Renal biopsy in high-risk patients with medical diseases of the kidney

Metabolomic profiling of amino acids study reveals a distinct diagnostic model for diabetic kidney disease

Diabetic kidney disease (DKD), a highly prevalent complication of diabetes mellitus, is a major cause of mortality in patients. However, identifying circulatory markers to diagnose DKD requires a thorough understanding of the metabolic mechanisms of DKD. In this study, we performed ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to reveal altered metabolic profiles of amino acids (AAs) in patients with DKD. We found decreased plasma levels of histidine and valine, increased urine levels of proline, decreased urine levels of histidine and valine, and increased saliva levels of arginine in patients with DKD compared with the levels in patients with type 2 diabetes mellitus (T2DM) and in healthy controls. Our analyses of the key metabolites and metabolic enzymes involved in histidine and valine metabolism indicated that the AAs level alterations may be due to enhanced carnosine hydrolysis, decreased degradation of homocarnosine and anserine, enhanced histidine methylation, and systemic enhancement of valine metabolism in patients with DKD. Notably, we generated a distinct diagnostic model with an AUC of 0.957 and an accuracy up to 92.2% on the basis of the AA profiles in plasma, urine and saliva differing in patients with DKD using logistic regression and receiver operating characteristic analyses. In conclusion, our results suggest that altered AA metabolic profiles are associated with the progression of DKD. Our DKD diagnostic model on the basis of AA levels in plasma, urine, and saliva may provide a theoretical basis for innovative strategies to diagnose DKD that may replace cumbersome kidney biopsies.

Nephroangiosclerosis not related to hypertension: A matter to resolve in the era of precision medicine

Nephroangiosclerosis (NAS) associated with hypertension continues to be one of the most causes of end stage renal diseases in Europe, but it is still poorly studied. The prevalence of NAS shows a large variability due to the difference among different countries regarding clinical presentations and the indication to perform renal biopsy. The study aimed to investigate the prevalence in biopsy-proven NAS patients and the association with hypertension and/or glomerulonephritis (GN). We included all patients referred for native kidney biopsy between 2003-2021 at Policlinic Umberto I of Rome. From 837 patients who underwent renal biopsy NAS was diagnosed in 80 (10.5%) patients. Serum creatinine was significantly higher in NAS [2.07 mg/dl (IQR 1.13-5.2) vs 1.1 mg/dl (IQR 0.8-2.1), p < 0.001] compared to patients without NAS. Hypertension was present in 45% of patients with NAS. Proteinuria was significantly higher in patients with mild-moderate NAS compared to patients with severe NAS [2.6 g/die (IQR 1-5) vs 1.5 g/die (IQR 0.86-2.3), p < 0.05]. We did not find any significant differences, including histological features, between NAS patients with hypertension and NAS patients without hypertension (p > 0.05). IgA nephropathy, focal segmental glomerulosclerosis and membranous nephropathy were the most frequent GN associated. In conclusion no specific histological features are reported in NAS with and without hypertension. More information on the phenotype, clinical presentation and markers are needed to improve histological and clinical diagnostics.

Machine learning in predicting T-score in the Oxford classification system of IgA nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is one of the leading causes of end-stage kidney disease (ESKD). Many studies have shown the significance of pathological manifestations in predicting the outcome of patients with IgAN, especially T-score of Oxford classification. Evaluating prognosis may be hampered in patients without renal biopsy.

Methods

A baseline dataset of 690 patients with IgAN and an independent follow-up dataset of 1,168 patients were used as training and testing sets to develop the pathology T-score prediction (T pre) model based on the stacking algorithm, respectively. The 5-year ESKD prediction models using clinical variables (base model), clinical variables and real pathological T-score (base model plus T bio), and clinical variables and T pre (base model plus T pre) were developed separately in 1,168 patients with regular follow-up to evaluate whether T pre could assist in predicting ESKD. In addition, an external validation set consisting of 355 patients was used to evaluate the performance of the 5-year ESKD prediction model using T pre.

