Pre- and perioperative predictors of short-term clinical outcomes in patients undergoing percutaneous nephrolitholapaxy

Predictors of acute kidney injury after percutaneous nephrolithotomy in adult patients: prospective observational study

PURPOSE

To assess the frequency and the predictive factors of Acute Kidney injury (AKI) in patients undergoing percutaneous nephrolithotomy (PNL).

METHODS

A prospective observational work. Demographic, preoperative laboratory data, stone characteristics, and intraoperative and postoperative data were gathered. Perioperative AKI had been defined as an elevation in serum creatinine by ≥ 0.3 mg/dl within 48 h, or ≥ 1.5 times baseline, or urine volume less than 0.5 ml/ kg/hour for 6 hours. A multivariate logistic regression analysis was performed to determine the predictive factors of AKI. ROC curves were utilized to determine the cutoff values of the risk variables. P-values were deemed statistically significant when they were less than 0.05.

RESULTS

A total of 418 participants had been involved. The frequency of AKI was 13.9, and 17.2% of patients with AKI developed CKD. The risk factors were age > 46.5 years, smoking, BMI > 28.5 kg/m2, hypertension, diabetes, utilization of angiotensin-converting enzyme inhibitors (ACEI), haemoglobin < 10.8 gm/dl, baseline creatinine > 1.41 mg/dl, eGFR < 65.2 ml/min./1.73 m2, serum uric acid > 5.2 mg/dl, stone volume > 1748 mm3, large tract size, long operative time, and intra-operative bleeding. Patients with AKI had a notably extended duration of hospitalization (3.2 days ± 0.45 vs 2.1 ± 0.42, p < 0.001).

CONCLUSIONS

Perioperative AKI occurred in 13.9% of individuals undergoing PNL. Identification and optimization of the risk factors and meticulous technique during PNL procedures should be attempted to decrease the risk of AKI.

Safety and efficacy of percutaneous nephrolithotripsy in comorbid patients: A 3 years prospective observational study

PURPOSE

To report the result of percutaneous nephrolithotripsy (PCNL) via standard nephrostomy tract in a single training institution. The perioperative complications in relation to the comorbid state are particularly assessed.

PATIENTS AND METHODS

A prospective interventional study between January 2019 to November 2022, included 210 patients scheduled for PCNL. The average age was 40.3 ± 11.8 years (range 18- 67 years). Patients were categorized into two groups. The first group comprised 146 cases (69 .5%) with no associated co-morbidities while the second group 64 (30.5%) had co-morbidities such as obesity in 4 cases (1.9%), hypertension (HTN) in 24 cases (11.4%) cases, diabetes mellitus (DM) in 17 (8.1%) cases, history of recurrent stone surgery in 11 (5.2%) cases and more than one in 8 cases (3.8%). Co-morbidities, stone burden, location of stone, time of surgery, stay in the hospital, further operations, and negative events were among the reported data. Complications and the stone-free rate were the main outcome indicators.

RESULTS

Intraoperative complications were reported in 40 (18.8%) patients (18 group 1 and 22 group 2) during PCNL. Bleeding occurred in 22 (10.5%) patients (9 group 1 and 13 group 2), blood transfusions were needed in 4 (1.9%) (2 group 1 and 2 group 2), extravasation was observed in 11 patients (5.2%) (6 group 1 and 5 group 2) and cardiac arrhythmia in 3 (1.4%) (1 group 1 and 2 group 2) patients. Postoperative complications occurred in 61 patients (29%) (24 group 1 and 37 group 2) in the form of fever in 10 patients (4.8 %) (3 group 1 and 7 group 2) and prolonged leakage in 50 patients (23.8%) (21 group 1 and 29 group 2). One patient of group 2 died from postoperative sepsis. Extravasation and postoperative leakage were higher in diabetic patients than in non-diabetics. Stonefree rate was 60.5% (127 of 210). Clinically significant residual fragments (CSRFs) found in 70 cases (33.3%) (33 group 1 and 37 group 2). In 13 cases (6.2%) (5 group 1 and 8 group 2), clinically insignificant residual fragments (CIRFs) were found. In 8 (3 group 1 and 5 group 2) of the 13 cases, spontaneous stone passage was observed within 4-6 weeks of surgery. Residual stones in three cases (1 group 1 and 2 group 2) were asymptomatic and 4 mm or less, whereas stones increased in two cases of group 2. Among all factors studied, stone burden was significantly correlated to both intraoperative and postoperative complications. The occurrence of postoperative fever increased with large stone burden.

