Percutaneous renal biopsy of native kidneys: efficiency, safety and risk factors associated with major complications

Automatic renal carcinoma biopsy guidance using forward-viewing endoscopic optical coherence tomography and deep learning

Percutaneous renal biopsy is commonly used for kidney cancer diagnosis. However, the biopsy procedure remains challenging in sampling accuracy. Here we introduce a forward-viewing optical coherence tomography probe for differentiating tumor and normal tissues, aiming at precise biopsy guidance. Totally, ten human kidney samples, nine of which had malignant renal carcinoma and one had benign oncocytoma, were used for system evaluation. Based on their distinct imaging features, carcinoma could be efficiently distinguished from normal renal tissues. Additionally, oncocytoma could be differentiated from carcinoma. We developed convolutional neural networks for tissue recognition. Compared to the conventional attenuation coefficient method, convolutional neural network models provided more accurate carcinoma predictions. These models reached a tissue recognition accuracy of 99.1% on a hold-out set of four kidney samples. Furthermore, they could efficiently distinguish oncocytoma from carcinoma. In conclusion, our convolutional neural network-aided endoscopic imaging platform could enhance carcinoma diagnosis during percutaneous renal biopsy procedures.

Effect of music therapy intervention on anxiety and pain during percutaneous renal biopsy: a randomized controlled trial

Background

Percutaneous renal biopsy (PRB) may subject patients to emotional distress and pain before and during the biopsy. The aim of this study was to evaluate the effects of complementary/non-pharmacological interventions such as music therapy (MT) on anxiety, pain and satisfaction in renal patients undergoing PRB.

Methods

A prospective, single-centre, single-blind, randomized controlled two-arm trial was conducted. Patients ≥18 years of age, hospitalized at the Nephrology, Dialysis and Transplantation Unit (Bari, Italy) and scheduled for PRB were screened. Participants were assigned to standard treatment (CG) or to the music therapy (MT) intervention group. Participants in the MT group received standard care and an MT intervention by a certified music therapist qualified in guided imagery and music. The CG patients received the standard of care. MT and CG patients were subjected to identical measurements (pre/post) of the parameters in the State Trait Anxiety Inventory Y1 (STAI-Y1), visual analogue scale for pain (VAS-P) and satisfaction (VAS-S) and heart rate variability.

Results

A statistically significant difference in the anxiety scores after PRB between MT and CG patients (STAI-Y1 35.4 ± 6.2 versus 42.9 ± 9.0) was observed. MT also had strong and significant effects on VAS-P compared with CG (5.0 ± 1.4 versus 6.3 ± 1.3, respectively; P < .001) and VAS-S (7.8 ± 1.0 versus 6.0 ± 0.9, respectively; P < .001). Decreased activity of the sympathetic nervous system and increased activity of the parasympathetic nervous system was observed after PRB in the MT group.

Conclusion

Our study supports the use of MT to mitigate the psychological anxiety, pain and sympathetic activation associated with PRB.

Automatic renal carcinoma biopsy guidance using forward-viewing endoscopic optical coherence tomography and deep learning

Percutaneous renal biopsy (PRB) is commonly used for kidney cancer diagnosis. However, current PRB remains challenging in sampling accuracy. This study introduces a forward-viewing optical coherence tomography (OCT) probe for differentiating tumor and normal tissues, aiming at precise PRB guidance. Five human kidneys and renal carcinoma samples were used to evaluate the performance of our probe. Based on their distinct OCT imaging features, tumor and normal renal tissues can be accurately distinguished. We examined the attenuation coefficient for tissue classification and achieved 98.19% tumor recognition accuracy, but underperformed for distinguishing normal tissues. We further developed convolutional neural networks (CNN) and evaluated two CNN architectures: ResNet50 and InceptionV3, yielding 99.51% and 99.48% accuracies for tumor recognition, and over 98.90% for normal tissues recognition. In conclusion, combining OCT and CNN significantly enhanced the PRB guidance, offering a promising guidance technology for improved kidney cancer diagnosis.

Glomeruli Count and Arterial Injury in Real-Time Ultrasound-Guided Needle Kidney Biopsy Specimens: Adequacy of Three Approaches for Pig Kidneys

INTRODUCTION

Real-time ultrasound-guided percutaneous kidney biopsy is essential for diagnosis and treatment planning; nonetheless, the optimal puncture approach has yet to be established. In vivo, performing different approaches on the same patient at once is not possible. This study aimed to determine the impact of different approaches on the number of obtained glomeruli and their potential to cause arterial injury using pig kidneys, which are similar to humans.

METHODS

A total of 120 pig kidneys (60 right-sided kidneys and 60 left-sided kidneys) for research were obtained from a slaughterhouse. The specimens were collected from the lower pole on the sagittal plane of the kidney using three different approaches on the same kidney: caudocranial approach, caudal to cranial; craniocaudal approach, cranial to caudal; and vertical approach, through the surface cortex. Five blinded pediatric nephrologists assessed the number of glomeruli and arterial injuries.

RESULTS

Overall, 360 specimens were collected from the kidneys through biopsy using a 16-gauge needle (mean vertical kidney length, 11.2 ± 0.7 cm; mean depth, 3.47 ± 0.23 cm). No significant difference in the incidence of arterial injury was observed between the three approaches (caudocranial vs. craniocaudal vs. vertical approaches: 78% vs. 87% vs. 87%, p = 0.14). In contrast, the vertical approach retrieved significantly more glomeruli than the caudocranial and craniocaudal approaches (caudocranial approach: 7.5 ± 2.8, craniocaudal approach: 7.8 ± 2.7, and vertical approach: 8.9 ± 3.3, p < 0.001).

CONCLUSIONS

Considering its efficacy and safety profile, the vertical approach may be preferred, as more glomeruli can be obtained without increasing the incidence of arterial injury. Although the results cannot be directly extrapolated to humans due to the differences between species, they still offer important insights into the characteristics of each approach.

Shear wave elastography using high-frequency linear probe for transplant kidney monitoring: A methodological study

OBJECTIVES

To investigate the influencing factors of the image quality of shear wave elastography (SWE) performed using a high-frequency probe and its reproducibility for renal allografts.

METHODS

A total of 211 patients with transplanted kidneys who underwent SWE examination performed using high-frequency or low-frequency probes were recruited for the study. The reproducibility of inter- and intraobserver agreements were analysed by using the intraclass correlation coefficient (ICC). According to the colour filling of the area of interest and imaging noise when conducting SWE, the image quality was classified as three grades: "good", "common", and "poor". A logistic regression was used to analyse the independent factors for SWE quality.