Results

The features selected by AUCRF for the T pre model included age, systolic arterial pressure, diastolic arterial pressure, proteinuria, eGFR, serum IgA, and uric acid. The AUC of the T pre was 0.82 (95% CI: 0.80-0.85) in an independent testing set. For the 5-year ESKD prediction model, the AUC of the base model was 0.86 (95% CI: 0.75-0.97). When the T bio was added to the base model, there was an increase in AUC [from 0.86 (95% CI: 0.75-0.97) to 0.92 (95% CI: 0.85-0.98); P = 0.03]. There was no difference in AUC between the base model plus T pre and the base model plus T bio [0.90 (95% CI: 0.82-0.99) vs. 0.92 (95% CI: 0.85-0.98), P = 0.52]. The AUC of the 5-year ESKD prediction model using T pre was 0.93 (95% CI: 0.87-0.99) in the external validation set.

Conclusion

A pathology T-score prediction (T pre) model using routine clinical characteristics was constructed, which could predict the pathological severity and assist clinicians to predict the prognosis of IgAN patients lacking kidney pathology scores.

Renal arteriovenous fistula discovered ~2 years after renal biopsy: A case report

Key Clinical Message

Although percutaneous renal biopsy is considered safe, this invasive procedure has complications such as renal arteriovenous fistula (RAVF). Even if complications such as RAVFs are not observed early after renal biopsy, considering the possibility of delayed renal hemorrhage, follow-up with ultrasound after renal biopsy even in asymptomatic cases could be important.

Abstract

Although percutaneous renal biopsy is considered safe, this invasive procedure can lead to complications such as renal arteriovenous fistula (RAVF). RAVF occurs when some arteries and veins communicate in the absence of capillaries in the renal hilum or renal parenchyma. It was previously thought to be relatively rare; however, with advances in imaging diagnostics, it is sometimes found asymptomatically. In addition, renal biopsy is the most common cause of acquired RAVF. In this case, RAVF was discovered 2 years after renal biopsy. Late-onset RAVF is scarce. This case highlights that even if complications such as RAVFs are not observed early after renal biopsy, considering the possibility of delayed RAVF, follow-up with ultrasound could be important.

N-Butyl Cyanoacrylate Embolization in Management of Iatrogenic Renal Hemorrhages—Single-Center Study Evaluating Safety and Efficacy

Objectives: The aim of the study was to evaluate the efficacy of endovascular N-butyl cyanoacrylate (NBCA)/glue embolization alone in the management of iatrogenic renal injuries and its effect on renal function.

Methods: Thirty-one patients who presented with significant iatrogenic renal injuries over a time period ranging from June 2013 to June 2018 were evaluated. The clinical features, lab parameters, and imaging findings were recorded. The embolizing agent used was exclusively NBCA. The success rate was calculated along with the effect of glue embolization on kidney in the form of postembolization ischemia and change in the serum creatinine levels in immediate pre- and postembolization period. The time between the iatrogenic injury and angioembolization as well as the time from angioembolization to discharge was also calculated. Recurrence was evaluated at 1 and 6 months follow-up.

Results: NBCA embolization showed 100% technical and clinical success in our study and no recurrence was noted at follow-up. Glue was also able to achieve complete embolization in patients with coagulopathy (n = 14, 45.1%). Percentage area deficit of normal renal blush in the postembolization check angiogram varied from 4 to 15.7% with a mean deficit of 7.65%. No significant difference in the serum creatinine was noted in immediate postembolization period.

Conclusions: We conclude that glue is an effective embolizing agent for management of iatrogenic renal injuries even in coagulopathy patients with minimal area of parenchymal loss, no significant effect on renal functions, and no recurrence on 6 months follow-up.

The role of intraoperative kidney mucosal biopsy on screening of squamous cell carcinoma of the kidney in nephrolithiasis patients with stones larger than 20 mm

Introduction:

Renal pelvic squamous cell carcinoma is a very rare tumor, with a prevalence <1% of all urinary tract tumors, about 0.5–8% of all kidney tumors, and the average age is 50–70 years. Although the incidence of renal squamous cell carcinoma is less common than renal cell carcinoma and renal transitional cell carcinoma, due to its more aggressive nature renal squamous cell carcinoma is often found intraoperatively and is already in an advanced stage or metastasis. The relevant medical history of squamous cell carcinoma is pyelonephritis, chronic nephrolithiasis, and a history of kidney stone surgery. Data which was obtained from previous research at Hasan Sadikin Hospital, from January 2014–December 2017, found the incidence of renal squamous cell carcinoma from nephrectomy procedures was 6%.

