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

Urinary soluble CD163 is useful as "liquid biopsy" marker in lupus nephritis at both diagnosis and follow-up to predict impending flares

Lupus nephritis (LN) diagnosis and follow-up requires noninvasive biomarkers. Therefore, the added value of coupling the urinary soluble (s)CD163/creatinuria ratio with serological markers was evaluated in a real-world clinical practice. To this end, a monocentric and retrospective study was conducted in 139 SLE patients with biopsy-proven nephritis having an active LN (LN-A, n = 63 with a positive SLEDAI-renal score) or inactive (n = 76), as well as 98 non-renal SLE patients. The urinary sCD163/creatinuria ratio outperformed serological markers for predicting LN-A (AUC>0.972; p < 10-4 with a 100 % specificity threshold fixed at 320 ng/mmol), and for monitoring renal activity allowing prediction of impending flares and remissions in follow-up (AUC = 0.789, p < 10-4). LN-A patients with an elevated spot proteinuria/creatinuria ratio (p = 8 × 10-6) and sCD163/creatinuria ratio (p = 10-3) were at risk for developing end-stage kidney disease but sCD163/creatinuria ratio cannot substitute kidney biopsy to discriminate LN-A from other glomerulonephritis. Among serological markers (n = 14), anti-dsDNA and anti-C1q antibodies (Abs) (AUC>0.750 versus non-LN patients, and AUC>0.640 versus LN-IR patients) best predicted LN-A, and higher levels were retrieved in class III/IV proliferative LN-A. In multivariate logistic regression analysis, the urinary sCD163/creatinuria ratio remained the only statistically significant biomarker to predict LN-A (p < 0.001). In conclusion, and as compared to classical serological markers, the urinary sCD163/creatinuria ratio provides an additional parameter for monitoring LN patients.

Safety and effectiveness of laparoscopic renal biopsy: a single-center review and meta-analysis

BACKGROUND

While renal biopsy remains the preferred diagnostic method for assessing proteinuria, hematuria, or renal failure, laparoscopic renal biopsy (LRB) can serve as an alternative for high-risk patients when percutaneous kidney biopsy (PKB) is not recommended. This study was aimed to evaluate the safety of LRB.

METHODS

In study 1, Fourteen patients from January 2021 to January 2023 had a LRB taken for various indications, such as morbid obesity, abnormal kidney construction, uncontrolled hypertension, and coagulopathy. We also conducted a Meta-analysis of the success rate and complication rate of previous LRB in study 2.

RESULTS

All the patients completed biopsies and adequate renal tissues were obtained. The success rate was 100%. The median number of glomeruli obtained was 22.5 (range:12.0, 45.0). The complication rate was 7.1% (urinary tract infection). There were no significant differences between levels of hemoglobin, serum creatinine, and urinary NAGL before and after surgery. In the meta-analysis, the success rate of operation, satisfactory rate of sample, and complication rate of surgery were 99.9%, 99.1%, and 2.6% respectively.

CONCLUSION

LRB can achieve a good success rate and specimen retrieval and does not increase the risk of complications for high-risk patients. It can present as one of the alternative methods for patients with glomerular diseases.

What can go wrong when doing right? A pictorial review of iatrogenic genitourinary complications

A growing number of treatments for genitourinary diseases can result in various iatrogenic complications. Multimodality imaging in the post-procedural setting is essential for early and accurate diagnosis to limit morbidity and mortality. We review common and uncommon treatment-induced pathologies affecting the genitourinary system via a case-based approach. We illustrate notable complications affecting the kidneys, ureters, bladder, and urethra induced by percutaneous procedures, external beam radiation, immunotherapy, laparoscopic/robotic pelvic surgery, and intravesicular BCG. Finally, we provide guidance on optimal imaging techniques for diagnosis and highlight the role of image-guided interventions for mitigation of complications.

Analysis of hemorrhage upon ultrasound-guided percutaneous renal biopsy in China: a retrospective study

PURPOSE

Ultrasound-guided percutaneous renal biopsy (PRB) has been considered as a golden standard for CKD diagnosis and is employed to identify potential therapeutic targets since 1950s. Post-biopsy hemorrhage is the most common complication, while severe bleeding complication might cause nephrectomy or death. Therefore, how to reduce the occurrence of complications while ensuring the success of PRB is always a clinical research topic.

METHODS

This study retrospectively collected and established a renal biopsy database of each patient who underwent ultrasound-guided PRB at a tertiary teaching hospital from September 2017 to December 2020 through the Health Information System. All the data were statistically processed by SPSS software.

RESULTS

A total of 1146 patients underwent PRB for various reasons. The overall rate of post-biopsy hemorrhage was 37.70% (432/1146). Of those bleedings, minor bleeding after PRB was found in 337 (29.41%), middle bleeding 84 (7.33%), major bleeding 11 (0.96%). Besides that, there were 96 patients (8.38%) reported their discomfort symptoms. There was no death. Females were at significantly increased risk of hemorrhagic complication than males (OR = 2.017, CI = 1.531-2.658). While the risk for hemorrhagic complication significantly decreased as BMI and platelet before renal biopsy increased (OR = 0.956, CI = 0.924-0.989; OR = 0.998, CI = 0.996-1.000). As the APTT time prolonged, the risk for hemorrhagic complication significantly increased (OR = 1.072, CI = 1.023-1.123). Those patients whose albumin were higher, also had higher risk for hemorrhagic complication than other patients (OR = 1.020, CI = 1.000-1.041). Specifically, postoperative urination within 4 h increased the risk for hemorrhagic complication (OR = 1.741, CI = 1.176-2.576).

CONCLUSION

Our analysis finds that the incidence of post-biopsy bleeding complication is 37.70%, and its risk is associated with female, lower BMI, lower platelet before renal biopsy, prolonged APTT, higher albumin, and postoperative urination within 4 h. The findings highlighted the importance of perioperative management for renal biopsy, including adequate risk assessment, tailored careful observation after PRB. And medical staff should pay more attention to fluid management after ultrasound-guided PRB.