CONCLUSIONS

PCNL is a therapeutic modality that is effective, feasible, and safe for a wide range of patients with concurrent medical issues. A steep curve is required to reduce intraoperative and postoperative complications.

Impact of pelvicalyceal anatomical variation on surgical outcomes of endoscopic combined intrarenal surgery

Objectives

The objective of this work is to investigate the impact of the pelvicalyceal anatomical system (PCS) on calyceal stone formation and surgical outcomes of endoscopic combined intrarenal surgery (ECIRS) for renal and/or proximal ureteral stones with a diameter >15 mm.

Patients and methods

PCS was classified as Type I (single pelvis) or Type II (divided pelvis) according to the simple anatomical Takazawa classification. Using prospectively collected data from January 2016 to April 2020, 219 patients were retrospectively reviewed. After excluding patients who underwent a staged procedure, had hydronephrosis greater than grade 2, prior nephrostomy tubes, and failed to access the renal collecting system, 115 patients (Type I: 81, Type II: 34) were included, and the distribution of calyceal stones and surgical outcomes in ECIRS were compared between Types I and II PCS.

Results

The median number of renal stone calyces in the Type II group was significantly more than that in the Type I group (p = 0.016). In particular, the Type II group possessed more upper stone calyces. Multivariate logistic regression analysis revealed that Type II PCS was associated with an increased odds ratio (OR) for the presence of upper stone calyces (OR: 2.93, p = 0.018). The stone-free (SF) status at 1 month after surgery, confirmed by abdominal plain radiography, was significantly higher in the Type I group compared with that in Type II (67.9% vs. 39.4%, respectively; p = 0.006). The requirement for additional surgical interventions was significantly higher in the Type II group compared with that in Type I (35.4% vs. 7.4%, respectively; p < 0.001). Multivariate analysis revealed that the number of stone calyces (OR: 4.26; p = 0.001) and Type II PCS (OR: 3.43; p = 0.009) were independent predictors of residual stones after ECIRS.

Conclusion

We first revealed that the anatomic properties of PCS play a role in both upper calyceal stone formation and in the success of the ECIRS procedure. Because the SF rate in Type II PCS was significantly lower than that in Type I PCS, additional percutaneous nephrolithotomy tracts might be required, even for ECIRS.

Comparison Between Percutaneous Nephrolithotomy and Retrograde Flexible Nephrolithotripsy in Obese Patients with 2 - 4 cm Renal Stones

Background: Nowadays, because of remarkable advancements in retrograde intrarenal surgery (RIRS), modest attention toward this procedure as the second or alternative choice for renal stones treatment has been drawn. Objectives: In the present study, we compared RIRS and percutaneous nephrolithotomy (PCNL) outcomes in treating obese patients with 2 - 4 cm renal stones. Methods: Eighty-two patients who underwent PCNL (n = 40) and RIRS (n = 42) between June 2015 and December 2018 at the Department of Urology of Sina Hospital were enrolled in our retrospective cohort study. Results: After the first surgery session, stone-free rates for the RIRS group were 92.9% and for the PCNL group was 95% (P value = 0.52). The mean operation time for the RIRS and PCNL groups were 71.6 ± 11 and 93.3 ± 12.2, respectively (P < 0.001). The hospitalization stay for all of the PCNL group was more than 1 day (mean = 2.5 days); however, that for the majority of the RIRS group was less than 1 day (P < 0.001). The analgesic use in the RIRS group was significantly lower than in the PCNL group (9.0 ± 5.5, 61.8 ± 13.6, respectively; P < 0.001). The overall complication rates were higher in the RIRS group. However, none of them were statically significant (P > 0.05). Conclusions: According to satisfactory outcomes obtained in the RIRS groups, it can be concluded that RIRS can be applied as an alternative or even the first choice in obese patients with 2 - 4 cm renal stones.

Do 3D-calculated volume distribution of a stone in pelvicalyceal system affect complications of percutaneous nephrolithotomy?

