Risk management of renal biopsy: 1387 cases over 30 years in a single centre

Renal Biopsy for Diagnosis in Kidney Disease: Indication, Technique, and Safety

Renal biopsies are the gold standard for diagnosis, staging, and prognosis of underlying parenchymal kidney disease. This article provides an overview of the current indications and highlights ways to reduce bleeding complications in order to achieve optimal diagnostic yield with minimal risk to the patient. Novel indications have emerged from the increasing use of new molecularly targeted oncologic therapies in recent years, which often induce immune-mediated renal disease. On the other hand, the detection of specific antibodies against target antigens on podocytes in the sera of patients with new-onset nephrotic syndrome has now relativized the indication for biopsy in membranous nephropathy. The use of semi-automatic spring-loaded biopsy devices and real-time ultrasound considerably declined the complication rate and is the current standard. Percutaneous renal biopsies are overall a safe procedure if contraindications are considered. A coagulation disorder needs to be excluded beforehand, and an elevated blood pressure must be reduced to the normotensive range with medications. A laparoscopic approach or a radiology interventional procedure through the internal jugular vein may be considered for obtaining a kidney tissue sample if there is an urgent indication and a bleeding tendency cannot be adequately corrected. Major bleeding after a percutaneous renal biopsy can usually be managed with selective arterial embolization of the injured renal vessel. The use of a 16-gauge needle is the most reasonable compromise between diagnostic benefit and risk of complication. In the routine diagnostic, the biopsy specimen is examined with light microscopy, immunohistochemistry, and electron microscopy. Combination with modern molecular pathology techniques will contribute to more precise insights into the development and progression of kidney disease, which will likely refine future treatments in nephrology.

Effects of Aspirin on Kidney Biopsy Bleeding Complications: A Systematic Review and Meta-Analysis (PROSPERO 2021 CRD42021261005)

Postprocedural bleeding is the main complication of percutaneous kidney biopsy (PKB). Therefore, aspirin is routinely withheld in patients undergoing PKB to reduce the bleeding risk. The authors aimed to examine the association between aspirin use and bleeding during PKB. This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The article search was performed on MEDLINE and Scopus using queries specific to each database. Article inclusion was limited to primary studies. The meta-analysis compared the risk of major bleeding events between the aspirin-exposed versus nonexposed group. Pooled effect estimate was examined using random effects presented as odds ratio with 95% confidence intervals. Heterogeneity was assessed through Cochrane I 2 test statistics. Sensitivity and subgroup analyses were also performed according to kidney type. Ten studies were included in the review and four studies were included in the meta-analysis, reviewing a total of 34,067 PKBs. Definitions for significant aspirin exposure were inconsistent between studies, limiting comparisons. Studies with broader definitions for aspirin exposure mostly showed no correlation between aspirin use and postbiopsy bleeding. Studies with strict definitions for aspirin exposure found an increased risk of hemorrhagic events in the aspirin-exposed group. No significant differences were found between the aspirin-exposed and comparison groups regarding major bleeding events (odds ratio 1.72; 95% confidence interval 0.50 to 5.89, I 2 =84%). High-quality evidence on the effect of aspirin on the bleeding risk is limited. Our meta-analysis did not show a significantly increased risk of major bleeding complications in aspirin-exposed patients. Further studies are needed to define a more comprehensive approach for clinical practice.

The impact of blood pressure on the risk of postbiopsy bleeding during the whole procedure of percutaneous kidney biopsy

PURPOSE

To investigate whether BP is related to postbiopsy bleeding in patients undergoing native percutaneous kidney biopsy (PKB) and to evaluate the dynamic changes in blood pressure (BP) pre- and post-kidney biopsy.

METHODS

A retrospective cross-sectional study was conducted. The whole-procedural systolic (SBP) and diastolic (DBP) BP for patients undergoing ultrasound-guided native PKB from October 2017 to December 2020 were recorded in the study. Propensity score matching was used to minimize selection bias. SBP and DBP were analyzed as the main risk factors for bleeding complications. Receiver operating characteristic (ROC) curves were employed to explore the optimal BP thresholds to differentiate between bleeding and nonbleeding. The rates of major bleeding complications were analyzed according to BP thresholds through logistic analysis.

RESULTS

Of 1146 biopsies, 432 (37.7%) patients suffered from postbiopsy bleeding, 88 (7.7%) patients had major bleeding complications, and 344 (30.0%) patients had minor bleeding complications. In the original data, for patients with SBP ≥ 160 mmHg before PKB, the rate of major bleeding complications was 17.6% (7.5% for SBP < 160 mmHg), and the rate of major bleeding complications was 19.0% in patients with DBP ≥ 100 mmHg (7.5% for DBP < 100 mmHg). For patients with DBP ≥ 85 mmHg to 100 mmHg after PKB, the rate of major bleeding complications ranged from 9.5 to 17.5%. The rate of major bleeding complications was lower (6.6-7.3%) in patients with DBP < 100 mmHg to 85 mmHg.

CONCLUSION

Patients who have high-level BP during the native PKB perioperative period are at higher risk for postbiopsy bleeding. High-level BP here does not refer to traditional hypertension according to the guidelines for the diagnosis and treatment of hypertension, but rather BP above a certain threshold related to bleeding risk.

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.

