Severe post-renal acute kidney injury, post-obstructive diuresis and renal recovery

Ultrathin semirigid retrograde ureteroscopy versus antegrade flexible ureteroscopy in treating proximal ureteric stones 1-2 cm, a prospective randomized multicenter study

To compare the outcomes of using Ultrathin semirigid retrograde ureteroscopy and antegrade flexible ureteroscopy to treat proximal ureteric stones of sizes 1-2 cm. A prospective randomized multicenter study included patients who had proximal ureteric stones 1-2 cm, amenable for ureteroscopy and laser lithotripsy between August 2023 and February 2024. Two hundred thirty patients were divided evenly into two treatment groups. Group I included patients treated with antegrade flexible ureteroscopy and holmium laser stone fragmentation, and Group II included patients treated with retrograde ultrathin semirigid ureteroscopy. The study groups were compared in terms of patient demographics, stone access success, operation time, reoperation rates, peri-operative complications, and stone-free status. Group I included 114 patients, while Group II included 111. The mean age of the patients was 33.92 ± 10.37 years, and the size of the stones was 15.88 ± 3 mm. The study groups had comparable demographics and stone characteristics. The mean operative time was significantly longer in group I than in group II (102.55 ± 72.46 min vs. 60.98 ± 14.84 min, respectively, P < 0.001). Most reported complications were MCCS grades I and II, with no significant difference between the study groups. The stone-free rate after four weeks was 92.1% and 81.1% for groups I and II, respectively, which increased to 94.7% and 85.6% after eight weeks (P > 0.05). Antegrade flexible ureteroscopy is equivalent to retrograde ultrathin semirigid ureteroscopy in treating proximal ureteric stones regarding stone-free status and procedure-related morbidity. However, the antegrade approach has a longer operative time, greater fluoroscopy exposure, and longer hospital stays.

Post-renal acute kidney injury complicated by urinary tract obstruction due to massive blood clots and severe thrombocytopenia in a patient with systemic lupus erythematosus: A case report

Systemic lupus erythematosus (SLE) is often seen with antiphospholipid antibody syndrome (APS), and these conditions may occur concurrently with severe immune thrombocytopenia (ITP) and even acute kidney injury (AKI); however, post-renal AKI due to bleeding is uncommon. Here, we describe a case of post-renal AKI and anuria in a patient with SLE and APS, which were attributable to urinary tract obstruction due to massive blood clots caused by secondary ITP. A 50-year-old Japanese woman was admitted to our hospital with anuria, abdominal tenderness, purpura in the trunk and in both legs, and severe thrombocytopenia. She had been receiving medical treatment for APS and SLE till the age of 45 years. Computed tomography revealed a blood clot without extravasation in both urinary tracts, and she was diagnosed with post-renal AKI due to complete obstruction of the urinary system. Additionally, based on her medical history, elevated platelet-associated Immunoglobulin G (IgG) levels, and increased megakaryocyte count, she was diagnosed with secondary ITP complicated by SLE and APS. She also had elevated APS-related autoantibodies, including antiphosphatidylserine/prothrombin Immunoglobulin M (IgM), and IgG. However, concomitant serositis such as lupus enteritis or cystitis was not seen. She was treated with a combination of glucocorticoids, intravenous immunoglobulin, and continuous haemodialysis/haemofiltration, which resulted in rapid improvement of her symptoms and renal dysfunction. Secondary ITP-induced massive bleeding of urinary tract can cause post-renal AKI. Appropriate diagnosis and aggressive treatment are necessary to improve prognosis in such patients.

Post-obstructive diuresis after posterior urethral valve treatment in neonates: a retrospective cohort study

BACKGROUND

The management of posterior urethral valve (PUV) in neonates requires close monitoring in the intensive care unit because of the risk of post-obstructive diuresis (POD). Our aim was to describe the incidence and factors associated with POD in newborns treated for PUV.

METHODS

Retrospective analysis of the medical records of all neonates who underwent surgical intervention for PUV in our neonatal intensive care unit between January 2014 and April 2021.

RESULTS

Of the 40 patients included, 15 (37.5%) had POD defined by urine output > 6 ml.kg-1.h-1 during the first 24 h following urinary tract obstruction relief. At prenatal ultrasound examinations, oligohydramnios was more common in the group with POD than in the group without (53.3% vs. 8%, p = 0.002). Preterm birth was more frequent in neonates with POD (66.7% vs. 8%; p < 0.001). Median serum creatinine (212 [137-246] vs. 95 [77-125] µmol.l-1; p < 0.001) and urea (8.5 [5.2-12.2] vs. 4.1 [3.5-4.7] mmol.l-1; p < 0.001) concentrations on the day of obstruction relief were significantly higher in the group with POD than in the group without. After adjustment for prematurity, logistic regression models confirmed correlation between the occurrence of POD and the severity of the consequences of urethral obstruction (i.e., oligohydramnios and serum creatinine levels; ß = 2.90 [0.88; 5.36], p = 0.013 and ß = 0.014 [0.003; 0.031], p = 0.034, respectively).

CONCLUSIONS

In neonates, POD is common after the relief of PUV-related obstruction. Our findings may help to identify patients at highest risk. A higher resolution version of the Graphical abstract is available as Supplementary information.

Acute Kidney Injury: Definition, Management, and Promising Therapeutic Target

Acute kidney injury (AKI) is caused by a sudden loss of renal function, resulting in the build-up of waste products and a significant increase in mortality and morbidity. It is commonly diagnosed in critically ill patients, with its occurrence estimated at up to 50% in patients hospitalized in the intensive critical unit. Despite ongoing efforts, the death rate associated with AKI has remained high over the past half-century. Thus, it is critical to investigate novel therapy options for preventing the epidemic. Many studies have found that inflammation and Toll-like receptor-4 (TLR-4) activation have a significant role in the pathogenesis of AKI. Noteworthy, challenges in the search for efficient pharmacological therapy for AKI have arisen due to the multifaceted origin and complexity of the clinical history of people with the disease. This article focuses on kidney injury's epidemiology, risk factors, and pathophysiological processes. Specifically, it focuses on the role of TLRs especially type 4 in disease development.