Methods:

This study was a cross-sectional study with a correlative analytic study, samples were taken consecutively from biopsy of kidney mucosa intraoperatively in hospitalized patients with kidney stones with size larger than 20 mm at the Department of Urology, Hasan Sadikin Hospital Bandung, which performed open kidney surgery or percutaneous nephrolithotomy from January–May 2019.

Results:

The number of samples in this study were from 30 patients, consisting of 16 males and 14 females. Five patients underwent open kidney surgery and 25 patients underwent percutaneous nephrolithotomy surgery, with an average of age of 49.5±11.8 years and 63.3% of patients were aged from 40–60 years. In this study, one patient (3.3%) showed squamous cell carcinoma of the kidney, a 57-year-old male patient with a left staghorn kidney stone who underwent left percutaneous nephrolithotomy surgery.

Conclusion:

There is a benefit for intraoperative kidney mucosal biopsy as a screening for squamous cell carcinoma of the kidney in nephrolithiasis patients with stones larger than 20 mm.

Level of evidence:

3

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

Background and Objectives:

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

Design setting, participants, and measurements:

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

Results:

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

Conclusions:

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

Biomarkers in Solid Organ Transplantation

After more than 6 decades of clinical practice, the transplant community continues to research noninvasive biomarkers of solid organ injury to help improve patient care. In this review, we discuss the clinical usefulness of selective biomarkers and how they are processed at the laboratory. In addition, we organize these biomarkers based on specific aims and introduce innovative markers currently under investigation.

Multiparameter diffusion-weighted imaging for characterizing pathological patterns in lupus nephritis patients: A preliminary study

BACKGROUND

Microstructural changes of lupus nephritis (LN) kidney such as inflammatory cell infiltration or fibrosis could influence water molecular movement or diffusion, which indicates that diffusion-weighted imaging (DWI) may become a valuable tool in evaluation of this disease.

PURPOSE

To explore whether multiparameter diffusion-weighted imaging (mDWI) could contribute to characterize pathological patterns in LN patients.

STUDY TYPE

Retrospective.

POPULATION

Twenty-two patients with LN.

FIELD STRENGTH/SEQUENCE

Multi-b value DWI was performed with a 3.0 T scanner.

ASSESSMENT

Apparent diffusion coefficient (ADC)_m , perfusion-related diffusion coefficient (D_f ), molecular diffusion coefficient (D_s ), perfusion fraction (f), ADC_s , α, ADC_k , and mean kurtosis (MK) were calculated by monoexponential, biexponential, stretched-exponential, and kurtosis models fits, respectively.

STATISTICAL TESTS

Independent sample t-test, Pearson analysis and receiver operating characteristic (ROC).

RESULTS

In the whole group, the activity index (AI) correlated significantly with alpha values in the medulla (rho = -0.54, P = 0.03). The chronicity index (CI) correlated significantly with D_s values in the medulla (rho = -0.61, P = 0.02). No significant association was found between any other diffusion parameter and histologic grade with all P > 0.05. For differentiating proliferative LN (Class III or IV) from Class V, the area under the ROC curve (AUC) of alpha in the medulla was 0.833 (P = 0.023). DATA CONCLUSION: mDWI might be used for the characterization of pathological patterns in LN patients.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:1075-1084.

Comparing laparoscopic and percutaneous renal biopsy for diagnosing native kidney disease: A matched pair analysis

BACKGROUND

Percutaneous renal biopsy is a well-established diagnostic procedure in patients with underlying medical renal disease. Aim of this study is to compare the adequacy of the biopsy material, the diagnostic yield, and the complication rates of the trans-peritoneal laparoscopic approach and the image-guided percutaneous approach to renal biopsy in the diagnosis of native kidney disease.

METHODS

We performed a matched-pair analysis matching 1:3 40 patients who underwent trans-peritoneal laparoscopic renal biopsy to 120 patients who underwent percutaneous renal biopsy in the same years. Patients were retrospectively analyzed. Differences in adequacy of biopsy material (i.e. number of glomeruli, continuous), diagnostic yield (categorical) and postoperative complications across the two groups were assessed using Wilcoxon Rank sum or χ² test.