In our study, we examined the effect of the three-dimensional (3D) stone segmentation volume and its ratio to the renal collecting system on complication rates. Data from141 patients who underwent PCNL surgery were analyzed retrospectively. Volume segmentation of both the renal collecting system and stones was obtained from 3D segmentation software with the images on CT data. After creation of a 3D surface volume rendering of renal stones and the collecting system, segmentation of the renal collecting system volume (RCSV) and analyzed stone volume (ASV) was analyzed and the ASV-to-RCSV ratio was calculated. Univariate analysis and multivariate logistic regression model were used to determine factors that affected complication status. Diagnostic value for the prediction of complication rates was analyzed using receiver operating characteristic (ROC) incline. Overall, there were 141 (92 male and 49 female) eligible patients included in the current study. The overall complication rate for PCNL monotherapy was 31.9%. Multivariate regression analysis (forward stepwise) revealed that the ASV-to-RCSV ratio and number of tracts were independent risk factors for developing complications (OR 1.17, p < 0.001; OR 7.87, p = 0.002; respectively). The ROC analysis revealed a cut-off value of 16.23% (AUC 0.869, p < 0.001, sensitivity 93.3%, specificity 78.1%) for the ASV-to-RCSV ratio. The distribution of stone burden volume in the pelvicalyceal system, which is calculated as a numerical value using the 3D volume segmentation method, is an important predictor of the complication rate before PCNL. The ASV-to-RCSV ratio as a quantitative value may be an instrument for urologists before surgery to help preoperative planning.

Risk factors for acute kidney injury after percutaneous nephrolithotomy: Implications of intraoperative hypotension

Percutaneous nephrolithotomy (PNL) is a minimally invasive technique for renal stone removal but can cause renal parenchymal injury. Renal stones can also affect renal function. We evaluated the risk factors for acute kidney injury (AKI) after PNL.The study cohort included 662 patients who underwent PNL. Patient characteristics, preoperative laboratory values, intraoperative data, and stone characteristics were collected. Univariate and multivariate logistic regression analyses were performed to identify risk factors for AKI after PNL. Postoperative outcomes such as hospitalization, intensive care unit admission rate and stay duration, and chronic kidney disease were also evaluated.Of the total study series, there were 107 (16.2%) cases of AKI after PNL (AKI group), and 555 (83.8%) patients who showed no injury (no-AKI group). The risk factors for AKI after PNL were found to be a higher preoperative serum uric acid level [odds ratio (OR) = 1.228; 95% confidence interval (95% CI) = 1.065-1.415; P = .005], longer operation time (OR = 1.009; 95% CI = 1.004-1.014; P < .001), and intraoperative hypotension (OR = 12.713; 95% CI = 7.762-20.823; P < .001). Hospitalization and intensive care unit stay duration were significantly longer in the AKI group (8.7 ± 5.2 vs 6.6 ± 2.8 days, P < .001; 0.34 ± 1.74 vs 0.07 ± 0.48 days, P = .002, respectively). Chronic kidney disease was also significantly higher in the AKI group (63.6% vs 32.7%, P = .024).As intraoperative hypotension is an important risk factor for AKI after PNL, which leads to poor postoperative outcomes, it should be prevented or managed vigorously during PNL.

Comparison of the outcomes of complete supine percutaneous nephrolithotomy in patients with radiopaque and radiolucent kidney stones

Objective

This study compared the stone opacity effect in patients who had radiopaque and radiolucent stones in percutaneous nephrolithotomy (PCNL) results.

Material and methods

The medical records of 171 complete supine PCNL procedures were gathered. Patients were categorized into two groups: those with radiopaque (n=141) and those with radiolucent (n=30) stones. Kidney, ureter and bladder x-ray was done a day after PCNL and Ultrasound imaging was done two weeks later to evaluate the stone free rate. A stone free result was defined as having less than 4 mm residual stone size. Outcome parameters were compared by univariate analysis and those which were significantly different between the two groups were assessed by multivariate binary logistic regression analysis.

Results

There were no significant differences in age, sex, body mass index, hypertension, diabetes mellitus, pre-surgery hemoglobin, pre-surgery serum creatinine, stone and also surgery-related parameters between the two groups. Stone free rate, surgery time, complication-related parameters, hemoglobin drop, serum creatinine and glomerular filtration rate (GFR) changes were similar in both groups based on univariate analysis. The radiopaque group had higher post-surgery GFR (p=0.04) and longer hospital stay (p=0.009). However, opacity had no effect on these outcomes after multivariate analysis. Higher post-surgery GFR was seen in patient with higher GFR before surgery (p<0.0001). Also, higher hemoglobin before surgery was correlated with less hospital stay (p=0.001).

Conclusion

The complete supine percutaneous nephrolithotomy outcomes are similar in patients with radiopaque and radiolucent stones.