Analysis of urine Raman spectra differences from patients with diabetes mellitus and renal pathologies

Background

Chronic kidney disease (CKD) poses a major public health burden. Diabetes mellitus (DM) is one of the major causes of CKD. In patients with DM, it can be difficult to differentiate diabetic kidney disease (DKD) from other causes of glomerular damage; it should not be assumed that all DM patients with decreased eGFR and/or proteinuria have DKD. Renal biopsy is the standard for definitive diagnosis, but other less invasive methods may provide clinical benefit. As previously reported, Raman spectroscopy of CKD patient urine with statistical and chemometric modeling may provide a novel, non-invasive methodology for discriminating between renal pathologies.

Methods

Urine samples were collected from renal biopsied and non-biopsied patients presenting with CKD secondary to DM and non-diabetic kidney disease. Samples were analyzed by Raman spectroscopy, baselined with the ISREA algorithm, and subjected to chemometric modeling. Leave-one-out cross-validation was used to assess the predictive capabilities of the model.

Results

This proof-of-concept study consisted of 263 samples, including renal biopsied, non-biopsied diabetic and non-diabetic CKD patients, healthy volunteers, and the Surine™ urinalysis control. Urine samples of DKD patients and those with immune-mediated nephropathy (IMN) were distinguished from one another with 82% sensitivity, specificity, positive-predictive value (PPV), and negative-predictive value (NPV). Among urine samples from all biopsied CKD patients, renal neoplasia was identified in urine with 100% sensitivity, specificity, PPV, and NPV, and membranous nephropathy was identified with 66.7% sensitivity, 96.4% specificity, 80.0% PPV, and 93.1% NPV. Finally, DKD was identified among a population of 150 patient urine samples containing biopsy-confirmed DKD, other biopsy-confirmed glomerular pathologies, un-biopsied non-diabetic CKD patients (no DKD), healthy volunteers, and Surine™ with 36.4% sensitivity, 97.8% specificity, 57.1% PPV, and 95.1% NPV. The model was used to screen un-biopsied diabetic CKD patients and identified DKD in more than 8% of this population. IMN in diabetic patients was identified among a similarly sized and diverse population with 83.3% sensitivity, 97.7% specificity, 62.5% PPV, and 99.2% NPV. Finally, IMN in non-diabetic patients was identified with 50.0% sensitivity, 99.4% specificity, 75.0% PPV, and 98.3% NPV.

Conclusions

Raman spectroscopy of urine with chemometric analysis may be able to differentiate between DKD, IMN, and other glomerular diseases. Future work will further characterize CKD stages and glomerular pathology, while assessing and controlling for differences in factors such as comorbidities, disease severity, and other lab parameters.

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.

The impact of blood pressure on the risk of major bleeding complication after renal transplant biopsy

PURPOSE

To assess the impact of elevated blood pressure on the rate of major hemorrhagic complication after renal transplant biopsy.

METHODS

Pre-procedural systolic (SBP), diastolic (SBP), and mean arterial (MAP) blood pressure for consecutive patients undergoing US-guided renal transplant biopsies from 08/01/2015 to 7/31/2017 were retrospectively recorded. Patients who had a major bleeding complication were identified. The risk of complication as a function of SBP, DBP, and MAP was statistically analyzed, with significance set at p < 0.05.

RESULTS

Of 1689 biopsies, there were 10 bleeding complications (10/1689, 0.59%). There was no statistically significant difference between biopsies with complication compared to those without complication based on SBP (p = 0.351), DBP (p = 0.088), or MAP (p = 0.132). Using risk dichotomization criteria, the odds ratio for hemorrhagic complication when the patient had SBP ≥ 180 mmHg and DBP ≥ 95 mmHg was 75.63 (95% CI 6.87-516.8, p = 0.002).

CONCLUSION

The rate of hemorrhagic complication from renal transplant biopsy is low, and there is no statistically significant threshold for increased biopsy risk based on SBP, DBP, or MAP alone. The risk of complication was significantly higher only when both the SBP is ≥ 180 mmHg and DBP is ≥ 95 mmHg.

Renal Biopsy in Children-Effect on Treatment Decisions: A Single-Center Experience

Renal biopsy is an important diagnostic tool, though invasive and carries risks involved with sedation. The authors wanted to compare suspect histopathological diagnosis with final diagnosis and find out impact of biopsy findings on treatment. They retrospectively analyzed 108 patients. Details of patients, diagnosis, treatment and complications due to kidney biopsy were documented. Statistical analysis was done using SPSS version 20.0 (IBM, NY). Indications of 108 children (69 boys, 39 girls) undergoing renal biopsy were steroid-resistant nephrotic syndrome (35.1%), steroid-dependent nephrotic syndrome requiring calcineurin inhibitors (CNI) (12%), nephrotic range proteinuria with atypical features (16.7%), lupus nephritis (13%), and acute kidney injury (AKI) stage 3 (17.6%). Suspect and histopathological diagnoses were similar in 53% cases with agreement factor of 0.462. Treatment changed in 28.7%. Renal biopsy made substantial impact in patients with nephrotic range proteinuria with atypical features (55.6%) and AKI stage 3 (52.6%). One (0.9%) had developed gross hematuria, which resolved spontaneously.

