Emergent percutaneous nephrostomy for the diagnosis and management of pyonephrosis

Identification of Calculous Pyonephrosis by CT-Based Radiomics and Deep Learning

Urgent detection of calculous pyonephrosis is crucial for surgical planning and preventing severe outcomes. This study aims to evaluate the performance of computed tomography (CT)-based radiomics and a three-dimensional convolutional neural network (3D-CNN) model, integrated with independent clinical factors, to identify patients with calculous pyonephrosis. We recruited 182 patients receiving either percutaneous nephrostomy tube placement or percutaneous nephrolithotomy for calculous hydronephrosis or pyonephrosis. The regions of interest were manually delineated on plain CT images and the CT attenuation value (HU) was measured. Radiomics analysis was performed using least absolute shrinkage and selection operator (LASSO). A 3D-CNN model was also developed. The better-performing machine-learning model was combined with independent clinical factors to build a comprehensive clinical machine-learning model. The performance of these models was assessed using receiver operating characteristic analysis and decision curve analysis. Fever, blood neutrophils, and urine leukocytes were independent risk factors for pyonephrosis. The radiomics model showed higher area under the curve (AUC) than the 3D-CNN model and HU (0.876 vs. 0.599, 0.578; p = 0.003, 0.002) in the testing cohort. The clinical machine-learning model surpassed the clinical model in both the training (0.975 vs. 0.904, p = 0.019) and testing (0.967 vs. 0.889, p = 0.045) cohorts.

Machine learning constructs a diagnostic prediction model for calculous pyonephrosis

In order to provide decision-making support for the auxiliary diagnosis and individualized treatment of calculous pyonephrosis, the study aims to analyze the clinical features of the condition, investigate its risk factors, and develop a prediction model of the condition using machine learning techniques. A retrospective analysis was conducted on the clinical data of 268 patients with calculous renal pelvic effusion who underwent ultrasonography-guided percutaneous renal puncture and drainage in our hospital during January 2018 to December 2022. The patients were included into two groups, one for pyonephrosis and the other for hydronephrosis. At a random ratio of 7:3, the research cohort was split into training and testing data sets. Single factor analysis was utilized to examine the 43 characteristics of the hydronephrosis group and the pyonephrosis group using the T test, Spearman rank correlation test and chi-square test. Disparities in the characteristic distributions between the two groups in the training and test sets were noted. The features were filtered using the minimal absolute value shrinkage and selection operator on the training set of data. Auxiliary diagnostic prediction models were established using the following five machine learning (ML) algorithms: random forest (RF), xtreme gradient boosting (XGBoost), support vector machines (SVM), gradient boosting decision trees (GBDT) and logistic regression (LR). The area under the curve (AUC) was used to compare the performance, and the best model was chosen. The decision curve was used to evaluate the clinical practicability of the models. The models with the greatest AUC in the training dataset were RF (1.000), followed by XGBoost (0.999), GBDT (0.977), and SVM (0.971). The lowest AUC was obtained by LR (0.938). With the greatest AUC in the test dataset going to GBDT (0.967), followed by LR (0.957), XGBoost (0.950), SVM (0.939) and RF (0.924). LR, GBDT and RF models had the highest accuracy were 0.873, followed by SVM, and the lowest was XGBoost. Out of the five models, the LR model had the best sensitivity and specificity is 0.923 and 0.887. The GBDT model had the highest AUC among the five models of calculous pyonephrosis developed using the ML, followed by the LR model. The LR model was considered be the best prediction model when combined with clinical operability. As it comes to diagnosing pyonephrosis, the LR model was more credible and had better prediction accuracy than common analysis approaches. Its nomogram can be used as an additional non-invasive diagnostic technique.