Guy's Stone Score (GSS) Based on Intravenous Pyelogram (IVP) Findings Predicting Upper Pole Access Percutaneous Nephrolithotomy (PCNL) Outcomes

Objective. To predict the success rate and complications following percutaneous nephrolithotomy via the upper pole using the Guy's Stone Score (GSS) based on the findings of a preoperative intravenous pyelogram (IVP). Patients and Methods. Two hundred and twenty-seven renal operations, which were carried out using PCNL via the upper pole, were classified according to the GSS assigned. Any complications were classified according to the Clavien classification. The success rates and incidence of any complications were compared between each GSS. Results. The immediate success rates were 87.50% of GSS1, 71.43% of GSS2, 53.62% of GSS3, and 38.46% of GSS4, P < 0.01. There were statistically significant differences between the groups in stone size, overall immediate success rate, operative time, number of access tracts, and frequency of tubeless PCNL. Major complications (a Clavien score of 3-5) were significantly higher in the cases with a higher GSS. Conclusion. A GSS based on an IVP is a simple and reliable tool in predicting the success rate and possible complications following upper pole access PCNL.

Efficacy and safety of mini percutaneous nephrolithotomy in obese patients

Purpose

We aimed to evaluate the effect of obesity on surgical outcomes of mini percutaneous nephrolithotomy (Mini-PNL).

Methods

Hundred and eighty two Mini-PNL procedures were performed between May 2013 and January 2015 and their results were evaluated retrospectively. Patients were classified as non-obese (BMI, 18.5–30 kg/m²) and obese (≥30 kg/m²) groups. Obese and non-obese patients were compared according to pre-operative demographic values, intra-operative surgery techniques and post-operative results.

Results

BMI values of 133 patients were lower than 30 kg/m² while 49 patient’s BMI values were higher than 30 kg/m². There were no significant difference between operation time, fluoroscopy time, number of access and access sites when two groups were compared. No significant difference was found in total length of hospital stay, hemoglobin drop, and complication rates. Stone-free rates were 70.7 % in the non-obese and 71.4 % in the obese group (p = 0.9).

Conclusions

Mini-PNL procedure is a safe and effective treatment modality, which should be strongly considered for obese patients with appropriate sized stones.

Value of CT angiography in reducing the risk of hemorrhage associated with mini-percutaneous nephrolithotomy

Purpose:

To evaluate the clinical value of computed tomography angiography (CTA) in reducing the risk of hemorrhage associated with mini-percutaneous nephrolithotomy (PCNL).

Materials and Methods:

A total of 158 patients with renal or ureter stones who had undergone mini-percutaneous nephrolithotomy were retrospectively enrolled into this study from May of 2011 to April of 2014. Group 1 (65 patients) underwent computed tomography angiography, and Group 2 (93 patients) underwent non-contrast CT. The clinical characteristics of the patients and hemorrhagic complications were recorded. The hematologic complications (transfusion rate, and preoperative and postoperative hemoglobin values) were assessed.

Results:

There were no statistically significant differences in age, body mass index(BMI), stone diameter, operative time, stone-free rate, and hospital stay between the 2 groups. In group 2, 1 patient (1.1%) developed a renal arteriovenous fistula and was treated with embolus therapy. In addition, Group 2 showed significantly drop in hemoglobin (3.6 g/dL vs. 2.4 g/dL, respectively; P <0.001) and more transfusions (9.7% vs. 1.5%, respectively; P <0.05) compared with Group 1.

Conclusion:

The study showed that patients who underwent computed tomography angiography prior to percutaneous nephrolithotomy had lower drop of hemoglobin and needed less transfusions. These findings may suggest that the use of computed tomography angiography may reduce the risk of bleeding during percutaneous nephrolithotomy.

Evaluation of stone-free rate using Guy's Stone Score and assessment of complications using modified Clavien grading system for percutaneous nephro-lithotomy

To prospectively evaluate the ability of Guy's Stone Score (GSS) in predicting stone clearance rate and complication rate (by modified Clavien grade) for renal stones treated by percutaneous nephrolithotomy (PNL). From January 2013 to June 2014, a total of 142 patients undergoing PNL were evaluated prospectively. Patients with co-morbidities like hypertension, diabetes, renal failure were excluded from the study. All patients were classified according to GSS based on the findings of pre-operative intravenous urography (IVU) and per-operative retrograde pyelography (RGP). All PNL procedures were done by standard technique in prone position and success was defined as no residual stone visible on X-ray KUB done on the third postoperative day. Complications were classified according to modified Clavien grading system. The initial stone clearance rate was 71.1% and overall final stone clearance rate was 90.14%. The complication rate according to Clavien grading system was 40.1%. The final stone clearance rates were 93.9, 85.71, 90.47, and 77.77% in GSS I, II, III, and IV, respectively (p<0.001, <0.05, <0.05 and >0.05, respectively). The Clavien complication rates were 23, 61, 52, and 77.7% in GSS I, II, III, and IV, respectively (p<0.001). The GSS is a simple and easily reproducible system to preoperatively predict stone-free rate and perioperative complication rate. It helps in better patient counseling preoperatively.