RESULTS

Laparoscopic biopsy was associated with a higher number of harbored glomeruli (median 50, IQR 20-77) compared to the percutaneous approach (median 10, IQR 7-15), P<0.001. Adequate biopsies containing at least ten glomeruli were obtained in a significantly higher percentage of patients in the laparoscopic group versus the percutaneous group (92.5% vs. 57.1%, P<0.001). The laparoscopic approach was also associated with a significantly higher diagnostic yield than the percutaneous approach (82.5% vs. 63.5%, P=0.027). Patients who underwent laparoscopic biopsy had no perioperative or postoperative complications, resulting in a significantly lower complication rate than percutaneous biopsy (0% vs. 4%, P<0.001), particularly in the need for transfusion for post-procedure bleeding (0% vs. 1.8%, P<0.001).

CONCLUSIONS

In this retrospective matched-pair analysis comparing patients undergoing renal biopsy for medical kidney disease, trans-peritoneal laparoscopic renal biopsy was safer and more effective for the diagnosis of medical renal diseases compared to percutaneous renal biopsy. Prospective trials with a good follow-up are needed to define the best candidate for each approach.

LEVEL OF EVIDENCE

4.

Role of color Doppler ultrasound in the early diagnosis of a major complication after percutaneous renal biopsy: two case reports

Percutaneous renal biopsy (PRB) is an important procedure in the diagnostic and prognostic evaluation of renal disorders. Despite the relative simplicity, it can be a possible cause of iatrogenic renovascular injury. We describe two cases of iatrogenic pseudoaneurysm, a major post-biopsy complication, in two pediatric patients with persistent micro- and macro-hematuria, promptly diagnosed using color Doppler ultrasound, confirmed with renal arteriography and treated with embolization.

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

Background

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

Objective

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

Design

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

Setting

Southern Alberta, Canada.

Patients

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

Measurements

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

Methods

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

Results

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

Limitations

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

Conclusions

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

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.

Urinary vitamin D-binding protein, a novel biomarker for lupus nephritis, predicts the development of proteinuric flare

Lupus nephritis (LN) is a major complication of systemic lupus erythematosus (SLE). Conventional biomarkers for assessing renal disease activity are imperfect in predicting clinical outcomes associated with LN. The aim of this study is to identify urinary protein biomarkers that reliably reflect the disease activity or predict clinical outcomes. A quantitative proteomic analysis was performed to identify protein biomarker candidates that can differentiate between SLE patients with and without LN. Selected biomarker candidates were further verified by enzyme-linked immunosorbent assay using urine samples from a larger cohort of SLE patients ( n = 121) to investigate their predictive values for LN activity measure. Furthermore, the association between urinary levels of a selected panel of potential biomarkers and prognosis of LN was assessed with a four-year follow-up study of renal outcomes. Urinary vitamin D-binding protein (VDBP), transthyretin (TTR), retinol binding protein 4 (RBP4), and prostaglandin D synthase (PTGDS) were significantly elevated in SLE patients with LN, especially in patients with active LN ( n = 21). Among them, VDBP well correlated with severity of proteinuria (rho = 0.661, p < 0.001) and renal SLE Disease Activity Index (renal SLEDAI) (rho = 0.520, p < 0.001). In the four-year follow-up, VDBP was a significant risk factor (hazard ratio 9.627, 95% confidence interval 1.698 to 54.571, p = 0.011) for the development of proteinuric flare in SLE patients without proteinuria ( n = 100) after adjustments for multiple confounders. Urinary VDBP correlated with proteinuria and renal SLEDAI, and predicted the development of proteinuria.

Coagulopathy as a complication of kidney biopsies in paediatric systemic lupus erythematosus patients with antiphospholipid syndrome

Children with systemic lupus erythematosus (SLE) generally undergo a pretreatment kidney biopsy. However, some of these patients, especially those with antiphospholipid syndrome (APS), may experience serious coagulopathic complications. We report herein two cases of paediatric SLE with APS in which, despite normal blood test results, the disparate coagulopathic complications of haemorrhage and embolism developed following a kidney biopsy. Case 1 was, an 8-year-old male in whom, primary APS was initially diagnosed. Fourteen months later SLE was diagnosed. Based on a percutaneous kidney biopsy, International Society of Nephrology and the Renal Pathology Society (ISN/RPS) class III-A lupus nephritis was histologically diagnosed. On post-biopsy Day 9, a giant haematoma in the fascia of the left kidney developed and was accompanied by changes in the vital signs. Case 2, a 13-year-old male, initially received the diagnosis of SLE with APS and underwent two courses of pulse methylprednisolone therapy. His coagulation abnormalities improved, and a percutaneous needle kidney biopsy was performed, leading to the histological diagnosis of ISN/RPS class III-A lupus nephritis. Furthermore, thrombotic microangiopathy was also detected in the renal histopathology. On post biopsy Day 6, the patient experienced right leg pain. A contrast CT and lower extremity ultrasonography detected a massive deep vein thrombosis and partial left pulmonary artery thrombosis. A kidney biopsy in children with SLE and APS can cause lethal coagulopathic complications, and the risks to such patients should be weighed carefully before the procedure is performed.