Ultrasound-Guided Pigtail Catheter Drainage: An Effective Alternative to Exploratory Laparotomy

Introduction It has been long established that open surgeries were the only options available for the management of intra-abdominal abscesses or collections. These were associated with increased morbidity and mortality. Traditionally, the idea of percutaneous needling could not gain popularity due to poor localization of collections. However, with the advent of ultrasound, percutaneous pigtail-catheter drainage has proven to be minimally invasive and allows precise localization of the drainage site. Objectives To study the effectiveness of ultrasound-guided pigtail catheter drainage as an alternative to exploratory laparotomy for the management of intra-abdominal abscesses or collections. Materials and methods A total of 48 patient cases, which included liver abscesses, perinephric collections, malignant ascites, splenic collections, pseudocysts, and psoas abscesses, were studied prospectively in a medical college in India from October 2020 to October 2021. The efficacy of the drainage was assessed by serial ultrasound. Results Out of 48 patients, 34 were male and 14 were female, ranging in age from 19 to 64 years, who were diagnosed with intra-abdominal abscesses or collections and underwent ultrasound-guided pigtail catheter drainage. The average hospital stay for patients was 2.5 days. They were followed up periodically for three months post-procedure, and none had significant complications or recurrence. Conclusion The pigtail catheter is the treatment of choice for liquefied intra-abdominal collections or abscesses, which helps to reduce post-procedure hospital stays and complications. Contribution This article reiterates the use of minimally invasive techniques in place of open surgeries with less morbidity.

Imaging of renal emergencies: Review of infectious, hemorrhagic, vascular, and traumatic etiologies

Diagnostic imaging allows for accurate and early recognition of acute renal pathologies, thus allowing for appropriate clinical triage, life-saving treatments, and preservation of renal function. In this review, we discuss the clinical presentation and imaging findings of renal emergencies with infectious, hemorrhagic, vascular, and traumatic etiologies.

Establishment of a Percutaneous Nephrostomy Service to Treat Obstructive Uropathy Secondary to Cervical Cancer in Tanzania

Background Cervical cancer is the fourth most common cancer among women globally. Age-standardized cervical cancer mortality is higher in East Africa than anywhere else in the world. Prior to October 2018, patients presenting with obstructive uropathy secondary to late-stage cervical cancer in Tanzania who were no longer eligible for palliative chemoradiation therapy were discharged home without intervention. The purpose of this study was to evaluate whether the establishment of a percutaneous nephrostomy service in a quaternary hospital in Dar es Salaam, Tanzania, a resource-limited country, benefits patients who have late-stage cancer induced obstructive uropathy.

Materials and Methods A retrospective study was performed on patients who presented with obstructive uropathy secondary to late-stage cervical cancer and have undergone percutaneous nephrostomy at Muhimbili National Hospital and Ocean Road Cancer Institute from October 2018 to May 2021. Twenty-one interventional radiology (IR) teaching teams consisting of IR attendings, IR technologists, and nurses travelled to Tanzania from North America on monthly 2-week trips during that period. A review of preprocedural, procedural, and follow-up data was performed using Research Electronic Data Capture. Statistical analysis and comparison were performed on patients' creatinine levels preprocedure, 7 days and 30 days postprocedure.

Results Sixty-two patients qualified to be included in this study. In addition to the initial 62 nephrostomy placements, 14 follow-up procedures were performed either under visiting faculty supervision or independently by the Tanzanian IR fellows. Technical success rate was 98.7%. Complications (SIR Class A and B) occurred in eight cases. The average preprocedure creatinine (1051.48 ± 704.08µmol/L) decreased by 59% 7 days postprocedure and by 77% 30 days postintervention. Postprocedural clinical information was obtained for 28 (45.2%) patients and 18 were able to restart chemotherapy following nephrostomy.

Conclusion Prior to 2018, percutaneous nephrostomy placement was not available in Tanzania. This study presented the initial safety, technical feasibility, and clinical benefit of establishing a percutaneous nephrostomy service in such a resource-limited setting.

Machine learning-assisted decision-support models to better predict patients with calculous pyonephrosis

Background

To develop a machine learning (ML)-assisted model capable of accurately identifying patients with calculous pyonephrosis before making treatment decisions by integrating multiple clinical characteristics.

Methods

We retrospectively collected data from patients with obstructed hydronephrosis who underwent retrograde ureteral stent insertion, percutaneous nephrostomy (PCN), or percutaneous nephrolithotomy (PCNL). The study cohort was divided into training and testing datasets in a 70:30 ratio for further analysis. We developed 5 ML-assisted models from 22 clinical features using logistic regression (LR), LR optimized by least absolute shrinkage and selection operator (Lasso) regularization (Lasso-LR), support vector machine (SVM), extreme gradient boosting (XGBoost), and random forest (RF). The area under the curve (AUC) was applied to determine the model with the highest discrimination. Decision curve analysis (DCA) was used to investigate the clinical net benefit associated with using the predictive models.