Case Report: Hyponatremia Secondary to Desmopressin Administration Prior to Percutaneous Kidney Biopsy: A Case-Based Review

Bleeding remains the most clinically relevant complication of kidney biopsy and several prophylactic approaches were proposed, including desmopressin administration. We present the case of a 60-year-old man with a history of liver transplantation, admitted for the evaluation of a renal dysfunction. As part of our department protocol, desmopressin 60 μg was administered orally, 2 h before the percutaneous kidney biopsy. The patient developed acute, severe, symptomatic hyponatremia (i.e., headache and recurrent vomiting), followed by a life-threatening upper gastrointestinal bleeding due to a Mallory-Weiss syndrome. Although it is often used as bleeding prophylaxis prior to kidney biopsy, data regarding the efficacy and safety of desmopressin in this setting are inconsistent. Accordingly, we performed a thorough literature review of the use of desmopressin as bleeding prophylaxis prior to kidney biopsy, focusing on the incidence of hyponatremia. The reported incidence of hyponatremia (<130 mmol/l) was 7–11%, probably because serum sodium was monitored in few studies. Nevertheless, hyponatremia was rarely symptomatic but, in some cases, like the one presented here, its complications could be severe. Pre-biopsy low serum sodium and estimated glomerular filtration rate as well as high spot urine sodium and non-restricted fluid intake were reported to be associated with hyponatremia incidence. However, the current evidence cannot clearly establish which patients benefit the most from desmopressin use with respect to bleeding complications. We propose that when desmopressin is used for bleeding prophylaxis prior to kidney biopsy, measurements of serum sodium levels, before and every 6 h after, should complement ultrasound and hemoglobin as part of the patient post-procedural monitoring. Also, water intake should be restricted in the day of biopsy. However, this proposed approach should be adequately evaluated in a clinical trial.

Formalin-fixed paraffin-embedded renal biopsy tissues: an underexploited biospecimen resource for gene expression profiling in IgA nephropathy

Primary IgA nephropathy (IgAN) diagnosis is based on IgA-dominant glomerular deposits and histological scoring is done on formalin-fixed paraffin embedded tissue (FFPE) sections using the Oxford classification. Our aim was to use this underexploited resource to extract RNA and identify genes that characterize active (endocapillary–extracapillary proliferations) and chronic (tubulo-interstitial) renal lesions in total renal cortex. RNA was extracted from archival FFPE renal biopsies of 52 IgAN patients, 22 non-IgAN and normal renal tissue of 7 kidney living donors (KLD) as controls. Genome-wide gene expression profiles were obtained and biomarker identification was carried out comparing gene expression signatures a subset of IgAN patients with active (N = 8), and chronic (N = 12) renal lesions versus non-IgAN and KLD. Bioinformatic analysis identified transcripts for active (DEFA4,TNFAIP6,FAR2) and chronic (LTB,CXCL6, ITGAX) renal lesions that were validated by RT-PCR and IHC. Finally, two of them (TNFAIP6 for active and CXCL6 for chronic) were confirmed in the urine of an independent cohort of IgAN patients compared with non-IgAN patients and controls. We have integrated transcriptomics with histomorphological scores, identified specific gene expression changes using the invaluable repository of archival renal biopsies and discovered two urinary biomarkers that may be used for specific clinical decision making.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

Introduction

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

Objectives

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

Methods

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

Results

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

Conclusions

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

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

Background

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

Methods

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

Results

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

Conclusion

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

Association between native T1 mapping of the kidney and renal fibrosis in patients with IgA nephropathy

Introduction

IgA nephropathy (IgAN) is the commonest global cause of glomerulonephritis. Extent of fibrosis, tubular atrophy and glomerulosclerosis predict renal function decline. Extent of renal fibrosis is assessed with renal biopsy which is invasive and prone to sampling error. We assessed the utility of non-contrast native T1 mapping of the kidney in patients with IgAN for assessment of renal fibrosis.

Methods

Renal native T1 mapping was undertaken in 20 patients with IgAN and 10 healthy subjects. Ten IgAN patients had a second scan to assess test-retest reproducibility of the technique. Native T1 times were compared to markers of disease severity including degree of fibrosis, eGFR, rate of eGFR decline and proteinuria.

Results

All patients tolerated the MRI scan and analysable quality T1 maps were acquired in at least one kidney in all subjects. Cortical T1 times were significantly longer in patients with IgAN than healthy subjects (1540 ms ± 110 ms versus 1446 ± 88 ms, p = 0.038). There was excellent test-retest reproducibility of the technique, with Coefficient-of-variability of axial and coronal T1 mapping analysis being 2.9 and 3.7% respectively. T1 correlated with eGFR and proteinuria (r = − 0.444, p = 0.016; r = 0.533, p = 0.003 respectively).

Patients with an eGFR decline > 2 ml/min/year had increased T1 times compared to those with a decline < 2 ml/min/year (1615 ± 135 ms versus 1516 ± 87 ms, p = 0.068), and T1 time was also higher in patients with a histological ‘T’-score of > 0, compared to those with a ‘T’-score of 0 (1575 ± 106 ms versus 1496 ± 105 ms, p = 0.131), though not to significance.

Conclusions

Cortical native T1 time is significantly increased in patients with IgAN compared to healthy subjects and correlates with markers of renal disease. Reproducibility of renal T1 mapping is excellent. This study highlights the potential utility of native T1 mapping in IgAN and other progressive nephropathies, and larger prospective studies are warranted.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1447-2) contains supplementary material, which is available to authorized users.

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.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

Imaging-Related Risk Factors for Bleeding Complications of US-Guided Native Renal Biopsy: A Propensity Score Matching Analysis

PURPOSE

To evaluate imaging-related hemorrhagic risk factors for ultrasound (US)-guided native kidney biopsy.

MATERIALS AND METHODS

A retrospective review was conducted of adult patients who underwent US-guided native kidney biopsy at a single center between January 2006 and March 2016 and identified 37 of 551 patients (6.72%) with postbiopsy bleeding complications, including 11 major complications (2.00%; n = 11) and 26 minor complications (4.72%; n = 26). Ten patients with major complications and 20 with minor complications were matched with 20 control subjects each by propensity score matching based on age, needle size, number of cores, blood pressure, partial thromboplastin time, prothrombin time, platelet count, and estimated glomerular filtration rate.

