Bleeding complications of native kidney biopsy: a systematic review and meta-analysis

Kidney Biopsy in Type 2 Diabetes: A Multicenter Cross-Sectional Study

INTRODUCTION

Kidney biopsies (KBs) are performed in patients with type 2 diabetes (T2D) to diagnose non-diabetic or hypertensive kidney disease (NDHKD) potentially requiring specific management compared to diabetic and or hypertensive nephropathy (absence of NDHKD). Indications for KB are based on the presence of atypical features compared to the typical course of diabetic nephropathy. In this study, we assessed the association of different patterns of atypical features, or KB indications, with NDHKD.

METHODS

Native KBs performed in patients with T2D were analyzed. Data were collected from the patients' records. KB indications were determined according to the presence of different atypical features considered sequentially: (1) presence of any feature suggesting NDHKD which is not among the following ones, (2) recent onset of nephrotic syndrome, (3) low or rapidly declining estimated glomerular filtration rate (eGFR), (4) rapid increase in proteinuria, (5) short duration of diabetes, (6) presence of hematuria, or (7) normal retinal examination.

RESULTS

Among the 463 KBs analyzed, NDHKD was diagnosed in 40% of the total population and 54, 40, 24, and 7% of the KBs performed for indications 1-4 respectively. Conversely, no patient who underwent KB for indications 5-7 displayed NDHKD. Logistic regression analyses identified eGFRCKD-EPI >15 mL/min/1.73 m2, urinary protein-to-Cr ratio <0.3 g/mmol, hematuria, HbA1c <7%, and diabetes duration <5 years as predictors of NDHKD, independently from the indication group.

CONCLUSION

NDHKD is frequent in T2D. Despite the association of hematuria with NDHKD, our results suggest that presence of hematuria and absence of DR are insufficient to indicate KB in the absence of concurrent atypical features. Conversely, rapid progression of proteinuria and rapid deterioration of eGFR are major signals of NDHKD.

Percutaneous Renal Biopsy Using an 18-Gauge Automated Needle Is Not Optimal

BACKGROUND

As percutaneous renal biopsies (PRBs) are increasingly performed by radiologists, an increase in the use of 18-gauge automated needle stands to compromise adequacy. We compare the adequacy and safety of PRB with 14-, 16-, and 18-gauge automated needles.

METHODS

PRB of native (N-592) and transplant (T-1,023) kidneys was performed from January 2002 to December 2019 using real-time ultrasound. Baseline clinical and laboratory data, biopsy data (number of cores, total glomeruli, and total glomeruli per core), and outcome (hematoma on renal US at 1-h, complications, and transfusion) were collected prospectively. PRB with N14g (337) versus N16g (255) and T16g (892) versus T18g (131) needles were compared. A p value of <0.05 was significant.

RESULTS

PRB with an 18-g needle yielded the lowest number of total glomeruli per biopsy (N14g vs. N16g: 33 ± 13 vs. 29 ± 12, p < 0.01 and T16g vs. T18g: 34 ± 16 vs. 21 ± 11, p < 0.0001), significantly fewer total glomeruli per core (T16g vs. T18g: 12.7 ± 6.4 vs. 9.6 ± 5.0, p < 0.001 and N16g vs. T18g: 14.2 ± 6.3 vs. 9.6 ± 5.0, p < 0.001). A hematoma by renal US 1-h post-PRB was similar for native (14g-35% vs. 16g-29%, p = 0.2), and transplant biopsies (16g-10% vs. 18g-9%, p = 0.9) and the complication rate for native (14g-8.9% vs. 16g-7.1%, p = 0.5), transplant biopsies (16g-4.6% vs. 18g-1.5%, p = 0.2) and transfusion rate for native (14g-7.7% vs. 16g-5.8%, p = 0.4), and transplant biopsies (16g-3.8% vs. 18g-0.8%, p = 0.1) were similar irrespective of needle size.

CONCLUSIONS

PRB of native and transplant kidneys with the use of a 16-gauge needle provides an optimal sample. However, our experience in transplant biopsies suggests the use of an 18-gauge needle stands to jeopardize the diagnostic accuracy of the PRB while not improving safety.

Safety and effectiveness of transjugular renal biopsy for systemic lupus erythematosus and antiphospholipid antibody syndrome patients taking antithrombotics

BACKGROUND

Renal biopsy is the cornerstone of systemic lupus erythematosus (SLE) nephritis and antiphospholipid syndrome (APS) nephropathy management. However, transcutaneous renal biopsy (TCRB) is hampered by the antithrombotic treatment frequently prescribed for those diseases. Transjugular renal biopsy (TJRB) offers an attractive alternative for patients at increased risk of bleeding. The primary objective of the study was to describe the safety profile and diagnostic performance of TJRB in SLE and APS patients.

METHODS

All SLE and/or APS patients who underwent a renal biopsy in our department (between January 2004 and October 2016) were retrospectively reviewed. Major complications were death, haemostasis nephrectomy, renal artery embolization, red blood cell transfusion, sepsis and vascular thrombosis; macroscopic haematuria, symptomatic perirenal/retroperitoneal bleeding and renal arteriovenous fistula without artery embolization were considered as minor complications.

RESULTS

Two hundred and fifty-six TJRBs-119 without antithrombotics (untreated), 69 under aspirin and 68 on anticoagulants and 54 TCRBs without antithrombotics-were analysed. Their major and minor complication rates, respectively, did not differ significantly for the four groups: 0 and 8% for untreated TJRBs, 1 and 6% for aspirin-treated, 6 and 10% for anticoagulant-treated and 2 and 2% for TCRBs. The number of glomeruli sampled and the biopsy contribution to establishing a histological diagnosis was similar for the four groups.

CONCLUSIONS

TJRBs obtained from SLE and APS patients taking antithrombotics had diagnostic yields and safety profiles similar to those of untreated TCRBs. Thus, TJRB should be considered for SLE and APS patients at risk of bleeding.

Spectrum of pediatricbiopsy-proven renal diseases: A single center experience

Glomerular diseases are considered to be a significant cause of chronic kidney disease. Kidney biopsy continues to be an essential diagnostic tool. We review the renal biopsies which were done on children below the age of 14 years in the past 10 years (from January 2008 to September 2018) in a single tertiary pediatric hospital in Saudi Arabia to determine the patterns of renal disease among Saudi children as well-correlating clinical presentation with histopathological diagnosis. A total of 203 pediatric kidney biopsies were performed. The mean age was 7.3 ± 3.9 years (3 months to 14 years). There were 105 males and 98 females. The most frequent indication for renal biopsy was nephrotic syndrome in 58.9% of patients, followed by acute glomerulo- nephritis in 20.8%. Other indications included significant proteinuria, persistent microscopic hematuria, acute kidney injury of uncertain etiology, in the remaining 20% of biopsies. Clinical diagnosis was consistent with histopathological diagnosis in 92% of the cases. Minimal change disease was the most common cause of primary glomerular diseases in 37.4%, followed by focal segmental glomerulosclerosis in 20.2%. Lupus nephritis represents the most common cause of the secondary renal disease (8.4%). Complications of kidney biopsy were observed in only 16.3% of patients, of whom 9.9% had perirenal hematomas and 6.4% of the patients developed either microscopic hematuria or macroscopic hematuria.

Characterization of interventional photoacoustic imaging (iPAI) capabilities in biological tissues

BACKGROUND

Interventional photoacoustic imaging (iPAI) could improve ultrasound-guided minimally invasive procedures by enabling high precision needle steering, target detection, and molecular and physiologic tissue assessment. However, iPAI capabilities including visualization field, imaging depth, and spatial resolution are not well understood in biological tissues commonly encountered in clinical practice. Therefore, the potential clinical utility of iPAI remains unclear. We aim to experimentally determine iPAI capabilities in a variety of biological tissues, to assess its potential for clinical translation.

METHODS

We constructed an iPAI system capable of simultaneous real-time ultrasound (US) and photoacoustic imaging. This system delivers light directly into tissues using optical fiber integrated into a 16-gauge needle and detects photoacoustic signals with an external linear array ultrasound probe. iPAI's geometric visualization field, maximum imaging depth, and spatial resolution were experimentally determined in fat, muscle, kidney, and liver tissues by processing photoacoustic signal intensities of reference targets placed circumferentially around the fiber tip. The maximum detection depths of blood and indocyanine green (ICG), important common endogenous and exogenous contrast agents, respectively, were estimated in each tissue type by comparing their signal intensities with the reference target signal.