Results

A total of 322 patients were included, with 225 patients in the training dataset, and 97 patients in the testing dataset. The XGBoost model showed good discrimination with the AUC, accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 0.981, 0.991, 0.962, 1.000, 1.000, and 0.989, respectively, followed by SVM [AUC =0.985, 95% confidence interval (CI): 0.970–1.000], Lasso-LR (AUC =0.977, 95% CI: 0.958–0.996), LR (AUC =0.936, 95% CI: 0.905–0.968), and RF (AUC =0.920, 95% CI: 0.870–0.970). Validation of the model showed that SVM yielded the highest AUC (0.977, 95% CI: 0.952–1.000), followed by Lasso-LR (AUC =0.959, 95% CI: 0.921–0.997), XGBoost (AUC =0.958, 95% CI: 0.902–1.000), LR (AUC =0.932, 95% CI: 0.878–0.987), and RF (AUC =0.868, 95% CI: 0.779–0.958) in the testing dataset.

Conclusions

Our ML-based models had good discrimination in predicting patients with obstructed hydronephrosis at high risk of harboring pyonephrosis, and the use of these models may be greatly beneficial to urologists in treatment planning, patient selection, and decision-making.

Hounsfield unit attenuation value can differentiate pyonephrosis from hydronephrosis and predict septic complications in patients with obstructive uropathy

We aimed to assess the role of computerized tomography attenuation values (Hounsfield unit-HU) for differentiating pyonephrosis from hydronephrosis and for predicting postoperative infectious complications in patients with obstructive uropathy. We analysed data from 122 patients who underwent nephrostomy tube or ureteral catheter placement for obstructive uropathy. A radiologist drew the region of interest for quantitative measurement of the HU values in the hydronephrotic region of the affected kidney. Descriptive statistics and logistic regression models tested the predictive value of HU determination in differentiating pyonephrosis from hydronephrosis and in predicting postoperative sepsis. A HU cut-off value of 6.3 could diagnose the presence of pyonephrosis with 71.6% sensitivity and 71.5% specificity (AUC 0.76; 95%CI: 0.66-0.85). At multivariable logistic regression analysis HU ≥ 6.3 (p ≤ 0.001) was independently associated with pyonephrosis. Patients who developed sepsis had higher HU values (p ≤ 0.001) than those without sepsis. A HU cut-off value of 7.3 could diagnose the presence of sepsis with 76.5% sensitivity and 74.3% specificity (AUC 0.79; 95%CI: 0.71-0.90). At multivariable logistic regression analysis, HU ≥ 7.3 (p ≤ 0.001) was independently associated with sepsis, after accounting for clinical and laboratory parameters. Measuring HU values of the fluid of the dilated collecting system may be useful to differentiate pyonephrosis from hydronephrosis and to predict septic complications in patients with obstructive uropathy.