Is There Any Effect of Retrograde Intrarenal Stone Surgery on Renal Functions in Childhood?

Purpose In this study, we aimed to demonstrate whether retrograde intrarenal stone surgery (RIRS) performed due to renal stones during the childhood period has any detrimental impact on renal functions. Materials and methods We retrospectively analyzed 121 patients aged 2 to 16 years who underwent RIRS for renal stones between March 2018 and February 2023. Data were available for 41 patients. The estimated glomerular filtration rate (eGFR) was computed using the modification of diet in renal disease (MDRD) formula on the day preceding the surgery and the third month after the surgery. We employed the National Kidney Foundation's chronic kidney disease (CKD) classification to categorize the glomerular filtration rate (GFR) into five groups. Preoperative and postoperative eGFR values of pediatric patients were compared by analyzing changes in CKD groups. Results Of the patients included in the study, 21 (51.2%) were male, while 20 (48.8%) were female children. No significant difference was found between the preoperative median eGFR and the postoperative median eGFR values (p=0.958). In the 3rd month after surgery, it was observed that 5 (12.1%) patients showed an improvement in their CKD stage, while deterioration was noted in 1 (2.4%) patient. Although a negative correlation was observed between the median eGFR change and both the operation time and the stone volume in Pearson correlation analysis, it was determined that this change did not create a significant difference (p=0.213 and p=0.295, respectively). Conclusion Stone surgery conducted with RIRS appears to yield positive outcomes on kidney function in the pediatric population. Nevertheless, being particularly attentive to patients with prolonged operation times and larger stone volumes is essential.

[Post-obstructive diuresis, by the internal physician]

Post-Obstructive Diuresis (POD) is a polyuria that occurs following the release of an obstruction from the urinary tract that prevents the flow of urine. POD requires prompt diagnosis to avoid complications. Although its pathophysiology is better understood, there is little scientific evidence for its treatment. Restoration of renal homeostasis requires correction of blood volume and electrolyte disturbances to prevent complications, which can be serious. In this article, we propose a synthesis of knowledge on the subject, as well as a management strategy.

Obstructive uropathy – acute and chronic medical management

Obstructive uropathy is an important cause of acute and chronic kidney disease. Decompression of the urinary tract is an essential aspect of treatment. The cause and aetiology of obstruction typically determine the surgical approach. Acute relief of obstruction is frequently complicated by fluid and electrolyte imbalance. Standard therapeutic interventions for acute or chronic renal failure also apply for cases of obstructive uropathy. This narrative review summarises the early and long-term medical management of obstructive uropathy.

Acute kidney injury due to bilateral malignant ureteral obstruction: Is there an optimal mode of drainage?

There is a well-known relationship between malignancy and impairment of kidney functions, either in the form of acute kidney injury or chronic kidney disease. In the former, however, bilateral malignant ureteral obstruction is a surgically correctable factor of this complex pathology. It warrants urgent drainage of the kidneys in emergency settings. However, there are multiple controversies and debates about the optimal mode of drainage of the bilaterally obstructed kidneys in these patients. This review addressed most of the concerns and provided a comprehensive presentation of this topic from the recent literature. Also, we provided different perspectives on the management of the bilateral obstructed kidneys due to malignancy. Despite the frequent trials for improving the success rates and functions of ureteral stents, placement of a percutaneous nephrostomy tube remains the most recommended tool of drainage due to bilateral ureteral obstruction, especially in patients with advanced malignancy. However, the disturbance of the quality of life of those patients remains a major unresolved concern. Beside the unfavorable prognostic potential of the underlying malignancy and the various risk stratification models that have been proposed, the response of the kidney to initial drainage can be anticipated and evaluated by multiple renal prognostic factors, including increased urine output, serum creatinine trajectory, and time-to-nadir serum creatinine after drainage.

Interventions for obstructive uropathy in advanced prostate cancer: a population-based study

OBJECTIVES

To develop and validate a coding framework to identify interventions for upper tract obstructive uropathy (UTOU) in men with locally advanced and metastatic prostate cancer (PCa) using administrative hospital data to assess clinical outcomes. There are no population-based studies on the incidence, treatment, and outcomes of this complication.

PATIENTS AND METHODS

Patients newly diagnosed with PCa between April 2014 and March 2019 were identified in the English cancer registry. A coding framework based on procedure (Office of Population Censuses and Surveys Classification of Surgical Operations and Procedures fourth edition) and diagnostic (International Classification of Diseases, 10th edition) codes was developed and validated. Subsequent clinical outcomes were determined using Hospital Episodes Statistics to determine the utility of the intervention.

RESULTS

A total of 77 010 patients newly diagnosed with locally advanced, and 30 083 patients with metastatic PCa were identified. Of these, 1951 (1.8%) patients underwent an intervention for UTOU according to our coding framework: 830 (42.5%) had locally advanced disease and 1121 (57.5%) had metastatic disease. In all, 844 (43.3%) had a percutaneous nephrostomy (PCN), 473 (24.2%) had a PCN with antegrade stent, and 634 (32.5%) had a retrograde stent. The mean follow-up was 43.2 months. The cumulative incidence of the use of these interventions at 1, 3, and 5 years was 2.5%, 3.6% and 4.2% in men with metastases compared to 0.5%, 0.9% and 1.4% in men with locally advanced disease.

CONCLUSION

A new coding framework, developed to identify procedures for UTOU was applied in the largest study to date of UTOU in men with primary locally advanced and metastatic PCa. Results demonstrated that 2% of men with locally advanced PCa and 4% of men with metastatic PCa require an intervention to resolve UTOU within 5 years of their PCa diagnosis.

Rapid recovery of male cats with postrenal acute kidney injury by treating with allogeneic adipose mesenchymal stem cell-derived extracellular vesicles

BACKGROUND

Acute kidney injury (AKI) is a complex disease and can be generally divided into prerenal, intrarenal, and postrenal AKI (PR-AKI). Previous studies have shown that mesenchymal stem cells (MSCs)-derived extracellular vesicles have protective function on prerenal and intrarenal AKI treatment, but whether they have therapeutic efficacy on PR-AKI remains unclear. In this study, we investigated the therapeutic efficacy of allogeneic adipose mesenchymal stem cell-derived extracellular vesicles (ADMSCEVs) on cat models of PR-AKI.