RESULTS

In the comparative analysis, high frequency, transection measurement and middle pole were selected as the appropriate measurement methods. Regarding reproducibility, the ICCs) of the intra- and interobserver agreements were 0.85 and 0.77, respectively. Multivariate analysis indicated that only the skin allograft distance and kidney width were independent variables for SWE quality. In the subgroup analysis of the skin-allograft distance, the "good" and "common" rates of images decreased as the distance increased, but the CV (coefficients of variation) showed the opposite trend. The SWE quality of kidney width <5.4 cm was significantly better than that of kidney width ≥5.4 cm.

CONCLUSIONS

High-frequency SWE can be used in the evaluation of transplanted kidneys due to its good repeatability and high successful measurement rate, but we should pay attention to the influence of the skin-allograft distance and kidney width on SWE quality.

Risk of bleeding after percutaneous native kidney biopsy in patients receiving low-dose aspirin: a single-center retrospective study

BACKGROUND

Although discontinuation of antiplatelet agents at least 5 days before kidney biopsy is commonly recommended, the evidence behind this practice is of low level. Indeed, few non-randomized studies previously showed an equivalent risk of bleeding in patients receiving aspirin therapy.

METHODS

We conducted a single center retrospective study comparing the risk of complications after percutaneous native kidney biopsy in patients who received low-dose aspirin (ASA) within 5 days from biopsy and those who did not. The main outcome was the difference in the incidence of major complications (red blood cell transfusion, need for selective arterial embolization, surgery, nephrectomy). Secondary outcomes included difference in minor complications, comparison between patients who received ASA within 48 h or within 3-5 days, identification of independent factors predictive of major complications.

RESULTS

We analyzed data on 750 patients, of whom 94 received ASA within 5 days from biopsy. There were no significant differences in the proportion of major complications in patients receiving or not receiving ASA (2.59% and 3.19%, respectively, percentage point difference 1%, 95% CI - 3 to 4%, p = 0.74). Groups were also comparable for minor complications; among patients receiving ASA, there were no differences in major bleeding between those who received ASA within 48 h or 3-5 days from biopsy. Significant baseline predictors of major bleeding in our cohort were platelet count lower than 120*10³/microliter, higher diastolic blood pressure and higher blood urea.

CONCLUSIONS

Treatment with low-dose ASA within 5 days from kidney biopsy did not increase the risk of complications after the procedure.

Simulation for ultrasound-guided renal biopsy using boiled egg

Real-time ultrasound-guided renal biopsy is generally applied to diagnose multiple kidney diseases. A practical simulation model is desired since it is an invasive technique with higher risks of complications such as bleeding. We developed a simple simulation tool for ultrasound-guided renal biopsy using boiled eggs. Boiled chicken eggs were embedded in the agar, and a biopsy simulation was performed using a real-time ultrasound-guided technique as the renal biopsy simulator by trainees and biopsy-proficient nephrologists, and the feedback from the participants was obtained. The ultrasonographic evaluation revealed a clear contrast between egg yolk and white, which clearly mimicked the kidney cortex and medulla region. In addition, we observed the needle entering the egg white under needle penetration, and we obtained the biopsy core consisting of egg white. As for the simulations, all the participants succeeded in obtaining the appropriate samples. A total of 92% of the trainees agreed that the simulation could reduce their fears of performing renal biopsies in patients. In addition, all the trainees and biopsy-proficient nephrologists recommend using the simulator for trainees before conducting renal biopsies on patients. The total cost of the simulator was low (<USD 1/simulator). Collectively, our simulation tool using boiled eggs may be a good candidate for practical simulation models of renal biopsy.

Safety and Adequacy of Ultrasound-Guided Percutaneous Renal Biopsy in Children: A Single-Center Experience

Background Ultrasound-guided percutaneous renal biopsy (PCRB) is a commonly used technique to obtain renal tissue for histopathological diagnosis in children and adolescents. The objectives of this study include determining the indications for renal biopsy, documenting the safety and efficacy of ultrasound-guided PCRB, and documenting its complications along with histopathological findings in children. Methodology The Ethical Review Committee approved this cross-sectional study. Data of all children with either nephrotic or nephritic syndrome from January 2017 to September 2020 (at The Kidney Center Post Graduate Training Institute Karachi) who underwent ultrasound-guided PCRB were collected and analyzed. An ultrasonic examination was performed both before and after the biopsy. Results During the research period, 104 individuals underwent PCRB. The average age of the children biopsied was 7.44 ± 4.12 years (range = 1-17 years). The most prevalent reason for biopsy was nephrotic syndrome. Almost 94% of PCRBs were effective. Post-biopsy complications were detected in 16 cases, with peri-nephric hematoma being the most prevalent. Conclusions In children, ultrasound-guided PCRB can safely be performed under sedation in experienced hands with an automated biopsy gun needle. The use of real-time ultrasound guidance as well as the automated biopsy gun ensures good outcomes.

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.

Safety of renal biopsy bleeding prophylaxis with desmopressin

BACKGROUND

Percutaneous renal biopsy (PRB) is invasive, and bleeding-related complications are a concern. Desmopressin (DDAVP) is a selective type 2 vasopressin receptor-agonist also used for haemostasis.

AIM

To evaluate the side effects of intravenous (IV) weight-adjusted desmopressin preceding PRB.

METHODS

This was a retrospective study of renal biopsies performed by nephrologists from 2013 to 2017 in patients who received single-dose DDAVP pre-PRB.

RESULTS

Of 482 PRBs, 65 (13.5%) received DDAVP (0.3 µg/kg); 55.4% of the PRBs were native kidneys. Desmopressin indications were altered platelet function analyser (PFA)-100 results (75.3% of the patients), urea >24.9 mmol/L (15.5%), antiplatelet drugs (6.1%) and thrombocytopaenia (3%). Of the 65 patients, 30.7% had minor asymptomatic complications, and 3 patients had major complications. Pre-PRB haemoglobin (Hb) <100 g/L was a risk factor for Hb decrease >10 g/L, and altered collagen-epinephrine (Col-Epi) time was a significant risk factor for overall complications. Mean sodium decrease was 0.6 ± 3 mmol/L. Hyponatraemia without neurological symptoms was diagnosed in two patients; no cardiovascular events occurred.

CONCLUSION

Hyponatraemia after single-dose DDAVP is rare. A single IV dose of desmopressin adjusted to the patient's weight is safe as pre-PRB bleeding prophylaxis.

Ultrasound-guided percutaneous renal biopsy at a university hospital: retrospective analysis of success and complication rates

OBJECTIVE

To evaluate the success and complication rates of ultrasound-guided renal biopsy at a tertiary care hospital.

MATERIALS AND METHODS

This was a retrospective analysis of 97 ultrasound-guided renal biopsies, all performed by the same radiologist, between 1 March, 2017 and 31 October, 2019.

RESULTS

Of the 97 biopsies evaluated, 87 had a definitive pathological diagnosis. In five cases (5.4%), the biopsy results were inconclusive and a second procedure was required. In seven procedures (7.6%), there were complications, all of which were properly resolved.