RESULTS

Biopsy needle passing through the renal sinus was identified in the patients with major (6 of 10; 60%) and minor complications (8 of 20; 40.0%) but not in the control groups. For patients with major complications, the needle-sinus distance was significantly shorter (5.11 mm ± 7.32 vs 11.14 mm ± 3.54; P = .023) and the needle-capsule distance was significantly longer (17.52 mm ± 8.04 vs 9.28 mm ± 3.29; P = .0004) than in control subjects. The bimodal distribution of cortical tangential angles (< 30° or ≥ 60°) in minor complication cases (17 of 20; 85.0%) was significantly greater than in the control group (8 of 20; 40.0%; odds ratio = 8.50; P = .004).

CONCLUSIONS

This study identifies imaging risk factors in US-guided native kidney biopsy and recommends an algorithm to manage them, including appropriate needle path position between the renal capsule and sinus and proper needle cortical tangential angle.

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.

Comparison of native and transplant kidney biopsies: diagnostic yield and complications

Background

The safety and adequacy are established for the native percutaneous renal biopsy (PRB) but no prospective studies exist that directly compare these with transplant PRB.

Methods

From 1995 to 2015, 1705 adults underwent percutaneous native [native renal biopsy (NRB)] or transplant renal biopsy (TRB) by the Nephrology service. Real-time ultrasound and automated biopsy needles (NRB, 14 or 16 gauge; TRB, 16 gauge) were used. Patients were observed for 24 h (NRB) or 8 h (TRB) post-procedure. Adequacy was defined as tissue required for diagnosis plus glomerular yield. Complications were defined as those resulting in the need for an intervention, such as surgery, interventional radiologic procedure, readmission, blood transfusion and death. Data were collected prospectively in all biopsies.

Results

At the time of biopsy, NRB patients were younger (mean ± SD, 47 ± 17 versus 50 ± 14 years, P < 0.0001) and more often female (62 versus 48%, P < 0.0001) compared with TRB. A fellow supervised by an attending performed the procedure in 91% of NRB compared with 63% of TRB (P < 0.0001). TRB patients were more hypertensive [systolic blood pressure (SBP) 140 ± 22 versus 133 ± 18 mmHg, P < 0.0001] and had a higher serum creatinine (3.1 ± 1.8 versus 2.3 ± 2.2 mg/dL, P < 0.0001), activated partial thromboplastin time (28 ± 4.3 versus 27 ± 5 s, P < 0.0001) as well as lower hemoglobin (Hgb) (11.2 ± 1.8 versus 11.7 ± 2.1 g/dL, P < 0.0001) compared with NRB. Adequate tissue for diagnosis was obtained in > 99% of NRB and TRB (P = 0.71). Compared with TRB, NRB had a greater drop in Hgb after the biopsy (0.97 ± 1.1 versus 0.73 ± 1.3 g/dL, P < 0.0001), a higher complication rate (6.5 versus 3.9%, P = 0.02) and higher transfusion rate (5.2 versus 3.3%, P = 0.045). There was one death in each group attributed to the biopsy.

Conclusions

Although death is equally rare, the complication rate is higher in NRB compared with TRB despite TRB having more of the traditional risk factors for bleeding. Differences in technique, operator (fellow or attending) or needle gauge may explain this variability.

Risk of percutaneous renal biopsy of native kidneys in the evaluation of acute kidney injury

Background

Percutaneous renal biopsy (PRB) of native kidneys (NKs) to better understand and treat acute kidney injury (AKI) is being advocated, but little is known about the risk of complications.

Methods

We performed a retrospective study of PRB of NKs in 955 adults from 1991 to 2015 at an academic medical center with real-time ultrasound and automated biopsy needles. Patients undergoing PRB for evaluation of AKI (n = 160) were compared with 795 patients biopsied for other reasons (not-AKI) for postbiopsy complications [need for transfusion of packed red blood cells (PRBCs), an interventional radiologic or surgical procedure, readmission or death].

Results

Patients biopsied for AKI were older (58 ± 16 versus 44 ± 16 years; P < 0.0001), with a higher serum creatinine (SCr) (4.5 ± 2.7 versus 1.8 ± 1.6 mg/dL; P < 0.0001) and lower hemoglobin (Hgb) (10.4 ± 1.7 versus 12.1 ± 2.1; P < 0.0001) and a greater proportion had an abnormal bleeding time (12.5% versus 7.4%, P 0.04), partial thromboplastin time (15.2% versus 5.3%, P < 0.0001) and/or prothrombin time (27.0% versus 12.8%; P < 0.0001) compared with not-AKI patients. Complications post-PRB were significantly greater in patients biopsied for AKI {11.3% versus 6.7%; P=0.04; odds ratio [OR] 1.78 [95% confidence interval (CI) 1.01–3.12]} with patients biopsied for AKI requiring more blood transfusions (10.0% versus 5.3%; P 0.02; OR 2.04 (95% CI 1.12–3.74)]. By multivariate analysis, baseline features predictive of a complication were increased SCr and decreased Hgb level, as well as female gender and increased systolic blood pressure.

Conclusion

Patients biopsied for evaluation of AKI are at greater risk of complications due to increased risk factors.