Associations of Biomarkers of Tubular Injury and Inflammation with Biopsy Features in Type 1 Diabetes

BACKGROUND

Whether biomarkers of tubular injury and inflammation indicate subclinical structural kidney pathology early in type 1 diabetes remains unknown.

METHODS

We investigated associations of biomarkers of tubular injury and inflammation with kidney structural features in 244 adults with type 1 diabetes from the Renin-Angiotensin System Study, a randomized, placebo-controlled trial testing effects of enalapril or losartan on changes in glomerular, tubulointerstitial, and vascular parameters from baseline to 5-year kidney biopsies. Biosamples at biopsy were assessed for kidney injury molecule 1 (KIM-1), soluble TNF receptor 1 (sTNFR1), arginine-to-citrulline ratio in plasma, and uromodulin and epidermal growth factor (EGF) in urine. We examined cross-sectional correlations between biomarkers and biopsy features and baseline biomarker associations with 5-year changes in biopsy features.

RESULTS

Participants' mean age was 30 years (SD 10) and diabetes duration 11 years (SD 5); 53% were women. The mean GFR measured by iohexol disappearance was 128 ml/min per 1.73 m 2 (SD 19) and median urinary albumin excretion was 5 μ g/min (interquartile range, 3-8). KIM-1 was associated with most biopsy features: higher mesangial fractional volume (0.5% [95% confidence interval (CI), 0.1 to 0.9] greater per SD KIM-1), glomerular basement membrane (GBM) width (14.2 nm [95% CI, 6.5 to 22.0] thicker), cortical interstitial fractional volume (1.1% [95% CI, 0.6 to 1.6] greater), fractional volume of cortical atrophic tubules (0.6% [95% CI, 0.2 to 0.9] greater), and arteriolar hyalinosis index (0.03 [95% CI, 0.1 to 0.05] higher). sTNFR1 was associated with higher mesangial fractional volume (0.9% [95% CI, 0.5 to 1.3] greater) and GBM width (12.5 nm [95% CI, 4.5 to 20.5] thicker) and lower GBM surface density (0.003 μ m 2 / μ m 3 [95% CI, 0.005 to 0.001] lesser). EGF and arginine-to-citrulline ratio correlated with severity of glomerular and tubulointerstitial features. Baseline sTNFR1, uromodulin, and EGF concentrations were associated with 5-year glomerular and tubulointerstitial feature progression.

CONCLUSIONS

Biomarkers of tubular injury and inflammation were associated with kidney structural parameters in early type 1 diabetes and may be indicators of kidney disease risk.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Renin Angiotensin System Study (RASS/B-RASS), NCT00143949.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_11_17_CJN0000000000000333.mp3.

Bleeding complications after percutaneous kidney biopsies - nationwide experience from Brunei Darussalam

BACKGROUND

Kidney biopsy serves as a valuable method for both diagnosing and monitoring kidney conditions. Various studies have identified several risk factors associated with bleeding complications following the procedure, but these findings have shown inconsistency and variation.

AIM

To investigate the risk of bleeding complications following percutaneous kidney biopsy in Brunei Darussalam. We sought to explore the relevant clinical and pathological risk factors associated with these complications while also considering the findings within the broader international literature context.

METHODS

We conducted a retrospective study of all adult patients who underwent kidney biopsy in Brunei Darussalam from October 2013 to September 2020. The outcomes of interest were post-biopsy bleeding and the need for blood transfusions. Demographics, clinical, laboratory and procedural-related data were collected. Logistic regression analysis was used to identify predictors of outcomes.

RESULTS

A total of 255 kidney biopsies were included, with 11% being performed on transplanted kidneys. The majority of biopsies were done under ultrasound guidance (83.1%), with the rest under computer tomography guidance (16.9%). The most common indications for biopsy were chronic kidney disease of undefined cause (36.1%), nephrotic syndrome (24.3%) and acute kidney injury (11%). Rate of bleeding complication was 6.3% - 2% frank hematuria and 4.3% perinephric hematoma. Blood transfusion was required in 2.8% of patients. No patient lost a kidney or died because of the biopsy. Multivariate logistic regression identified baseline hemoglobin [odds ratio (OR): 4.11; 95% confidence interval (95%CI): 1.12-15.1; P = 0.03 for hemoglobin ≤ 11 g/dL vs. > 11 g/dL) and the presence of microscopic hematuria (OR: 5.24; 95%CI: 1.43-19.1; P = 0.01) as independent risk factors for post-biopsy bleeding. Furthermore, low baseline platelet count was identified as the dominant risk factor for requiring post-biopsy transfusions. Specifically, each 10 109/L decrease in baseline platelet count was associated with an 12% increase risk of needing transfusion (OR: 0.88; 95%CI: 0.79-0.98; P = 0.02).

CONCLUSION

Kidney biopsies were generally well-tolerated. The identified risk factors for bleeding and transfusion can help clinicians to better identify patients who may be at increased risk for these outcomes and to provide appropriate monitoring and management.

Diagnostic yield and safety of percutaneous native kidney biopsy in pregnancy: 20-years of single-center experience

BACKGROUND

Percutaneous kidney biopsy is a fundamental procedure in nephrology. Although pregnancy is not a contraindication, a careful risk-benefit assessment is mandatory in pregnancy. We aimed to evaluate safety and diagnostic accuracy of percutaneous kidney biopsy in pregnancy in a single-center retrospective study.

METHODS

Percutaneous kidney biopsy was performed in 19 pregnant patients. Demographics, estimated glomerular filtration rates, serum albumin levels, and proteinuria levels at the time of biopsy were evaluated. Biopsy-related complications, diagnoses, and treatments during the follow-up were analyzed. In addition, delivery success, preeclampsia, early delivery, low birth weight rates, and long-term outcomes of the patients were retrieved and analyzed.

