Improving Outcomes of Percutaneous Nephrolithotomy: Access

Factors associated to hemoglobin decrease after percutaneous nephrolithotomy: a retrospective study

OBJECTIVE

This study aims to determine the preoperative and perioperative risk parameters associated with a decrease in hemoglobin (Hb) in patients undergoing percutaneous nephrolithotomy (PCNL).

METHODS

We collected prospective data of consecutive patients who underwent PCNL from January 2018 to December 2022. The median decrease in post-operative hemoglobin levels compared to pre-operative was found to be 1.5 g/dl. This value was the cut-off value that divided the sample into two groups. Group 1 has a decrease in Hb levels that is higher or equal to the cutoff, group 2 has a decrease in Hb levels that is lower than the cut-off. All preoperative, stone characteristics and perioperative factors were recorded.

RESULTS

A total of 273 patients were included in the study, 141 in Group 1 and 132 in Group 2. The mean age of Group 1 was significantly higher (55.48 ± 8.73 vs 45.9 ± 10.75 years, p < 0.05). The mean bleeding of Group 1 was significantly higher (285.85 ± 113.68 vs 135 ± 77.54 ml, p < 0.05). There was a significant difference in mean operation time between groups (86.35 ± 32.05 vs 64.89 ± 27.83 min, p < 0.05). Multivariate analysis showed that the variables age, comorbid diabetes mellitus, intraoperative bleeding amount, and operation time had a significant relationship with Hb reduction in patients undergoing PCNL (p < 0.05).

CONCLUSIONS

Older age, comorbid diabetes mellitus, large amounts of intraoperative bleeding, and longer operating time are factors associated with PCNL-related postoperative hemoglobin decrease.

Predicting the Stone-Free Status of Percutaneous Nephrolithotomy With the Machine Learning System: Comparative Analysis With Guy’s Stone Score and the S.T.O.N.E Score System

Purpose: The aim of the study was to use machine learning methods (MLMs) to predict the stone-free status after percutaneous nephrolithotomy (PCNL). We compared the performance of this system with Guy’s stone score and the S.T.O.N.E score system.

Materials and Methods: Data from 222 patients (90 females, 41%) who underwent PCNL at our center were used. Twenty-six parameters, including individual variables, renal and stone factors, and surgical factors were used as input data for MLMs. We evaluated the efficacy of four different techniques: Lasso-logistic (LL), random forest (RF), support vector machine (SVM), and Naive Bayes. The model performance was evaluated using the area under the curve (AUC) and compared with that of Guy’s stone score and the S.T.O.N.E score system.

Results: The overall stone-free rate was 50% (111/222). To predict the stone-free status, all receiver operating characteristic curves of the four MLMs were above the curve for Guy’s stone score. The AUCs of LL, RF, SVM, and Naive Bayes were 0.879, 0.803, 0.818, and 0.803, respectively. These values were higher than the AUC of Guy’s score system, 0.800. The accuracies of the MLMs (0.803% to 0.818%) were also superior to the S.T.O.N.E score system (0.788%). Among the MLMs, Lasso-logistic showed the most favorable AUC.

Conclusion: Machine learning methods can predict the stone-free rate with AUCs not inferior to those of Guy’s stone score and the S.T.O.N.E score system.

Which factors affect the success of pediatric PCNL? Single center experience over 20 years

OBJECTIVE

We aimed to investigate the impact of surgeons' experience on pediatric percutaneous nephrolithotomy (PCNL) outcomes.

MATERIALS AND METHODS

Between June 1997 and June 2018, 573 pediatric patients with 654 renal units underwent PCNL for renal stone disease by senior surgeons. Data were divided into two groups, group-1 (n = 267), first ten years period, group-2 (n = 387); second ten years period.

RESULTS

Mean ± SD age of patients was 7.6 ± 4.9 (1-17) years. The stone-free rates (SFR) assessed after 4 weeks were 74.9% vs. 83.4% in group-1 vs. group-2, respectively (p = 0.03). The mean operation time, fluoroscopy time, and the number of patients requiring blood transfusion significantly decreased in group 2 (100.4 ± 57.5 vs. 63.63 ± 36.3, 12.1 ± 8.3 vs. 8.3 ± 5.4, and 24.3% vs. 2.9%; p < 0.001, p < 0.001, and p = 0.002 in group-1 versus group-2, respectively). On multivariate analysis, increasing stone size increased operation time (p < 0.001), fluoroscopy time (p < 0.001), intraoperative and postoperative blood transfusion rates (p = 0.006 and p = 0.018, respectively), and hospital stay (p = 0.002) but was not associated with change of glomerular filtration rate (GFR) (p = 0.71). Sheath size also correlated with increased fluoroscopy time (p < 0.001), operation time (p < 0.001), intraoperative blood transfusion (p < 0.001) and hospital stay, but sheath size did not affect postoperative blood transfusion (p = 0.614) or GFR change (p = 0.994).

