Predicting oxygen tension along the ureter

Continuous measurement of bladder urine oxygen tension (PO2) is a new method to potentially detect renal medullary hypoxia in patients at risk of acute kidney injury (AKI). To assess its practicality, we developed a computational model of the peristaltic movement of a urine bolus along the ureter and the oxygen exchange between the bolus and ureter wall. This model quantifies the changes in urine PO2 as it transits from the renal pelvis to the bladder. The model parameters were calibrated using experimental data in rabbits, such that most of the model predictions are within ± 1 standard error (SEM) of the reported mean in the experiment, with the average percentage difference being 7.0%. Based on parametric studies performed using a model scaled to the geometric dimensions of a human ureter, we found that bladder-urine PO2 is strongly dependent on the bolus volume (i.e. bolus volume-to-surface area ratio), especially at a volume less than its physiological (baseline) volume (<0.2 ml). For the model assumptions, changes in peristaltic frequency resulted in a minimal change in bladder-urine PO2 (< 1 mmHg). The model also predicted there exists a family of linear relationships of the bladder-urine PO2 and the pelvic-urine PO2 for different input conditions. We conclude that it may technically be possible to predict renal medullary PO2 based on the measurement of bladder-urine PO2, provided there are accurate real-time measurements of model input parameters.

Urine neutrophil gelatinase-associated lipocalin (NGAL) measurement is not predictive for ureteral patency in pediatric patients following pyeloplasty: a pilot study

Objective: To evaluate the benefit of urine neutrophil gelatinase-associated lipocalin (NGAL) measurement to predict the ureteral patency in pediatric patients undergoing pyeloplasty. Materials and Methods: Ureteropelvic junction obstruction patients who underwent unilateral dismembered pyeloplasty had urine NGAL measurements taken intraoperatively during pyeloplasty and postoperatively at six months following surgery. All patients were evaluated preoperatively and postoperatively with renal scans. Pairwise comparisons and correlation analyses were performed to determine the dynamics and benefits of urine NGAL measurement. Results: Thirteen patients were included in this pilot study with a mean age of 3.2 years at surgery. Mean intraoperative bladder urine level was 4.43 ng/mL, and median intraoperative renal pelvic urine NGAL level was 3.70 ng/mL. There was no significant difference between these two levels (p-value = 0.76). Six months after pyeloplasty, 9/13 patients demonstrated significant reduction in the bladder urine NGAL level (at least 50% reduction), and 5/13 patients showed ureteral patency based on postoperative renal scan (more than 5% improvement in differential renal function or the conversion of diuretic half time. However, the finding of significant reduction of urine NGAL level did not correlate with ureteral patency (r = -0.50, p-value = 0.08). Conclusion: Although bladder urine NGAL level reduces in most pediatric patients following pyeloplasty, this decline is not reflective of the finding of ureteral patency from renal scanning. The benefits of urine NGAL measurement in this context remain unclear and require further large-scale investigation.

Urinary miRNA profiles discriminate between obstruction-induced bladder dysfunction and healthy controls

Urgency, frequency and incomplete emptying are the troublesome symptoms often shared between benign prostatic obstruction-induced (BLUTD) and neurogenic (NLUTD) lower urinary tract dysfunction. Previously, using bladder biopsies, we suggested a panel of miRNA biomarkers for different functional phenotypes of the bladder. Urine is a good source of circulating miRNAs, but sex- and age-matched controls are important for urinary metabolite comparison. In two groups of healthy subjects (average age 32 and 57 years old, respectively) the total protein and RNA content was very similar between age groups, but the number of secreted extracellular vesicles (uEVs) and expression of several miRNAs were higher in the young healthy male volunteers. Timing of urine collection was not important for these parameters. We also evaluated the suitability of urinary miRNAs for non-invasive diagnosis of bladder outlet obstruction (BOO). A three urinary miRNA signature (miR-10a-5p, miR-301b-3p and miR-363-3p) could discriminate between controls and patients with LUTD (BLUTD and NLUTD). This panel of representative miRNAs can be further explored to develop a non-invasive diagnostic test for BOO. The age-related discrepancy in the urinary miRNA content observed in this study points to the importance of selecting appropriate, age-matched controls.