CONCLUSION

Ultrasound-guided renal biopsy has proven to be a safe, effective method for the diagnosis of nephropathies, with high success rates.

Complications of Outpatient and Inpatient Renal Biopsy: A Systematic Review and Meta-Analysis

Background: The evidence indicates that the optimal observation period following renal biopsy ranges between 6 and 8 h. This systematic review and meta-analysis explored whether differences exist in the complication rates of renal biopsies performed in outpatient and inpatient settings. Methods: We searched the MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews from 1985 to February 2020. Two reviewers independently selected studies evaluating the bleeding risk from renal biopsies performed in outpatient and inpatient settings and reviewed their full texts. The primary and secondary outcomes were risks of bleeding and major events (including mortality) following the procedure, respectively. Subgroup analysis was conducted according to the original study design (i.e., prospective or retrospective). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effect meta-analysis. Heterogeneity was assessed using the I² test. Results: Data from all 10 eligible studies, which included a total of 1801 patients and 203 bleeding events, were included for analysis. Renal biopsies in outpatient settings were not associated with a higher bleeding risk than those in inpatient settings (OR = 0.81; 95% CI, 0.59–1.11; I² = 0%). The risk of major events was also comparable across both groups (OR = 0.45; 95% CI, 0.16–1.29; I² = 4%). Conclusions: Similar rates of bleeding and major events following renal biopsy in outpatient and inpatient settings were observed.

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.

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.

Bioinformatics analyses on the immune status of renal transplant patients, a systemic research of renal transplantation

BACKGROUND

Kidney transplantation is the most effective treatment for end-stage renal disease. Allograft rejections severely affect survivals of allograft kidneys and recipients.

METHODS

Using bioinformatics approaches, the present study was designed to investigate immune status in renal transplant recipients. Fifteen datasets from Gene Expression Omnibus (GEO) were collected and analysed. Analysis of gene enrichment and protein-protein interactions were also used.

RESULTS

There were 40 differentially expressed genes (DEGs) identified in chronic rejection group when compared with stable recipients, which were enriched in allograft rejection module. There were 135 DEGs identified in acute rejection patients, compared with stable recipients, in which most genes were enriched in allograft rejection and immune deficiency. There were 288 DEGs identified in stable recipients when compared to healthy subjects. Most genes were related to chemokine signalling pathway. In integrated comparisons, expressions of MHC molecules and immunoglobulins were increased in both acute and chronic rejection; expressions of LILRB and MAP 4 K1 were increased in acute rejection patients, but not in stable recipients. There were no overlapping DEGs in blood samples of transplant recipients.

CONCLUSION

By performing bioinformatics analysis on the immune status of kidney transplant patients, the present study reports several DEGs in the renal biopsy of transplant recipients, which are requested to be validated in clinical practice.

A Comparison between Kidney Allograft Biopsies Performed by Nephrologists and Surgeons Versus Interventional Radiologists

Introduction: Renal biopsy is an integral part of clinical nephrology practice that helps in the diagnosis of various renal diseases. Across the globe, it is performed by nephrologists and/or surgeons under ultrasound guidance. Lately, this novel procedure has been performed more frequently by the interventional radiologist (IR) as compared to nephrologists and surgeons.

Methods: We completed a retrospective review of 378 consecutive renal biopsies performed at our university hospital in the city center of Philadelphia, Pennsylvania, between September 2008 and June 2011 for various indications. Baseline characteristics were comparable except systolic blood pressure (SBP), prothrombin time (PT), and international normalized ratio (INR) which was higher. Hemoglobin was lower in patients who underwent biopsy by the IR compared to those who were biopsied by nephrologists and/or surgeons.

Results: The primary outcome showed the average number of glomeruli obtained with each biopsy was significantly lower by nephrology or surgical teams, 9.09 ± 5.17 vs. 19.17 ± 11.11 obtained by the interventional radiology team, p-value <0.0001. The number of cores obtained with each biopsy was significantly lower by nephrologist or surgeon at the bedside, 1.57 ± 1.05 vs. 2.42 ± 1.26, p-value <0.0001. The average number of attempts to obtain one core was 2.00 ± 1.10 vs. 2.60 ± 1.17 by nephrologist and surgeon vs. IR, respectively, p-value <0.0001.

Conclusion: Our study clearly shows the superior success of renal biopsy by the IR as compared to the nephrology and surgical teams. This calls for more robust training of nephrology fellows and surgery residents to obtain the renal biopsy to prevent the loss of this unique procedure skill by non-radiology clinicians.

Comparison of yield and complications of craniocaudal versus caudocranial needle trajectory for kidney biopsy

BACKGROUND

Percutaneous renal biopsy can result in serious complications. The study is aimed to compare the safety and yield between the two approaches of biopsy techniques: the conventional craniocaudal and the caudocranial trajectory of the biopsy needle under real-time ultrasound guidance.

METHODS

In this prospective observational study, a total of 80 serial kidney biopsies were performed, 40 with craniocaudal angulation and 40 with caudocranial angulation of the biopsy needle on the random allocation of 1:1 in each group. In the craniocaudal approach, the patient must hold the breath in deep inspiration to make a lower pole of the kidney approachable during unloading the biopsy gun, which was not required in caudocranial trajectory as the lower pole was approachable without holding the breath in deep inspiration. All kidney biopsies were performed percutaneously under real-time ultrasonogram guidance with a 16-cm-long, 16- or 18-gauge needles with a penetration depth of 22 mm and a sample notch of 18 mm. The yield and complications between the two groups were analyzed.

RESULTS

Both the groups were comparable in essential demographic characteristics. The study found that the caudocranial position of renal biopsy is equally suitable concerning tissue yield without any increase in the risk of complications and a smaller number of passes to obtain adequate tissue.

CONCLUSION

Caudocranial trajectory of the biopsy needle using a probe needle guide is as safe as the craniocaudal approach. Both approaches have similar yield and complications; however, the caudocranial approach provides ease to the patient during the procedure.

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.

Direction of the Biopsy Needle in Ultrasound-Guided Renal Biopsy Impacts Specimen Adequacy and Risk of Bleeding

INTRODUCTION

Although medical factors such as hypertension and coagulopathy have been identified that are associated with hemorrhage after renal biopsy, little is known about the role of technical factors. The purpose of our study was to examine the effects of biopsy needle direction on renal biopsy specimen adequacy and bleeding complications.

METHODS

Two hundred and forty-two patients who had undergone ultrasound-guided renal biopsies were included. A printout of the ultrasound picture taken at the time of the biopsy was used to measure the biopsy angle ("angle of attack" [AOA]) and to determine if the biopsy needle was aimed at the upper or lower pole and if the medulla was targeted or avoided.

