Who should perform the percutaneous renal biopsy: a nephrologist or radiologist?

Increasing Incidence of Inadequate Kidney Biopsy Samples Over Time: A 16-Year Retrospective Analysis From a Large National Renal Biopsy Laboratory

Introduction

Renal biopsy remains an essential tool for the diagnosis and treatment of patients with medical kidney disease. Recently, there has been a perceived change in the number of inadequate samples. The aim of this study was to determine the native renal biopsy miss rate from 2005 to 2020 at Arkana Laboratories, a nationwide kidney biopsy service.

Methods

From 2005 to 2020, a total of 123,372 native kidney biopsies were received from >2500 nephrologists practicing across 44 US states. The miss rate was determined by age and year. In a subset of biopsies received in 2005 and 2018, the biopsy operator was determined, nephrologist or radiologist. Furthermore, the miss rate, needle gauge, biopsy depth by operator, and biopsy core width by gauge were measured.

Results

The miss rate increased markedly from 2% in 2005 to 14% in 2020. Radiologists performed 5% of biopsies in 2005 and 95% in 2018 using smaller diameter (18g/20g) needles 92% of the time. Glomeruli per centimeter of core biopsy and mean core width were significantly lower with smaller needles. The miss rate deep was significantly lower for nephrologists and remained consistent within operator between the 2 time points. The miss rate did not correlate with the increasing age of the population who had biopsies.

Conclusion

This increase in kidney biopsy miss rate significantly affects patient care in the management of medical kidney disease. Its correlation with the complete reversal in operators suggests an urgent need for interaction with and training of radiologists in this critical technique.

Improvement of allograft kidney biopsy yield by using a handheld smartphone microscope as an on-site evaluation device

Background

Smart lens is a magnifying device that turns the smartphone into a microscopic exploring instrument. It is a convenient and inexpensive tool as an on-site evaluation device for the kidney biopsy specimen. We demonstrate the benefit of using a handheld smartphone microscope compared to the standard procedure in allograft kidney specimens.

Material and methods

This was a cohort study of allograft kidney biopsies performed between June 2015 and November 2017 in Srinagarind Hospital, Khon Kaen University, Thailand. The clinical utility of the “Chula smart lens” applied to the smartphone as an on-site evaluation device was studied. Clinical data, diagnostic quality, and complications were retrospectively reviewed and compared between the smart lens group and the standard group.

Results

The study cohort consisted of 93 allograft kidney biopsies (standard:47, smart lens:46). The mean age was 40.6 (18–48) years, and 63 patients (67.7%) were male. By using the smart lens device, the number of obtained tissue cores was higher (3.5 vs 2.9, p = 0.019) and the inadequacy rate for diagnosis was significantly lower (7% vs 21.3%, p = 0.05).

Conclusion

Using a handheld smartphone microscope as an on-site evaluation device resulted in more positive glomeruli and diagnostic yield compared to the standard procedure.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

An integrated pathology and ultrasonography-based simulation for training in performing kidney biopsy

Background: Medical practice trends and limitations in trainees’ duty hours have diminished the interest and exposure of nephrology fellows to percutaneous kidney biopsy (PKB). We hypothesized that an integrated nephrology-pathology-led simulation may be an effective educational tool. Materials and methods: A 4-hour PKB simulation workshop (KBSW), led by two ultrasonography (US)-trained nephrologists and two nephropathologists, consisted of 6 stations: 1) diagnostic kidney US with live patients, 2) kidney pathology with plasticine models of embedded torso cross-sections, 3) US-based PKB with mannequin (Blue Phantom™), 4) kidney pathology with dissected cadavers, 5) US-based PKB in lightly-embalmed cadavers, and 6) tissue retrieval adequacy examination by microscope. A 10-question survey assessing knowledge acquisition and procedural confidence gain was administered pre- and post-KBSW. Results: 21 participants attended the KBSW and completed the surveys. The overall percentage of correct answers to knowledge questions increased from 55 to 83% (p = 0.016). The number of “extremely confident” answers increased from 0 – 5% to 19 – 28% in all 4 questions (p = 0.02 – 0.04), and the number of “not at all confident” answers significantly decreased from 14 – 62% to 0 – 5% in 3 out of 4 questions (p = 0.0001 – 0.03). Impact of the imparted training on subsequent practice pattern was not assessed. Conclusion: A novel KBSW is an effective educational tool to acquire proficiency in PKB performance and could help regain interest among trainees in performing PKBs.

Diagnostic and Interventional Nephrology in Spain: A snapshot of current situation

BACKGROUND:

Diagnostic and Interventional Nephrology has been a rising field in recent years worldwide. Catheter insertion, renal biopsy, renal ultrasound, and peritoneal dialysis catheter or permanent dialysis catheter insertion are vital to our specialty. At present, many of these procedures are delegated to other specialties, generating long waiting lists and limiting diagnosis and treatment.

METHODS:

An online survey was emailed to all Nephrology departments in Spain. One survey response was allowed per center.

RESULTS:

Of 195 Nephrology departments, 70 responded (35.8%). Of them, 72.3% (52) had ultrasound equipment, 77.1% insert temporary jugular catheters, and 92.8% femoral. Up to 75.7% (53 centers) perform native renal biopsies, of which 35.8% (19) are real-time ultrasound guided by nephrologists. Transplant kidney biopsies are done in 26 centers, of which 46.1% (12) by nephrologists. Tunneled hemodialysis catheters are inserted in 27 centers (38.5%), peritoneal catheter insertion in 18 (31.6%), and only 2 centers (2.8%) perform arteriovenous fistulae angioplasty. In terms of ultrasound imaging, 20 centers (28.5%) do native renal ultrasound and 16 (22.8%) transplanted kidneys. Of all units 71.4% offer carotid ultrasound to evaluate cardiovascular risk, only in 15 centers (21%) by nephrologists. AVF ultrasound scanning is done in 55.7% (39).