RESULTS

iPAI could be performed in real-time concurrently with US and achieved a nearly spherical visualization field centering around the optical fiber tip in all tissues. Maximum imaging depths from the fiber tip were 54.1 ± 1.3, 50.0 ± 1.5, 32.7 ± 1.1, and 16.9 ± 1.3 mm in fat, muscle, kidney, and liver tissues, respectively. Calculated maximum detection depths for blood were 41.5 ± 3.0, 39.5 ± 2.1, 24.4 ± 4.0, and 8.6 ± 2.0 mm and detection depths for ICG at 0.05  mg/mL concentration were 46.6 ± 2.5, 42.6 ± 1.4, 28.2 ± 3.9, and 12.1 ± 1.5 mm in fat, muscle, kidney, and liver, respectively. Sub-100μ m axial resolution and submillimeter lateral resolution were achieved in all tissues, and resolution did not significantly vary with distance from the fiber tip.

CONCLUSIONS

Interventional photoacoustic imaging (iPAI) allows real-time visualization of a circumferential volume of tissue around an optical fiber tip, with submillimeter spatial resolution and tissue-dependent imaging depth. Our data strongly support further development of clinical iPAI systems as they could improve needle steering, target detection, and molecular and physiologic tissue assessment during minimally invasive procedures.

Transjugular Renal Biopsy Bleeding Risk and Diagnostic Yield: A Systematic Review

This study aimed to better define the safety and efficacy of transjugular renal biopsy (TJRB) based on published studies. Seventeen published articles were included (1,321 biopsies). Complications were classified as major if they resulted in blood transfusion or additional invasive procedures. All other bleeding complications were considered minor. Diagnostic tissue was obtained in 1,193 procedures (90.3%). The total incidence of bleeding complications among 15 articles with complete data was 202 of 892 procedures (22.6%): 162 (18.2%) minor and 40 (4.5 %) major. These results show that TJRB is a feasible procedure for obtaining renal tissue for diagnosis and that most complications are self-limiting.

Does Hemodialysis Need to be Initiated to Improve Platelet Function in CKD G5 Patients? A Pilot Prospective, Observational Cohort Study

Introduction:

We previously showed that patients with chronic kidney disease (CKD) Stage G4-5 have normal bleeding times. This made us question whether hemodialysis (HD) initiation was really necessary solely to improve platelet function.

Methods:

In this prospective observational study, two 5 ml citrated blood samples and one 2 ml EDTA blood sample were collected from incident HD patients fulfilling inclusion criteria prior to HD initiation (baseline sample) and after three sessions of short duration, low flow, counter-current HD. In each instance, one sample was used to perform Collagen adenosine diphosphate closure time (CADPCT) using the Platelet function analyzer (PFA 200, normal range 68-142 seconds) and the second for light transmission aggregometry (LTA) with ADP as agonist (normal ≥50%).

Results:

This study included 20 patients between October 2017 and February 2019. Overall, and in the subgroup with normal baseline CADPCT or LTA, there was no statistically significant improvement after HD. However, of the 30% of patients who had an abnormal baseline CADPCT, 50% attained a normal value after three HD sessions, and the overall reduction in CADPCT in this group was statistically significant (P = 0.02). Of those with a baseline normal CADPCT, 21% developed abnormal prolongation post HD.

Conclusion:

HD for the sole purpose of improving platelet function is only of benefit in the subgroup of patients with an abnormal CADPCT at baseline, with close to 50% normalizing their platelet function after three sessions of low flow, short duration, counter-current HD.

A Systematic Review of Complications Associated With Percutaneous Native Kidney Biopsies in Adults in Low- and Middle-Income Countries

Introduction

Kidney biopsy is an important tool for making diagnoses and for assessing the drug treatment requirements and disease prognosis in the management of kidney diseases. There are variations in the rate of complications associated with kidney biopsies across countries, and this depends on various clinical and technical factors. The aim of this study is to report on complications associated with kidney biopsy performed in low- and middle-income countries.

Methods

Two reviewers searched studies in MEDLINE, Embase, Cochrane Reviews, and African Journals Online. A random effects meta-analysis method was used to pool estimates of complications.

Results

We identified 39 studies reporting on 19,500 kidney biopsies with overall complications (major + minor) rate of 14.9% (95% confidence interval = 11.4%–18.7%). Fewer complications were reported in biopsies performed with real-time ultrasound scans compared to those pre-marked using ultrasound or blind procedures (12.4% vs. 14.9% vs. 24.5%; P = 0.037), respectively. Complications, albeit lower for procedures performed with automated needles (13.3%), were not significantly different from those performed with nonautomated needles (17.3%; P = 0.588). Major complications included macroscopic hematuria (1.48%), nephrectomy (0.04%), blood loss requiring red cell transfusion (0.24%), angiographic intervention (0.22%), and death (0.01%).

Conclusion

Complications associated with kidney biopsy in low- and middle-income countries are low, are comparable to those in other settings, and occur more sparingly when real-time ultrasound techniques or automated kidney biopsy needles are used. This suggests the need to expand the use of this procedure to improve diagnosis of kidney pathologies and choice of therapy when indicated.

Acute Kidney Disease Increases the Risk of Post-Kidney Biopsy Bleeding Complications

INTRODUCTION

Kidney biopsy, providing the insightful information for most kidney diseases, is an invasive diagnostic tool with certain risks ranging from the least severe macroscopic hematuria to the most severe life-threatening bleeding necessitating renal artery embolization. We aimed to compare the postbiopsy bleeding complications between 2 common methods and to further explore the risk factors of bleeding complications in patients using the negative pressure suction puncture (NPS) method.

METHODS

We retrospectively collected the data from percutaneous native kidney biopsies in 2016. The clinical, laboratory tests, pathological findings, and the occurrence of bleeding complications following kidney biopsy were analyzed. The kidney biopsy was performed in our center by experienced nephrologists with 2 different methods, namely, NPS method and real-time ultrasound-guided needle (RTU) method. We compared rates of complications between 2 methods and evaluated univariate and multivariate association of risk factors with bleeding complications in the NPS group.

RESULTS

626 kidney biopsies were performed between January 2016 and December 2016. There were 83.2% (521/626) participants in the NPS group and 16.8% (105/626) in the RTU group. There were more participants in the RTU group needing >1 needle pass during biopsy than those in the NPS group (61.0 vs. 14.7%, p < 0.001). Acute kidney disease (AKD) occurred before the procedure of kidney biopsy accounted for 13.8% (72/521) in the NPS group and 1.9% (2/105) in the RTU group. The renal pathological findings revealed higher number of glomeruli in the NPS group than in the RTU group (26.8 ± 13.0 vs. 17.2 ± 8.6, p < 0.001). The incidence of bleeding complications in the NPS group was lower than that in the RTU group (9.2 vs. 21.9%, p < 0.01). Logistic multivariate regression showed that AKD was independently associated with bleeding complications after kidney biopsy in the NPS group.

CONCLUSION

Regarding the bleeding risk, there was noninferiority of NPS over RTU. AKD contributes to higher risks of bleeding complications after kidney biopsy.

Systematic Review and Meta-Analysis of Native Kidney Biopsy Complications

BACKGROUND AND OBJECTIVES

Native kidney biopsies are commonly performed in the diagnosis of acute kidney diseases and CKD. Because of the invasive nature of the procedure, bleeding-related complications are not uncommon. The National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases-sponsored Kidney Precision Medicine Project requires that all participants undergo a kidney biopsy; therefore, the objective of this analysis was to study complication rates of native kidney biopsies performed using automated devices under kidney imaging.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a systematic review and meta-analysis of the literature published from January 1983 to March 2018. The initial PubMed search yielded 1139 manuscripts. Using predetermined selection criteria, 87 manuscripts were included in the final analysis. A random effects meta-analysis for proportions was used to obtain combined estimates of complication rates. Freeman-Tukey double-arcsine transformations were used to stabilize variance as complications were rare.

RESULTS

A total of 118,064 biopsies were included in this study. Patient age ranged from 30 to 79 years, and 45% of patients were women. On the basis of our meta-analysis, pain at the site of biopsy is estimated to occur in 4.3% of biopsied patients, hematomas are estimated to occur in 11%, macroscopic hematuria is estimated to occur in 3.5%, bleeding requiring blood transfusions is estimated to occur in 1.6%, and interventions to stop bleeding are estimated to occur in only 0.3%. Death attributed to native kidney biopsy was a rare event, occurring only in an estimated 0.06% of all biopsies but only 0.03% of outpatient biopsies. Complication rates were higher in hospitalized patients and in those with acute kidney disease. The reported complications varied on the basis of study type and geographic location.