Treatment of Rapidly Progressive Glomerulonephritis in the Elderly

As the population worldwide ages, the epidemic of kidney disease will also increase. Anti-neutrophil cytoplasmic antibodies (ANCA) positive rapidly progressive positive glomerulonephritis (RPGN) is the most common etiology for biopsied patients among the very elderly. Its pathological features and clinical course are well described, though there is still debate about the mechanism of injury involved in individual patients. From very ancient times, the cornerstone of treatment historically has been high-dose cyclophosphamide and a lengthy course of high-dose corticosteroids. Although this regimen has diminished the immediate mortality rate of RPGN, its intermediate and long-term adverse effects are not insignificant. Attempts to minimize toxicity and improve efficacy have been made through the years to allow physicians some options for therapy. Lower cumulative cyclophosphamide regimens, shorter corticosteroid courses, and the introduction of rituximab have modified the armamentarium for treatment of ANCA positive RPGN. As progress is made in understanding the molecular pathogenesis of this disease, new targets will be found for potential therapeutic attack. The complement system is an area of active interest for all glomerular diseases at this time. Indeed, animal studies and preliminary human studies suggest that targeting the complement system can ameliorate the course of ANCA-positive RPGN. Hopefully, as the population ages, we will see more and safer therapeutic options to treat this once rapidly fatal disease.

Candidate Urine Peptide Biomarkers for IgA Nephropathy: Where Are We Now?

Early detection, prognosis, and management of IgA nephropathy (IgAN) remain a challenge. Histological examination of renal tissue still comprises the only way to confirm an IgAN diagnosis. It is of great importance to establish noninvasive diagnostic, prognostic, and predictive biomarkers that would improve the clinical care and outcome of patients suffering from IgAN. This review summarises the findings from previous mass spectrometry- (MS-) based studies dedicated to the discovery of urinary peptide profiles specific to IgAN. There is a substantial number of urinary peptides that have been discovered to date, which show promise as biomarkers of IgAN; however, all of them require further, rigorous validation in well-planned studies, involving a large number of subjects who represent diverse and numerous populations.

Measuring hemoglobin prior to early discharge without routine surveillance ultrasound after percutaneous native renal biopsy in children

BACKGROUND

We aimed to evaluate the role of post-procedural hemoglobin (hb), without pre-discharge ultrasound (US), after US-guided renal biopsy in children.

METHODS

A retrospective review was conducted of consecutive outpatient native kidney biopsies over an 8-year period. Procedures were performed under real-time US guidance. Data collected included number of passes, presence and size of perinephric hematoma, age, body mass index (BMI), blood pressure (BP), fasting status, hb and platelets. Continuous variables were expressed as mean ± standard deviation, group differences were tested with Student's unpaired t test and analysis of variance and correlations were assessed using Pearson's r. Significance was defined as p < 0.05. Hb changes (g/L), percentage hb (%hb) change, hematoma size and positive and negative predictive values (PPV, NPV, respectively) were analyzed.

RESULTS

A total of 330 procedures in 300 children (141 females, mean age 11.2 ± 4.30 years) were analyzed. Post-procedural hematoma occurred in 63%. There was a significant (p = 0.0001) post-procedural hb decrease of 6.3 ± 5.5 g/L and %hb decrease of 4.56 ± 4.01%. Fasting during pre-procedural hb estimation and procedural hematoma was associated with a greater hb drop. A ≥10% hb drop had 73% PPV for repeat blood work and US and a 17% PPV for admission, whereas a <10% hb drop had a NPV of 84% and 98%, respectively. Hb change showed a weak correlation with age, and hematoma size showed a weak inverse correlation with platelet count, but no correlation with BMI, number of passes or BP.

CONCLUSIONS

Bleeding complications from US-guided native kidney biopsies in pediatric outpatients can be safely followed by a complete blood count at 6 h post procedure. A 10% hb decrease is strongly associated with requirement for further testing and/or admission.

Serum D-dimer is a potential predictor for thromboembolism complications in patients with renal biopsy

Renal biopsy has been widely recommended in clinic to determine the histological patterns of kidney disease. To prevent bleeding complications, patients should routinely stop anticoagulants prior to renal biopsy. However, patients with kidney disease are susceptible to thromboembolisms, particularly in those with severe hypoalbuminemia. This study was designed to investigate the application of serum D-dimer as a predictor for thrombotic events after renal biopsy. 400 consecutive native renal biopsies were prospectively included in this 2-month follow-up study. The overall incidence of bleeding and thrombotic complication is 4%, including hematuria or large perinephric hematoma (2.5%, n = 10) and thrombotic complication (1.5%, n = 6). Compared to low serum D-dimer (<2.00 μg/ml), subjects in the group of high serum D-dimer (≥2.00 μg/ml) were more incline to develop thrombotic complications (9.1% versus 0.3%; RR, 30.33; p < 0.001). D-dimer correlated positively with age (r_s = 0.258, P < 0.001). Inverse correlations were found for albumin (r_s = −0.339, P < 0.001). Taken together, patients with high serum D-dimer carry an increased risk of thrombotic complications after renal biopsy. Our findings suggest that serum D-dimer can serve as a potential predictor for thrombotic events in patients with kidney disease. Further cautions should be given to these subjects.

Diagnostic work-up and specific causes of acute kidney injury

Acute kidney injury (AKI) is common in critically ill patients and associated with grim short- and long-term outcome. Although in the vast majority of cases AKI is multifactorial, with sepsis, shock and nephrotoxicity accounting for most episodes, specific causes of AKI are not uncommon. Despite remaining uncertainties regarding their prevalence in the ICU, prompt recognition of specific aetiologies of AKI is likely to ensure timely management, limit worsening of renal dysfunction, and ultimately limit renal and systemic consequences of AKI. The ability to recognize conditions that may be associated with specific aetiologies and the appropriate use of clinical imaging, biological and immunological tests, along with optimal assessment of the need for renal biopsies, should be part of routine ICU care. In this review, we summarize uncertainties, current knowledge and recent advances regarding specific types of AKI. We describe the most common specific causes as well as rare aetiologies requiring urgent management, and outline available tools that may be used during the diagnostic work-up along with their limitations.