METHODS

The cat models of PR-AKI were established by using artificial urinary occlusion and then treated with ADMSCEVs. Histopathological section analysis, blood routine analysis, plasma biochemical test, imaging analysis, and plasma ultra-high performance liquid chromatography-MS/MS (UHPLC-MS/MS) were performed to evaluate the therapeutic efficacy of ADMSCEVs.

RESULTS

Physiological and biochemical test showed that the ADMSCEVs could recover creatinine, urea nitrogen and plasma phosphorus to homeostasis efficiently. Blood routine analysis showed that leukocytes in PR-AKI cats with ADMSCEVs treatment returned to normal physiological range more quickly than that of control. UHPLC-MS/MS analysis revealed that the plasma metabolome profile of PR-AKI cats treated with ADMSCEVs was highly similar to that of normal cats. Furthermore, UHPLC-MS/MS analysis also revealed six metabolites (carnitine, melibiose, D-Glucosamine, cytidine, dihydroorotic acid, stachyose) in plasma were highly correlated with the dynamic process of PR-AKI on cats.

CONCLUSIONS

We demonstrate the efficacy of ADMSCEVs in the treatment of PR-AKI on cats. Our study also suggests six metabolites to be novel PR-AKI markers and to be potential targets for ADMSCEVs therapy. Our findings will be useful to improve clinical treatment of both animal and human PR-AKI patients with ADMSCEVs in the future.

Acute renal failure and bladder tumors, about 106 cases

OBJECTIVES

The overall objective of the study was to determine the prevalence of acute renal failure due to bladder tumors by describing the clinical, paraclinical, therapeutic, histological and clinical evolution parameters.

MATERIALS AND METHODS

Retrospective study over a period of 2 years dating from the first of September 2017 to the 31 of October 2019 on a number of patients with acute renal failure due to bladder tumors treated at the department of urology in the Ibn Roch teaching Hospital in Casablanca.

RESULTS

In a series of 597 cases of bladder tumors, the prevalence of acute renal failure was 17.8%. The mean age was 69.5 years [51-88], with a male predominance (97%). The main clinical signs were hematuria (87%), lower back pain (62%), oligo-anuria (31%) and acute urine retention (12%). The mean serum creatinine on admission was 1316μmol/L (extremes: 155-2477) and The mean serum urea was 2.4g/L (0.8-4). Renal ultrasound showed hydronephrosis in 96% of cases, which was bilateral in 69% of cases. Hemodialysis was indicated in 23.6% of the cases, due to hyperkalemia (14.1%), metabolic acidosis (6.6%) and acute pulmonary oedema in (2.8%). Percutaneous nephrostomy was performed in 77% of cases, bladder catheterization in 21% of cases and double J-stenting in 2% of cases. As to the treatment of bladder tumors, endoscopic trans-urethral bladder resection was the main treatment and was performed in (71%) of cases. Meanwhile, 21% of the patients benefited from a cystoprostatectomy and combined radio-chemotherapy was indicated in 9% of cases. The main histological finding was transitional cell carcinoma (98%). The evolution of renal function was favorable in 87% of cases.

CONCLUSION

Acute renal failure is a frequent and severe complication of bladder tumors that can be life-threatening and makes it difficult to treat bladder tumors requiring multidisciplinary management.

Low-Flow Acute Kidney Injury: The Pathophysiology of Prerenal Azotemia, Abdominal Compartment Syndrome, and Obstructive Uropathy

AKI is a syndrome, not a disease. It results from many different primary and/or secondary etiologies and is often multifactorial, especially in the hospitalized patient. This review discusses the pathophysiology of three etiologies that cause AKI, those being kidney hypoperfusion, abdominal compartment syndrome, and urinary tract obstruction. The pathophysiology of these three causes of AKI differs but is overlapping. They all lead to a low urine flow rate and low urine sodium initially. In all three cases, with early recognition and correction of the underlying process, the resulting functional AKI can be rapidly reversed. However, with continued duration and/or increased severity, cell injury occurs within the kidney, resulting in structural AKI and a longer and more severe disease state with increased morbidity and mortality. This is why early recognition and reversal are critical.

The Release of 24 h Infravesical Obstruction in Mice: Changes in Molecular, Morphological, and Functional Parameters for 14-Day Observation

Bladder outlet obstruction (BOO) induces bladder dysfunction and altered bladder architecture. Irrespective of the release of the obstruction, persistent bladder dysfunction severely affects the quality of life. A better understanding of the repair process offers an opportunity to enhance postintervention management. We subsequently evaluated the postobstructive repair process in mice subjected to 24 h BOO followed by release. Male and female mice bladders were obstructed for 24 h by placing a clip around the bladder neck. After the release of obstruction, the mice were studied for 3, 7, and 14 days to observe the bladder repair process over time. Voiding frequency and volume were recorded using the voiding spot assay, and the transcutaneous glomerular filtration rate (tGFR) was measured. Fibrogenesis and associated gene expressions and altered protein levels were evaluated in the bladder using histology, quantatative polymerase chain reaction (qPCR), and Western blot analyses. Bladder wall thickness was increased in both genders over time but occurred later in female mice. Moreover, collagen deposition in the smooth muscle layer increased over time in both genders. Male mice showed a decreased average voided volume at 3 days post release, while female mice showed no significant change during the time course. Fibrosis-related molecular events, including upregulation of fibronectin (FN) protein and Collagen-3 (Col-3) mRNA expression, were transient and normalized again at 14 days in both genders. Transforming growth factor-β (TGF-β) and bone morphogenic protein (BMP)-7 mRNA expressions were upregulated at 14 days post release in both genders. Transcutaneous GFR remained normal during the time course. Release of 24 h BOO initiated a bladder remodeling process. The animal model enables a wide range of experiments to study bladder remodeling, and gender differences offer potential targets for understanding bladder fibrosis and adaptation with BOO.