The Effect of the Duration between Preoperative Bladder Urine Culture and Semirigid Ureteroscopic Lithotripsy on the Rate of Systemic Inflammatory Response Syndrome Postoperatively

Purpose The aim of this study is to analyze the preoperative and intraoperative factors that might induce systemic inflammatory response syndrome (SIRS) after semirigid ureteroscopic lithotripsy (SUL), and to evaluate the impact of duration between preoperative bladder urine culture (PBUC) and surgery on postoperative systemic inflammatory response syndrome (SIRS). Methods A retrospective review was conducted including patients who underwent SUL in our center between June 2015 and June 2020. Prior to surgery, PBUC were obtained from all patients and postoperatively patients were observed for signs of SIRS. Univariable and multivariable binary logistic regression analysis were implemented to demonstrate the factors that predict SIRS postoperatively. Results The entire study included a cohort of 572 patients. The rate of SIRS following SUL was 1.7%. Predictive factors for SIRS were listed as stone volume, surgical time, and history of recurrent urinary tract infection. No significant difference was detected in terms of the duration between PBUC and SUL when comparing the SIRS group with the other group. Conclusion The duration between PBUC and SUL is not efficacious factor for SIRS. It may be useful to conduct prospective studies to enlighten this issue as endourologists deal with this duration dilemma often in daily practice. Keywords: Semirigid ureteroscopic lithotripsy, Systemic inflammatory response syndrome, Preoperative bladder urine culture.

Should renal pelvic urine culture be obtained routinely in flexible ureterorenoscopy?

Background: Preoperative bladder urine culture (PBUC) analysis has become a standard application before any stone surgery. When growth is detected in PBUC, it is contraindicated to perform flexible ureterorenoscopy (f-URS). The results of the PBUC susceptibility test do not correlate well with those of the renal pelvic urine culture (RPUC) analysis. Previous studies have demonstrated the positivity of RPUC as an important marker for the development of infections after endoscopic operations. In the current study, we aimed to evaluate the consistency between PBUC and RPUC and to identify preoperative markers associated with a positive RPUC. Methods: Data from 129 patients who underwent f-URS on renal and proximal ureteral stones in two centers between 2015 and 2020 were prospectively recorded in a database and retrospectively analyzed. PBUC was obtained from all the patients preoperatively, and RPUC was taken at the beginning of the f-URS operation. The results of the two cultures were compared. Results: There was growth in PBUC in 25 (19.4%) patients and RPUC in 35 (27.1%) patients. Possible predictive markers in predicting a positive RPUC were evaluated using multivariate logistic regression analysis. Preoperative urine density at the renal pelvis [odds ratio (OR): 0.848, p<0.001],grade≥2 hydronephrosis (OR:18.970,p=0.001), and lower calyceal stone localization (OR:0.033,p=0.017) were determined as independent predictive factors for a positive RPUC. The ability of pelvis urine density to predict positive RPUC positivity was evaluated using the receiver operating characteristic analysis, in which the area under the curve value was determined to be 0.858 (0.780-0.936). The cut-off value of pelvis urine density in the prediction of RPUC positivity was 4.5, at which it had 80% sensitivity and 77.7% specificity. Conclusions: PBUC may not represent true colonization. Although bladder urine culture is negative before the operation, patients with preoperative hydronephrosis and low pelvis urine density may have RPUC growth.

The effect of the duration between urine culture and semirigid ureteroscopic on the rate of systemic inflammatory response syndrome postoperatively

Purpose: The aim of this study is to analyze the preoperative and intraoperative factors that might induce systemic inflammatory response syndrome after semirigid ureteroscopic lithotripsy (SULL) , and to evaluate the impact of duration between preoperative bladder urine culture (PBUC) and surgery on postoperative systemic inflammatory response syndrome (SIRS). Methods: A retrospective review was conducted including patients who underwent SULL in our center between January 2011 and June 2020. Prior to surgery, PBUC were obtained from all patients and postoperatively patients were observed for signs of SIRS. Univariable and multivariable binary logistic regression analysis were implemented to demonstrate the factors that predict SIRS postoperatively. Results: The entire study included a cohort of 572 patients. The rate of SIRS following SULL was 1.7%. Predictive factors for SIRS were listed as stone volume, surgical time, and history of recurrent urinary tract infection. No significant difference was detected in terms of the duration between PBUC and SULL when comparing the SIRS group with the other group. Conclusion: The duration between PBUC and SULL is not an efficacious factor for SIRS. It may be useful to conduct prospective studies to enlighten this issues as endourologists deal with this duration dilemma often in daily practice. Keywords: Semirigid ureteroscopic lithotripsy, Systemic inflammatory response syndrome, Preoperative bladder urine culture

The pelvis urinary microbiome in patients with kidney stones and clinical associations

