Finite element analysis of uncommonly large renal arteriovenous malformation--adjacent renal cyst complex.

BACKGROUND: Renal arteriovenous malformation (RAVM) represents abnormal communication between the intrarenal arterial and venous system. The purpose of this study was to investigate hemodynamics and biomechanics quantities which may influence the instability of RAVM and imply clinical complications. METHODS: A detailed 3D reconstruction of RAVM was obtained from the patient CT scans, aortic inlet flow was measured by color-flow Doppler ultrasound, while material characteristics were adopted from the literature. A numerical finite element analysis (FEA) of the blood flow was performed by solving the governing equations for the viscous incompressible flow. The physical quantities calculated at the systolic and diastolic peak moment were velocity, pressure, shear stress and drag forces. RESULTS: We reported a case of a 50-year-old patient with a large RAVM and adjacent renal cyst, who unsuccessfully underwent two attempts of embolization that resulted in the consequent nephrectomy. FEA showed that the cyst had a very low pressure intensity and velocity field (with unstable flow in diastolic peak). For both systolic and diastolic moments, increased values of wall shear stress were found on the places with intensive wall calcification. Unusually high values of drag force which would likely explain the presence of pressure in the cystic formation were found on the infero-medial side where the cyst wall was the thinnest and where the flow streamlines converged. CONCLUSIONS: FEA showed that the hemodynamics of the cyst-RAVM complex was unstable making it prone to rupture. Clinically established diagnosis of imminent rupture together with unfavorable hemodynamics of the lesion consequently made additional attempts of embolization risky and unsuccessful leading to total nephrectomy.

Scoring System Development and Validation for Prediction Choledocholithiasis before Open Cholecystectomy.

INTRODUCTION: Accurate precholecystectomy detection of concurrent asymptomatic common bile duct stones (CBDS) is key in the clinical decision-making process. The standard preoperative methods used to diagnose these patients are often not accurate enough. OBJECTIVE: The aim of the study was to develop a scoring model that would predict CBDS before open cholecystectomy. METHODS: We retrospectively collected preoperative (demographic, biochemical, ultrasonographic) and intraoperative (intraoperative cholangiography) data for 313 patients at the department of General Surgery at Gornji Milanovac from 2004 to 2007. The patients were divided into a derivation (213) and a validation set (100). Univariate and multivariate regression analysis was used to determine independent predictors of CBDS. These predictors were used to develop scoring model. Various measures for the assessment of risk prediction models were determined, such as predictive ability, accuracy, the area under the receiver operating characteristic curve (AUC), calibration and clinical utility using decision curve analysis. RESULTS: In a univariate analysis, seven risk factors displayed significant correlation with CBDS. Total bilirubin, alkaline phosphatase and bile duct dilation were identified as independent predictors of choledocholithiasis. The resultant total possible score in the derivation set ranged from 7.6 to 27.9. Scoring model shows good discriminatory ability in the derivation and validation set (AUC 94.3 and 89.9%, respectively), excellent accuracy (95.5%), satisfactory calibration in the derivation set, similar Brier scores and clinical utility in decision curve analysis. CONCLUSION: Developed scoring model might successfully estimate the presence of choledocholithiasis in patients planned for elective open cholecystectomy.

External validation of existing nomograms predicting lymph node metastases in cystectomized patients.

OBJECTIVES: Karakiewicz et al. and Green et al. created pre-cystectomy nomograms to predict lymph node involvement. The aim of the study was to externally validate these two nomograms in intermediate-volume institutions in Europe. PATIENTS AND METHODS: Data from a Serbian single-centre cystectomy series comprising 183 patients with bladder cancer were used for the validation of two US nomograms, which were originally based on data from 726 and 201 patients, respectively. A multivariate regression model assessed the value of the clinical parameters integrated in the two nomograms. The expected predictive accuracy, calibration and clinical utility according to the nomograms were calculated. RESULTS: Comparison of our dataset with the previously published data shows differences in nearly all underlying risk variables. Overall, 109 (59.6 %) patients had lymph node metastases. The analysis demonstrated that hydronephrosis and status of lymph nodes on computed tomography have independent prognostic value. The performance of the nomograms deteriorated from the development set, and the predictive accuracies for the two models showed moderate discriminatory ability (61.2-69.1 %). In the decision curve analysis, only the Green et al. model predicting lymph node positivity provided net benefit. CONCLUSIONS: The Green et al. nomogram seems applicable to patients from Europe, despite varying risk factors in the validation dataset. Acceptance of such a tool into daily clinical management may lead to more appropriate decision-making. Nevertheless, further improvement and implementation of novel statistical models with enhanced predictive accuracy is needed.