Factors affecting complications according to the modified Clavien classification in complete supine percutaneous nephrolithotomy

INTRODUCTION

An increase in percutaneous nephrolithotomy (PCNL) has been accompanied by an increase in complications. We identified the parameters affecting the severity of complications using the modified Clavien classification (MCC).

METHODS

From 2008 to 2013, 330 patients underwent complete supine PCNL using subcostal access, one-shot dilation, rigid nephroscopy, and pneumatic lithotripsy. We assessed the impact of the following factors on complication severity based on the MCC: age, gender, body mass index, hypertension, diabetes, previous stone surgery and extracorporeal shock wave lithotripsy, preoperative hemoglobin, renal dysfunction (creatinine >1.4 mg/dL), preoperative urinary tract infection, anatomic upper urinary tract abnormality (AUUTA), significant (moderate-severe) hydronephrosis, stone-related parameters (opacity, number, burden, location, staghorn, complex stones), anesthesia type, kidney side, imaging and calyx for access, tract number, tubeless approach, operative time, postoperative hemoglobin, and hemoglobin drop and stone-free results.

RESULTS

The complication rate was 19.7% (MCC: 0=80.3%, I=6.4%, II=11.2%, ≥III=2.1%). On univariate analyses, only the following factors affected MCC: gender, preoperative hemoglobin, AUUTA, significant hydronephrosis, imaging for access, calyx for access, tract number, postoperative hemoglobin, hemoglobin drop and stone-free result. Renal dysfunction was accompanied by higher complications, yet the results were not statistically significant. Multivariate logistic regression analysis demonstrated renal dysfunction, absence of significant hydronephrosis, AUUTA, multiple tracts, lower postoperative hemoglobin, and higher postoperative hemoglobin drop as the significant parameters which affected MCC and predicted higher grades. The paper's limitations include a low number of cases in the higher Clavien grades and some subgroups of variables, and not applying some techniques due to surgeon preference.

INTERPRETATION

Many of the complete supine PCNL complications were in the lower Clavien grades and major complications were uncommon. Renal dysfunction, AUUTA, significant hydronephrosis, tract number, postoperative hemoglobin, and hemoglobin drop were the only factors affecting MCC.

Comparative evaluation of upper versus lower calyceal approach in percutaneous nephrolithotomy for managing complex renal calculi

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is the treatment of choice for staghorn and large renal stones. The success of PCNL is highly related to optimal renal access. Upper calyceal puncture being more difficult and more demanding have relatively few studies presented.

AIMS AND OBJECTIVES

This prospective study was carried out to evaluate the effectiveness and safety of upper calyceal versus lower calyceal puncture for the removal of complex renal stones through PCNL.

MATERIALS AND METHODS

A total of 94 patients underwent PCNL for complex renal stone in our institute. Fifty-one of them underwent lower calyceal, while 43 underwent upper calyceal puncture. The two approaches are compared as per total duration of surgery, intraoperative blood loss, infundibular/pelvic tear, rate of complete clearance and rate of postoperative complications (pulmonary, bleeding, fever and sepsis, etc.).

OBSERVATION AND RESULTS

In our study, the success rate was 76.47% for those in the lower, 90.70% for those in the upper calyceal access group. Thoracic complications (hydrothorax) occurred to 1 patient in upper calyceal supracostal access group. Bleeding requiring blood transfusion happened to 5 patients in lower calyceal access and 1 in upper calyceal group.

CONCLUSION

In our study for the management of complex renal calculi, we conclude that in a previously unoperated kidney, upper calyceal puncture through subcostal or supra 12(th) rib is a feasible option minimizing lung/pleural rupture and gives a better clearance rate. We suggest that with due precautions, there should not be any hesitation for upper calyceal puncture in indicated patients.