CONCLUSIONS

Although the native kidney biopsy is an invasive diagnostic procedure, the rates of bleeding complications are low. Albeit rare, death can occur postbiopsy. Complications are more frequently seen after kidney biopsies of hospitalized patients with AKI.

Major Bleeding and Risk of Death after Percutaneous Native Kidney Biopsies: A French Nationwide Cohort Study

BACKGROUND AND OBJECTIVES

The risk of major bleeding after percutaneous native kidney biopsy is usually considered low but remains poorly predictable. The aim of the study was to assess the risk of major bleeding and to build a preprocedure bleeding risk score.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our study was a retrospective cohort study in all 52,138 patients who had a percutaneous native kidney biopsy in France in the 2010-2018 period. Measurements included major bleeding (i.e., blood transfusions, hemorrhage/hematoma, angiographic intervention, or nephrectomy) at day 8 after biopsy and risk of death at day 30. Exposures and outcomes were defined by diagnosis codes.

RESULTS

Major bleeding occurred in 2765 of 52,138 (5%) patients (blood transfusions: 5%; angiographic intervention: 0.4%; and nephrectomy: 0.1%). Nineteen diagnoses were associated with major bleeding. A bleeding risk score was calculated (Charlson index [2-4: +1; 5 and 6: +2; >6: +3]; frailty index [1.5-4.4: +1; 4.5-9.5: +2; >9.5: +3]; women: +1; dyslipidemia: -1; obesity: -1; anemia: +8; thrombocytopenia: +2; cancer: +2; abnormal kidney function: +4; glomerular disease: -1; vascular kidney disease: -1; diabetic kidney disease: -1; autoimmune disease: +2; vasculitis: +5; hematologic disease: +2; thrombotic microangiopathy: +4; amyloidosis: -2; other kidney diagnosis: -1) + a constant of 5. The risk of bleeding went from 0.4% (lowest score group =0-4 points) to 33% (highest score group ≥35 points). Major bleeding was an independent risk of death (500 of 52,138 deaths: bleeding: 81 of 2765 [3%]; no bleeding: 419 of 49,373 [0.9%]; odds ratio, 1.95; 95% confidence interval, 1.50 to 2.54; P<0.001).

CONCLUSIONS

The risk of major bleeding after percutaneous native kidney biopsy may be higher than generally thought and is associated with a twofold higher risk of death. It varies widely but can be estimated with a score useful for shared decision making and procedure choice.

Risk Factors for Major Hemorrhage Following Percutaneous Image-Guided Renal Biopsy: What is the "core" of the Problem? A Retrospective Case-control Study

Objectives:

Percutaneous renal biopsy (PRB) plays a critical role in the work-up of renal parenchymal disease. Although it is considered a low-risk procedure, additional interventions may be required in about 7% of the cases following biopsy. The purpose of this study was to identify risk factors for major hemorrhage by microscopic analysis of the cores obtained following PRB, with an intent to enhance the sensitivity and specificity of the risk stratification process, especially in patients undergoing this procedure in an outpatient setting.

Material and Methods:

A retrospective review identified 17 of 179 patients (9.50%) with major hemorrhage following PRB between July 2014 and June 2019. Using propensity score matching, 26 controls (without major hemorrhage) were matched to 17 cases (with major hemorrhage). The biopsy cores obtained from the cases and controls were analyzed by a single pathologist for medullary, cortical, total (medullary + cortical) lengths, and the number of arcuate arteries (AAs). Medullary:cortical (M:C), cortical:total (C:T), and medullary:total (M:T) length ratios were then calculated.

Results:

A stratified version of logistic regression was used to test for an association between each of the variables identified on the cores and the probability of a major hemorrhage. The analysis revealed that there was a statistically significant association between the number of AAs per specimen with the risk of major hemorrhage (P = 0.0006). When 0, 1, or >2 AAs were identified, the frequency of major hemorrhage was 13.04%, 66.67%, and 75.00%, respectively. The odds of major hemorrhage were 6 times higher with one AA and (95% CI, 1.28–32.30) and 15 times higher with >2 AAs (95% CI, 1.41–169.57). No significant association was found between medullary length (P = 0.228), medulla:cortex (M:C) (P = 0.089), medulla:total (M:T) (P = 0.108), or cortex:total (C:T) (P = 0.112) length ratios and major hemorrhage.

Conclusion:

There was a strong and incremental correlation between major renal hemorrhage following PRB and the number of AAs per core specimen. Identification of AAs by the pathologist, while assessing for sample adequacy, in the US suite can help predict major hemorrhage in patients undergoing PRBs.

Value of Immediate Post-Kidney Biopsy Ultrasound in Excluding Late Hemorrhagic Complications

BACKGROUND

Hemorrhage is the most serious potential complication of percutaneous kidney biopsy. Patients are typically observed for at least 6-8 hours after a kidney biopsy, with serial measurements of vital signs and hemoglobin to monitor for major hemorrhage. This study assessed whether an immediate postbiopsy ultrasound can reliably exclude delayed major hemorrhage.

METHODS

We retrospectively evaluated the clinical outcomes in 147 patients undergoing an outpatient native kidney biopsy with an 18-gauge needle at a large medical center during a 2.5-year period (January 2017 to June 2019). All patients underwent a standardized postbiopsy ultrasound to assess for active extravasation of blood. We extracted from the medical records vital signs and hemoglobin values obtained before the biopsy and at 2, 4, and 6 hours after the procedure. We ascertained whether any patients with a negative postbiopsy ultrasound developed a delayed major hemorrhage.

RESULTS

Each patient underwent two or three biopsy passes. The mean patient age was 48±17 years, 49% were female, 37% were black, 53% had hypertension, and 16% had diabetes. Of the 142 patients without evidence of active extravasation on ultrasound, the BP, heart rate, and hemoglobin remained stable during 6 hours of observation. All were discharged after 6 hours, and none had a late bleeding complication.

CONCLUSIONS

If the immediate postkidney biopsy ultrasound does not show active bleeding, the patient is extremely unlikely to develop a late major hemorrhagic complication (negative predictive value, 100%). Such patients can be discharged home safely after a 2-hour observation, thereby simplifying their management.

Adequacy and complication rates of percutaneous renal biopsy with 18- vs. 16-gauge needles in native kidneys in Chinese individuals

BACKGROUND

Percutaneous renal biopsy (PRB) is the primary biopsy technique and it was used by 16G needles or 18G needles in China, but there is controversy about the effect and safety of the two different diameters. The study aims to compare the adequacy, complication rate and pathological classification when using 18G vs. 16G needles to perform renal biopsy with ultrasound-guidedance on native kidneys in Chinese individuals.

METHODS

We retrospectively analyzed the number of glomeruli, adequate sample rates, complication rates and pathological classification in 270 patients with the use of 18G or 16G needles from January 2011 to May 2017 and verified whether the needle gauge affected the disease diagnosis.

RESULTS

A total of 270 kidney biopsies were performed. Among them,72 were performed with 18G needles, and 198 were performed with 16G needles. There was no difference in the number of glomeruli under light microscope using 18G relative to 16G needles (24 ± 11 vs. 25 ± 11, p = 0.265), whereas more glomeruli were found in the 16G group than in the 16G group using immunofluorescence microscopy (3 ± 2 vs. 5 ± 3, p < 0.05). There was no significant difference in the adequate sample rates between the 18G group and the 16G group (90.28% vs. 93.94%, p = 0.298). Minor complications including the incidence of lumbar or abdominal pain (4.17% vs. 7.07%, p = 0.57), gross hematuria (4.17% vs. 3.54%, p = 0.729), and perinephric hematoma without symptoms (4.17% vs. 1.52%, p = 0.195), were not significantly different between the 18G and 16G groups. In the 16G group, 2 cases of serious complications occurred: severe gross hematuria requiring blood transfusion and retroperitoneal hematoma requiring surgery. No serious complications were observed in the 18G group, although there was no significant difference in serious complications rates between the 18G and 16G groups (0% vs. 1.02%, p = 1).

CONCLUSION

There was no significant difference in the number of glomeruli, adequate sample rates, or complication rates when using 18G or 16G needles to perform renal biopsy, and the use of an 18G needle with a smaller diameter did not affect the pathological diagnosis or classification of IgA nephropathy and lupus nephritis.

Use of Desmopressin Prior to Kidney Biopsy in Patients With High Bleeding Risk

INTRODUCTION

To prevent bleeding after native kidney biopsy (NKB), nephrologists often prescribe desmopressin, especially for patients with reduced estimated glomerular filtration rate (eGFR) at risk of uremia-related platelet dysfunction. However, only 1 randomized study has suggested a beneficial effect for desmopressin in patients with eGFR ≥60 ml/min per 1.73 m2. This retrospective cohort study aimed to evaluate desmopressin effect on postbiopsy bleeding in all patients, regardless of eGFR and other comorbidities.