Yield and complications of kidney biopsy over two decades in a tertiary pediatric center

BACKGROUND

Kidney biopsy serves as an adjunct for the diagnosis of renal disease, but it is not always productive. This study evaluated the yield and risks of kidney biopsies performed in 1995-2014 at a tertiary pediatric medical center.

METHODS

The medical files of all patients who underwent closed percutaneous biopsy for various indications in native or transplanted kidneys were retrospectively reviewed for patient characteristics, technical and histopathologic findings, biopsy yield, and biopsy complications. Biopsy yield was considered positive if findings confirmed a probable diagnosis or led to a change in clinical diagnosis, disease severity/activity grade, treatment strategy, or prognosis; and negative, if findings were non-informative and in cases of technical failure.

RESULTS

During the study period, 216 biopsies were performed on native kidneys and 84 on transplanted kidneys. In the transplanted kidney group, the most common indications for biopsy were decreased glomerular filtration rate and suspected rejection. Rates of positive biopsy yield were 86.6% in the native kidney group and 82.1% in the transplanted kidney group; the difference was not statistically significant. Significant between-group differences were found in various technical and histopathological parameters, patient age at biopsy, and sex distribution. In the native kidney group, positive biopsy yield was associated with the presence of nephrotic-range proteinuria. Post-procedural complications occurred in three patients (1.3%) with native kidneys, and in one patient (1.1%) with a transplanted kidney.

CONCLUSIONS

Kidney biopsy is an efficient and safe procedure in both native and transplanted kidneys and provides helpful diagnostic information in most cases in which it is deemed necessary.

Renal pathological implications in type 2 diabetes mellitus patients with renal involvement

AIMS

To investigate the renal pathological implications in type 2 diabetes mellitus patients with renal involvement.

METHODS

A total of 328 type 2 diabetes mellitus (T2DM) patients with renal involvement who underwent a renal biopsy and received follow-up for at least one year were recruited in our study. The patients were divided into the diabetic nephropathy (DN), non-diabetic renal disease (NDRD), and NDRD superimposed on DN groups based on the pathological diagnosis. Renal outcomes were defined by the initiation of renal replacement therapy or doubling of the serum creatinine. Kaplan-Meier analysis was used to compare renal survival, and Cox proportional hazard analysis was used to determine the predictors of renal outcomes in the DN group.

RESULTS

Renal biopsy findings revealed that 188 patients (57.32%) had pure DN, 121 patients (36.89%) had NDRD alone, and 19 patients (5.79%) had NDRD superimposed on DN. The most frequent subclassification of NDRD was membranous nephropathy (MN). Compared with the NDRD and NDRD superimposed on DN groups, patients with pure DN had poorer renal function and lower renal survival rates. In the DN group, the five-year renal survival rates of glomerular classes of I, IIa, IIb, III and IV were 100%, 84.62%, 60%, 47.5% and 33.33%, respectively. Multivariate Cox proportional hazard analysis showed that the glomerular lesions, proteinuria and serum creatinine were independent risk factors for renal outcomes, while interstitial fibrosis/inflammation and arteriolar hyalinosis were not independently associated with renal outcomes in the DN group.

CONCLUSIONS

Making an accurate pathologic diagnosis by renal biopsy is crucial for diabetes mellitus (DM) patients with renal involvement. The findings of our present study indicated that patients with pure DN had poorer renal outcomes than patients with NDRD or NDRD superimposed on DN. The classification of glomerular lesions, proteinuria and serum creatinine were independent risk factors for renal outcomes in the DN group. More studies with large samples and longer time follow-up are needed to evaluate the relationship between pathological changes and clinical characteristics in T2DM patients who have renal involvement.

Retrospective Analysis of Ultrasound-Detected Bleeding Complications after Ultrasound-Guided Transcutaneous Kidney Biopsies

The aim of this retrospective single-center study was to examine ultrasound-detected complications after diagnostic parenchymal renal biopsies. After 471 ultrasound-guided kidney biopsies (225 native kidneys and 246 renal allografts), ultrasound revealed hematomas (21.9%), arterio-venous fistulas (8.9%), active bleeding (1.1%) and hematuria (0.4%). Only 0.8% of all patients required invasive intervention such as coiling (n = 3) and surgical procedures (n = 1). Three episodes of bleeding (0.6%) were solved with manual compression. One patient (0.2%) needed an irrigation catheter because of hematuria. Furthermore, six patients (1.3%) received blood transfusion. Ultrasound-guided biopsies are safe. With modern ultrasound machines using multi-frequency transducers with high resolution and harmonic imaging, even marginal bleeding after renal biopsy is detected.

The Utility of Viscoelastic Testing in Patients Undergoing IR Procedures

Whole-blood viscoelastic testing can identify patient-specific coagulation disturbances, allowing for targeted repletion of necessary coagulation factors and differentiation between coagulopathy and surgical bleeding that requires intervention. Viscoelastic testing complements standard coagulation tests and has been shown to decrease transfusion requirements and improve survival in bleeding patients. Viscoelastic testing also can be used to predict bleeding and improve the care of patients undergoing interventional radiology (IR) procedures.

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.