Background The long-held notion that, without urinary tract or circulatory infection, bladder urine and blood are sterile biofluids has been disproven. There have been no previous reports on the kidney pelvis urinary microbiome after bladder disinfection in kidney stone patients. This study aimed to determine whether a kidney pelvis urinary microbiome is present after eliminating the influence of the bladder urinary microbiome, whether the microbiome composition is different in patients with stone kidney pelvis (SKP) and non-stone kidney pelvis (NSKP), and the correlation between SKP and patient clinical characteristics. Results Comparisons of bacterial diversity and community structure exhibited that urine in bladder was similar to SKP and NSKP. However, the comparisons showed that urine samples were different from blood. The most common operational taxonomic units were shared by all three types of urine samples. Corynebacterium was significantly higher in SKP compared to NSKP. Several bacteria were associated with patient characteristics, including Lactobacillus, which was positively correlated with fasting blood glucose, and Prevotella was negatively correlated with BMI. Lactobacillus was significantly higher in SKP compared to blood but not in NSKP compared to blood. Conclusions The composition of the kidney pelvis urinary microbiome after disinfection of the bladder and its similarity to the bladder microbiome indicate that bladder urine can be used to replace kidney pelvis urine in microbiome research. Additionally, the comparison of SKP and NSKP and clinical associations suggest that the occurrence of kidney stones is responsible for the SKP urinary microbiome.

A prospective Comparative Clinical Study on Bladder Urine, Pelvic Urine and Renal Stone Culture & Sensitivity in Predicting Urosepsis Following Percutaneous Nephrolithotomy

Background: Urosepsis means a severe infection of urinary tract (UTI) and/or male genital tract (prostate) with features consistent with systemic inflammatory response syndrome. UTI may occur among all the age groups and produce a broad range of clinical syndromes ranging from asymptomatic bacteriuria to acute pyelonephritis with gram negative sepsis to septic shock. It is estimated that the mortality rate due to urosepsis ranges from 30 to 40 p.c respectively. Urosepsis may also cause multiple organ dysfunction, hypoperfusion or hypotension. Urosepsis due to percutaneous nephrolithotomy may be catastrophic despite prophylactic antibiotic coverage and negative midstream urine culture and sensitivity testing (C&S) and bacteria in the stone can be responsible for systemic infection. The aim of the study is to compare bladder urine (culture & sensitivity) and collecting system urine and stone (culture and sensitivity) in predicting urosepsis following percutaneous nephrolithotomy. Subjects and Methods: A hospital-based, analytical prospective clinical study was conducted among thirty cases who were present during the study period and had undergone percutaneous nephrolithotomy (PCNL). Cases were included irrespective of gender with renal calculi in whom percutaneous nephrolithotomy was about to be done at Narayana Medical College & Hospital, Chintareddypalem, Nellore, Andhra Pradesh during 1st February 2014 to 31st January 2015. Data collected was divided into three main groups Midstream urine (C&S); Pelvic urine (C&S); and Stone (C&S) respectively. Data obtained was entered in Microsoft Excel-2013 and analyzed in SPSS version-22 trial. Appropriate statistical tests were applied and p-value less than 0.05 was considered as significant. Results: Bladder urine (C&S) was positive in 3/30 (10.00%) patients, Pelvic urine (C&S) in 5/30 (16.66 %) patients and Stone (C&S) in 8/30 (26.66 %) patients. Most of the infected specimens grew Escherichia coli followed by pseudomonas, klebsiella, enterococcus. Systemic Inflammatory Response Syndrome (SIRS) was reported among 26.7 p.c (8) of the patients. In one patient (3.33%) septic shock developed but no deaths were reported. Conclusion: Stone (C&S) and Pelvic urine (C&S) are better predictors of urosepsis than Bladder urine (C&S).

The Comparable Results of Minimally Invasive Therapy versus Primary Anastomosis in the Management of Partial Posterior Urethral Stricture

BACKGROUND: Urinary retention has many etiologies. One of them is urethral stricture or the narrowing of urethral lumen due to fibrotic tissue. Urethral stricture is considered a medical emergency condition because it might cause complications in some extent. At present, there are several surgical techniques introduced with their advantages and disadvantages. AIM: The study aimed to compare the outcome of minimal invasive therapy (MIT) or excision and primary anastomosis (EPA) techniques. METHODS: A retrospective cohort study was performed on patients with partial posterior urethral stricture. The inclusion criteria were all patients with partial posterior urethral stricture who underwent MIT or EPA from 2014 to 2018. The data of International Prostate Symptom Score (IPSS), quality of life (QoL), urinary peak flow rate (Qmax), urine residue, erection hardness score, clean intermittent catheterization (CIC), recurrence, and penile perception scores (PPS) were obtained and analyzed postoperatively. RESULTS: Thirty-four patients included in the study, consisted of 17 patients for each group. EPA group showed significantly superior to MIT in Qmax (p < 0.001), CIC (p = 0.007), and PPS score (p = 0.003). However, no significance differences were found in QoL (p = 0.071), IPSS score (p = 0.083), bladder urine residue (p = 0.688), recurrence (p = 0.225), and erectile function (p = 0.303). CONCLUSION: EPA may be superior to MIT in some aspect. However, other advantages of MIT could be outweighed EPA techniques, such as QoL, IPSS, bladder urine residual, stricture recurrence, and erectile function. MIT still has a place to be the first-line management of partial posterior urethral stricture.