METHODS

In this retrospective cohort study, all adult patients who underwent an NKB from April 1, 2013, to April 30, 2018, in a tertiary hospital were identified. The association between desmopressin use and bleeding complications, including hemoglobin fall, transfusion, hematoma, symptomatic hematoma, urgent radiologic study, and hypotension, was analyzed using multivariable logistic regression models.

RESULTS

A total of 413 native kidney biopsies were studied, 79% of which were performed after receiving desmopressin. Patients receiving desmopressin had worse chronic kidney disease (eGFR 28 vs. 45 ml/min per 1.73 m2; P < 0.001) and were more often hospitalized (48% vs. 32%; P = 0.009). Despite higher bleeding risk, patients using desmopressin had a similar likelihood of symptomatic hematomas (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.13-1.14) and a lower need for urgent radiologic studies (OR, 0.33; 95% CI, 0.11-0.98).

CONCLUSION

Patients at higher risk of bleeding using desmopressin before kidney biopsy had bleeding complications similar to those not using desmopressin. These results highlight potential important clinical and financial benefits of desmopressin use before kidney biopsy.

A novel method for assessing the renal biopsy specimens using an activatable fluorescent probe

Gamma-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG) is an activatable fluorescent probe that can be activated by γ-glutamyltranspeptidase (GGT). The expression of GGT in the kidney, which is one of the major organs exhibiting enhanced GGT expression, is exclusively localised to the cortex. Here, we aimed to investigate the feasibility of gGlu-HMRG as a probe for the on-site assessment of renal biopsy specimens. gGlu-HMRG fluorescent probe was applied to the renal proximal tubular epithelial cells and cortical collecting duct cells in vitro, mouse kidneys ex vivo, and human biopsy specimens. In addition, the fluorescence intensities in the cortex and the medulla were comparatively evaluated in the biopsy specimens. The fluorescence signal was rapidly detected in the renal proximal tubular epithelial cells, whereas that in the cortical collecting duct cells was not detected. The fluorescence signal was detected in the mouse kidneys ex vivo without markedly affecting the tissue morphology. In the human biopsy specimens, the fluorescence signal in the cortex was significantly distinct from that in the medulla (p < 0.05). Thus, this fluorescent probe can be used to distinctly identify the renal cortex in the biopsy specimens.

A Color Flow Tract in Ultrasound-Guided Random Renal Core Biopsy Predicts Complications

OBJECTIVES

To determine patient and procedural risk factors for major complications in ultrasound (US)-guided random renal core biopsy.

METHODS

Random renal biopsies performed by radiologists in the US department at a single institution between 2014 and 2018 were retrospectively reviewed. The patient's age, sex, race, and estimated glomerular filtration rate (eGFR) were recorded. The biopsy approach, needle gauge, length of cores, number of throws, and presence of a color flow tract were recorded. Outcome data included minor and major complications. Associations between variables were tested with χ² analyses and univariable/multivariable logistic regression models.

RESULTS

A total of 231 biopsies (167 native and 64 allografts) were reviewed. There was no significant difference in the sex, age, race, or eGFR between native and allograft groups. The overall rate for any complication was 18.2%, with a 4.3% rate of major complications, which was significantly greater in native compared to allograft biopsies (6% versus 0%; P = .045). A risk analysis in native biopsies only showed that major complications were significantly associated with a low eGFR such that patients with stage 4 or 5 kidney disease had higher odds of complications (odds ratio [95% confidence interval]: stage 4, 9.405 [1.995-44.338]; P = .0393; stage 5, 10.749 [2.218-52.080]; P = .0203) than patients with normal function (eGFR >60 mL/min). The presence of a color flow tract portended a 10.7 times greater risk of having any complication (95% confidence interval, 4.595-24.994; P < .001). Other procedural factors were not significantly associated with complications.

CONCLUSIONS

There is an increased risk of major complications in US-guided random native kidney biopsy in patients with a low eGFR (<30 mL/min) and a patent color flow tract in the immediate postbiopsy setting.

Thromboelastography versus bleeding time for risk of bleeding post native kidney biopsy

Introduction

The risk of bleeding has led to screening of the primary hemostasis before renal biopsy. A bleeding time test (BT) is considered standard practice, but reliance on this test is controversial and its benefits remain questionable. A possible alternative is thromboelastography (TEG). However, data regarding TEG in patients with renal dysfunction is limited.

Objectives

To determine TEG abnormalities and their consequences in patients who underwent a native kidney biopsy.

Methods

A retrospective study of 417 consecutive percutaneous native renal biopsies performed in our Center. If serum creatinine >1.5 mg/dL, the patient underwent either a BT test (period A, January 2015–31 December 2016) or TEG (period B, January 2017–August 2018). In patients with prolonged BT, or an abnormal low maximal amplitude (MA) parameter of TEG, or suspected clinical uremic thrombopathy, the use of desmopressin acetate (DDAVP) was considered.

Results

Most biopsies (90.6%) were done by the same dedicated radiologist. Fifty-one patients had a BT test, which was normal in all tested patients. Seventy-one patients underwent TEG, and it was abnormal in 34 of them, most patients had combined abnormalities. The only parameter related to abnormal TEG was older age (Odds Ratio 1.21 [95% CI 1.09–2.38] p = 0.04 for abnormal Kinetics; OR 1.37 (1.05–1.96) p = 0.037 for abnormal MA). Twenty-six patients (6.23%) had bleeding complications. Risk of bleeding was significantly related to age (1.4 [1.11–7.48] p = 0.04), systolic blood pressure (1.85 [1.258–9.65] p = 0.02), and serum creatinine (1.21 [1.06–3.134] p = 0.048).

Conclusions

TEG abnormalities in patients with renal dysfunction are variable and fail to predict bleeding during kidney biopsy. The decision to administer DDAVP as a preventive measure during these procedures should be based on clinical judgment only.

A complex dual-modality kidney phantom for renal biopsy studies

We developed a reliable and repeatable process to create hyper-realistic, kidney phantoms with tunable image visibility under ultrasound (US) and CT imaging modalities. A methodology was defined to create phantoms that could be produced for renal biopsy evaluation. The final complex kidney phantom was devised containing critical structures of a kidney: kidney cortex, medulla, and ureter. Simultaneously, some lesions were integrated into the phantom to mimic the presence of tumors during biopsy. The phantoms were created and scanned by ultrasound and CT scanners to verify the visibility of the complex internal structures and to observe the interactions between material properties. The result was a successful advancement in knowledge of materials with ideal acoustic and impedance properties to replicate human organs for the field of image-guided interventions.

Frequency, Timing, and Prediction of Major Bleeding Complications From Percutaneous Renal Biopsy

Background and Objectives:

The risk and timing of bleeding events following ultrasound-guided percutaneous renal biopsy are not clearly defined.

Design setting, participants, and measurements:

We performed a retrospective study of 617 consecutive adult patients who underwent kidney biopsy between 2012 and 2017 at a tertiary academic hospital in London, Canada. We assessed frequency and timing of minor (not requiring intervention) and major (requiring blood transfusion, surgery, or embolization) bleeds and developed a personalized risk calculator for these.

Results:

Bleeding occurred in 79 patients (12.8%; 95% confidence interval [CI]: 10.4%-15.7%). Minor bleeding occurred in 67 patients (10.9%; 95% CI: 8.6%-13.6%). Major bleeding occurred in 12 patients (1.9%; 95% CI: 1.1%-3.4%); 2 required embolization or surgery (0.3%; 95% CI: 0.09%-1.2%) and 10 required blood transfusion (1.6%; 95% CI: 0.9%-3.0%). Seventy-three of 79 events were identified immediately on post-procedure ultrasound (92.4% of cases; 95% CI: 84.4%-96.5%). Four of 617 patients experienced a minor event not detected immediately (0.6%; 95% CI: 0.3%-1.7%). Two patients (0.3%; 95% CI: 0.09%-1.2%) suffered a major complication that was not recognized immediately; both required blood transfusions only. There were no deaths or nephrectomies. A risk calculator using age, body mass index, platelet count, hemoglobin concentration, size of the target kidney, and whether the kidney is native, or an allograft predicted minor (C-statistic, 0.70) and major bleeding (C-statistic, 0.83).