RESULTS

Mean patient age was 27 (range 16-41) years. Median gestational week at kidney biopsy was 20th. All but one biopsies were diagnostic. Median gestational week of delivery was 35 (range 23-39) gestational weeks. Preterm delivery (< 37 gestational weeks) and low birth weight (< 2500 mg) occurred in 73.7% and 52.6% of cases, respectively. Median weight at birth was 2500 mg. The incidence of preeclampsia was 57.9%. Overall 89.5% of the children survived. Median post-biopsy follow-up was 64 months. Maternal mortality was not observed during the follow-up period. End stage kidney disease developed in one patient. The results of percutaneous kidney biopsy led to therapeutic decisions in 73.7% of cases.

CONCLUSIONS

Although percutaneous kidney biopsy is not frequently performed during pregnancy, it is relatively safe and usually diagnostic, and may guide further follow-up.

Immunological mechanisms underlying clinical phenotypes and noninvasive diagnosis of immune checkpoint inhibitor-induced kidney disease

Immune checkpoint inhibitors (ICIs) have become a mainstay of cancer therapy, with over 80 FDA-approved indications. Used in a variety of settings and in combination with each other and with traditional chemotherapies, the hyperactive immune response induced by ICIs can often lead to immune-related adverse events in bystander normal tissues such as the kidneys, lungs, and the heart. In the kidneys, this immune-related adverse event manifests as acute interstitial nephritis (ICI-AIN). In the era of widespread ICI use, it becomes vital to understand the clinical manifestations of ICI-AIN and the importance of prompt diagnosis and management of these complications. In this review, we delve into the clinical phenotypes of ICI-AIN and how they differ from traditional drug-induced AIN. We also detail what is known about the mechanistic underpinnings of ICI-AIN and the important diagnostic and therapeutic implications behind harnessing those mechanisms to further our understanding of these events and to formulate effective treatment plans to manage ICI-AIN.

Comparative analysis of blind vs real-time ultrasound-guided pediatric renal biopsies: A cross-sectional study

Background

Renal biopsy has a definite role in the management of pediatric kidney diseases. Most centers have given up the earlier practice of performing blind biopsy using Tru-Cut needle and started doing real time ultrasound-guided renal biopsy with an automated spring-loaded gun, which has become standard of care in the last decade or so.

Methods

We performed a cross-sectional analysis of the pediatric biopsies conducted at our center over the years by both methods to evaluate whether ultrasound-guided renal biopsy with a disposable automated spring-loaded gun was superior to blind biopsy with a disposable needle of the same size in terms of reduction of complications and improving the yield. We also reviewed the indications and the histopathological diagnosis of pediatric renal biopsies at our center.

Results

A total of 45 native kidney biopsies were performed blind and 48 ultrasound-guided biopsies using the curvilinear probe (frequency 3-5 Hz) of GE Logiq P3 ultrasound machine with disposable spring-loaded automated guns. There was a significant increase in the yield of biopsy in terms of the number of glomeruli per pass. A significant increase in the mean number of glomeruli was noted when a biopsy was performed under ultrasound guidance (P < 0.0001). Gross hematuria was significantly reduced as compared to the earlier biopsies done blind i.e., without ultrasound (P ¼ 0.03). Nephrotic syndrome was the commonest indication for biopsy in our patients during both time periods studied. The most common histopathological diagnosis was MesPGN among the children who underwent kidney biopsy from 2005 to 2007, while Minimal Change Disease (MCD) and Focal Segmental Glomerulosclerosis (FSGS) were most frequently reported.

Conclusion

Ultrasound guided kidney biopsies in pediatric age group have significant reduction in incidence of post gross hematuria and significant increase in the mean number of glomeruli per pass.

The Role of PLA2R in Primary Membranous Nephropathy: Do We Still Need a Kidney Biopsy?

Membranous nephropathy (MN) is the most prevalent cause of nephrotic syndrome amongst the non-diabetic adult population. A fifth of idiopathic nephrotic syndrome cases can be attributed to MN, rising to more than 40% in older patients over 60 years. Most MN cases are classified as being of a primary cause, where there is absence of a secondary disease process explaining its manifestation. Traditionally, the standard approach of diagnosing MN involves performing a kidney biopsy as histological evaluation offers not only conclusive evidence of the diagnosis but also provides valuable information regarding disease chronicity and the presence of any other kidney histopathological features. Nevertheless, kidney biopsy is an invasive procedure which poses risks for the patient including bleeding and pain and bears greater costs for the health system. The identification of the phospholipase A2 receptor (PLA2R) antigen in 2009 was a landmark discovery, one which has evolved our understanding of the disease processes in MN and subsequently our management approach of this condition. Antibodies against PLA2R (PLA2RAb) have since emerged as an attractive non-invasive test option to be applied for the diagnosis and prognostication of primary MN. However, much debate and unknowns remain about the accuracy and reliability of testing for PLA2RAb across various primary MN scenarios. We provide a review summarizing the historical journey of PLA2R in relation to its significance in primary MN and, more importantly, evidence emerging over the years which contemplated the role of PLA2RAb as a diagnostic and prognostic tool in primary MN.

Research Letter-Outcomes of Outpatient Native Kidney Biopsies at the McGill University Health Center: A Quality Assurance Audit

Background

Percutaneous kidney biopsies are essential for diagnosis and management of kidney diseases. However, post-procedural bleeding is a significant risk associated with biopsies. At the McGill University Health Center, the 2 main hospitals, the Royal Victoria Hospital and the Montreal General Hospital, have different observation protocols for outpatient native kidney biopsies. Currently, patients are admitted for a 24-hour inpatient observation at the Montreal General Hospital, whereas patients biopsied at the Royal Victoria Hospital are discharged after 6 to 8 hours of observation at the end of the day. Most Canadian centers do not admit patients for an overnight observation, and it was unclear why this practice continued at the Montreal General Hospital.

Objective

Our objective was to determine the incidence of complications post-renal biopsy over the past 5 years at both hospital sites, and compare them to each other, as well as to established rates in the available literature.

Design

This assessment was designed as a quality assurance audit.

Setting

This audit was conducted from a local registry of renal biopsies performed at the McGill University Health Center between January 2015 to January 2020.