Presentation Variables Associated With the Development of Severe Post-obstructive Diuresis in Male Cats Following Relief of Urethral Obstruction

Background

Diuresis following relief of urethral obstruction is a potentially life-threatening complication of feline urethral obstruction. Evidence regarding the incidence of post-obstructive diuresis (POD) in cats is scarce. Establishing historical, physical examination, and initial clinicopathologic variables associated with risk for developing POD may better enable clinicians to direct treatment for this common feline emergency and to educate clients regarding financial expectations.

Objectives

To report the incidence of POD in a large group of cats with urethral obstruction and determine whether select presenting physical examination or initial clinicopathologic variables may predict the onset or severity of POD.

Methods

The records of 260 cats that were admitted to the University of California, Davis, Veterinary Medical Teaching Hospital for urethral obstruction were reviewed. Urine output after urethral catherization was categorized into no POD (urine output ≤ 2 mL/kg/h), mild-moderate POD (urine output > 2 but <5 mL/kg/h) and severe POD (urine output ≥ 5 mL/kg/h). Select presentation physical examination, venous acid-base, electrolyte, serum biochemistry, and urinalysis results were compared among the groups.

Results

67.7% of cats experienced POD, and in 35% of cats it was categorized as severe. Evaluated historical and physical examination variables correlated with development of POD were lower body weight and, for severe POD, hypovolemia. Clinicopathologic variables associated with development of POD included acidemia, azotemia, hyperphosphatemia, hyperkalemia, hyponatremia, hypochloremia, hypocalcemia, hypermagnesemia, and hypoalbuminemia. Cats with severe POD were hospitalized a median of 1 day longer than those without POD.

Conclusions

Results of the present study indicate that there are presentation variables associated with onset and severity of POD following relief of feline urethral obstruction.

Severe Hydronephrosis Secondary to Ovarian Serous Carcinoma

This case study examines a patient with severe hydronephrosis caused by ureteral obstruction, secondary to ovarian serous carcinoma. Gynecologic malignancies, especially advanced ovarian carcinoma, are common extrinsic causes of obstructive hydronephrosis. Sonography is a valuable modality to visualize the kidneys, diagnose hydronephrosis, and determine the grade of hydronephrosis. The treatment of hydronephrosis aims to remove the build-up of urine, prevent permanent kidney damage, and treat the underlying cause. Prolonged or severe cases of hydronephrosis can lead to acute kidney injury.

Clinical Profile of Adult Patients Presenting With Renal Dysfunction to a Tertiary Hospital Emergency Department

Background Renal dysfunction is a potentially life-threatening condition that is commonly encountered in the emergency department (ED). This study aimed to describe the clinical profile of patients presenting with renal dysfunction to a tertiary-level hospital ED. Methods Medical records of patients presenting to the ED with renal dysfunction over a six-month period (July-December 2017) were reviewed. A descriptive analysis of the data was performed. Results Serum creatinine levels were measured in 7,442 (69.9%) of the 10,642 patients that were triaged into the ED. Of these, 208 (2.8%) were identified with renal dysfunction, of which 192 consented to study participation. The median age of study subjects was 49.5 (IQR 38.8-63.0) years; 108 (56.3%) were male; proteinuria on urine dipsticks was demonstrated in 108 (56.3%); 72 (37.5%) were HIV-positive; 66 (39.6%) required dialysis; 11 (5.7%) were admitted to the ICU; and 59 (30.7%) died prior to hospital discharge. More patients presented with acute kidney injury (AKI) (46.9%) compared to chronic kidney disease (CKD) (27.6%) and acute on chronic kidney disease (AoCKD) (25.5%). Sepsis was the most common precipitant of AKI (42.2%) and AoCKD (30.6%), while chronic hypertension (35.8%) and diabetes mellitus (34.0%) were the most common comorbidities in subjects with CKD. Conclusion Patients presenting to the ED with various risk factors and comorbidities, including HIV, sepsis, hypertension, and diabetes mellitus, may have underlying renal dysfunction. ED clinicians should therefore adopt a low threshold to screen for renal dysfunction in these patients.

Development and validation of a novel prediction model for predicting renal function recovery after diversion in patients with obstructive uropathy

OBJECTIVE

To develop and validate a novel prediction model predicting renal function recovery following diversion in patients with obstructive uropathy (OU) to the emergency department (ED).

METHODS

After a systematic literature search, a novel prediction model called PGIMER Obstructive Uropathy Score (POUS) was constructed including five variables: age (<60 or >60 years), duration of symptoms (<4 or >4 weeks), presence of solitary functioning kidney, baseline hemoglobin levels and venous blood pH. This model was then validated in a prospective, observational single-center study of patients presenting with OU caused by various etiologies. Patients with OU and raised serum creatinine (>2 mg/dL) presenting to our ED were included. Renal function recovery was defined as creatinine value <1.5 mg/dL at 4 weeks following diversion.

RESULTS

In this study, 174 consecutive patients with OU were recruited, and 74 (42.5%) patients had renal function recovery. All the variables included in the POUS were noted to be statistically significant on univariate analysis. On multivariate logistic regression analysis, only POUS was identified as an independent predictor of renal function recovery. On receiver operating curve analysis, the area under the curve for POUS was 0.832 for predicting recovery. A POUS of 5 or more had specificity and sensitivity of 83% and 73.6%, respectively, in predicting renal function recovery. The goodness of fit and calibration plots showed good concordance of the predicted values with the observed values.

CONCLUSIONS

The POUS model is an accurate and simple-to-use tool for predicting renal function recovery. POUS model requires external validation prior to clinical use in different populations.

Acute Kidney Injury Caused by Obstructive Nephropathy

Acute kidney injury secondary to obstructive nephropathy is a frequent event that accounts for 5 to 10% of all acute kidney injury cases and has a great impact on the morbidity and mortality in those affected. The obstruction in the urinary tract has a profound impact on kidney function due to damage produced by ischemic and inflammatory factors that have been associated with intense fibrosis. This pathology is characterized by its effects on the management of fluids, electrolytes, and the acid-base mechanisms by the renal tubule; consequently, metabolic acidosis, hyperkalemia, uremia, and anuria are seen during acute kidney injury due to obstructive nephropathy, and after drainage, polyuria may occur. Acute urine retention is the typical presentation. The diagnosis consists of a complete medical history and should include changes in urinary voiding and urgency and enuresis, history of urinary tract infections, hematuria, renal lithiasis, prior urinary interventions, and constipation. Imaging studies included tomography or ultrasound in which hydronephrosis can be seen. Management includes, in addition to drainage of the obstructed urinary tract system, providing supportive treatment, correcting all the metabolic abnormalities, and initiating renal replacement therapy when required. Although its recovery is in most cases favorable, it seems to be an undervalued event in nephrology and urology. This is because it is mistakenly believed that the resolution and recovery of kidney function is complete once the urinary tract is unobstructed. It can have serious kidney sequelae. In this review, we report the epidemiology, incidence, pathophysiological mechanisms, diagnosis, and treatment of acute kidney injury due to obstructive nephropathy.