Conclusions:

This retrospective study of 617 patients who had percutaneous ultrasound-guided renal biopsies supports the safety of short post-biopsy monitoring for most patients. A risk calculator can further personalize estimates of complication risk (http://perioperativerisk.com/kbrc).

Risk of incident bleeding after acute kidney injury: A retrospective cohort study

PURPOSE

End-stage kidney disease (ESKD) causes bleeding diathesis; however, whether these findings are extrapolable to acute kidney injury (AKI) remains uncertain. We assessed whether AKI is associated with an increased risk of bleeding.

METHODS

Single-center retrospective cohort study, excluding readmissions, admissions <24 h, ESKD or kidney transplants. The primary outcome was the development of incident bleeding analyzed by multivariate time-dependent Cox models.

RESULTS

In 1001 patients, bleeding occurred in 48% of AKI and 57% of non-AKI patients (p = .007). To identify predictors of incident bleeding, we excluded patients who bled before ICU (n = 488). In bleeding-free patients (n = 513), we observed a trend toward higher risks of bleeding in AKI (22% vs. 16%, p = .06), and a higher risk of bleeding in AKI-requiring dialysis (38% vs. 17%, p = .01). Cirrhosis, AKI-requiring dialysis, anticoagulation, and coronary artery disease were associated with bleeding (HR 3.67, 95%CI:1.33-10.25; HR 2.82, 95%CI:1.26-6.32; HR 2.34, 95%CI:1.45-3.80; and HR 1.84, 95%CI:1.06-3.20, respectively), while SOFA score and sepsis had a protective association (HR 0.92 95%CI:0.84-0.99 and HR 0.55, 95%CI:0.34-0.91, respectively). Incident bleeding was not associated with mortality.

CONCLUSIONS

AKI-requiring dialysis was associated with incident bleeding, independent of anticoagulant administration. Studies are needed to better understand how AKI affects coagulation and clinical outcomes.

Pre-procedural shear wave elastography on prediction of hemorrhage after percutaneous real-time ultrasound-guided renal biopsy

PURPOSE

To evaluate the relationship between renal elasticity which was determined with shear wave elastography (SWE) and hemorrhage in patients who undergone percutaneous renal parenchyma biopsy (PRB).

MATERIALS AND METHODS

In total, 60 patients who were performed ultrasound-guided PRB after the B-mode ultrasonography and SWE assessment were recruited in this study. All patients' serum creatinine, blood urea nitrogen and coagulation tests before PRB were obtained from medical records. The patients were divided into two groups who did and did not develop hemorrhage after PRB. We investigated whether there was any statistically significant difference between the two groups in terms of laboratory findings, B-mode ultrasonographic measurements and SWE measurements.

RESULTS

Of the 60 patients, 23 (38.3%) had post-procedure hemorrhage and 37 (61.7%) had not. Mean hemorrhage size was 17.04 mm (7-50 mm). The mean value of renal cortical shear wave velocity of all patients was 1.91 m/s (0.96-3.57 m/sn). Patients with post-procedure hemorrhage had significantly lower mean shear wave velocity compared with patients with no hemorrhage (p < 0.05). ROC curve analysis suggested that the optimum SWV cutoff point for hemorrhage presence was 1.21 m/sn, with 39.1% sensitivity and 97.3% specificity. There was no other statistically significant demographic, ultrasonographic or laboratory value differences between two groups.

CONCLUSION

Although shear wave velocities have low sensitivity for hemorrhage after renal biopsy, high specificity and statistically significant difference in hemorrhage and non-hemorrhage group suggest that patients who have lower renal cortical shear wave velocity have a tendency to hemorrhage after PRB.

A nationwide survey on clinical practice patterns and bleeding complications of percutaneous native kidney biopsy in Japan

Background

Practice patterns and bleeding complications of percutaneous native kidney biopsy (PNKB) have not recently been investigated and the Japanese Society of Nephrology performed a nationwide questionnaire survey in 2018.

Methods

The survey consisted of nine sections about PNKB: (1) general indications; (2) indications for high-risk patients; (3) informed consent; (4) pre-biopsy evaluation; (5) procedures; (6) sedation; (7) post-biopsy hemostasis, bed rest, and examinations; (8) bleeding complications; and (9) specimen processing. A supplementary survey examined bleeding requiring transcatheter arterial embolization (TAE).

Results

Overall, 220 directors of facilities (nephrology facility [NF], 168; pediatric nephrology facility [PF], 52) completed the survey. Indications, procedures, and monitoring protocols varied across facilities. Median lengths of hospital stay were 5 days in NFs and 6 days in PFs. Gauge 14, 16, 18 needles were used in 5%, 56%, 33% in NFs and 0%, 63%, 64% in PFs. Mean limits of needle passes were 5 in NFs and 4 in PFs. The bed rest period was 16–24 h in 60% of NFs and 65% of PFs. Based on 17,342 PNKBs, incidence rates of macroscopic hematuria, erythrocyte transfusion, and TAE were 3.1% (NF, 2.8%; PF, 6.2%), 0.7% (NF, 0.8%; PF, 0%), and 0.2% (NF, 0.2%; PF, 0.06%), respectively. Forty-six percent of facilities processed specimens all for light microscopy, immunofluorescence, and electron microscopy, and 21% processed for light microscopy only. Timing of bleeding requiring TAE varied among PNKB cases.

Conclusion

Wide variations in practice patterns of PNKB existed among facilities, while PNKBs were performed as safely as previously reported.

Electronic supplementary material

The online version of this article (10.1007/s10157-020-01869-w) contains supplementary material, which is available to authorized users.

Bleeding Complications After Percutaneous Native Kidney Biopsy: Results From the Boston Kidney Biopsy Cohort

Background

The major risk of kidney biopsy is severe bleeding. Numerous risk factors for bleeding after biopsy have been reported, but findings have been inconsistent.

Methods

We retrospectively reviewed medical records of adult patients enrolled in a native kidney biopsy cohort study to identify major bleeding events (red blood cell [RBC] transfusions, invasive procedures, kidney loss, or death). We used logistic and linear regression models to identify characteristics associated with postbiopsy RBC transfusions and decline in hemoglobin within a week after the procedure.

Results

Major bleeding events occurred in 28 of 644 (4.3%) patients (28 required an RBC transfusion, 4 underwent angiographic intervention, and 1 had open surgery to control bleeding). No patient lost a kidney or died because of the biopsy. Postbiopsy RBC transfusion risk was driven by the baseline hemoglobin level (odds ratio [OR] 13.6; 95% confidence interval [CI] 5.4–34.1 for hemoglobin <10 vs. ≥10 g/dl). After adjusting for hemoglobin, no other patient characteristics were independently associated with RBC transfusions. Female sex (β = 0.18; 95% CI: 0.04–0.32), estimated glomerular filtration rate (eGFR) <30 ml/min per 1.73 m² (β = 0.32; 95% CI: 0.14–0.49), and baseline hemoglobin (β = 0.09; 95% CI: 0.05–0.13, per g/dl increase) were independently associated with a larger drop in hemoglobin. Histopathologic lesions were not independently associated with major bleeding after biopsy.

Conclusion

Biopsies were generally well tolerated. Baseline hemoglobin was the dominant risk factor for RBC transfusions, but female sex and eGFR <30 ml/min per 1.73 m² were also associated with a larger decline in hemoglobin after the procedure.

Positron emission tomography as an adjuvant diagnostic test in the evaluation of checkpoint inhibitor-associated acute interstitial nephritis

Background

Acute interstitial nephritis is an immune-related adverse event that can occur in patients receiving immune checkpoint inhibitor therapy. Differentiating checkpoint inhibitor-associated acute interstitial nephritis from other causes of acute kidney injury in patients with cancer is challenging and can lead to diagnostic delays and/or unwarranted immunosuppression. In this case report, we assess the use of ¹⁸F-flourodeoxyglucose positron-emission tomography imaging as an alternative diagnostic modality in the evaluation of potential acute interstitial nephritis.

Case presentation

A 55-year-old woman with metastatic vulvar melanoma underwent treatment with two cycles of ipilimumab plus nivolumab, followed by seven cycles of nivolumab combined with radiation therapy. During her treatment, she developed non-oliguric acute kidney injury to a creatinine of 4.5 mg/dL from a baseline of 0.5 mg/dL. A clinical diagnosis of acute interstitial nephritis was made, and steroids were initiated, with rapid improvement of her acute kidney injury. Retrospectively, four positron-emission tomography scans obtained for cancer staging purposes were reviewed. We found a markedly increased ¹⁸F-flourodeoxyglucose uptake in the renal cortex at the time acute interstitial nephritis was diagnosed compared to baseline. In three cases of acute kidney injury due to alternative causes there was no increase in ¹⁸F-flourodeoxyglucose uptake from baseline.