Community Acquired Urosepsis: A surgical intensive care Experience

Urosepsis contributes significantly to the epidemiology of sepsis. Urosepsis can be classified as community acquired or hospital acquired, depending upon the origin of infection acquisition: either from the community or from a healthcare facility. A great deal of literature is available about nosocomial urosepsis, but the literature regarding community-acquired urosepsis (CAUs) is limited, and studies are underpowered. The aim of our study was to determine the epidemiology, bacteriology, severity, and outcome of CAUs. Methods and Patients: All patients admitted from the emergency department to the surgical intensive care unit (SICU) with urosepsis over a period of 10 years were identified and included retrospectively from the SICU registry. The study was retrospective. Data were entered into the SPSS program version 23, and groups were compared by using chi-square and t-tests. Results were considered statistically significant at p ≤ 0.05. Results: During the study period, 302 patients with CAUs were admitted to the SICU. The common etiology was obstructive uropathy (60%). The Local Arab population outnumbered the non-Arab population (164/54.3%), and there were equal numbers of patients of both genders. Diabetes mellitus and hypertension together were the common comorbidities. Seventy-five percent of patients had acute kidney injury (AKI). Thirty-eight percent of patients had percutaneous nephrostomy, and 24.8% of patients underwent endoscopic stent insertion to relieve the obstruction. Ninety-three percent of patients were admitted with septic shock, and 71.5% had bacteremia. The common bacteria (36.1%) was extended-spectrum beta-lactamase-(ESBL)-producing bacteria, with a predominance of Escherichia coli (31.5%). Fifty-four percent of patients required a change of antibiotics to carbapenem. Eighty-two percent of patients had acute respiratory distress syndrome (ARDS). Patients with bacteremia had a statistically significant AKI, ARDS, and septic shock (p < 0.001). Male patients had a significantly higher incidence of oliguria, intubation, and ARDS (p < 0.05). Eight patients died of urosepsis during the study period, giving a mortality rate of 2.6%. Conclusion: In our patients, obstruction of urine flow was the most common cause of CAUs. Our urosepsis patients had a higher bacteremia rate, which led to higher incidences of organ dysfunction and septic shock. ESBL bacteria were a frequent cause of urosepsis, requiring a change of the initial antibiotic to carbapenem. Male patients had a significantly higher rate of organ dysfunction. Mortality in our urosepsis patients was lower than mentioned in the literature.

Emergent Percutaneous Nephrostomy for Pyonephrosis: A Primer for the On-Call Interventional Radiologist

Pyonephrosis is gross accumulation of pus within an obstructed renal collecting system that, if left untreated, can lead to potentially fatal septic shock. Treatment requires urgent decompression coupled with systemic antibiotics. Percutaneous nephrostomy (PCN) placement, first described in 1976 for the treatment of pyonephrosis, is now widely utilized for emergent decompression in these patients. When performed by an experienced interventional radiologist, PCN is a safe procedure with technical success rates of over 96 to 99%. This article will address the clinical presentation of pyonephrosis, and will discuss the indications, technique, complications, and outcomes of emergent PCN placement. Additionally, the expanded indications for PCN placement in nonemergent scenarios will also be described.

Identifying emergency pathology on abdominopelvic CT for non-radiologists

Abdominal and pelvic computed tomography (CT) scans can be complex to interpret but sometimes significant abnormalities are relatively easy to recognize. In emergencies it is beneficial if physicians and surgeons can identify significant pathology that may immediately change patient management. Early image interpretation will allow clinicians to alert radiologists to provide prompt urgent reports, facilitate early referral to other specialities or expedite emergency surgery. This article provides non-radiologists with a systematic approach to identifying emergency pathology on abdominal and pelvic CT scans. It reviews the relevant cross-sectional anatomy and discusses the CT appearances of bowel perforation, bowel obstruction, bowel ischaemia (gangrene), bleeding, appendicitis and hydronephrosis using illustrative examples from the authors' clinical practice. Underlying causes for these conditions and the importance of interpreting the radiological appearances in conjunction with the patient's clinical condition and history are discussed. The authors hope that by using the POGBAH acronym and a systematic approach readers will be able to identify emergency pathology on abdominal and pelvic CT which may improve patient care.

Development and validation of a risk-prediction nomogram for patients with ureteral calculi associated with urosepsis: A retrospective analysis

Objectives

To develop and validate an individualized nomogram to predict probability of patients with ureteral calculi developing into urosepsis.

Methods

The clinical data of 747 patients with ureteral calculi who were admitted from June 2013 to December 2015 in Affiliated Nanhai Hospital of Southern Medical University were selected and included in the development group, while 317 ureteral calculi patients who were admitted from January 2016 to December 2016 were included in the validation group. The independent risk factors of ureteral calculi associated with urosepsis were screened using univariate and multivariate logistic regression analyses. The corresponding nomogram prediction model was drawn according to the regression coefficients. The area under the receiver operating characteristic curves and the GiViTI calibration belts were used to estimate the discrimination and calibration of the prediction model, respectively.

Results

Multivariate logistic regression analysis showed that the five risk factors of gender, mean computed tomography(CT) attenuation value of hydronephrosis, functional solitary kidney, urine white blood cell(WBC) count and urine nitrite were independent risk factors of ureteral calculi associated with urosepsis. The areas under the receiver operating characteristic curve of the development group and validation group were 0.913 and 0.874 respectively, suggesting that the new prediction model had good discrimination capacity. P-values of the GiViTI calibration test of the two groups were 0.247 and 0.176 respectively, and the 95% CIs of GiViTI calibration belt in both groups did not cross the diagonal bisector line. Therefore the predicted probability of the model was consistent with the actual probability which suggested that the calibration of the prediction model in both groups were perfect and prediction model had strong concordance performance.

