0.802).

Conclusion

Our study demonstrated that longer SCD was not a predictive factor for stone-free rates after mPNL. However, SCD over 75mm was associated with longer operation time and fluoroscopy time with lower rates of transfusion.

The Effect of Obesity on Perioperative Outcomes Following Percutaneous Nephrolithotomy

OBJECTIVES

To test if obesity predisposes to higher rates of adverse outcomes after percutaneous nephrolithotomy (PCNL).

MATERIALS AND METHODS

Within the Nationwide Inpatient Sample (NIS), we identified patients treated with PCNL between 1998 and 2010 for kidney stones. We examined the temporal trends in PCNL use and charges among obese and nonobese patients. We then tested the effect of obesity on perioperative complications, transfusions, length of stay (LOS), and total hospital charges (THCs). LOS and THCs were defined as a continuous variable and were also dichotomized according to the 75th percentile into prolonged LOS (pLOS) and increased THCs (iTHCs). Then, multivariable models were fitted.

RESULTS

Overall, a weighted sample of 90,529 individuals treated with PCNL between 1998 and 2010 was examined. Of those patients, 9300 were obese (10.3%). The proportion of PCNLs performed in obese patients increased throughout the years from 7.4% to 16.7% (p < 0.001). Overall complication rates were 21.6% vs 22.0% (p = 0.3) and transfusion rates were 4.3% vs 4.0% (p = 0.1) for obese and nonobese patients, respectively. Obese patients had fewer genitourinary complications (13.4% vs 15.0%, p < 0.001), but had higher rates of sepsis (1.7% vs 1.3%, p = 0.009) as well as respiratory (3.0% vs 2.5%, p = 0.002) and vascular complications (0.3% vs 0.2%, p = 0.007). Conversely, pLOS (20.9% vs 18.8%, p < 0.001) and iTHCs (30.8% vs 24.4%, p < 0.001) were more frequently recorded in obese patients. In multivariable analyses, obesity was neither associated with higher rates of overall complications (odds ratio [OR], p = 0.3) nor with higher rates of transfusions (p = 0.3). However, obesity was associated with pLOS (OR: 1.21, p = 0.002) as well as iTHCs (OR: 1.17, p = 0.002).

CONCLUSIONS

PCNL in obese patients did not result in higher rates of individual complications or transfusions. However, it resulted in higher rates of pLOS and iTHCs.

Adopting Ultrasound Guidance for Prone Percutaneous Nephrolithotomy: Evaluating the Learning Curve for the Experienced Surgeon

OBJECTIVES

To define the learning curve associated with adopting ultrasound guidance for prone percutaneous nephrolithotomy (PCNL) for the experienced surgeon.

METHODS

A prospective cohort study of consecutive patients undergoing PCNL with ultrasound guidance for renal tract access and dilation was performed. Clinical data reviewed included success in gaining renal access with ultrasound guidance, total fluoroscopic screening time, and radiation exposure dose. PCNL cases performed with fluoroscopic guidance matched for stone size served as control cases.

RESULTS

One hundred consecutive ultrasound-guided procedures performed by a single experienced endourologist were divided into five experience groups. Significant improvement in renal access success rate with ultrasound was seen after 20 cases (p < 0.05). Total fluoroscopic screening time, radiation exposure dose, and operative time were also statistically significantly improved over the study period. When compared with fluoroscopy-guided PCNL, significant decreases in total fluoroscopic screening time (33.4 ± 35.3 seconds vs 157.5 ± 84.9 seconds, p < 0.05) and radiation exposure (7.0 ± 8.7 mGy vs 47.8 ± 45.9 mGy, p < 0.05) were seen. No differences in complication rates were found.

CONCLUSIONS

Ultrasound-guided renal access for PCNL can be performed effectively after 20 cases. Transition to the use of ultrasound will quickly reduce radiation exposure for patients and intraoperative personnel.

Study of predictive factors affecting the prolonged urinary leakage after percutaneous nephrolithotomy

Objective:

To evaluate the factors that may influence the prolonged urinary leakage following percutaneous nephrolithotomy (PCNL).