Conclusions

To our knowledge, this is the first report describing increased ¹⁸F-flourodeoxyglucose uptake in the renal cortex in a patient with checkpoint inhibitor-associated acute interstitial nephritis. Our findings suggest that ¹⁸F-flourodeoxyglucose positron-emission tomography may be a valuable test for diagnosing immune-mediated nephritis, particularly in patients where timely kidney biopsy is not feasible.

Risk Factors Associated with Major Complications after Ultrasound-Guided Percutaneous Renal Biopsy of Native Kidneys

INTRODUCTION

Percutaneous renal biopsy (PRB) of native kidneys is an important tool for diagnosis and management of renal disease. In this study, we analyzed the success, safety, and risk complications of PRB in our center.

METHODS

A retrospective review of ultrasound-guided PRB done at our institution from January 1998 to December 2017 was performed. Clinical and laboratory data were collected for 661 PRBs. Statistical analysis was performed using the Mann-Whitney U test for continuous variable and chi-square test for categorical variables. Multivariate analysis using logistic regression was performed to assess factors associated with increased risk of complications after PRB.

RESULTS

The median age was 56 (42-68) years old, the majority were male (64%) and white (82%). Ten glomeruli were present in 63.5% of PRBs. Overall, the rate of complications was 16.6%, where 15.1% of them were minor complications and 1.5% were major complications. Perinephritic hematoma accounted for the minor complication that occurred most frequently, whereas the need of a blood transfusion was the prevalent for major complications. By multivariate analysis, increased activated partial thromboplastin time (aPTT; OR 1.11, 95% CI 1.035-1.180) and prebiopsy lower hemoglobin (Hgb; OR 1.61, 95% CI 1.086-2.304) were identified as independent risk factors for major complications. In addition, older patients (OR 1.057, 95% CI 1.001-1.117) were identified as an independent risk factor for blood transfusion requirement.

CONCLUSION

The current risk of complications after native PRB is low. Major complications are most common in case of increased aPTT and decreased Hgb baseline level.

Desmopressin and bleeding risk after percutaneous kidney biopsy

Background

Desmopressin is used to reduce bleeding after kidney biopsy but evidence supporting its use is weak, especially in patients with elevated creatinine. The present study was undertaken to evaluate efficacy of desmopressin in reducing bleeding after percutaneous kidney biopsy.

Methods

Retrospective cohort study. 269 of 322 patients undergoing percutaneous kidney biopsy between January 1, 2014 and January 31, 2018 were included. Patients had normal bleeding time, platelet count and coagulation profile. Primary outcome was defined as composite of hemoglobin drop ≥1 g/dL, hematoma on post biopsy ultrasound, gross hematuria, erythrocyte transfusion or angiography to stop bleeding. Association of desmopressin with outcomes was assessed using linear (for continuous variables) and logistic (for binary variables) regression models. Propensity score was used to minimize potential confounding.

Results

Desmopressin was administered to 100/269 (37.17%) patients. After propensity score adjustment patients who received desmopressin had increased odds of post biopsy bleeding [OR 3.88 (1.95–7.74), p < 0.001]. Creatinine at time of biopsy influenced bleeding risk; gender, emergent vs elective biopsy, obesity, AKI, diabetes, hypertension or bleeding time did not influence bleeding risk. Administration of desmopressin to patients with serum creatinine ≥1.8 mg/dL decreased bleeding risk [OR 2.11 (95% CI 0.87–5.11), p = 0.09] but increased bleeding risk when serum creatinine was < 1.8 mg/dL (OR 9.72 (95% CI 2.95–31.96), p < 0.001).

Conclusion

Desmopressin should not be used routinely prior to percutaneous kidney biopsy in patients at low risk for bleeding but should be reserved for patients who are at high risk for bleeding.

Clinical parameters predicting complications in native kidney biopsies

Background

Renal biopsies are essential in nephrology but they are invasive and complications can occur. The aim of this study was to explore clinical parameters that can be used as predictors for biopsy complications.

Methods

Clinical parameters such as demographics, biopsy indications, serology, comorbidities and clinical chemistry were retrieved from a regional biopsy registry between 2006 and 2015 and from a nationwide registry between 2015 and 2017. Clinical data before biopsy were compared with data on major biopsy complications. Fisher’s exact and χ² tests were used and odds ratios (ORs) with 95% confidence intervals (CIs) were presented. Univariate and multiple binary logistic regression analyses were performed with complications as outcome. A two-sided P-value <0.05 was considered significant.

Results

In total, 2835 consecutive native kidney biopsies were analysed (39% women and 61% men, median age 57 years). No death and nephrectomy due to biopsy complications were registered. The frequency of major biopsy complications was 5.65%. In the multiple logistic regression, the risk for complications increased in women [OR 1.51 (95% CI 1.08–2.11)] and decreased with age: 45–64 years age group [OR 0.66 (95% CI 0.44–0.99)] and >74 years age group [OR 0.51 (95% CI 0.27–0.96)]. Among comorbidities, patients with diabetes mellitus type 2 [OR 2.07 (95% CI 1.15–3.72)] and non-ischaemic heart disease [OR 3.20 (95% CI 1.64–6.25)] had a higher risk for major biopsy complications.

Conclusions

Female gender, younger age (≤44 years), diabetes mellitus type 2 and non-ischaemic heart disease were found as risk factors for major biopsy complications.

Role of MR texture analysis in histological subtyping and grading of renal cell carcinoma: a preliminary study

PURPOSE

The study evaluated the usefulness of magnetic resonance imaging (MRI) texture parameters in differentiating clear cell renal carcinoma (CC-RCC) from non-clear cell carcinoma (NC-RCC) and in the histological grading of CC-RCC.

MATERIALS AND METHODS

After institutional ethical approval, this retrospective study analyzed 33 patients with 34 RCC masses (29 CC-RCC and five NC-RCC; 19 low-grade and 10 high-grade CC-RCC), who underwent MRI between January 2011 and December 2012 on a 1.5-T scanner (Avanto, Siemens, Erlangen, Germany). The MRI protocol included T2-weighted imaging (T2WI), diffusion-weighted imaging [DWI; at b 0, 500 and 1000 s/mm² with apparent diffusion coefficient (ADC) maps] and T1-weighted pre and postcontrast [corticomedullary (CM) and nephrographic (NG) phase] acquisition. MR texture analysis (MRTA) was performed using the TexRAD research software (Feedback Medical Ltd., Cambridge, UK) by a single reader who placed free-hand polygonal region of interest (ROI) on the slice showing the maximum viable tumor. Filtration histogram-based texture analysis was used to generate six first-order statistical parameters [mean intensity, standard deviation (SD), mean of positive pixels (MPP), entropy, skewness and kurtosis] at five spatial scaling factors (SSF) as well as on the unfiltered image. Mann-Whitney test was used to compare the texture parameters of CC-RCC versus NC-RCC, and high-grade versus low-grade CC-RCC. P value < 0.05 was considered significant. A 3-step feature selection was used to obtain the best texture metrics for each MRI sequence and included the receiver-operating characteristic (ROC) curve analysis and Pearson's correlation test.

RESULTS

The best performing texture parameters in differentiating CC-RCC from NC-RCC for each sequence included (area under the curve in parentheses): entropy at SSF 4 (0.807) on T2WI, SD at SSF 4 (0.814) on DWI b500, SD at SSF 6 (0.879) on DWI b1000, mean at SSF 0 (0.848) on ADC, skewness at SSF 2 (0.854) on T1WI and skewness at SSF 3 (0.908) on CM phase. In differentiating high from low-grade CC-RCC, the best parameters were: entropy at SSF 6 (0.823) on DWI b1000, mean at SSF 3 (0.889) on CM phase and MPP at SSF 5 (0.870) on NG phase.

CONCLUSION

Several MR texture parameters showed excellent diagnostic performance (AUC > 0.8) in differentiating CC-RCC from NC-RCC, and high-grade from low-grade CC-RCC. MRTA could serve as a useful non-invasive tool for this purpose.

Intranasal desmopressin reduces renal biopsy-related bleeding and serum sodium levels in patients with reduced renal function

Background

The use of desmopressin in preventing renal biopsy-related bleeding is not established and its effects on serum sodium levels are not well studied. The study aimed to compare the bleeding complication rates between the groups with and without desmopressin use prebiopsy and to observe the effect of desmopressin on postbiopsy serum sodium levels.