CONCLUSION:

Diagnostic and Interventional Nephrology is slowly spreading in Spain. It includes basic techniques to our specialty, allowing nephrologists to be more independent, efficient, and reducing waiting times and costs, overall improving patient care. Nowadays, more nephrologists aim to perform them. Therefore, appropriate training on different techniques should be warranted, implementing an official certification and teaching programs.

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.

Incidence of major complications after percutaneous native renal biopsies in adults from low-income to middle-income countries: a protocol for systematic review and meta-analysis

INTRODUCTION

Kidney biopsy is an essential tool for guiding clinicians towards diagnoses, treatment and determining prognosis in renal disease. However, the procedure can be marred by various complications. The reported occurrence of complications varies among countries or regions and is also affected by several clinical and technical factors. This systematic review and meta-analysis aims to evaluate the incidence of major complications after percutaneous native renal biopsy in low-income to middle-income countries (LMICs).

METHODS AND ANALYSIS

We will include studies of populations from LMIC as per World Bank 2017 country list. Relevant abstracts published from 1 January 1980 to 30 December 2017 will be searched in PubMed, Cochrane, Excerpta Medica Database (Embase) and African Journals Online, without language restriction. Two reviewers will independently screen, select studies, extract data and assess the risk of bias in each study. A third reviewer will arbitrate in cases of disagreements. The study-specific estimates will be pooled through a random-effects model meta-analysis to obtain an overall summary estimate of the incidence of major complications across studies. Clinical and statistical heterogeneity will be evaluated by Cochrane's Q statistic. Funnel-plot analysis and Egger's test will be used to assess publication bias. Results will be presented by geographical region and income group.

ETHICS AND DISSEMINATION

This study will use published data. Therefore, there is no requirement for ethical approval. This systematic review and meta-analysis is expected to inform healthcare workers and providers about the occurrence of major complications following renal biopsies and highlight possible actions needed to improve the safety of the procedure in LMICs. The final report will be published as an original article in a peer-reviewed journal. Findings will also be presented at a conference and submitted to relevant health authorities.

PROSPERO REGISTRATION NUMBER

CRD42017077656.

Arteriovenous fistulae after renal biopsy: diagnosis and outcomes using Doppler ultrasound assessment

BACKGROUND

Percutaneous renal biopsy (PRB) is an important technique providing relevant information to guide diagnosis and treatment in renal disease. As an invasive procedure it has complications. Most studies up to date have analysed complications related to bleeding. We report the largest single-center experience on routine Doppler ultrasound (US) assessment post PRB, showing incidence and natural history of arteriovenous fistulae (AVF) post PRB.

METHODS

We retrospectively analysed 327 consecutive adult PRB performed at Ramon Cajal University Hospital between January 2011 and December 2014. All biopsies were done under real-time US guidance by a trained nephrologist. Routine Doppler mapping and kidney US was done within 24 h post biopsy regardless of symptoms. Comorbidities, full blood count, clotting, bleeding time and blood pressure were recorded at the time of biopsy. Post biopsy protocol included vitals and urine void checked visually for haematuria. Logistic regression was used to investigate links between AVF, needle size, correcting for potential confounding variables.

RESULTS

46,5% were kidney transplants and 53,5% were native biopsies. Diagnostic material was obtained in 90,5% (142 grafts and 154 native). Forty-seven AVF's (14.37%) were identified with routine kidney Doppler mapping, 95% asymptomatic (n = 45), 28 in grafts (18.4%) and 17 natives (9.7%) (p-value 0.7). Both groups were comparable in terms of comorbidities, passes, cylinders or biopsy yield (p-value NS). 80% were <1 cm in size and 46.6% closed spontaneously in less than 30 days (range 3-151). Larger AVF's (1-2 cm) took a mean of 52 days to closure (range 13-151). Needle size was not statistically significant factor for AVF (p-value 0.71).

CONCLUSIONS

Contrary to historical data published, AVF's are a common complication post PRB that can be easily missed. Routine US Doppler mapping performed by trained staff is a cost-effective, non-invasive tool to diagnose and follow up AVF's, helping to assess management.

Achieving Procedural Competence during Nephrology Fellowship Training: Current Requirements and Educational Research

Concerns have previously been raised as to whether training programs are ensuring that nephrology fellows achieve competence in the procedural skills required for independent practice. We sought to review the current requirements for procedural training as well as educational research pertaining to achieving competence in the core nephrology procedures of nontunneled (temporary) hemodialysis catheter insertion and percutaneous kidney biopsy. At this time, there is no universal approach to procedural training and assessment during nephrology fellowship. Nonetheless, simulation-based mastery learning programs have been shown to be effective in improving fellows' skills in nontunneled (temporary) hemodialysis catheter insertion and should be provided by all nephrology training programs. For percutaneous kidney biopsy, the development and evaluation of inexpensive simulators are a promising starting point for future study. Current practice with respect to procedural training during nephrology fellowship remains imperfect; however, the ongoing shift toward competency-based evaluation provides opportunities to refocus on improvement.

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.