External validation and evaluation of reliability and validity of the S-ReSC scoring system to predict stone-free status after percutaneous nephrolithotomy

Objectives

The Seoul National University Renal Stone Complexity (S-ReSC) scoring system was developed to predict the stone-free rate (SFR) after single-tract percutaneous nephrolithotomy (PCNL). This study is an external validation of this scoring system.

Materials and methods

A retrospective review included 327 patients who underwent PCNL at 2 tertiary referral centers. The S-ReSC score was assigned from 1 to 9 based on the number of sites involved. The stone free status was defined as either complete clearance or clinically insignificant residual fragments <4 mm in size at 1 month follow-up imaging. Inter-observer and test-retest reliabilities were evaluated. The statistical performance of the prediction model was assessed by its predictive accuracy, predictive probability, and clinical usefulness.

Results

The overall SFR was 65.4%. SFRs were 83.9%, 47.6%, and 21.4% in low (1–2), intermediate (3–4), and high (5–9) score groups, respectively, with significant differences (P<0.001). Inter-observer and test-retest reliabilities revealed almost perfect agreements. External validation of the S-ReSC scoring system revealed an AUC of 0.731 (95% CI 0.675–0.788). The AUC of 3-titered S-ReSC score groups was 0.691 (95% CI, 0.629–0.753). The calibration plot showed that the predicted probability of SFR had a concordance comparable to that of the observed frequency. The Hosmer–Lemeshow goodness-of-fit statistic revealed an adequate performance of the predictive model (P = 0.10). Inter-observer and test-retest reliability showed a good level of agreement.

Conclusions

The S-ReSC scoring system is useful in predicting the post-PCNL SFR and in describing the complexity of renal stones.

Time-dependent oxidative stress effects of percutaneous nephrolithotomy

Aim of this study was to investigate the effects of operation time of percutaneous nephrolithotomy (PCNL) on renal function and hemodynamic response. Thirty-four patients (14 male, 20 female) with normal renal function who underwent unilateral single-tract PCNL between December 2010 and June 2011 were included in the study. The age, sex, stone size, grade of hydronephrosis, operative time, access pole, shock number of lithotripter, complications, stone-free rate, and hemodynamic parameters during operation were recorded. Total blood count and oxidative stress parameters such as paraoxonase 1 (PON1), total antioxidant status (TAS), total oxidant status (TOS), and malonyldialdehyde (MDA) levels were examined before the operation as baseline levels and then at 30, 60, 90, and 120 min during the operation. The mean age of the patients was 31.4 ± 18.8 (9-66 years) years. Mean stone size was 35.5 ± 15.6 mm. Mean serum BUN and creatinine did not change postoperatively (p > 0.05), whereas mean WBC and 24-h urine cortisol were positively and hematocrite were negatively changed significantly (p < 0.05). Oxidative stress parameters such as PON1 and TAS showed statistically significant decreases, while TOS and MDA showed statistically significant increases with increased operation time, especially after 1 h (p < 0.005). A bivariate correlation test showed correlation between oxidative stress parameters and operation time (p = 0.002), but no correlation was found between oxidative stress parameters and other parameters (p > 0.05). Oxidative stress and response to it increased with increasing operative time during a PCNL procedure, especially after 1 h. Further studies with a larger and longer series should be performed to clarify this issue further.

Predictors of immediate postoperative outcome of single-tract percutaneous nephrolithotomy

OBJECTIVE

To evaluate the efficacy of single tract percutaneous nephrolithotomy (sPCNL) and investigate the preoperative predictive factors associated with stone clearance after sPCNL.

METHODS

A retrospective review of 351 cases of sPCNL performed at a single institution by 1 of 2 endourologists between January 2000 and March 2010 was performed. The primary outcome evaluated was stone-free rate (SFR) as assessed immediately after either an initial procedure or a second-look nephroscopy performed on postoperative day 2. Preoperative patient and stone factors, including age, sex, body mass index (BMI), preoperative hematocrit and creatinine, previous surgeries, comorbidities, renal anomalies, stone size, shape, location, and history of any previous treatment to the active stone burden were included in the univariate analysis. Significant or clinically relevant factors on univariate analysis were included in a logistic regression the multivariate analysis.

RESULTS

SFR after either an initial procedure or a second-look nephroscopy was 76%. On univariate analysis, rising preoperative creatinine, hypertension, increasing stone diameter, complete staghorn stone, presence of stones in the upper pole and absence of prior SWL were associated with lower SFR. Stone size, presence of stones in the upper pole, and prior SWL for the active burden were independent predictors of SFR on multivariate analysis.