CONCLUSIONS

The percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure and is well accepted because of its lower complication rate and high efficiency for pediatric patients. Stone and sheath size are predictive factors for blood loss and hospital stay. During 20 years, our fluoroscopy time, operation time, blood loss, and complication rates decreased, and stone-free rate increased.

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.

[Calyceal stones]

The natural course of untreated, asymptomatic calyceal calculi has not yet been clearly defined regarding disease progression and risk of surgical interventions. The decision for an active treatment of calyceal calculi is based on stone composition, stone size and symptoms. Extracorporeal shockwave lithotripsy (ESWL) has a low complication rate and is recommended by the current guidelines of the German (DGU) and European (EAU) Associations of Urology as a first-line therapy for the treatment of calyceal stones <2 cm in diameter. However, immediate removal of stones is not achieved with ESWL. The primary stone-free rates (SFR) after ESWL depend on stone location and stone composition and can show remarkable differences. Minimally invasive procedures, such as percutaneous nephrolitholapaxy and ureteroscopy are alternatives for the treatment of calyceal stones which have low morbidity and high primary SFR when performed in centres of excellence.

Reliability of percutaneous nephrolithotomy in pediatric patients: comparison of complications with those in adults

PURPOSE

To assess the reliability of percutaneous nephrolithotomy (PNL) in pediatric patients by comparing complications between pediatric patients and adults by use of the modified Clavien grading system.

MATERIALS AND METHODS

The data of 74 pediatric (0 to 16 years) and 535 adult (17 years and older) patients who underwent PNL owing to kidney stone disease between January 2005 and December 2011 were analyzed retrospectively. The complications in the pediatric and adult patients were classified in five grades according to the modified Clavien system.

RESULTS

The most frequent cause of grade I complications was fever requiring antipyretics, which was seen in 4 pediatric patients (5.4%) and 30 adult patients (5.6%). Grade II complications (blood transfusions, <12 hours urinary leakage) were observed in 11 pediatric patients (14.8%) and 80 adult patients (14.9%). Grade III complications were also seen in 6 pediatric patients (8.1%) (grade IIIb; D-J catheter implantation under general anesthesia) and 78 adult patients (14.5%) (grade IIIa; D-J catheter implantation and angio-embolization under local anesthesia). There was no statistically significant difference between the two groups in terms of grade I, II, or III complications (p>0.05). Colonic injury occured in one patient (1.3%) in the pediatric group (grade IVa). In the adult group, one patient (0.2%) died as the result of myocardial infarction (grade V).

CONCLUSIONS

Thanks to technological developments and minimalization of the equipment used, when indicated, pediatric patients can be safely treated with PNL with low complication rates similar to those in adult patients.

Factors affecting operative time during percutaneous nephrolithotomy: our experience with the complete supine position

BACKGROUND AND PURPOSE

Operative time influences surgical outcomes, operation-related and indirectly anesthesia-related complications. We investigated variables that affect operative time during percutaneous nephrolithotomy (PCNL) with the complete supine position.

PATIENTS AND METHODS

We reviewed data of 120 patients who underwent complete supine PCNL by one surgeon. Correlation between age, sex, body mass index (BMI), preoperative serum creatinine and hemoglobin levels, history (stone surgery, shockwave lithotripsy (SWL), hypertension, diabetes), stone (side, opacity, burden, complexity), imaging for access, calix for access, number of tracts, and tubeless approach with operative time were assessed by univariate and multivariate statistical tests.

RESULTS

Mean operative time was 60.62±30.70 minutes. In univariate analysis, age, sex, groups of BMI, hypertension, diabetes, previous stone surgery and SWL, stone opacity, operation side, number of tracts, and tubeless approach had no effect on operative time. BMI (P=0.029, negative correlation), stone burden (P=0.001, positive correlation), imaging for access (P=0.001, fluoroscopy<ultrasonography), calix for access (P=0.035, upper>lower>middle) and probably complex stones (P=0.057, complex>noncomplex) were effective factors on operative time. Multiple linear regression revealed association between BMI (P=0.000, negative correlation), stone burden (P=0.005, positive correlation), imaging for access (P=0.000, fluoroscopy<ultrasonography), and calix for access (P=0.023) with operative time. In lower calix access, mean operative time was less than upper calix access (P=0.022, significant) and higher than middle calix access (P=0.930, nonsignificant).