Are endourological procedures for nephrolithiasis treatment associated with renal injury? A review of potential mechanisms and novel diagnostic indexes

Nephrolithiasis is one of the most common urological conditions with a huge socio-economic impact. About 50% of recurrent stone-formers have just one lifetime recurrence and >10% of patients present with a high recurrent disease requiring subsequent and sometimes multiple surgical interventions. The advent of new technology has made endourological procedures the pinnacle of stone treatment, including procedures like percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery and miniaturized PCNL procedures. Researchers have primarily focused on comparisons with respect to stone-free rates, procedure parameters and post-operative complications. However, the effect of these three procedures on renal function or indexes of renal injury has not been sufficiently examined. This was only reported in a few studies as a secondary objective with the use of common and not the appropriate and detailed renal parameters. This review presents current literature regarding the use of novel and highly predictive biomarkers for diagnosing acute kidney injury, discusses potential mechanisms through which endourological procedures for renal stone treatment may affect renal function and proposes areas with open questions where future research efforts in the field should focus.

Factors associated with postobstructive diuresis following decompressive surgery with placement of ureteral stents or subcutaneous ureteral bypass systems for treatment of ureteral obstruction in cats: 37 cases (2010-2014)

OBJECTIVE

To describe postobstructive diuresis (POD) in cats undergoing surgical placement of ureteral stents or subcutaneous ureteral bypass systems for treatment of ureteral obstruction in cats and to identify factors associated with duration and maximum severity of POD.

DESIGN

Retrospective case series.

ANIMALS

37 client-owned cats with ureteral obstruction treated between August 2010 and December 2014.

PROCEDURES

Medical records were reviewed, and data extracted included signalment, history, results from physical examinations and clinical laboratory analyses, treatment, urine output, and outcome. Data were evaluated to identify factors associated with POD duration and maximum severity, alone or in combination.

RESULTS

Serum concentrations of creatinine, potassium, phosphorus, and BUN before surgery positively correlated with duration and maximum severity of POD. Absolute changes in serum concentrations of creatinine, potassium, and BUN from before surgery to after surgery positively correlated with POD duration. Cats with anuria before surgery had longer POD than did other cats; however, there was no difference in POD duration or maximum severity with unilateral versus bilateral ureteral obstruction. Thirty-four of 37 (92%) cats survived to hospital discharge, which was not associated with whether ureteral obstruction was unilateral or bilateral. Azotemia resolved in 17 of the 34 (50%) cats that survived to hospital discharge.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of the present study indicated that several factors were associated with POD duration and maximum severity, alone or in combination, and that with intensive management of fluid and electrolyte derangements, regardless of the extent of the original azotemia, a high percentage of cats survived to hospital discharge.

Post-obstructive diuresis; underlying causes and hospitalization

Objective: This paper aims to estimate the incidence of post-obstructive diuresis (POD) among patients with urinary retention, explore possible underlying causes and identify patients who need hospitalization.Material and methods: This retrospective study includes patients admitted for urinary retention in Zealand University Hospital, Denmark. We collected demographic characteristics, health information and laboratory results from patients' charts and analyzed data statistically.Results: We assessed 64 patients, and POD occurred in 29.7%. A significant correlation was observed between POD and residual urine, serum creatinine, serum urea and systolic and diastolic blood pressure. We identified increased residual urine volume as an independent predictor of POD by OR 1.21 (95% CI: 1.06-1.40), p = 0.006 per 100 mL and creatinine of >120 umol/L is an independent predictor of POD by OR 7.17 (95% CI; 1.63-31.37), p = 0.009. Patients with residual urine at the time of diagnosis of more than 1150 ml will suffer POD with a probability of area under curve (AUC) 0.874 (p < 0.001) with 84% sensitivity and 78% specificity. Patients with creatinine >120 umol/L will suffer POD with a probability of AUC 0.774 (p < 0.001) with 68% sensitivity and 82% specificity.Conclusion: In this small retrospective study residual urine of more than 1150 mL and elevated creatinine are independent predictors of POD in patients with urinary retention. However, larger prospective studies are needed to confirm these findings.

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.

Acute Renal Failure of Nosocomial Origin

BACKGROUND

10-20% of hospitalized patients develop acute kidney injury (AKI)/acute renal failure during their hospital stay. The mortality of nosocomial AKI is approximately 30%.

METHODS

This review is based on relevant publications retrieved by a search in multiple databases (PubMed and Uptodate), archives, and pertinent medical journals.

RESULTS

The most common causes of nosocomial AKI are volume depletion, sepsis, heart diseases, polytrauma, liver diseases, and drug toxicity. AKI can also be of postrenal (obstructive) origin, or a result of renal diseases including glomeruloneph- ritis, vasculitis, tubulointerstitial nephritis, and cholesterol embolism. In about 13% of cases, nosocomial AKI develops on the basis of pre-existing chronic renal disease. Patients with AKI are at elevated risk of developing chronic renal disease and must be followed up appropriately after they are discharged from the hospital. Indispens- able elements of the evaluation of nosocomial AKI include renal ultrasonography, the exclusion of postrenal obstruction, urine chemistry, and microbiological urinaly- sis. Potentially nephrotoxic drugs and those that impair renal hemodynamics must be avoided to the greatest possible extent in patients with acute renal damage. Hypotension must be avoided as well.

CONCLUSION

Early, specific nephrological diagnosis and treatment are important components of the management of nosocomial AKI, particularly because causally directed treatment is available for some of the conditions that underlie it.