Renal biopsy: Still a landmark for the nephrologist

Renal biopsy was performed for the first time more than one century ago, but its clinical use was routinely introduced in the 1950s. It is still an essential tool for diagnosis and choice of treatment of several primary or secondary kidney diseases. Moreover, it may help to know the expected time of end stage renal disease. The indications are represented by nephritic and/or nephrotic syndrome and rapidly progressive acute renal failure of unknown origin. Nowadays, it is performed mainly by nephrologists and radiologists using a 14-18 gauges needle with automated spring-loaded biopsy device, under real-time ultrasound guidance. Bleeding is the major primary complication that in rare cases may lead to retroperitoneal haemorrhage and need for surgical intervention and/or death. For this reason, careful evaluation of risks and benefits must be taken into account, and all procedures to minimize the risk of complications must be observed. After biopsy, an observation time of 12-24 h is necessary, whilst a prolonged observation may be needed rarely. In some cases it could be safer to use different techniques to reduce the risk of complications, such as laparoscopic or transjugular renal biopsy in patients with coagulopathy or alternative approaches in obese patients. Despite progress in medicine over the years with the introduction of more advanced molecular biology techniques, renal biopsy is still an irreplaceable tool for nephrologists.

The clinical significance of antiphospholipid antibodies in systemic lupus erythematosus

Antiphospholipid syndrome (APS) is the association of thrombosis and/or pregnancy morbidity with antiphospholipid antibodies (aPL). Thirty to forty percent of systemic lupus erythematosus (SLE) patients are tested positive for aPL, which may have an impact on the SLE presentation, management, and prognosis. Compared with SLE patients without aPL, those with aPL have a higher prevalence of thrombosis, pregnancy morbidity, valve disease, pulmonary hypertension, livedo reticularis, thrombocytopenia, hemolytic anemia, acute/chronic renal vascular lesions, and moderate/severe cognitive impairment; worse quality of life; and higher risk of organ damage. The use of low-dose aspirin (LDA) is controversial for primary thrombosis and pregnancy morbidity prevention because of the lack of strong prospective controlled data. Similarly, the use of anticoagulation is controversial for patients with an aPL-related nephropathy. Until further studies are available, physicians should discuss the risk/benefits of LDA or anticoagulation as well as the available literature with patients.

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.

Implementation and Results of a Percutaneous Renal Allograft Biopsy Protocol to Reduce Complication Rate

Percutaneous renal transplant biopsy (PRTB) is the gold standard for evaluating allograft rejection after renal transplant. Hemorrhage is the predominant complication. We describe the implementation of a standardized protocol for PRTB at a single institution, with the aim of reducing bleeding complications. Utilizing the plan-do-study-act model for quality improvement, we created and deployed a protocol centered on controlling patient's hypertension, platelet function, and anticoagulation status. The 4-year study encompassed a total of 880 PRTBs, before and after implementation of the protocol. Total complication rate, which was 5.8% in the 2 years leading up to implementation of the protocol, was reduced to 2.9% after the protocol was introduced (P = .04). A standardized approach to PRTB can potentially lower complication rates; we present a framework for implementating a quality improvement protocol at other institutions.

Factors Contributing to the Success of Ultrasound-Guided Native Renal Biopsy

OBJECTIVES

The purpose of this study was to evaluate factors contributing to the success of ultrasound-guided native renal biopsy.

METHODS

We retrospectively identified patients who had ultrasound-guided native renal biopsy at our institution over a 10-year period. We reviewed the imaging and electronic medical records to collect demographic information and clinical data, including pathologic results. Biopsy samples were categorized and compared on the basis of the number of glomeruli (optimal [≥20] versus suboptimal [<20]) and the pathologist's reported diagnostic confidence (high confidence versus limited confidence). Procedure details, including the operator and the use of the cortical tangential approach, were also obtained.

RESULTS

For 282 patients with biopsies using 18-gauge needles, the number of passes made was significantly higher for optimal (P < .001) and high-confidence (P < .001) specimens than for suboptimal and limited-confidence specimens. The cortical tangential approach was used more frequently for optimal (P< .001) and high-confidence (P = .01) specimens than for suboptimal and limited-confidence specimens. Radiologists routinely doing ultrasound-guided procedures of all types had significantly more optimal (P= .01) and high-confidence (P= .001) specimens than radiologists with limited ultrasound experience. The distance to the kidney, cortical thickness, glomerular filtration rate, and body mass index were not significant factors.

CONCLUSIONS

The ultrasound-guided procedural experience of the operator, taking more than 1 specimen, and the use of the cortical tangential approach significantly improved the pathologic material obtained during native renal biopsies.

Clinical factors influencing the decision to transfuse after percutaneous native kidney biopsy

Background

Transfusion of erythrocytes is the most common intervention after a complicated percutaneous renal biopsy (PRB). Anemia is considered to be a leading risk factor for bleeding following a PRB, and based on recent studies of transfusions in hospitalized patients, many institutions are restricting the threshold for erythrocyte transfusion to a lower hemoglobin concentration (Hgb). The purpose of this study is to analyze factors that influence the transfusion decision after a PRB, and to determine whether anemia is truly a risk factor for bleeding or anemic patients are simply more likely to receive a transfusion because of their already lower pre-PRB Hgb.

Methods

PRB of native kidneys was performed using real-time ultrasound with automated biopsy needles from January 1990 to April 2014. All patients were prospectively followed for bleeding with a 24-h inpatient observation. An intervention for a bleeding complication (BL-I) was defined by undergoing a procedure (cystoscopy, embolization), receiving a blood transfusion (BL-T), death and/or readmission related to the biopsy. To further define the effect of anemia, patients were divided into three pre-PRB Hgb groups: <9.0 g/dL (n = 79), 9.0–11.0 g/dL (n = 266) and >11.0 g/dL (n = 565).