CONCLUSIONS

BMI, stone burden, imaging for access, and calix for access were effective parameters on operative time in complete supine PCNL. Groups of BMI, previous stone surgery and SWL, number of tracts, and tubeless approach had no effect on operative time.

Does pelvicaliceal system anatomy affect success of percutaneous nephrolithotomy?

OBJECTIVE

To investigate the effect of the pelvicaliceal system (PCS) anatomy on the percutaneous nephrolithotomy (PCNL) success rate. Although the caliceal anatomy is effective for stone clearance after shock wave lithotripsy and retrograde intrarenal lithotripsy, the effect of the caliceal anatomy after PCNL has not been evaluated to date.

METHODS

A total of 498 patients who had undergone PCNL and preoperative intravenous urography were enrolled in our study. Kidney-related anatomic factors, such as the PCS surface area and type, degree of hydronephrosis, infundibulopelvic angle, upper-lower calix angle, infundibular length, and infundibular width were calculated using intravenous urography. The association between the PCNL success rate and kidney-related anatomic factors was retrospectively analyzed using chi-square tests, Fisher's exact test, Mann-Whitney U test, and forward stepwise regression analysis.

RESULTS

A success rate of 78.1% was achieved. No difference was seen the success rates among the PCS types. The mean PCS surface area was 20.1 ± 9.7 cm(2) in patients with successful outcomes and 24.5 ± 10.2 cm(2) in patients with remaining stones (P = .001). The mean infundibulopelvic angle, upper-lower calix angle, infundibular length, and infundibular width were similar in both groups. Multivariate binary logistic regression analysis showed that stone configuration and PCS surface area were independent factors affecting the PCNL success rates.

CONCLUSION

The results of our study have shown that the PCS surface area is the only anatomic factor that affects the PCNL success rate and patients with a PCS surface area <20.5 cm(2) have greater PCNL success.

Factors affecting bleeding during percutaneous nephrolithotomy: single surgeon experience

PURPOSE

To investigate variables that affect bleeding during percutaneous nephrolithotomy (PCNL), focusing on the experience of a single surgeon.

PATIENTS AND METHODS

The records of 649 PCNL procedures that were performed by the same surgeon were reviewed retrospectively. The effect of surgical experience; patient and stone-related factors, including age, sex, hypertension, and diabetes, serum creatinine level, history of ipsilateral renal procedures, stone surface area and type, degree of hydronephrosis, preoperative hemoglobin level; operative factors, such as the calix of puncture, number of accesses, operative time; and intraoperative complications, such as pelvicaliceal system perforation on bleeding (described as decrease in hemoglobin level and need for blood transfusion), were investigated. For statistical assessment, univariate analyses and multivariate stepwise regression analyses were used.

RESULTS

A 92.3% success rate was achieved after one session PCNL. The overall blood transfusion rate was 10.8%. The number of accesses, stone type, diabetes, preoperative hemoglobin level, and operative time were the most important factors for blood transfusion requirement. In the receiver operating characteristic curve, the best cutoff point of operative time was 58 minutes for the blood transfusion requirement. Multivariate stepwise regression analyses showed that there was an association between diabetes, operative time, number of accesses, and stone type with the decrease in hemoglobin levels. No correlation between surgical experience and decrease in hemoglobin level as well as blood transfusion necessity was found.

CONCLUSIONS

Depending on the results achieved by a single surgeon, multiple access tracts, staghorn calculi, presence of diabetes, and prolonged operative time, but not surgical experience, significantly increased blood loss during PCNL.

Tubeless procedure is most important factor in reducing length of hospitalization after percutaneous nephrolithotomy: results of univariable and multivariable models

OBJECTIVES

To evaluate the effects of kidney stones and patient-related parameters on the length of hospitalization (LOH), which is one important factor affecting the cost effectiveness of percutaneous nephrolithotomy (PCNL). Recently, increases in healthcare costs have highlighted the importance of evaluating the cost effectiveness of a treatment as much as its efficacy.

MATERIAL AND METHOD

During an 8-year period, the records of 1669 patients with renal calculi who underwent PCNL were reviewed retrospectively. Eleven patients with urosepsis were excluded from the present study. A total of 1658 patients were categorized into 2 groups (group 1 = ≤2 days; group 2 = >2 days) according to the median LOH (median = 2 days). Multivariate binary logistic regression analysis was used to detect the effects of independent variables, including the patient age, gender, body mass index, history of extracorporeal shock wave lithotripsy or open surgery, stone size and opacity, presence of hydronephrosis, and localization and number of accesses, on the LOH after PNL.