RESULTS

Of the 3 groups of biopsy angle, an AOA of between 50°-70° yielded the most glomeruli per core (P = .001) and the fewest inadequate specimens (4% vs 15% for > 70°, and 9% for < 50°, P = .038). Biopsy directed at a pole vs an interpolar region resulted in fewer inadequate specimens (8% vs 23%, P = .005), while biopsies that were medulla-avoiding resulted in fewer inadequate specimens (5% vs 16%, P = .004) and markedly reduced bleeding complications (12% vs 46%, P < .001) compared to biopsies where the medulla was entered.

DISCUSSION

An AOA of approximately 60°, aiming at the poles, and avoiding the medulla were each associated with fewer inadequate biopsies and bleeding complications. While biopsy of the medulla is necessary for some diagnoses, the increased bleeding risk emphasizes the need for communication between nephrologist, pathologist, and radiologist.

Superselective renal artery embolization for bleeding complications after percutaneous renal biopsy: a single-center experience

OBJECTIVE

This study aimed to determine if superselective renal artery embolization is a safe and effective method of treating bleeding complications after percutaneous renal biopsy.

METHODS

From January 2006 to December 2017, 43 patients (22 men and 21 women, mean age: 44.5 ± 14.0 years) underwent angiography for post-biopsy bleeding complications following percutaneous biopsy. Patients underwent angiography and superselective artery embolization. We recorded serum creatinine and hemoglobin values to assess the effect of embolization.

RESULTS

Successful embolization was achieved in all patients. There was a pseudoaneurysm in 10 cases, arteriovenous fistula in eight, contrast media extravasation in 16, arteriovenous fistula combined with contrast media extravasation in five, and pseudoaneurysm combined with arteriovenous fistula in four. The embolic substance was a microcoil only or combined with a gelatin sponge. The mean creatinine value was not different at 1 day and 1 week after embolization compared with before embolization. Mean hemoglobin values were significantly higher at 1 day and 1 week after embolization than before embolization.

CONCLUSIONS

Superselective renal artery embolization is a safe and effective treatment for post-biopsy bleeding complications after percutaneous renal biopsy. Lumbar or iliolumbar artery angiography is necessary if renal arteriography shows no signs of hemorrhage.

Kidney Biopsy-Related Complications in Hospitalized Patients with Acute Kidney Disease

BACKGROUND AND OBJECTIVES

Patients are informed of the risk of kidney biopsy-related complications using data from nonhospitalized patients, which may underestimate the risk for hospitalized patients. We evaluated the rate and risk factors of kidney biopsy-related complications in hospitalized patients with acute kidney disease (AKD) to better estimate the risk in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used data from the Yale biopsy cohort to evaluate rates of kidney biopsy-related complications including adjudicated procedure-related bleeding requiring blood transfusions or angiographic interventions, medium- or large-sized hematomas, reimaging after biopsy including abdominal ultrasonography or computed tomography, and death in hospitalized patients with AKD (including AKI). We evaluated univariable and multivariable association of risk factors with transfusions. We compared rates of complications between hospitalized and nonhospitalized patients.

RESULTS

Between 2015 and 2017, 159 hospitalized patients underwent a kidney biopsy for AKD evaluation, of which 80 (51%) had stage 1 AKI, 42 (27%) had stage 2 (or higher) AKI, and 27 (17%) had AKD (without AKI). Of these, 12 (8%; 95% confidence interval [95% CI], 5% to 15%) required a transfusion, three (2%; 95% CI, 1% to 5%) required an intervention, 11 (7%; 95% CI, 4% to 12%) had hematoma, and 31 (20%; 95% CI, 14% to 26%) required reimaging after biopsy. Of the four (3%; 95% CI, 1% to 6%) deaths during hospitalization, none were related to the biopsy. Female sex, lower platelet count, and higher BUN were associated with postbiopsy transfusions on univariable and multivariable analyses. Trainee as proceduralist and larger needle gauge were associated with transfusions in univariable, but not multivariable, analysis. Nonhospitalized patients had lower rates of transfusion than hospitalized patients, although the latter also had lower prebiopsy hemoglobin and greater surveillance after biopsy.

CONCLUSIONS

Hospitalized patients experience higher risk of postbiopsy complications than previously reported and several factors, such as lower platelet count, female sex, and higher BUN, are associated with this risk.

Simple risk score for prediction of haemorrhagic complications after a percutaneous renal biopsy

AIM

To derive a simple risk score to predict the individual risk of major complications for patients undergoing a percutaneous renal biopsy procedure of native kidneys.

METHODS

The risk score was derived from a cohort of 1205 adult patients subjected to percutaneous renal biopsy and assigned to training and validation datasets. Factors associated with major complications were derived from univariate analysis and then modelled by stepwise multivariate logistic regression. Based on the odds ratio, independent predictors were assigned a weighted integer. The risk score is calculated from the sum of the integers.

RESULTS

The overall incidence of major complications was 3.2%. Independent factors associated with MC were lower pre-biopsy haemoglobin, lower platelets, higher blood urea nitrogen, documented chronic kidney disease features in pre-biopsy ultrasound (US) and the presence of haematoma in the post-biopsy US. A score for pre-biopsy evaluation included the first four predictors and stratified patients in three categories with increasing risk at higher scores (low-risk 0.1%, moderate-risk 3.0% and high-risk 26.1%). The score demonstrated good discriminative power (AUC = 0.872). The addition of post-biopsy US findings increased the discriminative power (AUC = 0.938). A higher post-biopsy risk score was also associated with a higher incidence of MC (low-risk 0.2%, moderate-risk 2.7%, high-risk 16.9%).

CONCLUSION

The risk of major complications after a percutaneous renal biopsy can be assessed by a simple risk score calculated from readily available information.

Trends in Biopsy-Based Diagnosis of Kidney Disease: A Population Study

Background

Kidney biopsy is considered the gold standard for diagnosis of renal disease. It is increasingly performed in cases of diagnostic uncertainty, including in patients with coexistent diabetes and hypertension, for which a presumptive clinical diagnosis can be made. Little is known about the incidence and distribution of biopsy-proven kidney diseases. Changes in the distribution of biopsy diagnoses over time may have significant implications for resource allocation and future research.

Objective

We studied the relative frequency of kidney diseases in Southern Alberta over the past 30 years, to determine whether the population-standardized annual biopsy rate and incidence of selected diagnostic categories have changed. We hypothesized an increasing incidence of renal biopsies and a growing proportion of nonglomerular diseases (eg, tubulointerstitial disorders) likely due to evolving indications for biopsy. Given the rise in obesity, diabetes, and aging population with chronic kidney disease (CKD), we anticipated a rise in nephroangiosclerosis and diabetic nephropathy over time.

Design

Retrospective population-based cohort study using the Biobank for the Molecular Classification of Kidney Disease (BMCKD).

Setting

Southern Alberta, Canada.

Patients

All patients who underwent renal biopsy between 1985 and 2015 in our database.