CONCLUSION

sPCNL is an efficient procedure to clear renal stones, especially when used in conjunction with routine second-look nephroscopy. Increasing stone size and upper pole stones are associated with lower rates of stone clearance, whereas SWL performed before percutaneous nephrolithotomy (PCNL) is associated with improved stone clearance. The role of SWL before PCNL warrants further prospective investigation.

Long-term outcomes of percutaneous nephrolithotomy in 177 patients with chronic kidney disease: a single center experience

PURPOSE

We evaluated the long-term outcomes of percutaneous nephrolithotomy in patients with chronic kidney disease.

MATERIALS AND METHODS

Data on 1,904 patients who underwent percutaneous nephrolithotomy between 2002 and 2011 were retrospectively collected. The estimated glomerular filtration rate for each patient was retrospectively calculated using a 4-variable modification of diet in renal disease equation. Patients were staged for chronic kidney disease by National Kidney Foundation guidelines.

RESULTS

A total of 242 patients (12.7%) had a preoperative glomerular filtration rate of less than 60 ml per minute/1.73 m(2). Those monitored a minimum of 1 year were included in analysis. The study included 177 patients with a mean ± SD age of 54.3 ± 12.1 years. Perioperative and postoperative complications were noted in 15.2% of patients. At a mean followup of 43.4 ± 22.7 months renal function in 29.4% of patients had improved but it remained the same or deteriorated in 54.2% and 16.4%, respectively. On multivariate regression analysis diabetes and preoperative or postoperative complications predicted renal function. The stone-free rate 3 months postoperatively was 80.2% (142 of 177 cases). Stones recurred during long-term followup in 36 of these patients (25.3%). Spontaneous stone passage was detected in 12 of the 35 patients (34.2%) with residual stones but 8 (22.8%) with residual stones experienced an increase in stone size.

CONCLUSIONS

At long-term followup renal function was maintained or improved in greater than 80% of patients with chronic kidney disease who underwent percutaneous nephrolithotomy. Stones recurred or residual stones grew in approximately 25% of these patients.

Variables that influence operative time during percutaneous nephrolithotomy: an analysis of 1897 cases

BACKGROUND AND PURPOSE

Operative time is an important perioperative factor and is related to postoperative complications and procedural cost-effectiveness. There are few studies, however, investigating factors that affect operative time during percutaneous nephrolithotomy (PCNL). In this study, patient and kidney stone-related factors that influence operative time were analyzed.

MATERIALS AND METHODS

Clinical records from 1897 patients with renal calculi who underwent PCNL were retrospectively reviewed, and these patients were divided into two groups based on their median operative time (group 1: ≤60 min; group 2: >60 min). Multivariate analyses as well as univariate analyses including chi-square, Fisher exact and Mann Whitney U tests were used to investigate the effects of independent variables on operative time, including patient and kidney stone-related factors such as age, sex, body mass index, history of ipsilateral open surgery, shockwave lithotripsy, presence of hydronephrosis, stone burden, stone type and opacity, and surgical experience.

RESULTS

The mean operative time was 64.9±27.6 minutes (range 10-220 min). Univariate analyses determined that a history of open surgery, presence of hydronephrosis, stone type and size, and surgical experience correlated with operative time (P<0.05 for all). Multivariate analyses revealed that presence of hydronephrosis (odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.17-1.78, P=0.002), stone type (OR: 2.12, 95% CI: 1.69-2.70, P<0.0001), stone burden (OR: 2.44, 95% CI: 1.85-3.12, P<0.0001), and surgical experience (OR: 0.56, 95% CI: 0.46-0.70, P<0.0001) were significant independent factors in influencing operative time.

CONCLUSIONS

Presence of hydronephrosis, renal stone size and type significantly affect the operative time during PCNL. The duration of the operation was also observed to decrease with increased surgical experience.

Operating times and bleeding complications in percutaneous nephrolithotomy: a comparison of tract dilation methods in 5,537 patients in the Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study

PURPOSE

The study investigated factors that affect operating times and bleeding complications associated with percutaneous nephrolithotomy (PCNL) in the PCNL Global Study.

PATIENTS AND METHODS

All patients who underwent PCNL for primary or secondary treatment of kidney stone indications during the study period (November 2007-December 2009) were eligible for inclusion. PCNL procedures were performed according to local clinical guidelines and practices. Nephrostomy tract dilation was performed using balloon dilation, metal telescopic dilation, or Amplatz serial dilation. Hematologic complications assessed included bleeding rates, transfusion rates, and preoperative and postoperative hematocrit values.