RESULTS

Overall success was achieved in 86.2% of cases after one session of PCNL. The mean length of hospitalization was 2.89 ± 1.66 days (range, 1-21). According to the outcome of the multivariate analysis, diabetes (P = .0001, OR = 1.67), impaired kidney function (P = .03, OR = 1.64), stone size (P = .031, OR = 1.31), number of accesses (P = .001, OR = 1.59), intercostal access (P = .001, OR = 1.79), and tubeless procedure (P = .0001, OR = 0.23) were variables influencing LOH.

CONCLUSIONS

The presence of diabetes, a large stone burden, intercostals access, multiple accesses, and impaired kidney function prolong the LOH after PCNL. The use of the tubeless procedure was able to diminish the LOH.

Characteristics of patients requiring Double-J placement because of urine leakage after percutaneous nephrolithotomy

OBJECTIVES

Prolonged urine leakage (PUL) from the percutaneous tract after percutaneous nephrolithotomy is a major complication that necessitates the placement of a urethral Double-J stent. We analyzed the characteristics of patients who had this complication to find out its risk factors.

PATIENTS AND METHODS

During a 6-year period, 1407 standard percutaneous nephrolithotomy procedures were performed at our institution. Medical charts were reviewed focusing on the patients who required Double-J placement because of PUL from the percutaneous tract for more than 24 hours after removal of the nephrostomy tube. A total of 81 patients in whom a Double-J stent was placed because of ureteropelvic injury or pelvicaliceal extravasation or as a part of percutaneous endopyelotomy were excluded from the study. Factors that are considered to have an impact on this untoward event were analyzed and compared.

RESULTS

Double-J stent was placed in a total of 57 (4.3%) patients who were found to have PUL. Stone size was significantly larger in the stented group (10.0 +/- 5.6 cm(2) vs. 7.8 +/- 5.3 cm(2)). The stones were classified as complex in 68.4% of patients in the stented group and in 53.4% of patients in the nonstented group, and this difference was also statistically significant. Stone-free rate was significantly higher in the nonstented group (p < 0.05). Residual stone and additional treatment rates were statistically higher in the stented group (p < 0.05). Access number and location as well as per-operative bleeding were not predictive factors for PUL development.

CONCLUSION

The necessity for Double-J placement due to PUL from the percutaneous tract, diminishes with increase in stone-free rates. Stone size and stone complexity are other predictive factors for PUL development.

Management of infectious complications in percutaneous nephrolithotomy

Infectious complications are one of the most frequent and feared adverse medical events in percutaneous nephrolithotomy. They represent a dangerous and life-threatening condition, especially when postoperative septicemia or severe sepsis develops. In order to limit morbidity and mortality it is crucial to recognize preoperative and intraoperative risk factors that could be clear contributors to an adverse infectious event; those factors are mainly immunosuppression caused by some comorbidities, presence of urinary infection or colonization, stone characteristics, obstruction, long-lasting operation, and high intrapelvic pressure during nephrolithotomy. Close observation during the immediate and early postoperative period must be established and a high index of suspicion must be maintained to identify a major complication. The early recognition and prompt multidisciplinary management of sepsis is mandatory to optimize the final outcome. Appropriate therapy is a continuum of management of infection, ranging from adequate drainage and broad-spectrum antibiotics to aggressive fluid resuscitation and invasive monitoring with medical management in the intensive care setting until the causative agent is found and eradicated.

Percutaneous nephrolithotomy under a multimodal analgesia regime

OBJECTIVES

To evaluate the possibility of performing percutaneous nephrolithotomy (PCNL) under a multimodal analgesia regime.

PATIENTS AND METHODS

During a period of 3 years, 51 patients requiring PCNL were enrolled in the study. All patients received a multimodal analgesic regime that included paracetamol, a COX(2) inhibitor, epidural morphine, and infiltration of the surgical field with local anesthetics. Percutaneous renal tract access was created with ultrasound guidance. All patients were informed about the possibility of experiencing short periods of discomfort or pain, and all patients completed a visual analog pain scale questionnaire postoperatively.

RESULTS

All 51 patients completed the study, and the procedure was well tolerated. Intraoperative problems or postoperative complications were attributed mainly to the procedure itself (PCNL) rather than to the analgesic regimen administered. We observed no morphine-related side effects. Patients were transferred directly back to the ward immediately after the operation. The use of analgesics postoperatively was minimal.