Scoring system development for prediction of extravesical bladder cancer.

BACKGROUND/AIM: Staging of bladder cancer is crucial for optimal management of the disease. However, clinical staging is not perfectly accurate. The aim of this study was to derive a simple scoring system in prediction of pathological advanced muscle-invasive bladder cancer (MIBC). METHODS: Logistic regression and bootstrap methods were used to create an integer score for estimating the risk in prediction of pathological advanced MIBC using precystectomy clinicopathological data: demographic, initial transurethral resection (TUR) [grade, stage, multiplicity of tumors, lymphovascular invasion (LVI)], hydronephrosis, abdominal and pelvic CT radiography (size of the tumor, tumor base width), and pathological stage after radical cystectomy (RC). Advanced MIBC in surgical specimen was defined as pT3-4 tumor. Receiving operating characteristic (ROC) curve quantified the area under curve (AUC) as predictive accuracy. Clinical usefulness was assessed by using decision curve analysis. RESULTS: This single-center retrospective study included 233 adult patients with BC undergoing RC at the Military Medical Academy, Belgrade. Organ confined disease was observed in 101 (43.3%) patients, and 132 (56.7%) had advanced MIBC. In multivariable analysis, 3 risk factors most strongly associated with advanced MIBC: grade of initial TUR [odds ratio (OR) = 4.7], LVI (OR = 2), and hydronephrosis (OR = 3.9). The resultant total possible score ranged from 0 to 15, with the cut-off value of > 8 points, the AUC was 0.795, showing good discriminatory ability. The model showed excellent calibration. Decision curve analysis showed a net benefit across all threshold probabilities and clinical usefulness of the model. CONCLUSION: We developed a unique scoring system which could assist in predicting advanced MIBC in patients before RC. The scoring system showed good performance characteristics and introducing of such a tool into daily clinical decision-making may lead to more appropriate integration of perioperative chemotherapy. Clinical value of this model needs to be further assessed in external validation cohorts.

Scoring system for prediction of lymph node metastasis in radical cystectomy cohort.

OBJECTIVES: The objective of the study was to assess whether pretreatment clinical parameters combined with computed tomography can improve the prediction of lymph node metastasis in patients with bladder cancer treated with radical cystectomy. PATIENTS AND METHODS: In a single-center retrospective study, demographic and clinicopathological information (initial transurethral resection [grade, stage, multiplicity of tumors, lymphovascular invasion], hydronephrosis, abdominal and pelvic computed tomography) and the presence of lymph node disease on final pathology of 183 patients with bladder cancer undergoing radical cystectomy and pelvic lymph node dissection were reviewed. Logistic regression and bootstrap methods were used to create an integer score for estimating the risk of positive lymph nodes. Various measures for predictive ability and clinical utility were determined. RESULTS: On pathological examination, 59.6% of patients had positive lymph nodes. In a multivariable analysis, status lymph nodes on computed tomography and hydronephrosis were the most strongly associated predictors. The resultant total possible score ranged from 0 to 10, with a cut-off value of >4 points. The area under the receiver operating characteristic curve was 0.806. Relative integrated discrimination improvement was 14.3%. In the decision curve analysis, the model provided net benefit throughout the entire range of threshold probabilities. However, the final model was roughly equivalent to using the clinical exam. CONCLUSIONS: The pre-cystectomy scoring system improved the prediction of lymph node status in patients with bladder cancer. Our model represented a user-friendly staging aid, but a large multi-center study should be performed before widespread implementation.

Micropapillary carcinoma of the bladder presented with spontaneous intraperitoneal bladder rupture.

Spontaneous bladder perforation is a rare presenting feature of bladder malignancy. We describe an unusual case of a patient, admitted to emergency, with diffuse abdominal pain due to spontaneous bladder rupture in association with a micropapillary carcinoma. A diagnosis of an intraperitoneal bladder perforation was made during an emergency operation. Aspects of etiology, clinical presentation, diagnosis and management are described. Although cases of spontaneous carcinomatous bladder rupture are associated with high morbidity and mortality, prompt identification and treatment can lead to favourable outcomes.