RESULTS

The median operating time with balloon dilation (n=2277) was significantly longer than with telescopic/serial dilation (n=3260) at 94.0 vs 60.0 minutes, respectively (P<0.0001). In the balloon dilation group, there was significantly more bleeding (9.4% vs 6.7%, respectively; P<0.0001) and more transfusions (7.0% vs 4.9%, respectively; P=0.001) compared with the telescopic/serial dilator group. Univariate analysis showed that the probability of bleeding complications was higher with balloon vs telescopic/serial dilation (odds ratio [OR] 1.75; P=0.0001) and larger sheath size (OR 1.42; P=0.0001). By multivariate analysis, sheath size but not dilation method was predictive of bleeding complications. Other significant predictive factors included operating time, stone load, and caseload.

CONCLUSION

This study shows that in PCNL, factors that are associated with bleeding/transfusion include sheath size, operating time, stone load, and caseload.

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

OBJECTIVES

To investigate the prognostic factors associated with the treatment efficacy of minimally invasive percutaneous nephrolithotomy (MPCNL) and develop a preoperative logistic regression model for predicting the stone-free rate after the initial procedure.

METHODS

We retrospectively analyzed the records of 865 patients who had undergone MPCNL in our department from January 2006 to September 2009. Patient age, sex, body mass index, degree of hydronephrosis, and stone side, number, size, and location were the investigated variables. According to the treatment outcome, the patients were divided into 2 groups, those who became stone free and those who did not. Student's t test, chi-square test, and multiple logistic regression analysis were performed to determine the statistically significant variables and to develop a predictive mathematical model.

RESULTS

The stone-free rate after primary MPCNL was 80.1% (693 of 865). On univariate analysis, the stone number, size, and location and degree of hydronephrosis were identified as significant factors between the 2 groups. On multivariate analysis, they were also independent predictors of the surgical outcome. Next, a logistic regression model was developed using these variables to estimate the stone-free rate after MPCNL.

CONCLUSIONS

The results of our study have demonstrated that an increased stone number and size, location in a calix, staghorn calculus, and moderate to severe hydronephrosis were associated with decreased stone-free rates after MPCNL. We have developed a mathematical model for predicting the stone-free rate that will be helpful for patient counseling and surgeon decision-making regarding the management of upper urinary tract calculi.

Long-term outcomes of percutaneous nephrolithotomy compared to shock wave lithotripsy and conservative management

PURPOSE

Percutaneous nephrolithotomy is successful at achieving stone-free status but long-term safety data are lacking. We report our long-term experience with percutaneous nephrolithotomy and compare these results with other treatment modalities.

MATERIALS AND METHODS

We identified 87 patients treated with percutaneous nephrolithotomy from 1983 to 1984 who continue to receive care at our institution. Retrospective chart review was performed. Long-term results were compared to those of a group of 288 patients with stones treated nonsurgically (controls) and a group of 288 patients treated with shock wave lithotripsy followed for 19 years.

RESULTS

Average followup was 19.2 years (range 12.7 to 23.0). After percutaneous nephrolithotomy new onset renal insufficiency was noted in 9 patients (10.6%), hypertension in 29 (34.1%), diabetes mellitus in 20 (23.5%) and ureteropelvic junction obstruction in 3 (3.5%). Stone recurrence occurred in 32 patients (36.8%). Recurrent stone events were associated with residual fragments after percutaneous nephrolithotomy (p = 0.049). Compared to shock wave lithotripsy there were no significant differences in the development of renal insufficiency, hypertension or diabetes mellitus. Stone recurrence was more common following shock wave lithotripsy (53.5%) compared to percutaneous nephrolithotomy (p = 0.033). Compared to controls there were no significant differences in the development of renal insufficiency or hypertension. On univariate analysis percutaneous nephrolithotomy was associated with the development of diabetes mellitus (p <0.001) but this association did not persist in multivariate analysis.

CONCLUSIONS

At 19 years of followup stone recurrences were less frequent following percutaneous nephrolithotomy compared to shock wave lithotripsy. Recurrent stone events were associated with residual fragments after percutaneous nephrolithotomy. Percutaneous nephrolithotomy was not associated with the development of adverse medical conditions compared to shock wave lithotripsy or conservatively managed stone cases.