Effects on renal outcome of concomitant acute pyelonephritis, acute kidney injury and obstruction duration in obstructive uropathy by urolithiasis: a retrospective cohort study

OBJECTIVE

Obstruction release from urolithiasis can be delayed with a lack of suggested time for preventing the deterioration of renal function. The objective of this study was to investigate the effect of obstruction duration, concomitant acute kidney injury (AKI) or acute pyelonephritis (APN) during the obstruction on the prognosis of renal function.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

1607 patients from a urolithiasis-related obstructive uropathy cohort, between January 2005 and December 2015.

OUTCOME MEASURES

Estimated glomerular filtration rate (eGFR) decrease ≥30% and/or end-stage renal disease (ESRD), and eGFR decrease ≥50% and/or ESRD, according to obstruction duration, AKI and APN accompanied by obstructive uropathy.

RESULTS

When the prognosis was divided by obstruction duration quartile, the longer the obstruction duration the higher the probability of eGFR reduction >50% (p=0.02). In patients with concomitant APN or severe AKI during hospitalisation with obstructive uropathy, an eGFR decrease of >30% and >50% occurred more frequently, compared with others (p<0.001). When we adjusted for sex, age, hypertension, diabetes mellitus, APN, AKI grades and obstruction release >7 days for multivariate analysis, we found that concomitant APN (HR 3.495, 95% CI 1.942 to 6.289, p<0.001), concomitant AKI (HR 3.284, 95% CI 1.354 to 7.965, p=0.009 for AKI stage II; HR 6.425, 95% CI 2.599 to 15.881, p<0.001 for AKI stage III) and an obstruction duration >7 days (HR 1.854, 95% CI 1.095 to 3.140, p=0.001) were independently associated with an eGFR decrease >50%. Tree analysis also showed that AKI grade 3, APN and an obstruction duration >7 days were the most important factors affecting renal outcome.

CONCLUSIONS

In patients with urolithiasis-related obstructive uropathy, concomitant APN was strongly associated with deterioration of renal function after obstruction release. The elapsed time to release the obstruction also affected renal function.

Vanin-1 in Renal Pelvic Urine Reflects Kidney Injury in a Rat Model of Hydronephrosis

Urinary tract obstruction and the subsequent development of hydronephrosis can cause kidney injuries, which results in chronic kidney disease. Although it is important to detect kidney injuries at an early stage, new biomarkers of hydronephrosis have not been identified. In this study, we examined whether vanin-1 could be a potential biomarker for hydronephrosis. Male Sprague-Dawley rats were subjected to unilateral ureteral obstruction (UUO). On day 7 after UUO, when the histopathological renal tubular injuries became obvious, the vanin-1 level in the renal pelvic urine was significantly higher than that in voided urine from sham-operated rats. Furthermore, vanin-1 remained at the same level until day 14. There was no significant difference in the serum vanin-1 level between sham-operated rats and rats with UUO. In the kidney tissue, the mRNA and protein expressions of vanin-1 significantly decreased, whereas there was increased expression of transforming growth factor (TGF)-β1 and Snail-1, which plays a pivotal role in the pathogenesis of renal fibrosis via epithelial-to-mesenchymal transition (EMT). These results suggest that vanin-1 in the renal pelvic urine is released from the renal tubular cells of UUO rats and reflects renal tubular injuries at an early stage. Urinary vanin-1 may serve as a candidate biomarker of renal tubular injury due to hydronephrosis.

Risk factors for postobstructive diuresis in pediatric patients with ureteropelvic junction obstruction, following open pyeloplasty in three high complexity institutions

INTRODUCTION

Postobstructive diuresis (POD) is a polyuric state in which large quantities of salt and water are eliminated after solving a urinary tract obstruction. These patients are at increased risk of severe dehydration, electrolytic disturbances, hypovolemic shock, and death. Ureteropelvic junction obstruction (UPJO) is the most common etiology of collecting system dilatation in the fetal kidney, and a significant number of patients require pyeloplasty. There are limited data regarding prognostic risk factors for POD in this scenario.

OBJECTIVE

To describe possible clinical risk factors for POD in the pediatric population after open pyeloplasty.

STUDY DESIGN

This was a retrospective case series study of consecutive patients diagnosed with UPJO at three high complexity centers, managed with open pyeloplasty from 2006 to 2016. Multiple qualitative and quantitative variables possibly associated with POD were included according to the literature review. They were statistically analyzed with STATA 14 software.

RESULTS

A total of 88 patients with UPJO following open pyeloplasty were analyzed. Twenty-seven patients (30%) had POD. A tendency to present POD in younger patients was found, with a mean age of 20.2 months vs. 72.3 months. There was also an increased risk of POD in patients with previous diagnosis of tubular acidosis.

CONCLUSIONS

There are no data about prognostic clinical risk factors for POD after open pyeloplasty in the pediatric population. Our study corresponds to one of the larger series reported so far. It suggests that younger patients and patients with a previous diagnosis of tubular acidosis could be at greater risk of POD. Consequently, prospective studies are required for validation of our results, and possible impact on patient follow-up.

Outcome in cats with benign ureteral obstructions treated by means of ureteral stenting versus ureterotomy

OBJECTIVE To evaluate the outcome for cats with benign ureteral obstructions treated by means of ureteral stenting and to compare the outcome for these cats with outcome for a historical cohort of cats treated by means of ureterotomy only. DESIGN Prospective study with historical cohort. ANIMALS 62 client-owned cats with benign ureteral obstructions, including 26 cats treated with ureteral stenting and 36 cats previously treated with ureterotomy. PROCEDURES Data were recorded prospectively (ureteral stent cases) or collected retrospectively from the medical records (ureterotomy cases), and results were compared. RESULTS Cats treated with ureteral stents had significantly greater decreases in BUN and serum creatinine concentrations 1 day after surgery and at hospital discharge, compared with values for cats that underwent ureterotomy. Six cats in the ureteral stent group developed abdominal effusion after surgery, and cats in this group were significantly more likely to develop abdominal effusion when a ureterotomy was performed than when it was not. Cats that developed abdominal effusion after surgery were significantly less likely to survive to hospital discharge. Cats that underwent ureteral stenting were significantly more likely to have resolution of azotemia prior to hospital discharge than were cats that underwent ureterotomy alone. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that cats with benign ureteral obstructions treated with ureteral stenting were more likely to have resolution of azotemia prior to hospital discharge, compared with cats undergoing ureterotomy alone. Results of ureteral stenting were encouraging, but further investigation is warranted.