Patients

We included all adult patients (between the ages 18 and 80) with outpatient native kidney biopsies performed at the McGill University Health Center between 2015 and 2020.

Measurements

We collected the included patients' baseline demographics and risk factors at the time of biopsy, including age, BMI, creatinine, estimated glomerular filtration rate, pre- and post-biopsy hemoglobin, platelet, urea, coagulation profile, blood pressure, kidney side/size as well as needle size, and number of passes made.

Methods

We compared the incidence of both minor and major bleeding complications at the Montreal General and the Royal Victoria Hospital. Variables that were measured included hemoglobin before and after biopsy, incidence of minor bleeding complications (defined by hematomas and gross hematuria), and incidence of major complications (defined by post-biopsy bleeding requiring either transfusions or another procedure to stop the bleeding), as well as the incidence of admissions post-biopsy.

Results

The incidence of major complications was 2.87% over 5 years (5/174 patients), which is comparable with that reported in the literature. Our transfusion incidence was 1.72% (3/174 patients) and our embolization incidence was 2.3% (4/174 patients) over the 5 study years. Our total number of major events was low and the patients who had major events had significant risk factors for bleeding. All events occurred within 6 hours of observation.

Limitations

This was a retrospective study with a low event number. Additionally, since the events included only those recorded at the McGill University Health Center, it is possible that the events of interest may have occurred at other hospital sites without the author's knowledge.

Conclusions

Based on the results of this audit, all major bleeding events occurred within 6 hours of a percutaneous kidney biopsy, suggesting that patients should be monitored for 6 to 8 hours following biopsy. The next step after this quality assurance audit is a quality improvement project and a cost-effectiveness analysis to assess whether post-biopsy practices should be amended at the McGill University Health Center.

Risk of bleeding-related complications after kidney biopsy in patients with systemic lupus erythematosus

OBJECTIVE

Kidney biopsy is essential for the diagnosis and classification of lupus nephritis. Percutaneous biopsy has a risk of bleeding-related complications; however, data on the risk of percutaneous kidney biopsy in patients with systemic lupus erythematosus (SLE) are scarce. In this study, we aimed to investigate the rate of bleeding-related complications and to examine the risk factors for complications of kidney biopsy in patients with systemic lupus erythematosus (SLE).  METHODS: We retrospectively reviewed the medical records of patients with SLE who underwent ultrasound-guided percutaneous kidney biopsy between 2002 and 2020 at a tertiary referral center. Minor complications were defined as hematoma and passing hematuria not requiring an intervention. Major complications included bleeding events that required interventions after the biopsy. Statistical analysis with a multivariate logistic regression model was performed.

RESULTS

In a total of 277 patients with SLE, the rate of overall bleeding-related complications after kidney biopsy was 19.9% (minor 13.0%; major 6.9%). Among patients with major complications, 84.2% needed blood transfusion alone without embolization or surgery, whereas the remaining three patients needed embolization for bleeding control. Multivariate analysis revealed that thrombocytopenia (odds ratio [OR] 7.186, 95% confidence interval [CI] 2.315-22.300), and low eGFR (OR 3.478, 95% CI 1.094-11.056) were significantly associated with the risk of major bleeding-related complications after kidney biopsy.

CONCLUSION

Percutaneous kidney biopsy is accompanied by the risk of bleeding-related complications; however, most events in our study did not require vascular intervention for bleeding control. Low platelet count and low estimated glomerular filtration rate (eGFR) significantly increase the risk of complications after kidney biopsy in patients with SLE. Key Points • The rate of overall bleeding-related complications after kidney biopsy was about 20% of patients with SLE. • The most commonly observed events were gross hematuria followed by blood transfusion. • Thrombocytopenia and poor kidney function areis an important risk of bleeding-related complications after kidney biopsy.

Cytokines and Immune Cell Phenotype in Acute Kidney Injury Associated With Immune Checkpoint Inhibitors

Introduction

Immune checkpoint inhibitors (ICIs) induce impressive antitumor responses but may lead to acute kidney injury (AKI) associated with ICI therapy (AKI-ICI). Biomarkers distinguishing AKI-ICI from AKI because of other causes (AKI-other) are currently lacking. Because ICIs block immunoregulatory pathways, we hypothesized that biomarkers related to immune cell dysregulation, including tumor necrosis factor alpha (TNF-α) and other markers of B and T cell activation in the systemic circulation and kidney tissue, may aid with the diagnosis of AKI-ICI.

Methods

This is a prospective study consisting of 24 participants who presented with AKI during ICI therapy, adjudicated to either have AKI-ICI (n = 14) or AKI-other (n = 10). We compared markers of kidney inflammation and injury (neutrophil gelatinase-associated lipocalin, kidney injury molecule-1) as well as plasma and urine levels of T cell-associated cytokines (TNF-α, interferon-γ, interleukin (IL)-2, IL-4, IL-6, IL-8, IL-9, and IL-10) between groups. We also compared T-cell responses in the systemic circulation and in kidney tissue across groups, using mass cytometry systems.

Results

We observed increase in several specific immune cells, including CD4 memory, T helper cells, and dendritic cells in the kidney tissue, as well as in the urine cytokines IL-2, IL-10, and TNF-α, in patients who developed AKI-ICI compared to patients with AKI-other (P < 0.05 for all). The discriminatory ability of TNF-α on AKI cause was strong (area under the curve = 0.814, 95% confidence interval: 0.623-1.00. The CD4+ T cells with memory phenotype formed the dominant subset.

Conclusion

These results suggest that specific T-cell responses and their respective cytokines may be indicative of AKI associated with ICI therapy and may help to differentiate AKI-ICI from AKI-other. Urine TNF-α is a promising biomarker for AKI-ICI, which is most often caused by acute interstitial nephritis (AIN), and TNF-α pathway may serve as a potential target for therapeutic intervention.