Results

BL-I occurred in 71/910 (7.8%) of PRBs. The majority of these were BL-T (57/71, 80%; 57/910, 6.3% overall). Patients with BL-I had lower pre-PRB Hgb than those without BL-I (mean ± SD; 10.3 ± 2.0 versus 12.0 ± 2.1 g/dL, P < 0.0001) and a greater change (Δ) in Hgb (2.1 ± 1.6 versus 1.0 ± 0.8 g/dL, P < 0.0001). When compared with higher Hgb, patients with Hgb <9.0 g/dL had more traditional risk factors for bleeding (older age: 49 ± 18 versus 48 ± 18 versus 45 ± 16 years, P = 0.02; female: 72 versus 70 versus 56%, P < 0.0001; higher serum creatinine: 4.0 ± 2.9 versus 2.9 ± 2.6 versus 1.7 ± 1.4 mg/dL, P < 0.0001; higher systolic blood pressure: 138 ± 18 versus 133 ± 19 versus 133 ± 18 mmHg, P = 0.06; higher bleeding time: 7.6 ± 1.8 versus 7.4 ± 2.0 versus 6.7 ± 1.8 min, P < 0.0001). When BL-T was stratified by pre-PRB Hgb, there were more transfusions in those with lower pre-PRB Hgb (24 versus 9 versus 3%, P < 0.0001). However, these patients not only had fewer hematomas (58 versus 83 versus 87%, P = 0.04) but also demonstrated a smaller ΔHgb post-PRB (1.3 ± 1.0 versus 1.8 ± 0.8 versus 3.2 ± 1.6, P < 0.0001) compared with patients with higher pre-PRB Hgb, yet still received a transfusion.

Conclusions

While patients with lower pre-PRB Hgb have more of the traditional risk factors for a complication after PRB, there was actually less clinically evident bleeding in these patients who were transfused. Although anemia itself has been considered to be a risk factor for a complication in the past, it more accurately represents only a predictor of receiving an erythrocyte transfusion. In the setting of the PRB, the decision for transfusion is influenced more by the severity of anemia at baseline as opposed to clinically evident bleeding.

The Native Kidney Biopsy: Update and Evidence for Best Practice

The kidney biopsy is the gold standard in the diagnosis and management of many diseases. Since its introduction in the 1950s, advancements have been made in biopsy technique to improve diagnostic yield while minimizing complications. Here, we review kidney biopsy indications, techniques, and complications in the modern era. We also discuss patient populations in whom special consideration must be given when considering a kidney biopsy and the important role that the kidney biopsy plays in nephrology training. These data are presented to develop best practice strategies for this essential procedure.

Renal disease presenting as acute kidney injury: the diagnostic conundrum on the intensive care unit

PURPOSE OF REVIEW

Acute kidney injury (AKI) is commonplace in most ICUs. In many cases the cause is believed to be multifactorial with sepsis being a major component. However, occasionally intrinsic renal disease will present to the ICU and as such critical care practitioners should be aware of this possibility and the ways in which such conditions may present.

RECENT FINDINGS

Although a relatively rare occurrence the treatment for patients with intrinsic renal disease, particularly those who present as part of a vasculitic process, differs considerably from usual organ support employed on intensive care. Recent studies indicate that the outlook for these patients is poor particularly when the diagnosis is delayed. The use of serological investigations as well as other diagnostic techniques are discussed.

SUMMARY

Not all AKI as described by changes in creatinine and urine output which presents or develops on the ICU is the same. AKI is a syndrome which encompasses many conditions and as such is nondiagnostic. Clinicians, when faced with AKI should satisfy themselves as to the likely cause of the AKI.

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.

A clinicopathological study of renal biopsies from 288 elderly patients: analysis based on 4,185 cases

PURPOSE

To investigate the clinical characteristics and histopathological features of kidney disease in elderly patients.

METHODS

We retrospectively analyzed the results of 4,185 consecutive renal biopsies, and 288 patients aged >60 years at the Second Hospital of Jilin University from January 1998 to December 2013 were finally included. All patients had been clinically and histologically diagnosed with kidney disease.

RESULTS

Nephrotic syndrome was the main clinical indication for biopsy. Twenty-four patients (8.33 %) experienced a minor complication related to their biopsy procedure. Among patients diagnosed as primary glomerulonephritis (GN), membranous nephropathy (MN) was the most frequent subclassification (24.7 %), followed by mesangioproliferative glomerulonephritis (MsPGN, 11.1 %) and IgA nephropathy (IgAN, 8.0 %). Amyloidosis (8.7 %) was the most common secondary GN, followed by antineutrophil cytoplasmic autoantibody (ANCA)-associated pauci-immune GN (5.2 %) and diabetic nephropathy (DN, 3.8 %). Based on renal biopsies results, 143/288 patients received immunosuppressive therapy and showed an overall remission rate (complete plus partial remissions) of 74.1 %. Among 71 MN patients, 29 patients received steroids plus cyclophosphamide and showed a remission rate of 79.3 %, while 42 patients received steroids and tacrolimus and showed a remission rate of 90.5 %. Among 25 patients with amyloidosis, 22 cases received melphalan plus dexamethasone and showed a remission rate of 40.9 %, while three patients received vincristine, adriamycin, and dexamethasone and showed a remission rate of 66.7 %.

CONCLUSION

Making an accurate pathologic diagnosis by renal biopsy is crucial for selecting the proper treatment for elderly patients with kidney disease.

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.