Overlap of Post-obstructive Diuresis and Unmasked Diabetes Insipidus in a Case of IgG4-related Retroperitoneal Fibrosis and Tuberoinfundibular Hypophysitis: A Case Report and Review of the Literature

The clinical picture of IgG4-related disease (IgG4-RD) is diverse because various organs can be affected. We describe the case of a 56-year-old man with acute renal failure and tuberoinfundibular hypophysitis due to IgG4-RD. Steroid therapy lowered the serum IgG4 level and ameliorated renal dysfunction, bilateral hydronephrosis and retroperitoneal fibrosis. However, polyuria from post-obstructive diuresis and unmasked central diabetes insipidus ensued. The patient's polyuria continued despite the administration of a therapeutic dose of glucocorticoid; the patient's pituitary swelling and anterior pituitary dysfunction were partially ameliorated. The pituitary swelling recurred seven months later. In patients with IgG4-RD, the manifestation of polyuria after steroid therapy should prompt suspicion of post-obstructive diuresis and the unmasking of central diabetes insipidus.

Postobstructive diuresis in cats with naturally occurring lower urinary tract obstruction: incidence, severity and association with laboratory parameters on admission

OBJECTIVES

The objectives of this retrospective study were to investigate the actual incidence of postobstructive diuresis after relief of urethral obstruction in cats, as well as to identify changes in blood and urine parameters that might be associated with postobstructive diuresis (POD), and to assess the impact of fluid therapy.

METHODS

The medical records of 57 male cats with urethral obstruction that were treated with an indwelling urinary catheter were retrospectively analysed. Absolute urine output in ml/kg/h every 4 h and the incidence of cats with polyuria (urine volume >2 ml/kg/h) at any time point over a 48 h period after the re-establishment of urine flow were investigated. In addition, postobstructive diuresis in relation to fluid therapy (PODFR) was defined as urine output greater than the administered amount of intravenous fluids on at least two subsequent time points. Polyuria and PODFR were investigated for their association with blood and urine laboratory parameters.

RESULTS

After 4 h, 74.1% (40/54) of the cats had polyuria, with a urine output of >2 ml/kg/h. Metabolic acidosis was present in 46.2% of the cats. Venous blood pH and bicarbonate were inversely correlated with urine output in ml/kg/h after 4 h. The overall incidence of POD within 48 h of catheterisation was 87.7%. There was a significant correlation between intravenous fluid rate at time point x and urine output at time point x + 1 at all the time points except for the fluid rate at time point 0 and the urine output after 4 h. PODFR was seen in 21/57 cats (36.8%).

CONCLUSIONS AND RELEVANCE

POD is a frequent finding in cats treated for urethral obstruction, and can be very pronounced. Further studies are required to determine whether or not a change in venous blood pH actually interferes with renal concentrating ability. The discrepancy between the frequency of cats with polyuria and PODFR (87.7% vs 36.8%) in the present study indicates that administered intravenous fluid therapy might be the driving force for the high incidence of polyuria in some cats with naturally occurring obstructive feline lower urinary tract disease.

Impact of retrograde flexible ureteroscopy and intracorporeal lithotripsy on kidney functional outcomes

Objective:

The aim of the study was to evaluate renal function and to identify factors associated with renal function deterioration after retrograde intrarenal surgery (RIRS) for kidney stones.

Materials and Methods:

We retrospectively analyzed patients with renal stones treated by RIRS between January 2010 and June 2013 at a single institute. We used the National Kidney Foundation classification of chronic kidney disease (CKD) to classify Glomerular Filtration Rate (GFR) in 5 groups. The baseline creatinine level was systematically pre-operatively and post-operatively evaluated. All patients had a creatinine blood measurement in June 2013. A change toward a less or a more favorable GFR group following RIRS was considered significant.

Results:

We included 163 patients. There were 86 males (52.8%) and 77 females (47.3%) with a mean age of 52.8±17 years. After a mean follow-up of 15.5±11.5 months, median GFR was not significantly changed from 84.3±26.2 to 84.9±24.5 mL/min (p=0.675). Significant renal function deterioration occurred in 8 cases (4.9%) and significant renal function amelioration occurred in 23 cases (14.1%). In univariate analysis, multiple procedures (p=0.023; HR: 5.4) and preoperative CKD (p=0.011; HR: 6.8) were associated with decreased renal function. In multivariate analysis these factors did not remain as predictive factors.

Conclusion:

Stone management with RIRS seems to have favorable outcomes on kidney function; however, special attention should be given to patients with multiple procedures and preoperative chronic kidney disease.

Matrix Metalloproteinase-2 Knockout and Heterozygote Mice Are Protected from Hydronephrosis and Kidney Fibrosis after Unilateral Ureteral Obstruction