Ultrasound Versus Computed Tomography-Guided Native Parenchymal Kidney Biopsies for Hospitalized Patients: Comparison of Clinical Outcomes and Complications

ABSTRACT

Percutaneous native kidney biopsies performed with ultrasound (US) or computed tomography (CT) guidance are important in the workup of medical renal disease, with modality choice often dependent on the performing institution, with various complication rates reported. We compared the complication rates and types of complication of US- versus CT-guided native parenchymal renal biopsy among hospitalized patients. One hundred five consecutive inpatient US- and CT-guided native parenchymal renal biopsies performed by radiologists at a tertiary care academic center between 2006 and 2020 were reviewed retrospectively. Complication rates of biopsy were calculated and compared between the 2 modalities. Comparisons with regard to types of complications were made using the Society of Interventional Radiology grading scale, American Society of Anesthesiologists score, and other clinical data. One hundred five hospitalized adult patients (58 women and 47 men; average age, 53 years) underwent native parenchymal kidney biopsy during the study period. Sixty-three (60%) were CT-guided and 42 (40%) were US-guided. Complication rates between CT- versus US-guided biopsies were 40% versus 19% ( P = 0.03), respectively. There were 7 major and 18 minor complications for CT-guided biopsies and 3 major and 5 minor complications for US-guided biopsies. No statistically significant difference was found in preprocedural American Society of Anesthesiologists Classification score, international normalized ratio, platelet count, or body mass index. Computed tomography-guided native parenchymal kidney biopsy was associated with a higher overall complication rate compared with US-guided biopsy for hospitalized patients. Most complications were minor, which required no treatment or additional follow-up.

A Participant-Centered Approach to Understanding Risks and Benefits of Participation in Research Informed by the Kidney Precision Medicine Project

An understanding of the ethical underpinnings of human subjects research that involves some risk to participants without anticipated direct clinical benefit-such as the kidney biopsy procedure as part of the Kidney Precision Medicine Project (KPMP)-requires a critical examination of the risks as well as the diverse set of countervailing potential benefits to participants. This kind of deliberation has been foundational to the development and conduct of the KPMP. Herein, we use illustrative features of this research paradigm to develop a more comprehensive conceptualization of the types of benefits that may be important to research participants, including respecting pluralistic values, supporting the opportunity to act altruistically, and enhancing benefits to a participant's community. This approach may serve as a model to help researchers, ethicists, and regulators to identify opportunities to better respect and support participants in future research that entails some risk to these participants as well as to improve the quality of research for people with kidney disease.

Sonoporation of Human Renal Proximal Tubular Epithelial Cells In Vitro to Enhance the Liberation of Intracellular miRNA Biomarkers

Ultrasound has previously been demonstrated to non-invasively cause tissue disruption. Small animal studies have demonstrated that this effect can be enhanced by contrast microbubbles and has the potential to be clinically beneficial in techniques such as targeted drug delivery or enhancing liquid biopsies when a physical biopsy may be inappropriate. Cavitating microbubbles in close proximity to cells increases membrane permeability, allowing small intracellular molecules to leak into the extracellular space. This study sought to establish whether cavitating microbubbles could liberate cell-specific miRNAs, augmenting biomarker detection for non-invasive liquid biopsies. Insonating human polarized renal proximal tubular epithelial cells (RPTECs), in the presence of SonoVue microbubbles, revealed that cellular health could be maintained while achieving the release of miRNAs, miR-21, miR-30e, miR-192 and miR-194 (respectively, 10.9-fold, 7.17-fold, 5.95-fold and 5.36-fold). To examine the mechanism of release, RPTECs expressing enhanced green fluorescent protein were generated and the protein successfully liberated. Cell polarization, cellular phenotype and cell viability after sonoporation were measured by a number of techniques. Ultrastructural studies using electron microscopy showed gap-junction disruption and pore formation on cellular surfaces. These studies revealed that cell-specific miRNAs can be non-specifically liberated from RPTECs by sonoporation without a significant decrease in cell viability.

The risks associated with percutaneous native kidney biopsies: a prospective study

BACKGROUND

The known risks and benefits of native kidney biopsies are mainly based on the findings of retrospective studies. The aim of this multicentre prospective study was to evaluate the safety of percutaneous renal biopsies and quantify biopsy-related complication rates in Italy.

METHODS

The study examined the results of native kidney biopsies performed in 54 Italian nephrology centres between 2012 and 2020. The primary outcome was the rate of major complications 1 day after the procedure, or for longer if it was necessary to evaluate the evolution of a complication. Centre and patient risk predictors were analysed using multivariate logistic regression.

RESULTS

Analysis of 5304 biopsies of patients with a median age of 53.2 years revealed 400 major complication events in 273 patients (5.1%): the most frequent was a ≥2 g/dL decrease in haemoglobin levels (2.2%), followed by macrohaematuria (1.2%), blood transfusion (1.1%), gross haematoma (0.9%), artero-venous fistula (0.7%), invasive intervention (0.5%), pain (0.5%), symptomatic hypotension (0.3%), a rapid increase in serum creatinine levels (0.1%) and death (0.02%). The risk factors for major complications were higher plasma creatinine levels [odds ratio (OR) 1.12 for each mg/dL increase, 95% confidence interval (95% CI) 1.08-1.17], liver disease (OR 2.27, 95% CI 1.21-4.25) and a higher number of needle passes (OR for each pass 1.22, 95% CI 1.07-1.39), whereas higher proteinuria levels (OR for each g/day increase 0.95, 95% CI 0.92-0.99) were protective.

CONCLUSIONS

This is the first multicentre prospective study showing that percutaneous native kidney biopsies are associated with a 5% risk of a major post-biopsy complication. Predictors of increased risk include higher plasma creatinine levels, liver disease and a higher number of needle passes.