Percutaneous ultrasound-guided renal biopsy; A comparison of axial vs. sagittal probe location

BACKGROUND

Renal biopsy is an important method for diagnosis of renal parenchymal abnormalities. Here, we compare the effectiveness and complications of percutaneous ultrasound-guided renal biopsy using axial vs. sagittal probe locations.

METHODS

In a cross-sectional survey, in 2012, patients with a nephrologist order were biopsied by a radiology resident. Renal biopsy was done on 15 patients using axial (A group) and the same number of biopsies done with sagittal probe location (S group). The two groups were compared in term of the yields and complications of each method.

RESULTS

In the A group, the ratio of glomeruli gathered to the number of obtained samples was significantly higher than in the S group. Nine patients in the A group (60%) required only two samplings, whereas 66.7% in the S group required more than two attempts. Microscopic hematuria was more common in the A; conversely, gross hematuria was less common in the A group. Meagre hematomas were more frequent in the S group. When compared with hemoglobin level before biopsy, its level 24 hours after biopsy was similar within groups.

CONCLUSION

Our study shows that percutaneous ultrasound-guided renal biopsy using axial probe provides better yield with fewer efforts and fewer serious complications.

Renal pseudoaneurysm formation post allograft biopsy: a case report

Renal pseudoaneurysm (PSA) is a rare complication post kidney transplant biopsy that accounts for less than 1% of allograft dysfunction. Imaging guidelines in the diagnosis of renal PSA have not yet been developed owing to the low occurrence and limited data availability. However, contrast-enhanced CT and magnetic resonance angiography (MRA) are the preferred modalities in detecting PSA owing to the high contrast and spatial resolution. However, magnetic resonance angiography is preferred since non-contrast imaging techniques can see blood flow patterns in renal PSA without the use of contrast media that may alter renal function. We present a rare complication in a 48-year-old male receiving a living related kidney transplant and found to have renal PSA post allograft biopsy. We review the clinical features, imaging and treatment outcome with the developed PSA in the transplanted kidney post allograft biopsy.

Safety and effectiveness of transjugular renal biopsy: A single center study

Although percutaneous renal biopsy remains the preferred method, there are several scenarios where transjugular approach is more suitable. We hereby describe our technique of transjugular renal biopsy (TJRB) and evaluate its safety and efficacy. We retrospectively collected data regarding indication for the transjugular route of biopsy, its complications, clinical and laboratory data, and adequacy of samples from patients' records. TJRB was performed when the patients were at a high risk for bleeding from percutaneous renal biopsy. Tissue samples were assessed by a pathologist for adequacy. All patients were followed up with ultrasonographic scan 3 h after the procedure and on day 3. Nine patients (age 41.5 ± 15.4 years; 8 men) underwent 9 TJRB procedures. The procedure was technically successful in all patients. Six patients (66.67%) had a platelet count of <50,000/mcL, 2 (33.3%) had an elevated International Normalized Ratio of more than 1.4, and 1 had both. 3.2 ± 0.4 cores were obtained, with median (range) number of glomeruli being ten (7-11). Adequate renal tissue sample was obtained in all the patients. Though capsular perforation developed in 5 patients, none had major complication requiring management (endovascular treatment or blood transfusion). TJRB is a safe and effective in patients with contraindications to percutaneous biopsy.

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.

Hemodynamic characteristics and the occurrence of renal biopsy-related arteriovenous fistulas in native kidneys

Purpose

Renal biopsy-related arteriovenous fistula (RB-AVF), although usually asymptomatic, may sometimes result in serious clinical implications. The aim of the study was to prospectively evaluate the incidence of RB-AVF in native kidneys, together with the assessment of hemodynamic characteristics and the impact of the histopathological results of biopsy.