Materials and Methods:

A total of 936 consecutive patients underwent PCNL during the study period from April 2013 to December 2014 at our center, and data were recorded prospectively. Patients who required stage PCNL, chronic renal failure and diabetic patients, concurrent ureteric stone and patients in whom double-J stent was placed because of ureteropelvic injury, or pelvicalyceal extravasation were excluded from the study. After exclusion, 576 patients were included in the study. The predictive factors that may lead to prolonged urinary leakage after PCNL were broadly categorized into patient-related factors and procedure-related factors. Patients were divided into two groups: Group 1 (n = 32) – Required double-J stent placement due to prolonged urinary leakage (>48 h) after removal of the nephrostomy tube. Group 2 (n = 544) – Did not require double-J stent placement.

Results:

Patient-related factors such as stone complexity, grade of hydronephrosis, renal parenchymal thickness in access line, and intra-parenchymal renal pelvis were most important factors for prolonged urinary leakage (P < 0.05, P < 0.05, P < 0.05, and P < 0.05, respectively), while procedure-related factors such as multiple punctures, surgeon's experience, and residual stones were most important factors for prolonged urinary leakage (P < 0.05, P < 0.05, and P < 0.05, respectively).

Conclusion:

In the present study, several factors appear to affect post-PCNL prolonged urinary leakage. We suggest that patients who are at increased risk of prolonged urinary leakage double-J stent should be placed at the end of PCNL procedure.

Optimal Skin-to-Stone Distance Is a Positive Predictor for Successful Outcomes in Upper Ureter Calculi following Extracorporeal Shock Wave Lithotripsy: A Bayesian Model Averaging Approach

Objectives

To investigate whether skin-to-stone distance (SSD), which remains controversial in patients with ureter stones, can be a predicting factor for one session success following extracorporeal shock wave lithotripsy (ESWL) in patients with upper ureter stones.

Patients and Methods

We retrospectively reviewed the medical records of 1,519 patients who underwent their first ESWL between January 2005 and December 2013. Among these patients, 492 had upper ureter stones that measured 4–20 mm and were eligible for our analyses. Maximal stone length, mean stone density (HU), and SSD were determined on pretreatment non-contrast computed tomography (NCCT). For subgroup analyses, patients were divided into four groups. Group 1 consisted of patients with SSD<25^th percentile, group 2 consisted of patients with SSD in the 25^th to 50^th percentile, group 3 patients had SSD in the 50^th to 75^th percentile, and group 4 patients had SSD≥75^th percentile.

Results

In analyses of group 2 patients versus others, there were no statistical differences in mean age, stone length and density. However, the one session success rate in group 2 was higher than other groups (77.9% vs. 67.0%; P = 0.032). The multivariate logistic regression model revealed that shorter stone length, lower stone density, and the group 2 SSD were positive predictors for successful outcomes in ESWL. Using the Bayesian model-averaging approach, longer stone length, lower stone density, and group 2 SSD can be also positive predictors for successful outcomes following ESWL.

Conclusions

Our data indicate that a group 2 SSD of approximately 10 cm is a positive predictor for success following ESWL.

Effectiveness of retrograde intrarenal stone surgery in obese patients

BACKGROUND

A number of comorbid health problems can be found in obese patients. These problems increase the surgical risk in obese patients.

AIMS

To determine the effectiveness of retrograde intrarenal surgery for renal stone treatment in obese patients.

METHODS

We retrospectively reviewed the data of 106 patients who had retrograde intrarenal surgery with the diagnosis of renal stone in our clinic. The patients were divided into three groups regarding their body mass indexes: ≥30 kg/m² being obese (group 1), 25-29.9 kg/m² being overweight (group 2), and <25 kg/m² being normal weight (group 3). The patients were compared for age, gender, and stone characteristics. In addition, the duration of surgery, stone-free rate (SFR), complication rate, and the duration of the hospital stay were compared among the groups.

RESULTS

Twenty eight patients were obese (group 1), 49 patients were overweight (group 2), and 29 patients were normal weight (group 3). The mean ages of groups 1, 2 and 3 were 51.5 (29-84), 47 (30-76) and 35 (19-84) years, respectively (p = 0.001). SFR was 85.7 % in group 1, 89.8 % in group 2, and 75.9 % in group 3 (p = 0.24). The duration of surgery was similar in groups 1, 2, and 3, being 45.5 (25-95), 50 (30-120), and 45.5 (10-100) min, respectively (p = 0.23). None of the patients had major complications.

CONCLUSIONS

Our results indicate that retrograde intrarenal surgery is a safe and efficient surgical method for renal stone treatment in obese and overweight patients.