Effect of Hemocoagulase on the Prevention of Bleeding after Percutaneous Renal Biopsy

A percutaneous renal biopsy is an essential tool for the diagnosis of various renal diseases; however, post-biopsy bleeding is a major complication. Hemocoagulase is a detoxified and purified snake venom enzyme that is widely used to prevent post-procedural bleeding. In this study, we retrospectively analyzed the effect of hemocoagulase on post-renal biopsy bleeding. We included 221 patients who underwent percutaneous renal biopsy between April 2017 and December 2020 and analyzed post-renal biopsy hemoglobin (Hb) decline in patients who were administered a periprocedural hemocoagulase injection. After the renal biopsy, the mean Hb decrease in the entire patient cohort was 0.33 ± 0.84 g/dL. Periprocedural hemocoagulase injection lowered the Hb decline post-renal biopsy (0.50 ± 0.87 vs. 0.23 ± 0.80 g/dL, p = 0.0204). The propensity-matched cohort was also adjusted for factors influencing postprocedural bleeding; periprocedural hemocoagulase injection reduced the Hb decline post-renal biopsy (0.56 ± 0.89 vs. 0.17 ± 0.74 g/dL, p = 0.006). There were no adverse events (e.g., thrombosis and anaphylactic shock) due to hemocoagulase. Our study demonstrated the beneficial effect of hemocoagulase on post-renal biopsy Hb decline, suggesting its clinical value in preventing post-renal biopsy bleeding.

Safety of Obtaining an Extra Biobank Kidney Biopsy Core

Background and objectives: Kidney biopsy (KB) is the “gold standard” for the diagnosis of nephropathies and it is a diagnostic tool that presents a low rate of complications. Nowadays, biobank collections of renal tissue of patients with proven renal pathology are essential for research in nephrology. To provide enough tissue for the biobank collection, it is usually needed to obtain an extra kidney core at the time of kidney biopsy. The objective of our study is to evaluate the complications after KB and to analyze whether obtaining an extra core increases the risk of complications. Material and methods: Prospective observational study of KBs performed at Vall d’Hebron Hospital between 2019 and 2020. All patients who accepted to participate to our research biobank of native kidney biopsies were included to the study. Clinical and laboratory data were reviewed and we studied risk factors associated with complications. Results: A total of 221 patients were included, mean age 56.6 (±16.8) years, 130 (58.8%) were men, creatinine was 2.24 (±1.94) mg/dL, proteinuria 1.56 (0.506–3.590) g/24 h, hemoglobin 12.03 (±2.3) g/dL, INR 0.99 (±0.1), and prothrombin time (PT) 11.86 (±1.2) s. A total of 38 patients (17.2%) presented complications associated with the procedure: 13.1% were minor complications, 11.3% (n = 25) required blood transfusion, 1.4% (n = 3) had severe hematomas, 2.3% (n = 5) required embolization, and 0.5% (n = 1) presented arterio-venous fistula. An increased risk for complication was independently associated with obtaining a single kidney core (vs. 2 and 3 cores) (p = 0.021). Conclusions: KB is an invasive and safe procedure with a low percentage of complications. Obtaining an extra kidney core for research does not increase the risk of complications during the intervention, which remains low in concordance with previously published reports.

Association Between Diabetes and Major Bleeding Complications of Renal Biopsy

Introduction

Nephrologists have recently recognized the heterogeneity of kidney diseases among patients with diabetes and begun to actively perform percutaneous renal biopsies (PRBs). Nevertheless, the association between diabetes and major bleeding complications of PRB remains unclear.

Methods

In this retrospective cohort study using the Diagnosis Procedure Combination database in Japan, we identified patients who underwent an elective PRB from July 2010 to March 2018. The primary outcome was the occurrence of major bleeding complications, defined as red blood cell transfusion within 7 days after PRB or invasive hemostasis after PRB. Multivariable regression analysis was performed to analyze the association between diabetes and major bleeding complications with adjustment for patient and hospital characteristics.

Results

We identified 76,302 patients, including 8245 with diabetes. The proportion of PRBs performed for patients with diabetes continuously increased over time. Major bleeding complications occurred in 678 patients (0.9%), including 622 (0.8%) with red blood cell (RBC) transfusion and 109 (0.1%) with invasive hemostasis. Diabetes was significantly associated with major bleeding complications (relative risk [RR] = 2.41; 95% CI 2.00–2.90). Among patients with diabetes, multiagent or insulin treatment had significant association with major bleeding complications (RR = 1.57; 95% CI 1.18–2.10), compared with single-agent diabetes treatment.

Conclusion

Diabetes is significantly associated with major bleeding complications of PRBs. Moreover, severity of diabetes has association with increases in major bleeding complications. Thus, nephrologists should carefully judge whether the anticipated benefits outweigh the relatively high risk of major bleeding complications when considering PRB for patients with diabetes.

Point of Care Ultrasound in Monitoring of Post-Renal Biopsy Bleeding

A 32-year-old male presented with hypertensive emergency and features of thrombotic microangiopathy. He underwent a kidney biopsy after renal dysfunction persisted despite clinical improvement otherwise. The kidney biopsy was performed with direct ultrasound guidance. The procedure was complicated by hematoma formation and persistent turbulent flow on color Doppler concerning for ongoing bleeding. Serial point of care ultrasounds of the kidney with color flow Doppler were used to monitor the size of the hematoma and determine if there was evidence of ongoing bleeding. These serial ultrasounds showed stable hematoma size, resolution of biopsy-associated Doppler signal and prevented further invasive interventions.

Nephrologists' Attitudes Toward Native Kidney Biopsy: A Qualitative Study

Rationale & Objective

Although kidney biopsy is a useful tool, nephrologists' approach toward biopsies is inconsistent for reasons incompletely understood, including lack of established clinical guidelines. We examined contemporary clinical decision-making patterns among nephrologists to perform native kidney biopsy.

Study Design

Qualitative study using semistructured interviews.

Setting & Participants

Purposive sampling was used to select nephrologists from different regions in the United States. Semistructured interviews were continued until thematic saturation.

Analytical Approach

A modified grounded theory was used to identify dominant themes reflecting the nephrologists' decision-making styles about kidney biopsy.