Methods

The study included 138 patients (age 46.2 ± 15.2; 70 F, 68 M), who underwent percutaneous renal biopsy (PRB) of the native kidney. In all patients, 2D and color Doppler ultrasound was performed 24 h after PRB in order to exclude RB-AVF.

Results

Bleeding complications in the form of hematomas were found in 136 patients (98.55 %), and 23 cases of RB-AVF were observed (16.67 %). RB-AVF group had an increased maximal hematoma diameter and reduced number of glomeruli in PRB. The segmental arteries supplying the fistulas are characterized by higher maximum flow velocity (FV) and a lower resistance index (RI) compared to the normal segmental arteries (difference 45.9 ± 20.0 cm/s and 0.252 ± 0.104, respectively). In the ROC analysis, RI ≤ 0.524 allowed to detect RB-AVF with a sensitivity of 91 % and specificity of 100 % (AUC 0.998, p < 0.001). In approximately 39 % of RB-AVF cases, 2D ultrasound detected a hyperechogenic ischemic area between the fistula and the renal capsule.

Conclusions

Arteriovenous fistula is a quite frequent complication of native renal biopsy and can cause ischemia in the renal parenchyma detected by ultrasound. The arteries supplying the fistula are characterized by an increased flow velocity and reduced resistance index.

Kidney, Ureter, and Bladder Biopsy

Percutaneous urologic biopsy is a safe and effective technique and can comprise a significant proportion of the daily workload of the interventional radiologist. This article discusses the indications and rationale for the performance of renal, ureter, and bladder biopsy as well as the approach to performing such biopsies, pitfalls, and potential complications.

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

[Hemorrhagic shock following a renal biopsy: report of a case]

La ponction biopsie rénale (PBR) est un examen indispensable en néphrologie mais à risque de complications graves surtout hémorragique. Nous rapportons l'observation d'un patient âgé de 27 ans ayant bénéficié d'une PBR pour un diagnostic étiologique d'une insuffisance rénale aigue, l’évolution après la biopsie a été marquée par l'installation d'un choc hémorragique d'où la prise en charge en réanimation avec une néphrectomie d'hémostase.

Differential urinary glycoproteome analysis of type 2 diabetic nephropathy using 2D-LC-MS/MS and iTRAQ quantification

Background

Diabetic nephropathy (DN) is the leading cause of chronic kidney failure and end-stage kidney disease. More accurate and non-invasive test for the diagnosis and monitoring the progression of DN is urgently needed for the better care of such patients.

Methods

In this study we utilized urinary glycoproteome to discover the differential proteins during the course of type 2 DN. The urinary glycoproteins from normal controls, normalbuminuira, microalbuminura, and macroalbuminuria patients were enriched by concanavalin A (ConA) and analyzed by 2DLC/MS/MS and isobaric tags for relative and absolute quantitation quantification.

Results

A total of 478 proteins were identified and 408 were annotated as N-linked glycoproteins. A total of 72, 107 and 123 differential proteins were identified in normalbuminuria, microalbuminuria and macroalbuminuria, respectively. By bioinformatics analysis, in normalbuminruia state, cell proliferation and cell movement were activated, which might reflect the compensatory phase during the disease development. In micro- and macro-albuminuria, cell death and apoptosis was activated, which might reflect the de-compensatory phase. Pathway analysis showed acute phase proteins, the member of high density lipoprotein and low density lipoprotein proteins were changed, indicating the role of the inflammatory response and lipid metabolism abnormality in the pathogenesis of DN. Six selected differential proteins were validated by Western Blot. Alpha-1-antitrypsin (SERPINA1) and Ceruloplasmin are the two markers with excellent area under curve values (0.929 and 1.000 respectively) to distinguish the microalbuminuria and normalbuminuria. For the first time, we found pro-epidermal growth factor and prolactin-inducible protein were decreased in macroalbuminuria stage, which might reflect the inhibition of cell viability and the activation of cell death in kidney.

Conclusions

Above data indicated that urinary glycoproteome could be useful to distinguish the differences in protein profiles in different stages in DN, which will help better individualized care of patients in DN.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0712-9) contains supplementary material, which is available to authorized users.