Conclusion

The individualized prediction model for patients with ureteral calculi can facilitate improved screening and early identification of patients having higher risk of urosepsis.

Obstruction of the Biliary and Urinary System

Biliary and urinary obstructions can be managed endoscopically or cystoscopically, surgically or by percutansous intervention or drainage. If the obtructed system is infected, emergent decompression is needed. Early recognition and treatment is paramount in both conditions. Acute cholangitis can present many different ways, from mild symptoms to fulminant sepsis. It is usually a result of ascending bacterial colonization and biliary obstruction resulting in bacterial overgrowth. Therefore, those patients with recent biliary instrumentation or previous biliary modification are at higher risk. Charcot's triad of fever, right upper quadrant abdominal pain, and jaundice is only seen in 50%-70% of patients. Fever is seen in over 90% of cases, pain is seen in 70% of cases, and jaundice is seen in 60% of cases. Altered mental status and hypotension are associated with severe cases. All 5 symptoms of fever, right upper quadrant abdominal pain, jaundice, altered mental status, and hypotension are referred to as Reynold's Pentad. Acute pyonephrosis can also present many different ways, from minimal symptoms to fulminant sepsis. Fever, chills, and flank pain are the classic symptoms, although some patients may be relatively asymptomatic. Pyonephrosis may present with a classic triad of fever, flank pain, and hydronephrosis, or simply hydronephrosis and sepsis. Pyonephrosis usually occurs as a result of urinary obstruction with either an ascending infection of the urinary tract or hematogenous spread of a bacterial pathogen as the culprit. Up to 75% of cases are related to urinary stone disease. Patients are at increased risk for pyonephrosis when they haven anatomic urinary tract obstruction, certain chronic diseases (diabetes meliitus and AIDS), or are immunosuppressed due to immunodeficiency or medications, (chronic steroid therapy).

[Comparison of results of open simple nephrectomy secondary to lithiasis in patients with and without nephrostomy]

BACKGROUND

Simple nephrectomy is the procedure of choice in the treatment of excluded kidneys. The purpose of this study was to describe and compare surgical results in open simple retroperitoneal nephrectomies in patients with and without nephrostomy.

METHODOLOGY

58 patients were analyzed. The demographic parameters of patients with nephrostomy were compared to patients without nephrostomy (age, gender, weight, lithium localization, transoperative variables (surgical time, transoperative bleeding) and postoperative variables (need for intensive care, need for transfusion, surgical wound infection and hospital stay days) RESULTS: Statistically significant differences were found for the variables of operative bleeding (p=0.0442), surgical time (p=0.0093), hospital stay days (p=0.0040), and transfusion requirements (p=0.0170). There were no differences in the need for intensive care (p=0.6314), transoperative complications (p=0.7414) and surgical wound infection (p=0.2762).

CONCLUSIONS

The presence of a nephrostomy catheter in patients undergoing open simple nephrectomy leads to an increased risk of morbidity, with increased bleeding, surgical time, need for transfusion, and hospital stay days.

Computerized tomography attenuation values can be used to differentiate hydronephrosis from pyonephrosis

PURPOSE

To determine the diagnostic value of computerized tomography (CT) in differentiating pyonephrosis from hydronephrosis on the basis of attenuation values (Hounsfield unit-HU).

METHODS

Data of the patients with grades 1-3 hydronephrosis on abdominopelvic CT, who underwent nephrostomy tube placement for decompression of the collecting system, were retrospectively analyzed. Patient demographics and CT findings were recorded along with the first access urine culture results. Three physicians calculated the surface areas and the attenuation values of the dilated collecting systems using the system software. Mean HU of pyonephrosis and hydronephrosis cases was compared.