Measurements

We used descriptive and quantitative analysis to characterize demographics and biopsy-based diagnoses.

Methods

We conducted a retrospective population-based cohort study to analyze all consecutive patients who underwent at least one kidney biopsy over a 30-year period in Southern Alberta (1985-2015). We considered the first adequate biopsy. We described the annual standardized incidence of biopsy-proven kidney diseases over time and summarized associated patient characteristics. We assumed a Poisson distribution for biopsy counts and used provincial demographic information to standardize rates.

Results

During the study period, 6434 people (58% male; mean age: 47.9 years) underwent a kidney biopsy. The population-standardized annual biopsy rate increased from 10.8 biopsies per 100 000 person-years in the first 5 years of the study (1985-1989) to 18.2 biopsies per 100 000 person-years in the last 5 years (2010-2014). The mean age at the time of biopsy increased from 42.5 years (1985-1989) to 51.4 years (2010-2014). Glomerular diseases remained the most prevalent histopathological group, with a growing representation of diabetic kidney disease from 3.69% to 16.18%, and a relative decrease in the proportion of other glomerular diseases from 72.32% to 62.92% of glomerular diagnoses. Tubulointerstitial diseases increased from 5.87% to 7.36% of total diagnoses.

Limitations

Classification schemes have changed over time, so recently recognized conditions may have been misclassified in earlier data. There was a changing group of pathologists and nephrologists over this period. Variations in interpretation and application of biopsy indications by physician may influence recorded prevalence of certain diagnoses. We do not yet have complete information on indications or patient outcomes linked to the database.

Conclusions

In Southern Alberta, kidney biopsy is being utilized more frequently and in older people. Diabetic nephropathy is increasingly diagnosed, which may reflect either or both changes in the prevalence of causative factors and local biopsy practices.

A retrospective analysis of complication and adequacy rates of ultrasound-guided native and transplant non-focal renal biopsies

PURPOSE

To assess non-focal ultrasound (US)-guided renal biopsy complication and adequacy rates at our institution.

METHODS

A retrospective analysis of 1067 non-focal renal biopsy cases between 2012 and 2015. Information collected including type of US-guided procedure (US-localized by nephrology vs. real-time US-guided by radiology), sample adequacy, complications, blood work, and histologic data.

RESULTS

602 biopsies were performed by radiology (56.4%) and 465 (43.6%) by nephrology. The overall adequacy rate was 96.1%, with an US-localized rate of 95.7% and real-time US-guided rate of 96.3% (p = 0.58). A lower adequacy rate was noted for 1 biopsy core but there were no differences between 2 and 6 cores (p = 0.001). A lower adequacy rate was found for transplant biopsies vs. native biopsies (p = 0.03). Complication rates were as follows-minor 5.9%, major 4.3%, and life-threatening 0.8%. There were no differences in complication rates between the US-localized and real-time US-guided techniques (p = 0.63). Complications were more likely in patients with a lower hemoglobin, higher serum creatinine, and lower albumin (p < 0.05). No differences were found between the number of cores performed and the complication rates. The complication rate was similar between transplant biopsies vs. native biopsies (p = 0.2). The adequacy rate was lower in trainees (p = 0.01) than experienced radiologists.

CONCLUSIONS

No significant differences were found between US-localized vs. real-time US-guided techniques. A lower adequacy rate was found for trainee radiologists and for transplant biopsies. A lower adequacy rate was also observed when only 1 biopsy pass was performed.

Routine haemostasis testing before transplanted kidney biopsy: a cohort study

Kidney biopsy can result in bleeding complications. Prebiopsy testing using bleeding time (BT) is controversial. New whole blood haemostasis tests, such as platelet function analyser-100 (PFA-100) and multiple electrode aggregometry (MEA), might perform better. We postulated that PFA-100 would be suitable to replace BT prebiopsy. In 154 patients, transplanted kidney biopsies were performed after measurement of bleeding time, PFA-100, MEA and mean platelet volume (MPV). Bleeding outcome (haemoglobin (Hb) drop, haematuria (±bladder catheterization), ultrasound finding of a bleeding, need for (non)surgical intervention and/or transfusion) after the biopsy was correlated to each test. Male-female ratio was 2:1. 50% had a surveillance biopsy at either three or 12 months. Around 17% (had) used acetylsalicylic acid (ASA) prebiopsy. Of 17 bleeding events, one subject needed a transfusion. Most bleeding events were Hb reductions over 1 mmol/l and all resolved uneventful. BT, PFA-100, MEA and MPV did not predict a bleeding outcome; prior ASA use however could (odds ratio 3.19; 95%-CI 1.06 to 9.61). Diagnostic performance data and Bland-Altman analysis showed that BT could not be substituted by PFA-100. ASA use was the best determinant of bleeding after kidney biopsy. Routine haemostasis testing prebiopsy has no added value.

Absorption fever characteristics due to percutaneous renal biopsy-related hematoma

This study aims to describe the unique characteristics of absorption fever in patients with a hematoma after percutaneous renal biopsy (PRB) and distinguish it from secondary infection of hematoma.We retrospectively studied 2639 percutaneous renal biopsies of native kidneys. We compared the clinical characteristics between 2 groups: complication group (gross hematuria and/or perirenal hematoma) and no complication group. The axillary temperature of patients with a hematoma who presented with fever was measured at 06:00, 10:00, 14:00, and 18:00. The onset and duration of fever and the highest body temperature were recorded. Thereafter, we described the time distribution of absorption fever and obtained the curve of fever pattern.Of 2639 patients, PRB complications were observed in 154 (5.8%) patients. Perirenal hematoma was the most common complication, which occurred in 118 (4.5%) of biopsies, including 74 small hematoma cases (thickness ≤3 cm) and 44 large hematoma cases (thickness >3 cm). Major complications were observed in only 6 (0.2%) cases resulting from a large hematoma. Of 118 patients with a perirenal hematoma, absorption fever was observed in 48 cases. Furthermore, large hematomas had a 5.23-fold higher risk for absorption fever than the small ones.Blood pressure, renal insufficiency, and prothrombin time could be risk factors for complications. Fever is common in patients with hematoma because of renal biopsy and is usually noninfectious. Evaluation of patients with post-biopsy fever is necessary to identify any obvious infection sources. If no focus is identified, empiric antibiotic therapy should not be initiated nor should prophylactic antibiotics be extended for prolonged durations. Absorption fevers will resolve in time without specific therapeutic interventions.