Methods

In this single-center, prospective and retrospective interventional study, from June 2018 onwards, patients with serum creatinine >132.6 μmol/L but not on dialysis and undergoing ultrasound-assisted needle-guided renal biopsy received 150 μg of desmopressin (D-amino D-arginine vasopressin (DDAVP)) (Group II). Data from patients from June 2017 to May 2018 were included in Group I in whom desmopressin was not used. Bleeding complications were monitored by clinical and ultrasound surveillance. Serum sodium levels were checked prior to and 24 h following desmopressin in Group II.

Results

A total of 194 patients were included in the study: 105 in Group I and 89 in Group II. Group II had lower overall minor bleeding complications and perinephric hematomas than Group I (15.7% versus 31.4%, 14% versus 27% and 7.8% versus 19% in Group II and Group I, respectively, with P < 0.05). Not using desmopressin and female sex were significant predictors for overall risk of bleeding on multivariate logistic regression. Serum sodium levels fell in 94% of patients in Group II. Lower prebiopsy serum sodium, higher estimated glomerular function rate and higher spot urine sodium values were associated with a greater decrease in serum sodium after desmopressin.

Conclusion

Intranasal desmopressin reduces bleeding complications during renal biopsies performed in patients with reduced renal function not requiring dialysis, albeit with a risk of developing hyponatremia.

Diagnostic role of renal biopsy in PLA2R1-antibody-positive patients with nephrotic syndrome

Renal biopsy is the gold standard for diagnosis of membranous nephropathy. Circulating PLA₂R1 antibody found in 75% of patients with membranous nephropathy is very specific for the diagnosis of this disease. Therefore, the question arises whether PLA₂R1-antibody-positive patients still need a diagnostic renal biopsy. In this study we investigated whether additional relevant information is obtained by performing renal biopsy in nephrotic patients, who are PLA₂R1-antibody positive. A detailed analysis of renal biopsies, including immunohistochemistry and electron microscopy, was performed in 263 patients with biopsy-proven membranous nephropathy, of whom 194 patients were PLA₂R1-antibody positive, to detect diagnostic features additional to membranous nephropathy. Twelve (6%) of the 194 PLA₂R1-antibody-positive patients had a second relevant diagnosis in addition to membranous nephropathy: five (3%) patients had interstitial nephritis, in five (3%) other patients a diabetic nephropathy was diagnosed and two (1%) patients had IgA nephropathy. Patients with a second diagnosis in addition to membranous nephropathy had a significantly higher serum creatinine (p < 0.01) and lower eGFR (p = 0.04) compared to patients in whom only the diagnosis of membranous nephropathy was made. In 7 (10%) of 69 PLA₂R1-antibody-negative patients, renal biopsies showed an additional diagnosis to membranous nephropathy: one (1%) case of IgA nephropathy, cholesterol emboli, IgG4-related disease, necrotising glomerulonephritis, thrombotic microangiopathy, interstitial nephritis and diabetic nephropathy each. The advantage of detecting an additional diagnosis to membranous nephropathy in 6% of PLA₂R1-antibody-positive patients by renal biopsy has to be balanced to the potential risks and costs of the biopsy procedure. Renal biopsy is particularly relevant in patients presenting with impaired renal function and abnormalities in urinalysis going beyond proteinuria. Immunohistochemical staining for PLA₂R1 was the only histomorphologic analysis allowing a reliable differentiation of PLA₂R1-antibody-positive from PLA₂R1-antibody-negative membranous nephropathy.

Inflammatory leucocyte infiltrates are associated with recovery in biopsy-proven acute interstitial nephritis: a 20-year registry-based case series

Background

Acute interstitial nephritis (AIN) is a renal injury causing renal function deterioration and requiring renal replacement therapy (RRT) in a substantial number of cases. Therapy is based on withdrawal of suspicious causative drugs or the underlying diseases and/or steroid application if renal function is not restored after cessation of the underlying condition. Hard clinical evidence for augmenting steroid therapy is not available.

Methods

We reviewed the course and diagnosis for >20 years among all 1126 biopsied samples of our tertiary renal centre.

Results

49 (4.4%) were diagnosed with primary AIN, corresponding to an annual incidence of 1/100 000 population; 17 out of 49 biopsy-proven AIN patients required short-term or long-term (n = 5) RRT. According to a combined outcome criterion of coming off dialysis and/or reaching serum creatinine <200 µmol/L, 19 patients reached recovery whereas 20 did not. Among 39 patients with a comprehensive clinical and histopathological data set, presence of cortical scars, AIN histological activity (acute leucocyte infiltrates) and proteinuria were baseline parameters discriminating significantly between groups with or without recovery. No associations with the presence of specific drugs were found. Therapeutic use of steroids was associated with a lower probability of recovery (P = 0.008), presumably due to inclusion bias.

Conclusions

Following our basic finding of the importance of histopathological parameters of acuity associated with recovery, we argue for the inauguration of grading measures to characterize this issue quantitatively and make it usable for future controlled investigations. Finally, we provide a suggestion for a therapeutic algorithm in the management of AIN.

Percutaneous Kidney Biopsy and the Utilization of Blood Transfusion and Renal Angiography Among Hospitalized Adults

Introduction

Data on percutaneous kidney biopsy (KBx) incidence and frequencies of hemorrhagic complications among inpatients are limited.

Methods

Using nationally representative US hospitalization discharge data, we report temporal trends in inpatient KBx rates from 2007 to 2014 and estimate frequencies of, and risk factors for, utilization of packed red blood cell (pRBC) transfusion and renal angiography.

Results

From 2007 to 2014, rates of native KBx among adult inpatients increased from 8.2 to 10.0 per 100,000, while transplant KBx rates declined from 3.6 to 3.1 per 100,000. We studied 35,183 and 14,266 discharge records with native and transplant KBx. We found that 5.7% (95% confidence interval [CI]: 5.3%–6.0%) of inpatients undergoing native KBx and 4.9% (4.2%–5.5%) of those undergoing transplant KBx received a pRBC transfusion within 2 days of biopsy. Similarly, 0.6% (0.5%–0.7%) of inpatients undergoing native KBx and 0.4% (0.2%–0.5%) undergoing transplant KBx received a renal angiogram within 2 days of KBx. For inpatient native KBx, female sex, older age, higher chronic kidney disease stage, acute renal failure, lupus, vasculitis, cirrhosis, multiple myeloma/paraproteinemia, and anemia of chronic disease were independently associated with increased odds of pRBC transfusion; cirrhosis and end-stage renal disease (ESRD) were associated with increased odds, and nephrotic syndrome was associated with decreased odds, of renal angiography.

Conclusions

In this large population-based study of inpatient KBx practices, we demonstrate increasing rates of inpatient native KBx among US adults and provide accurate estimates of the frequencies of, and risk factors for, pRBC transfusion and renal angiography following inpatient KBx.

Arteriovenous fistula-related renal bleeding 5 days after percutaneous renal biopsy

A 32-year-old Japanese woman was admitted to our hospital for evaluation of microscopic hematuria with a positive family history. Percutaneous renal biopsy was performed under real-time ultrasound guidance using a 16-gauge automated needle and three specimens were obtained. She had no risk factors for hemorrhage. However, macroscopic hematuria developed from 5 days after biopsy and persisted for 4 days. Her Hb decreased markedly from 15.0 to 8.1 g/dL. Enhanced computed tomography revealed urinary tract hematoma, while the early arterial phase showed inflow of contrast medium into the left renal vein from a pseudoaneurysm on a branch left renal artery. Renal transcatheter arterial embolization was performed using platinum microcoils and the arteriovenous fistula was occluded. The patient did not require blood transfusion. Severe renal bleeding that causes urinary tract hematoma usually occurs within 24 h after renal biopsy, but the possibility of late-onset renal bleeding should be kept in mind.