RESULTS

A total of 105 patients with the mean age of 47.7 ± 15.5 (range 20-80) were included. The interclass correlation coefficient of three physicians was 0.981 for HU measurement and 0.999 for calculation of collecting system surface area. Of the patients, 47 (44.8 %) had pyonephrosis. Mean surface areas of the collecting system were similar in patients with pyonephrosis and hydronephrosis (1481.13 ± 1562.94 vs. 1612.94 ± 2261.4 mm², p = 0.735). Urine cultures were positive in all patients with pyonephrosis, whereas 12.7 % of hydronephrosis cases had bacterial in first access urine culture. The HU of the patients with pyonephrosis was significantly higher that that of patients with hydronephrosis (13.51 ± 13.29 vs. 4.67 ± 5.37, p = 0.0001). Having a HU of 9.21 or over diagnosed pyonephrosis accurately with 65.96 % sensitivity and 87.93 % specificity.

CONCLUSION

Measuring attenuation values of the collecting system may be useful to differentiate pyonephrosis from hydronephrosis. Diagnosing pyonephrosis accurately may avoid septic complications.

Urinary Drainage Procedures in Interventional Radiology

Urinary drainage procedures are used to treat a wide range of clinical situations including pyonephrosis, preservation of renal function in patients with ureteral obstruction, as a means to access the collecting system for stone retrieval or lithotripsy and to divert urine from a distal leak or fistula. Several different drainage devices are available and include those that provide obligatory external drainage (nephrostomy), both internal and external drainage (nephroureteral stent) and internal drainage (double-J stent). Each device requires some maintenance and effort on the patient's part-from having to undergo routine exchange of double-J stents every 3-6 months to the daily management of an external catheter and drainage bag. Ideally, the desired outcome can be attained with minimal effect on patient lifestyle. In this article, we present our approach to patients who require urinary drainage, with a focus on choosing and placing the most appropriate device in a variety of clinical scenarios.

Retrograde ureteric stent insertion in the management of infected obstructed kidneys

OBJECTIVES

To quantify the outcomes of retrograde ureteric stenting in the setting of infected hydronephrosis secondary to ureteric calculi.

PATIENTS AND METHODS

Prospective analysis of all patients over a 15-month period admitted with infected obstructed kidneys secondary to ureteric calculi. Inclusion criteria were based on clinical evidence of systemic inflammatory response syndrome (SIRS) and radiological evidence of obstructing ureteric calculi. Outcome measures included success of procedure, admission to intensive care unit (ICU), length of hospital stay, morbidity, and all-cause mortality during hospital admission.

RESULTS

In all, 52 patients were included. Success of retrograde ureteric stenting was 98%. In all, 17% of patients required an ICU admission, with a post ureteric instrumentation ICU admissions rate of 6%. The mean white cell count and serum creatinine improved significantly after the procedure. Major complication rate included septic shock 6%, but there were no episodes of major haemorrhage and no deaths.

CONCLUSION

Retrograde ureteric stenting is safe and effective in infected obstructed kidneys with results comparable to percutaneous nephrostomy tube insertion. Post instrumentation ICU admissions occur in 6% of retrograde stentings.

Long-Term Results after Acute Therapy of Obstructive Pyelonephritis

Introduction: To evaluate therapeutic results till 5 years after therapy of obstructive pyelonephritis (OPN) emphasizing regular follow-up. Material and Methods: During 5 years, 57 patients with OPN were treated. The patients' charts were reviewed retrospectively for clinical data. These were completed by a questionnaire. Results: In the group of 57 patients (average age 56 years), about two third were women. Urolithiasis (65%) and tumors (21%) were the main causes of obstruction; fever (91%) and loin pain (86%) the main symptoms. Three fourth of the patients showed renal insufficiency and nearly 50% anemia. E. coli and Proteus spp. were the dominating organisms. Sonography detected obstruction in 93% cases. In one third of cases, CT scan was added; 81% percutaneous nephrostomy and 19% ureteral stenting were the initial methods of urinary drainage. During therapy, 23% nephrectomies (19% complete, 4% partial) were performed. Long-term follow-up showed 11% recurrent OPN and 33% recurrent UTI. Conclusions: After diagnosis of OPN, primary nephrostomy or ureteral stenting and antibiotic therapy are the first measures. If recurrent urinary tract infections or OPN occur, long-term follow-up and low-dose antibiotic prophylaxis may be discussed.