Results

Twenty nephrologists were interviewed: 16 (80%) were from academic centers, 3 (15%) performed their own biopsies, and 7 (35%) had been in practice for less than 10 years. The median time of practice was 14 years. We found substantial variability among the nephrologists in their attitude toward using kidney biopsy, which reflected individual differences in weighing the risks and benefits of the procedure for an individual patient. Five overarching themes were identified: operator comfort with biopsy and availability of interventional radiologist, exposure to biopsy during training and years of experience, concerns about the invasiveness of biopsy and inflicting harm, perception of evidence base and limited treatment options, and patient characteristics and preference.

Limitations

Generalizability was limited because the nephrologists sampled may not have been broadly representative.

Conclusions

Multiple factors influence nephrologists' decision to pursue kidney biopsy, with substantial variability among nephrologists that can have meaningful clinical implications. This suggests the need to establish consensus guidelines to make biopsy practice more standardized.

Emerging Insights Into Chronic Renal Disease Pathogenesis in Hypertension From Human and Animal Genomic Studies

The pathogenic links between elevated blood pressure and chronic kidney disease remain obscure. This article examines progress in population genetics and in animal models of hypertension and chronic kidney disease. It also provides a critique of the application of genome-wide association studies to understanding the heritability of renal function. Emerging themes identified indicate that heritable risk of chronic kidney disease in hypertension can arise from genetic variation in (1) glomerular and tubular protein handling mechanisms; (2) autoregulatory capacity of the renal vasculature; and (3) innate and adaptive immune mechanisms. Increased prevalence of hypertension-associated chronic kidney disease that occurs with aging may reflect amplification of heritable risks by normal aging processes affecting immunity and autoregulation.

Noninvasive Diagnosis of PLA2R-Associated Membranous Nephropathy: A Validation Study

BACKGROUND AND OBJECTIVES

Kidney biopsy is the current gold standard to diagnose membranous nephropathy. Approximately 70%-80% of patients with primary membranous nephropathy have circulating anti-phospholipase A2 receptor antibodies. We previously demonstrated that in proteinuric patients with preserved eGFR and absence of associated conditions (e.g., autoimmunity, malignancy, infection, drugs, and paraproteinemia), a positive anti-phospholipase A2 receptor antibody test by ELISA and immunofluorescence assay confirms the diagnosis of membranous nephropathy noninvasively. These data have not been externally validated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The clinical and pathologic characteristics of patients with a positive anti-phospholipase A2 receptor antibody test at the Mayo Clinic, the University Hospital Vall D'Hebron (Barcelona), and the Columbia University Medical Center (New York) were retrospectively reviewed. Biopsy findings and presence or absence of a potential associated condition were assessed.

RESULTS

From a total of 276 patients with positive anti-phospholipase A2 receptor serology, previously reported patients (n=33), kidney transplant recipients (n=9), pediatric patients (n=2), and patients without kidney biopsy (n=69) were excluded. Among the 163 remaining patients, associated conditions were identified in 47 patients, and 15 patients had diabetes mellitus. All 101 patients of the final cohort had a primary diagnosis of membranous nephropathy on kidney biopsy. In the 79 patients with eGFR≥60 ml/min per 1.73 m2, none of the biopsy findings altered diagnosis or management. Among the 22 patients with decreased eGFR, additional findings included superimposed acute interstitial nephritis (n=1).

CONCLUSIONS

In patients with preserved eGFR and absence of associated conditions or diabetes, a positive anti-phospholipase A2 receptor test by either ELISA >20 RU/ml or a positive immunofluorescence assay confirms the diagnosis of membranous nephropathy, precluding the requirement for a kidney biopsy.

Complications after native kidney biopsy: definitive data

PURPOSE OF REVIEW

To assess the risk of complications associated with native kidney biopsies. This review will highlight recent advances on the risk factors for major bleeding and risk management in patients with native kidney biopsy.

RECENT FINDINGS

Recent studies provided new important data regarding the individualization of the risk of bleeding after kidney biopsy. A new bleeding risk score was proposed as a risk stratification tool, useful for shared decision making and procedure choice.

SUMMARY

The risk of complications is low (<1%) in most patients but varies widely. Risk factors include Charlson index, frailty index, female gender, dyslipidemia, anemia, thrombocytopenia, cancer, abnormal kidney function, glomerular disease, autoimmune disease, vasculitis, hematologic disease, and thrombotic microangiopathy. A new bleeding score can help physicians and patients to assess the risk of bleeding enabling informed consent, and decide to perform it or not, and to prefer transjugular vs percutaneous route.

Major Bleeding of Transjugular Native Kidney Biopsies. A French Nationwide Cohort Study

Introduction

The risk of bleeding associated with transjugular kidney biopsies is unclear, and which patients are the best candidates for this route is unknown.

Methods

This was a retrospective cohort study comparing proportion of bleeding associated with transjugular versus percutaneous native kidney biopsies in all patients in France in the 2010–2019 period. Major bleeding at day 8 (i.e., blood transfusions, hemorrhage/hematoma, angiographic intervention, nephrectomy) and risk of death at day 30 were assessed, and we used a bleeding risk score initially developed for the percutaneous route.

Results

Our analysis included 60,331 patients (transjugular route: 5305; percutaneous route: 55,026 patients). The observed proportion of major bleeding varied widely (transjugular vs. percutaneous): 0.4% versus 0.5% for the lowest risk scores (0–4) to 19.1% versus 30.8% for the highest risk scores (≥35). Transjugular was more frequently used than percutaneous route (39% vs. 24%) when the risk score was ≥20 (15,133/60,331; 25% of all patients). Transjugular was associated with a lower risk of major bleeding than percutaneous route in multivariate analyses (odds ratio [OR]: 0.88 [0.78–0.99]), especially for scores ≥20 (OR: 0.83 [0.72–0.96], (i.e., 25% of patients). Major bleeding was associated with an increased risk of death both for transjugular (OR: 1.77 [1.00–3.14]) and percutaneous (OR: 1.80 [1.43–2.28]) routes.