Diagnosis and Management of Immune Checkpoint Inhibitor-Associated Renal Toxicity: Illustrative Case and Review

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies directed at negative regulatory components on T cells, such as cytotoxic T lymphocyte-associated antigen 4, programmed cell death-1 (PD-1), and its ligand, programmed cell death ligand-1. ICIs initate antitumor immunity; however, these agents are associated with immune-related adverse events (irAEs) that may affect a variety of organs. Renal irAEs most commonly present with asymptomatic acute kidney injury (AKI), which is often detected by routine laboratory testing. The severity of AKI associated with irAEs ranges from mild (grade 1-2) to severe (grade 3-4). It is often challenging to diagnose because this group of patients often have multiple reasons to have AKI (dehydration, sepsis, or nephrotoxic medication exposure). We present an illustrative case of a 60-year-old man with metastatic melanoma who presented with AKI during treatment with nivolumab and review the literature to address frequently asked questions concerning the diagnosis and management of renal irAEs in patients with advanced cancer. Importantly, most patients will recover completely, and some may tolerate a rechallenge of ICI therapy, with prompt and effective treatment. KEY POINTS: Renal immune-related adverse events (irAEs) are less frequently reported than other irAEs; however, it is possible that available data underestimate their true incidence because of missed diagnoses and under-reporting. Although severe renal irAEs are more easily detected, smaller rises in creatinine may not be appreciated or may be attributed to other causes, because the differential diagnosis of acute kidney injury (AKI) in patients with cancer is broad.Baseline creatinine should be established prior to beginning immune checkpoint inhibitorss (ICIs), and it should be monitored with every cycle. If a patient develops AKI, the ICI should be held while the evaluation is pursued. A thorough workup of suspected renal irAEs must exclude other potential causes of AKI such as infection, dehydration, urinary tract obstruction, and nephrotoxin exposure.Acute kidney injury after ICI therapy does not appear to be more common in patients with baseline estimated glomerular filtration rate <60 mL per min per 1.73 m. One particular concern, however, is that those with baseline renal disease have less "renal reserve," and repeated AKI events may push a patient closer to end-stage renal disease. Thus, clinicians must exert caution when rechallenging patients with pre-existing renal disease with ICI therapy in the event of a prior AKI from ICI-related allergic interstitial nephritis.

Risk factors associated with significant bleeding events after ultrasound-guided percutaneous native renal biopsies: a review of 2204 cases

OBJECTIVE

To review the incidence of significant bleeding complications after ultrasound-guided percutaneous core native renal biopsies at a single center using a standardized technique.

MATERIALS AND METHODS

A retrospective review of ultrasound (US)-guided percutaneous native renal core biopsies done at our institution from September 2005 to December 2015 was performed. Demographic and clinical data were collected at the time of biopsy, with additional clinical information recorded 24 h and 3 months after the biopsy. Bleeding complications were defined using the Common Terminology Criteria for Adverse Events (CTCAE, version 4.0) created by the National Institutes of Health.

RESULTS

2204 US-guided native renal core biopsies were performed during the study period, with 37 hemorrhages (1.64%) that were CTCAE grade 3 or higher. The rate of inadequate sampling as reported by pathology was extremely low (1.1%). Factors demonstrating a significant association with bleeding risk included estimated glomerular filtration rate (eGFR), specifically when the eGFR was less than 60 (p = 0.025), platelet count (p = 0.002), including a statistically significant decreased risk of bleeding with a platelet count greater than 100 (10⁹/L) (p = <0.001), and performing four or more needle passes (p = 0.012). While female gender was also associated with an increased bleeding risk (p = 0.05), there was a significant association between females with a BMI ≥ 25 and a decreased bleeding risk (0.034). No statistically significant association between post-biopsy hemorrhage and aspirin use within 10 days prior to biopsy or a prior diagnosis of amyloidosis was demonstrated.

CONCLUSION

US-guided native renal biopsy is a safe procedure with a low rate of significant bleeding complications and a high tissue adequacy rate using an 18-gage spring-loaded biopsy device. Factors associated with increased bleeding risk include female gender, lower platelet counts, decreased eGFR and performing four or more needle passes, which has not been reported previously. Interestingly, females with a BMI ≥ to 25 demonstrated a decreased bleeding risk, and aspirin (81 mg or 325 mg) within 10 days of the procedure did not demonstrate a significant effect. While not shown in this current study, the relationship of very recent aspirin therapy with bleeding is yet to be defined. Similarly, the statistically significant decreased risk of bleeding complications in overweight or obese females requires further investigation.

Needle Biopsy Adequacy in the Era of Precision Medicine and Value-Based Health Care

CONTEXT.—

Needle biopsy of diseased tissue is an essential diagnostic tool that is becoming even more important as precision medicine develops. However, the capability of this modality to efficiently provide samples adequate for diagnostic and prognostic analysis remains quite limited relative to current diagnostic needs. For physicians and patients, inadequate biopsy frequently leads to diagnostic delay, procedure duplication, or insufficient information about tumor biology leading to delay in treatment; for health systems, this results in substantial incremental costs and inefficient use of scarce specialized diagnostic resources.

OBJECTIVE.—

To review current needle biopsy technology, devices, and practice with a perspective to identify current limitations and opportunities for improvement in the context of advancing precision medicine.

DATA SOURCES.—

PubMed searches of fine-needle aspiration and core needle biopsy devices and similar technologies were made generally, by tissue site, and by adequacy as well as by health economics of these technologies.

CONCLUSIONS.—

Needle biopsy adequacy can be improved by recognizing the importance of this diagnostic tool by promoting common criteria for needle biopsy adequacy; by optimizing needle biopsy procedural technique, technologies, clinical practice, professional education, and quality assurance; and by bundling biopsy procedure costs with downstream diagnostic modalities to provide better accountability and incentives to improve the diagnostic process.

Complications of Percutaneous Renal Biopsy

Percutaneous renal biopsy is widely used for diagnosis, prognosis, and management of nephropathies. Complications may arise after renal biopsy, most commonly in the form of bleeding. Efforts should be taken to optimize modifiable risk factors such as hypertension, thrombocytopenia, and coagulopathy prior to the procedure. Unmodifiable risk factors such as poor renal function, gender, and underlying histologic diagnosis may be used to identify high-risk patients. Delayed presentation of bleeding complications is common, and close clinical follow-up is crucial.

The efficacy of blind versus real-time ultrasound-guided percutaneous renal biopsy in developing country

Introduction:

Renal biopsy is a useful diagnostic procedure. In developing countries, two techniques of renal biopsy, blind percutaneous renal biopsy and real-time ultrasound-guided percutaneous renal biopsy, have been performed. The majority of studies compared these using different types and sizes of biopsy needle. The aim of this study was to compare both techniques in resource constraint country.

Method:

We reviewed renal biopsy database, between 1 January 2014 to 30 June 2017. The primary outcome was the total number of glomeruli. The other outcomes were tissue adequacy and bleeding complications. We also analyzed multivariable logistic regression to find factors associated with tissue adequacy and bleeding complications.

Result:

Of the 204 renal biopsies, 100 were blind percutaneous renal biopsy and 104 real-time ultrasound-guided percutaneous renal biopsy. The number of native renal biopsies was 169 (82.8%). Baseline characteristics of two groups were comparable. The mean number of total glomeruli from real-time ultrasound-guided percutaneous renal biopsy was significantly more than blind percutaneous renal biopsy (20.8 ± 12.1 vs 16.0 ± 13.0, p = 0.001). The real-time ultrasound-guided percutaneous renal biopsy obtained more adequate tissues than blind percutaneous renal biopsy (45.2% vs 16%, p < 0.001) and was the only factor associated with adequate tissue. Moreover, 16 renal biopsies from blind percutaneous renal biopsy obtained inadequate tissue. The overall bleeding complications were not statistically different. We found being female, lower eGFR and lower hematocrit were associated with bleeding complications.

Conclusion:

In comparison with blind percutaneous renal biopsy, real-time ultrasound-guided percutaneous renal biopsy obtained more adequate tissue and number of glomeruli. While the complications of both were comparable. We encourage to practice and perform real-time ultrasound-guided percutaneous renal biopsy in resource constraint countries.

Towards minimally-invasive, quantitative assessment of chronic kidney disease using optical spectroscopy

The universal pathologic features implicated in the progression of chronic kidney disease (CKD) are interstitial fibrosis and tubular atrophy (IFTA). Current methods of estimating IFTA are slow, labor-intensive and fraught with variability and sampling error, and are not quantitative. As such, there is pressing clinical need for a less-invasive and faster method that can quantitatively assess the degree of IFTA. We propose a minimally-invasive optical method to assess the macro-architecture of kidney tissue, as an objective, quantitative assessment of IFTA, as an indicator of the degree of kidney disease. The method of elastic-scattering spectroscopy (ESS) measures backscattered light over the spectral range 320-900 nm and is highly sensitive to micromorphological changes in tissues. Using two discrete mouse models of CKD, we observed spectral trends of increased scattering intensity in the near-UV to short-visible region (350-450 nm), relative to longer wavelengths, for fibrotic kidneys compared to normal kidney, with a quasi-linear correlation between the ESS changes and the histopathology-determined degree of IFTA. These results suggest the potential of ESS as an objective, quantitative and faster assessment of IFTA for the management of CKD patients and in the allocation of organs for kidney transplantation.