Prediction of Renal Allograft Acute Rejection Using a Novel Non-Invasive Model Based on Acoustic Radiation Force Impulse

Point shear wave elastography based on acoustic radiation force impulse is a novel technology used to quantify tissue stiffness by measuring shear wave speed. A total of 115 kidney transplantation recipients were consecutively enrolled in this prospective study. The patients were subdivided into two groups using 1 mo post-transplantation as the cutoff time for determining the development of acute rejection (AR). Shear wave speed was significantly higher in the AR group than in the non-AR group. We created a model called SEV, comprising shear wave speed, estimated glomerular filtration rate and kidney volume change, that could successfully discriminate patients with or without AR. The area under the receiver operating characteristic curve of SEV was 0.89, which was higher than values for other variables; it was even better in patients within 1 mo post-transplantation (0.954), but was lower than the estimated glomerular filtration rate in patients after 1 mo post-transplantation. Therefore, the SEV model may predict AR after renal transplantation with a high degree of accuracy, and it may be more useful in the early post-operative stage after renal transplantation.

A histopathological outlook on nephrotic syndrome: A pediatric perspective

The developing world is observing changing histopathological patterns of idiopathic nephrotic syndrome (INS). However, the true burden of non-minimal change disease (non-MCD) presenting as INS remains unestimated owing to a paucity of data on renal biopsies. Data were collected from January 2006 to June 2014 on 75 children up to 16 years of age who underwent renal biopsies for INS. Mean age at biopsy was 11.2 ± 3.7 years. The male to female ratio was 1.5:1. A total of 25 (33.3%) children were steroid sensitive, 36 (48%) were steroid resistant, 10 (13.3%) were steroid dependent and 4 (5.3%) came with relapse of nephrotic syndrome (NS). Focal segmental glomerulosclerosis (FSGS) was the most common histopathological subtype observed in 35 (46.8%) children followed by membranous glomerulonephritis (MGN) in 11 (14.7%), membranoproliferative glomerulonephritis (MPGN) and mesangioproliferative glomerulonephritis (MSGN) in 4 (5.3%) each and IgA nephropathy in one (1.3%). MCD was the histological lesion in 19 (25.3%) children. The histopathology established FSGS as the main underlying cause of steroid resistant NS. The study highlights the emergence of non-MCD as the common cause of INS in the pediatric population and signifies the importance of renal biopsies in children with INS.

Positive trends in paediatric renal biopsy service provision in the UK: a national survey and re-audit of paediatric renal biopsy practice

BACKGROUND

Paediatric renal biopsy standards introduced in the UK in 2010 were intended to reduce variation and improve practice. A concurrent national drive was aimed at building robust paediatric nephrology networks to ensure services cater for the needs of the family and minimise time away from home. We aimed to identify current national practice since these changes on behalf of the British Association for Paediatric Nephrology.

METHODS

All UK paediatric nephrology centres were invited to complete a survey of their biopsy practice, including advance preparation. From 1 January to 30 June 2012, a national prospective audit of renal biopsies was undertaken at participating centres comparing practice with the British Association for Paediatric Nephrology (BAPN) standards and audit results from 2005.

RESULTS

Survey results from 11 centres demonstrated increased use of pre-procedure information leaflets (63.6 % vs 45.5 %, P = 0.39) and play preparation (90.9 % vs 9.1 %, P = 0.0001). Audit of 331 biopsies showed a move towards day-case procedures (49.5 % vs 32.9 %, P = 0.17) and reduced major complications (4.5 % vs 10.4 %, P = 0.002). Biopsies with 18-gauge needles had significantly higher mean pass rates (3.2 vs 2.3, P = 0.0008) and major complications (15.3 % vs 3.3 %, P = 0.0015) compared with 16-gauge needles.

CONCLUSIONS

Percutaneous renal biopsy remains a safe procedure in children, thus improving family-centered service provision in the UK.

Teaching percutaneous renal biopsy using unfixed human cadavers

BACKGROUND

Percutaneous renal biopsy (PRB) is an important diagnostic procedure. Despite advances in its safety profile there remains a small but significant risk of bleeding complications. Traditionally, operators train to perform PRB through tutor instruction and directly supervised PRB attempts on real patients. We describe an approach to teaching operators to perform PRB using cadaveric simulation.

METHODS

We devised a full day course hosted in the Clinical Anatomy Skills Centre, with places for nine candidates. Course faculty consisted of two Consultant Nephrologists, two Nephrology trainees experienced in PRB, and one Radiologist. Classroom instruction included discussion of PRB indications, risk minimisation, and management of complications. Two faculty members acted as models for the demonstration of kidney localisation using real-time ultrasound scanning. PRB was demonstrated using a cadaveric model, and candidates then practised PRB using each cadaver model.

RESULTS

Written candidate feedback was universally positive. Faculty considered the cadaveric model a realistic representation of live patients, while the use of multiple cadavers introduced anatomical variation.

CONCLUSIONS

Our model facilitates safe simulation of a high risk procedure. This might reduce serious harm associated with PRB and improve patient safety, benefiting trainee operators and patients alike.

Evaluation of kidney allograft status using novel ultrasonic technologies

Early diagnosis of kidney allograft injury contributes to proper decisions regarding treatment strategy and promotes the long-term survival of both the recipients and the allografts. Although biopsy remains the gold standard, non-invasive methods of kidney allograft evaluation are required for clinical practice. Recently, novel ultrasonic technologies have been applied in the evaluation and diagnosis of kidney allograft status, including tissue elasticity quantification using acoustic radiation force impulse (ARFI) and contrast-enhanced ultrasonography (CEUS). In this review, we discuss current opinions on the application of ARFI and CEUS for evaluating kidney allograft function and their possible influencing factors, advantages and limitations. We also compare these two technologies with other non-invasive diagnostic methods, including nuclear medicine and radiology. While the role of novel non-invasive ultrasonic technologies in the assessment of kidney allografts requires further investigation, the use of such technologies remains highly promising.

A novel simple noninvasive index to predict renal transplant acute rejection by contrast-enhanced ultrasonography

PURPOSE

This study aimed to evaluate the application of quantitative contrast-enhanced ultrasonography (CEUS) in the assessment of renal allograft dysfunction and to establish a new noninvasive index to predict acute rejection (AR).

METHODS

Fifty-seven renal transplant recipients were enrolled in this prospective study. Before renal allograft biopsy, CEUS examinations were performed.The biopsy results proved 23 cases of AR (AR group), 10 cases of acute tubular necrosis (ATN group), and 24 with normal evolution (stable group). Contrast-enhanced ultrasonography parameters including rising time (RT), time to peak (TTP), and the delta-time among regions of interest (ΔRT and ΔTTP) were analyzed.

RESULTS

In the AR group, RT and TTP of interlobar artery and medulla (RTi, RTm, TTPi, and TTPm) as well as ΔRT and ΔTTP between medulla and cortex (ΔRTm-c and ΔTTPm-c) were significantly higher compared with those in the stable group. RTm and TTPm as well as ΔRTm-c and ΔTTPm-c were remarkably higher compared with those in the ATN group. ΔRTm-c and estimated glomerular filtration rate (eGFR) were identified as independent predictors by multivariate analysis (P = 0.008 and P = 0.024). On the basis of the multivariate analysis results and area under the receiver operating characteristic curves of individual markers, we constructed a new simple index, P = -0.587 + 0.286 ×ΔRTm-c − 0.028 × eGFR; new index = e(P)/(1 + e(P)), to discriminate AR, which had better area under the receiver operating characteristic curves than eGFR or individual CEUS parameters.