Scoring system development and validation for initial treatment failure in suppurative kidney infections.

BACKGROUND: Suppurative kidney infections (SKIs) have potentially lethal implications and a high incidence of treatment-related morbidity and death. Until this point, there has been no study that has derived a prognostic model for adverse early outcomes in SKI. Therefore, our aim was to derive and validate a simple scoring system of early treatment failure in SKI. METHODS: Logistic regression and bootstrap methods were used to create an integer score for estimating the risk of early treatment failure using patient characteristics, severity of disease, bacterial etiology, type of pathology, initial antibiotic therapy, and early urologic procedures. RESULTS: This study included 92 adult patients with 104 SKIs. Early treatment failure was observed in 57 patients (54.8%). The length of the hospital stay and the treatment complications were significantly longer and more common, respectively, in patients with early treatment failure. The factors associated most strongly with early treatment outcome were whether there had been an early complete urologic procedure, the adequacy of early antibiotic therapy, and the presence or absence of sepsis syndrome. The total possible score ranged from 0 to 22 points, with a cut-off value of 5 points. A score of ≤ 5 points identified early success correctly in 85.3% of patients, whereas a score > 5 points correctly identified early failure in 93.2%. The scoring system retained its predictive ability on the validation set. CONCLUSION: A scoring system was created to predict early treatment failure for a given patient with SKI. Although the system has good performance characteristics and provides a possible intervention measure, further studies should be performed before widespread implementation.

Risk factors for treatment failure in renal suppurative infections.

There are conflicting results of published studies about prognostic value of various factors in purulent renal infections. The purpose of this study was to identify and quantify potential risk factors for early and late treatment failure in such infections. A retrospective review of 75 renal suppurative infections, at three tertiary Serbian Clinics of Urology, was conducted. We considered numerous potential risk factors in a multivariate analysis. This series was comprised of 49 women and 26 men, with mean age of 56.7 years. There were 38 and 37 patients who experienced successful and unfavorable early treatment outcome, respectively. Overall mortality rate was 9.3%. Comorbidity [odds ratio (OR) = 1.6], complex suppurative pathological findings (OR = 3.6), presence of Pseudomonas spp. (OR = 6.7), multiple bacterial strains (OR = 2.7), and positive culture itself (OR = 3.6) were the predictors of poor early prognosis. A urological intervention and presence of pyonephrosis significantly increased the chance for good initial outcome (OR = 0.32 and 0.37, respectively). In the late treatment failure analysis presence of comorbidities (OR = 5.8) and treatment complications (OR = 7.5) significantly increased chance for fatal outcome. Patients' baseline health status and complexity of suppuration itself were the most important predictors of clinical outcomes. Surgical drainage dominated over antimicrobial therapy.

Predictors of surgical site infection in dirty urological surgery.

OBJECTIVES: Risk factors for surgical site infection (SSI) following urologic dirty operations have not been clearly identified. This study was conducted to describe incidence, potential risk factors and common causative pathogens of the SSI in such operations. METHODS: Medical records of patients who had undergone simple nephrectomy or lumbotomy for suppurative renal infection at our institutions from 1999 to 2006 were retrospectively evaluated. The following data were retrieved: presence of SSI, demographic data, laboratory findings, comorbidities, microbiological data, type of renal suppuration, type of urological surgery and antibiotic regimen. Risk factors for SSI were evaluated using the multiple logistic regression model. RESULTS: Sixty-five patients (mean age 55.6 +/- 13.1 years) were eligible for data analysis. In 20 of them (30.8%) a SSI was identified. The most common isolated pathogens were gram-negative bacteria. At univariate logistic regression analysis risk factors significantly associated with SSI included: presence of emphysematous infection, hypoalbuminemia, number of predisposing conditions, emergency operations, isolation of Enterobacteriaceae, positive pus culture. The use of trimethoprim/sulfamethoxazole was associated with a decreased risk for SSI. Multiple logistic model identified only the emergency operations and isolated Enterobacteriaceae as independent predictors of SSI (odds ratio [OR] = 11.1) (95% confidence interval [CI] = 3.0-40.8) and OR = 3.9 (1.0-14.8), respectively. CONCLUSIONS: Patients with suppurative renal infections are submitted to life-saving emergency surgery. Urological surgeons should keep in mind that this carries a high risk for subsequent SSI. Effective preventive measures in these circumstance cannot be identified. Further research in this area is necessary to clarify this issue.