Matrix Metalloproteinase-2 (Mmp2) is a collagenase known to be important in the development of renal fibrosis. In unilateral ureteral obstruction (UUO) the obstructed kidney (OK) develops fibrosis, while the contralateral (CL) does not. In this study we investigated the effect of UUO on gene expression, fibrosis and pelvic remodeling in the kidneys of Mmp2 deficient mice (Mmp2-/-), heterozygous animals (Mmp2+/-) and wild-type mice (Mmp2+/+). Sham operated animals served as controls (Cntrl). UUO was prepared under isoflurane anaesthesia, and the animals were sacrificed after one week. UUO caused hydronephrosis, dilation of renal tubules, loss of parenchymal thickness, and fibrosis. Damage was most severe in Mmp2+/+ mice, while both Mmp2-/- and Mmp2+/- groups showed considerably milder hydronephrosis, no tubular necrosis, and less tubular dilation. Picrosirius red quantification of fibrous collagen showed 1.63±0.25% positivity in OK and 0.29±0.11% in CL (p<0.05) of Mmp2+/+, Mmp2-/- OK and Mmp2-/- CL exhibited only 0.49±0.09% and 0.23±0.04% (p<0.05) positivity, respectively. Mmp2+/- OK and Mmp2+/- CL showed 0.43±0.09% and 0.22±0.06% (p<0.05) positivity, respectively. Transcriptomic analysis showed that 26 genes (out of 48 examined) were differentially expressed by ANOVA (p<0.05). 25 genes were upregulated in Mmp2+/+ OK compared to Mmp2+/+ CL: Adamts1, -2, Col1a1, -2, -3a1, -4a1, -5a1, -5a2, Dcn, Fbln1, -5, Fmod, Fn1, Itga2, Loxl1, Mgp, Mmp2, -3, Nid1, Pdgfb, Spp1, Tgfb1, Timp2, Trf, Vim. In Mmp2-/- and Mmp2+/- 18 and 12 genes were expressed differentially between OK and CL, respectively. Only Mmp2 was differentially regulated when comparing Mmp2-/- OK and Mmp2+/- OK. Under stress, it appears that Mmp2+/- OK responds with less Mmp2 upregulation than Mmp2+/+ OK, suggesting that there is a threshold level of Mmp2 necessary for damage and fibrosis to occur. In conclusion, reduced Mmp2 expression during UUO protects mice against hydronephrosis and renal fibrosis.

Renal impairment in cirrhosis unrelated to hepatorenal syndrome

Renal impairment is common in liver disease and may occur as a consequence of the pathophysiological changes that underpin cirrhosis or secondary to a pre-existing unrelated insult. Nevertheless, the onset of renal impairment often portends a worsening prognosis. Hepatorenal syndrome remains one of the most recognized and reported causes of renal impairment in cirrhosis. However, other causes of renal impairment occur and can be classified into prerenal, intrinsic or postrenal, which are the subjects of the present review.

Voiding dysfunction due to detrusor underactivity: an overview

Detrusor underactivity (DUA) is defined as a voiding contraction of reduced strength and/or duration, which prolongs urination and/or prevents complete emptying of the bladder within a 'normal' period of time. This issue is associated with voiding and postmicturition urinary symptoms, and can predispose to urinary infections and acute urinary retention. The aetiology of DUA is influenced by multiple factors, including ageing, bladder outlet obstruction, neurological disease, and autonomic denervation. The true prevalence of this condition remains unknown, as most data come from referral populations. Urodynamic testing is used to diagnose the condition, either by assessing the relationship between bladder pressures and urinary flow, or by interrupting voiding to measure detrusor pressure change under isovolumetric conditions. Current treatments for DUA have poor efficacy and tolerability, and often fail to improve quality of life; muscarinic receptor agonists, in particular, have limited efficacy and frequent adverse effects. Bladder emptying might be achieved through Valsalva straining, and intermittent or indwelling catheterization, although sacral nerve stimulation can reduce dependency on catheterization. Novel stem-cell-based therapies have been attempted; however, new drugs that increase contractility are currently largely conceptual, and the complex pathophysiology of DUA, difficulty achieving organ specificity of treatment, the limited availability of animal models, and the subjective nature of current outcome measures must be addressed to facilitate the development of such agents.

Isolated calyx mistaken for a cyst: inappropriately performed catheter-directed sclerotherapy and safe removal of the catheter after selective embolization

We present a case of isolated calyx that was mistaken for a large cyst. A 47-year-old woman was referred for sclerotherapy of a large cystic lesion on her left kidney. Computed tomography (CT) and ultrasound showed that the cystic lesion was a large cyst. We noticed that the cystic lesion was not a typical simple cyst, even after two sessions of catheter-mediated sclerotherapy. Isolated calyx was presumed by medical history review and was confirmed by aspirated fluid analysis and far delayed-phase CT after intravenous contrast injection. We performed meticulous selective arterial embolization for an isolated calyx and inserted a catheter that could be removed without complication.

Outcomes of distal ureteral reconstruction through reimplantation with psoas hitch, Boari flap, or ureteroneocystostomy for benign or malignant ureteral obstruction or injury

OBJECTIVE

To assess functional outcomes and complications of ureteroneocystotomies (UNCs) with or without psoas hitch or Boari flap in the reconstruction and repair of the ureter.

METHODS

We reviewed a consecutive series of patients that underwent open ureteral reconstruction for ureteral obstruction or injury. Underlying ureteral disorder, preoperative and postoperative estimated glomerular filtration rate (eGFR), and imaging studies regarding resolution of hydronephrosis were assessed.

RESULTS

A total of 100 ureteral reimplantations performed at our institution from November 1986 to August 2012 were identified: 24 primary ureteroneocystotomies, 58 with psoas hitch, and 18 with Boari flap. Median follow-up was 48.7 months (range 12.3-253 months). The most common underlying disorder was ureteral transitional cell cancer (TCC). Men were found to have more frequent underlying chronic ureteral disorders with chronic renal failure when compared to women. Ureteral stents were placed in 81% and were removed after a median of 33 days (range 2-161 days). Resolution of hydronephrosis was noted in 81% of the patients. The eGFR deteriorated significantly over time only in male patients (P = .001). Postoperative complications included stent-related dysuria, urinary tract infection, and contrast-extravasation on cystogram necessitating prolonged urethral and ureteral catheter drainage.

CONCLUSION

Excellent functional outcome without significant morbidity associated with ureteral reimplantation/reconstruction was achieved. Despite resolution of hydronephrosis in the vast majority of patients, those with chronic underlying ureteral disorder and renal failure did not show improvement of their eGFR.

Epidemiology of acute kidney injury in the intensive care unit

The incidence of acute kidney injury (AKI) in the intensive care unit (ICU) has increased during the past decade due to increased acuity as well as increased recognition. Early epidemiology studies were confounded by erratic definitions of AKI until recent consensus guidelines (RIFLE and AKIN) standardized its definition. This paper discusses the incidence of AKI in the ICU with focuses on specific patient populations. The overall incidence of AKI in ICU patients ranges from 20% to 50% with lower incidence seen in elective surgical patients and higher incidence in sepsis patients. The incidence of contrast-induced AKI is less (11.5%–19% of all admissions) than seen in the ICU population at large. AKI represents a significant risk factor for mortality and can be associated with mortality greater than 50%.