CONCLUSION

Contrast-enhanced ultrasonography parameters are reliable markers for differentiating the perfusion status of transplanted kidneys. Furthermore, the new simple index can easily predictAR with a high degree of accuracy.

Evaluating renal biopsy-associated hemorrhage complications by the equation and providing an early intervention: a single-center experience

BACKGROUND

The aim was to evaluate the risk for major hemorrhage complications (MHC) prior to percutaneous renal biopsy and apply a specific procedure in high-risk patients to decrease their incidence. Hemorrhage complications that required blood transfusion or other interventions were diagnosed as MHC.

METHODS

One retrospective (Group A, n = 1314) and two prospective cohorts (Group B, n = 249 and Group C, n = 422) were involved in the study. Group A was used to establish a risk equation for MHC, Group B to test its performance, and Group C to evaluate the efficacy of the proposed procedure to reduce MHC incidence. Group C was classified, based on the equation, into high-risk (C1) and low-risk (C2) patients, who received different interventions. The intervention in Group C1 consisted of use of 18-gauge needles, a 12-h rest period post-operation, and reptilase injection; in Group C2, 16-gauge needles were used, with a 6-h rest, and no reptilase injection. Group B was also divided into B1 (high-risk) and B2 (low-risk) using the same cut-off, for further comparison.

RESULTS

(1) In Group A, 4.8% of patients experienced MHC and the equation: Logit (PMHC) = 0.022 × mean arterial pressure (mmHg) + 0.216 × bleeding time (min) - 0.011 × eGFR [ml/(min 1.73 m(2))] - 0.894 × kidney length (cm) - 2.100 × renal cortical thickness (cm) + 6.225 (cutoff = -1.664) was established. (2) The area under the receiver operating characteristic curve was 0.848 (95 % CI 0.797-0.890) for Group B. (3) MHC occurred in 4.8 and 2.8% of patients in Group B and C, respectively; Group B1 suffered significantly more frequent gross hematuria, hematoma and MHC than Group C1; however, no significant difference except for large hematoma was found between Groups B2 and C2 for all complications.

CONCLUSIONS

The equation is reliable to predict the risk for MHC; the interventions proposed can decrease the incidence of MHC in high-risk patients.

C5b-9-targeted molecular MR imaging in rats with Heymann nephritis: a new approach in the evaluation of nephrotic syndrome

Membranous nephropathy (MN) is the major cause of adult nephrotic syndrome, which severely affects patients’ quality of life. Currently, percutaneous renal biopsy is required to definitively diagnose MN. However, this technique is invasive and may cause severe complications. Therefore, an urgent clinical need exists for dynamic noninvasive monitoring of the renal state. In-depth molecular imaging studies could assist in finding a solution. Membrane attack complex C5b-9 is the key factor in the development of MN, and this protein primarily deposits in the glomerulus. The present study bound polyclonal antibodies to C5b-9 with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles to obtain C5b-9-targeted magnetic resonance molecular imaging probes. The probes were injected intravenously into rats with Heymann nephritis, a classic disease model of MN. The signal intensity in the T2*-weighted imaging of kidneys in vivo using 7.0 Tesla magnetic resonance imaging decreased significantly 24 hours after injection compared to the untargeted and control groups. This signal change was consistent with the finding of nanoparticle deposits in pathological glomeruli. This study demonstrated a novel molecular imaging technique for the assessment of MN.

Real-time ultrasound-guided percutaneous renal biopsy with needle guide by nephrologists decreases post-biopsy complications

Background

Percutaneous renal biopsy (PRB) can result in serious complications. The study is aimed to compare the biopsy yield and complications rate of the real-time ultrasonagram (USG)-guided PRB and needle tracking with and without needle guide in two different study periods.

Methods

We compared the yield and complications of 2138 kidney biopsies performed in two different periods, 1510 biopsies during the first period from April 2004–December 2010 and 628 biopsies during second period from January 2011–March 2013. All biopsies in both periods were performed by nephrologists. Radiologists provided the real-time image without needle guide during the first period while nephrologists performed both imaging and biopsy with needle guide during the second period.

Results

Of all the 2138 patients, 226 (10.5%) patients developed 118 minor and 108 major complications. Only 13 (2.1%) major complications occurred in the second period and 95 (6.7%) in the first period (P < 0.001). The relative risk of developing a major complication without guide was 3.04 times greater than that of the biopsies performed with use of the guide. The mean number of glomeruli per biopsy obtained during the second period (17.98 ± 6.75) was significantly greater than that of the first period (14.14 ± 6.01) (P = 0.004). The number of passes to acquire adequate tissue (P = 0.001) and percentage of cortex on biopsy (P = 0.001) were also significantly better in the second period. The optimal observation period post biopsy is 24 h.

Conclusions

Real-time USG imaging supported by needle guide device is associated with better biopsy yield and fewer complications.

Ultrasound-guided percutaneous renal biopsy in 295 children and adolescents: role of ultrasound and analysis of complications

Introduction

Percutaneous renal biopsy (PRB) is a decisive diagnostic procedure for children and adolescents with renal diseases. Aim of this study was to evaluate retrospectively the complication rates of percutaneous kidney biopsies and their therapeutic consequences to assess the role of ultrasound-guidance including Doppler ultrasound examinations in preparation, execution and follow-up care and to present a recommended protocol.

Patients and Methods

Institutional review board approved this retrospective study; informed consent was waived. Between 1997 and 2011 a total of 438 ultrasound-guided biopsies were performed in 295 patients, 169 of the biopsies were performed on kidney transplants. Average age of patients was 10.2+/−5.2 years (range of 15 days until age of 23). Before and post biopsy ultrasound examination including Doppler examination was carried out. Biopsy itself was ultrasound monitored. Complications were analysed with regard to age of patient, kidney transplants, year of occurrence, number of punctures, performing physician and time interval of occurrence to develop an optimized protocol for ultrasound-guidance.

Results

In 99% of cases successful PRB were performed, i.e. enough kidney parenchyma for histological analysis was obtained. No lethal or major complication that required surgical intervention occurred. Eighteen relevant complications were observed (complication rate: 4.1%). Except in one case in which additional MRI diagnostic was necessary, ultrasound examination after 4 hours post biopsy or even earlier when symptoms occurred, was able to detect complications and determine indications for intervention.

Conclusion

Ultrasound-guided PRB is an established and effective method in children and adolescents, but shows a certain rate of complications and therefore should not be indicated without diligence. Ultrasound including Doppler ultrasound is a valuable tool in preparation, guidance of biopsy, detection of complications and in follow-up care. Ultrasound examinations (including Doppler) pre-, during and 4 hours post kidney biopsy and, depending from case, a few days until weeks after biopsy is recommended.