CONCLUSIONS

The use of our multimodal analgesia regime is a well-tolerated and safe alternative to general or regional anesthesia for patients undergoing PCNL.

Classification of percutaneous nephrolithotomy complications using the modified clavien grading system: looking for a standard

OBJECTIVES

A classification (modified Clavien system) has been proposed to grade perioperative complications. We reviewed our experience with percutaneous nephrolithotomy (PNL), grading the complications according to this new classification.

METHODS

A total of 811 PNLs were performed between 2003 and 2006, and charts were retrospectively reviewed focusing on complications observed. According to the modified Clavien classification system, perioperative complications were stratified into five grades. Grade 1 defined all events that, if left untreated, would have a spontaneous resolution or needed a simple bedside intervention. Grade 2 complications required specific medication, including antibiotics and blood transfusion. Grade 3 complications necessitated surgical, endoscopic, or radiologic intervention (3a without general anesthesia, 3b under general anesthesia). Neighboring organ injuries and organ failures were classified as grade 4, and death was considered a grade 5 complication. Kidney stones treated with PNL were also classified as simple and complex and complication rates were compared.

RESULTS

A total of 255 perioperative complications were observed in 237 (29.2%) patients. There were 33 grade 1 (4%), 132 grade 2 (16.3%), 54 grade 3a (6.6%), 23 grade 3b (2.8%), 9 grade 4a (1.1%), and 3 grade 4b (0.3%) complications, and 1 death (0.1%). Most complications were related to bleeding and urine leakage. Grade 2 and 3a complications were significantly more common in patients with complex renal stones.

CONCLUSIONS

A graded classification scheme for reporting the complications of PNL may be useful for monitoring and reporting outcomes. However, minor modifications concerning auxiliary treatments are needed and further studies are awaited.

Does Previous Open Nephrolithotomy Affect the Outcome of Percutaneous Nephrolithotomy?

PURPOSE

To determine the effects of previous open nephrolithotomy on the results and morbidity of subsequent percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

Between March 2005 and January 2006, 89 patients underwent PCNL at our institution. We compared the patients who had had previous open surgery on the same kidney (group 1; n = 27) with those who had had no previous surgery (group 2; n = 62). The two groups did not differ significantly in age (45.4 v 44 years), stone burden (361.3 mm(2) v 482.4 mm(2) ), stone number, or laterality. Operative time, hospital stay, success rate, visual analog pain scores 8 hours after surgery, analgesic doses (diclofenac sodium), and intraoperative and postoperative complications were compared.

RESULTS

There were no differences in operating time, postoperative analgesic doses, pain scores, intraoperative and postoperative complications, the number of accesses, or the stone-free rate.

CONCLUSIONS

The morbidity and efficacy of PCNL are similar in patients who have had previous open nephrolithotomy and those having no previous surgery. Previous open surgery does not affect the success of PCNL.

Tubeless percutaneous nephrolithotomy in selected patients: a prospective randomized comparison

OBJECTIVES

To prospectively compare the outcome of standard and tubeless percutaneous nephrolithotomy (PNL) in a selected group of patients with renal stones.

METHODS

Patients with simple, isolated renal pelvis or lower pole caliceal stones and no significant hydronephrosis were randomly enrolled to undergo either standard PNL, in which routine nephrostomy tube was placed at the end of operation, or tubeless PNL. Occurrence of intraoperative complications, total operative time exceeding 2 h, indication for additional access or second-look PNL due to residual stones were exclusion criteria.

RESULTS

There were 11 isolated lower pole caliceal stones (mean stone burden: 3.1 cm(2)) and 6 isolated renal pelvis stones (mean stone burden: 2.8 cm(2)) in the tubeless PNL group (n: 17), and 9 isolated lower pole caliceal stones (mean stone burden: 3.4 cm(2)) and 9 isolated renal pelvis stones (mean stone burden: 3.1 cm(2)) in the standard PNL group (n: 18). Mean operation time was 59.6 +/- 9.1 (range: 50-90) min in the tubeless group, and 67.3 +/- 10.1 (range: 60-115) min in the standard PNL group (P > 0.05). Successful stone removal was achieved in all patients, and no significant complication was observed in any case. The mean postoperative analgesic requirement was significantly less in the tubeless group (P < 0.05). Mean hospital stay was 1.6 +/- 0.4 (range: 1-3) days in the tubeless group, and 2.8 +/- 0.9 (range: 2-4) days in the former group (P < 0.05).

CONCLUSION

Our results indicate that tubeless PNL is safe in the management of selected patients and that mean analgesic requirement as well as hospitalization time is diminished with this modification.