Conclusions

The transjugular route is independently associated with a lower risk of bleeding than the percutaneous route, especially in high-risk patients identified by a preprocedure risk score ≥20 (i.e., 25% of patients). Major bleeding is associated with an increased risk of death for both routes.

Membranous nephropathy

Membranous nephropathy (MN) is a glomerular disease that can occur at all ages. In adults, it is the most frequent cause of nephrotic syndrome. In ~80% of patients, there is no underlying cause of MN (primary MN) and the remaining cases are associated with medications or other diseases such as systemic lupus erythematosus, hepatitis virus infection or malignancies. MN is an autoimmune disease characterized by a thickening of the glomerular capillary walls due to immune complex deposition. Identification of the phospholipase A2 receptor (PLA2R) as the major antigen in adults in 2009 induced a paradigm shift in disease diagnosis and monitoring and several other antigens have since been characterized. Disease outcome is difficult to predict and around one-third of patients will undergo spontaneous remission. In those at high risk of progression, immunosuppressive therapy with cyclophosphamide plus corticosteroids has substantially reduced the need for kidney replacement therapy. Owing to carcinogenic risk, other treatments (calcineurin inhibitors and CD20-targeted B cell depletion therapy (rituximab)) have been developed. However, disease relapses are frequent when calcineurin inhibitors are stopped and the remission rate with rituximab is lower than with cyclophosphamide, particularly in patients with high PLA2R antibody titres. Other new drugs are already available and antigen-specific immunotherapies are being developed.

Narrative review of vascular iatrogenic trauma and endovascular treatment

Iatrogenic injury is unfortunately a leading cause of morbidity and mortality for patients worldwide. The etiology of iatrogenic injury is broad, and can be seen with both diagnostic and therapeutic interventions. While steps can be taken to reduce the occurrence of iatrogenic injury, it is often not completely avoidable. Once iatrogenic injury has occurred, prompt recognition and appropriate management can help reduce further harm. The objective of this narrative review it to help reader better understand the risk factors associated with, and treatment options for a broad range of potential iatrogenic injuries by presenting a series of iatrogenic injury cases. This review also discusses rates, risk factors, as well as imaging and clinical signs of iatrogenic injury with an emphasis on endovascular and minimally invasive treatments. While iatrogenic vascular injury once required surgical intervention, now minimally invasive endovascular treatment is a potential option for certain patients. Further research is needed to help identify patients that are at the highest risk for iatrogenic injury, allowing patients and providers to reconsider or avoid interventions where the risk of iatrogenic injury may outweigh the benefit. Further research is also needed to better define outcomes for patients with iatrogenic vascular injury treated with minimally invasive endovascular techniques verses conservative management or surgical intervention.

Safety and utility of kidney biopsy in patients with estimated glomerular filtration rate < 30 ml/min/1.73 m2

AIM

Kidney biopsy (KBx) is the gold standard for evaluation of kidney disease, but is associated with a higher risk of complications in patients with reduced glomerular filtration rate (GFR). We studied the safety and utility of KBx in patients with eGFR <30 ml/min/1.73 m2 .

METHODS

Consecutive adult patients with eGFR <30 ml/min/1.73 m2 , who were planned for a KBx and consented to participate were prospectively enrolled. Patients with solitary/transplant kidney or acute kidney injury were excluded. Haemoglobin was checked on the day of KBx and repeated 18-24 h later along with a screening ultrasound. Post-KBx complications were noted and their risk-factors analysed. The utility of the KBx was graded as effecting significant, some, or no change to subsequent management.

RESULTS

Of the 126 patients included, 75% were male, 27.7% were diabetic, and the median eGFR was 13.5 ml/min/1.73m2 . Major complications occurred in 5.6%. Peri-renal haematomas were detected in 37.3%, and haematomas ≥2 cm were significantly more frequent in those with eGFR <15 ml/min/1.73 m2 (29.2% vs. 13%, p = .032). Dialysis was a risk factor, while pre KBx blood transfusion, diabetes and higher serum albumin were protective against any complication. KBx was more likely to make a significant difference in management in those with eGFR 15-29 ml/min/1.73m2 (44.1% vs. 11.1%, p < .001). Increasing age, lower serum creatinine and albumin were independently associated with KBx utility.

CONCLUSION

KBx is relatively safe in severe kidney disease but its risk to benefit balance needs to be carefully considered when eGFR is <15 ml/min/1.73m2 .

Estimation of risk for major bleeding in native kidney biopsies in patients with multiple risk factors

BACKGROUND AND AIMS

Individuals undergoing kidney biopsy are increasingly older and may have concurrent illnesses that cause deranged hematological and renal parameters that are associated with post-biopsy bleeding. We aimed to develop a clinical risk model to quantify bleeding risks in high-risk individuals with multiple risk factors.

METHODS

Single-center retrospective cohort study of consecutive adults with serum creatinine ≥ 2 mg/dL (176 µmol/L) and had ultrasound-guided percutaneous native kidney biopsies between June 2011 and July 2015 in our tertiary referral center. The primary outcome was major bleeding, defined as need for red cell transfusion, radiological or surgical intervention, or if bleeding led to death within 7 days after kidney biopsy.

RESULTS

Among 184 native kidney biopsies with serum creatinine ≥ 2 mg/dL, median age was 54.1 years and eGFR was 18.8 ml/min/1.73 m². Major bleeding occurred in 19 biopsies (10.3%). Multivariate analysis accounting for age, weight, hemoglobin, platelet, prothrombin time and urea found that higher hemoglobin (adjusted OR 0.51, 95% CI 0.33-0.79, p = 0.003) and platelet (adjusted OR 0.99, 95% CI 0.98-0.99, p = 0.01) were independently associated with reduced major bleeding. A risk model that included (1) age ≥ 62 years old, (2) hemoglobin < 10 g/dL and (3) platelets ≤ 216 × 10⁹/L as categorical variables predicted major bleeding post-biopsy.

CONCLUSION

We developed a risk model that included multiple risk factors to quantify bleeding risks in native kidney biopsies with renal impairment.

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.