A study of clinical complications and risk factors in 1,001 native and transplant kidney biopsies in Sweden

BACKGROUND

In Sweden, native and transplant kidney biopsies are usually performed in major renal medical centers.

PURPOSE

To clarify risk factors in native and transplant kidney biopsies to improve patient safety.

MATERIAL AND METHODS

A total of 1001 biopsies (in 352 women and 565 men) were included. The median age was 54 years (range, 16-90 years). Data were derived from 826 native kidney biopsies (640 prospective and 186 retrospective) and 175 transplant kidney biopsies (170 prospective and 5 retrospective). Various factors and complications were registered while performing native and transplant kidney biopsies, focusing on major (e.g. blood transfusions, invasive procedures) and minor complications. The prospective protocol was used at six centers and at one center data were obtained retrospectively.

RESULTS

Women were at greater risk of overall complications than men (12.2% vs. 6.5%; P = 0.003; odds ratio [OR], 2.0; confidence interval [CI], 1.3-3.1) as well as of major complications (9.6% vs. 4.5%; P = 0.002; OR, 2.2, CI 1.3-3.7). Major complications occurred more commonly after biopsies from the right kidney, in women than in men (10.8% vs. 3.1%; P = 0.005; OR, 3.7; CI, 1.5-9.5), and in patients with lower BMI (25.5 vs. 27.3, P = 0.016) and of younger age (45 years vs. 52.5 years; P = 0.001). Lower mean arterial pressure in transplant kidney biopsies indicated a risk of major complications (90 mmHg vs. 98 mmHg; P = 0.039). Factors such as needle size, number of passes, serum creatinine, and eGFR did not influence complication rates.

CONCLUSION

The present findings motivate greater attention being paid to the risk of major side-effects after right-side biopsies from women's kidneys, as well as after biopsies from younger patients and patients with lower BMI.

Factors that can minimize bleeding complications after renal biopsy

Renal biopsy is a very important diagnostic tool in the evaluation of renal diseases. However, bleeding remains to be one of the most serious complications in this procedure. Many new techniques have been improved to make it safer. The risk factors and predictors of bleeding after percutaneous renal biopsy have been extensively reported in many literatures, and generally speaking, the common risk factors for renal biopsy complications focus on hypertension, high serum creatinine, bleeding diatheses, amyloidosis, advanced age, gender and so on. Our primary purpose of this review is to summarize current measures in recent years literature aiming at minimizing the bleeding complication after the renal biopsy, including the drug application before and after renal biopsy, operation details in percutaneous renal biopsies, nursing and close monitoring after the biopsy and other kinds of biopsy methods.

Risk factors and timing of native kidney biopsy complications

Background

The appropriate observation period, rate and risk factors of complications after a percutaneous renal biopsy remain debated.

Methods

We retrospectively studied native kidney biopsies performed in our institution between January 2007 and July 2011. Outpatients had either an 8- (67%) or a 24-hour (33%) observation period.

Results

312 biopsies were reviewed (287 patients), 51% of patients were female and the mean age was 54 ± 15 years. Half of these biopsies were performed in outpatients. A total of 15% of patients developed a symptomatic hematoma, 9% received a red blood cell transfusion and 1% required an angio-intervention. Eighty-four percent of the complications manifested within the first 8 h, 86% at 12 h and 94% at 24 h. Outpatients experienced significantly less complications, all manifesting within the first 8 h, 14% required an observation period longer than planned. The risk of symptomatic hematoma increased to 11, 20, 35 and 40% in patients with >200, 140-200, 100-140 and <100 × 10⁹/l platelets, respectively (p = 0.002). It also increased in hemodialysis patients (29% compared to 14%, p = 0.02). We found no association of risk with the number of biopsy passes and only a trend with needle size.

Conclusion

Symptomatic hematomas occurred in 15% of kidney biopsies and were strongly associated with platelet count and hemodialysis. Outpatients experienced fewer complications; therefore, we can conclude that same-day discharge in selected patients is safe.

Complications of automated spring fired biopsy gun technique. A retrospective analysis of 230 cases

BACKGROUND

Renal biopsy (RB) is a procedure which allows obtaining kidney tissue for a morphological diagnosis. As an invasive procedure, RB could lead to some complications. The aim of the study was to assess the incidence and the severity of various complications of renal biopsy(RB) performed by automated spring fired biopsy gun with needles 16 and 18G.

MATERIAL AND METHODS

A total number of 230 RB obtained from patients over 18 years of age, within the period from January 2009 to July 2013, were analyzed retrospectively. All RB were performed by a standartized technique using an automated spring fired biopsy gun, with 16, and 18 G disposable needle. The average age of the patients was 45.5 ± 22.3 years, 119 male and 111 female. As many as 170 biopsies were performed with 16 G needle and 60 with 18G. The assessment of the early post-biopsy complications was done by renal ultrasound (US).

RESULTS

Of all RB, 92.7% were successfully performed. In 60% of the failed RB 18 G needle was used. No post-biopsy complications were noted in 93.4%. Hematomas were observed in 15 out of 230 cases (6.6%). Of those, 80% were assessed as minor hematomas (12/15) with an average size of 20.4mm ± 11mm and they appeared to be asymptomatic.While 8 cases (66%) of all 12 minor hematomas were obtained by two passes (66%), only 4 cases (34%) of hematoma were observed after one pass <0.01. The cases of hematomas obtained with 16 G needle were significantly higher than those in the group with 18G (8 to 4, p<0,05). However, when the number of hematomas in both groups referred to the number of all biopsies in the corresponding group, no significant difference of this complication was observed, p > 0.05. The incidence of major complications was 1.3%.

CONCLUSION

The optimal period for US examination of the kidneys for early diagnosis of complications is up to 24 hours after RB. The experience of the physician performing the procedure is of great importance for reducing the risk of complications as well as the RB technique used. An automated spring fired biopsy gun with needle 16G is recommended.

Retrieval of kidney tissue for light microscopy from frozen tissue processed for immunofluorescence: A simple procedure to avoid repeat kidney biopsies

We highlight a method that is helpful in situations where the tissue sent for LM is inadequate whereas the tissue sent for IF showed glomeruli useful for interpretation. We utilized the leftover frozen tissue after the sections for IF were taken. This tissue was post-fixed in formalin for the purpose of light microscopic diagnosis. The glomerular pathology could be commented upon with a fair degree of accuracy and a repeat biopsy was avoided in 74.7% of the cases. However, the tubules showed marked fixation artefact and tubular pathology was distorted. This procedure can help to reach a correct diagnosis in large percentage of cases otherwise labeled as inadequate biopsy and hence, save the patient from the trauma of a repeat biopsy.