Endovascular embolization of pseudoaneurysm of left colic artery developing after renal biopsy

Vascular complications after percutaneous renal biopsy are uncommon and may require interventional management. In most of these cases, the pathology is a renal arterial pseudoaneurysm (PsA) or an arterio-venous fistula. Injury to other vessels like aorta, lumbar arteries or mesenteric arteries is rare with only one case of left colic artery PsA reported in literature. We report a case of a 60-year-old female, who developed left colic artery PsA after renal biopsy, which was successfully embolized through endovascular route using microcoils.

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 non-invasive laboratory panel as a diagnostic and prognostic biomarker for thrombotic microangiopathy: development and application in a Chinese cohort study

Background

Thrombotic microangiopathy (TMA) in the kidney is a histopathologic lesion that occurs in a number of clinical settings and is often associated with poor renal prognosis. The standard test for the diagnosis of TMA is the renal biopsy; noninvasive parameters such as potential biomarkers have not been developed.

Methods

We analyzed routine parameters in a cohort of 220 patients with suspected TMA and developed a diagnostic laboratory panel by logistic regression. The levels of candidate markers were validated using an independent cohort (n = 46), a cohort of systemic lupus erythematosus (SLE) (n = 157) and an expanded cohort (n = 113), as well as 9 patients with repeat biopsies.

Results

Of the 220 patients in the derivation cohort, 51 patients with biopsy-proven TMA presented with a worse renal prognosis than those with no TMA (P = 0.002). Platelet and L-lactate dehydrogenase (LDH) levels showed an acceptable diagnostic value of TMA (AUC = 0.739 and 0.756, respectively). A panel of 4 variables - creatinine, platelets, ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats 13) activity and LDH - can effectively discriminate patients with TMA (AUC = 0.800). In the validation cohort, the platelet and LDH levels and the 4-variable panel signature robustly distinguished patients with TMA. The discrimination effects of these three markers were confirmed in patients with SLE. Moreover, LDH levels and the 4-variable panel signature also showed discrimination values in an expanded set. Among patients undergoing repeat biopsy, increased LDH levels and panel signatures were associated with TMA status when paired evaluations were performed. Importantly, only the 4-variable panel was an independent prognostic marker for renal outcome (hazard ratio = 3.549; P<0.001).

Conclusions

The noninvasive laboratory diagnostic panel is better for the early detection and prognosis of TMA compared with a single parameter, and may provide a promising biomarker for clinical application.

Safety and tissue yield for percutaneous native kidney biopsy according to practitioner and ultrasound technique

Background

Although percutaneous renal biopsy remains an essential tool in the diagnosis and treatment of renal diseases, in recent times the traditional procedure of nephrologists has been performed by non-nephrologists rather than nephrologists at many institutions. The present study assessed the safety and adequacy of tissue yield during percutaneous renal biopsy according to practitioners and techniques based on ultrasound.

Methods

This study included 658 native renal biopsies performed from 2005 to 2010 at a single centre. The biopsies were performed by nephrologists or expert ultrasound radiologists using the ultrasound-marked blind or real-time ultrasound-guided techniques.

Results

A total of 271 ultrasound-marked blind biopsies were performed by nephrologists, 170 real-time ultrasound-guided biopsies were performed by nephrologists, and 217 real-time ultrasound-guided biopsies were performed by radiologists during the study period. No differences in post-biopsy complications such as haematoma, need for transfusion and intervention, gross haematuria, pain, or infection were observed among groups. Glomerular numbers of renal specimens from biopsies performed by nephrologists without reference to any technique were higher than those obtained from real-time ultrasound-guided biopsies performed by expert ultrasound radiologists.

Conclusions

Percutaneous renal biopsy performed by nephrologists was not inferior to that performed by expert ultrasound radiologists as related to specimen yield and post-biopsy complications.

Transvenous Renal Transplant Biopsy via a Transfemoral Approach

Percutaneous renal biopsy (PRB) of kidney transplants might be prevented by an elevated risk of bleeding or limited access to the allograft. In the following, we describe our initial experience with 71 transvenous renal transplant biopsies in 53 consecutive patients with unexplained reduced graft function who were considered unsuitable candidates for PRB (4.2% of all renal transplant biopsies at our institution). Biopsies were performed via the ipsilateral femoral vein with a renal biopsy set designed for transjugular renal biopsy (TJRB) of native kidneys. Positioning of the biopsy system within the transplant vein was achievable in 58 of 71 (81.7%) procedures. The specimen contained a median of 10 glomeruli (range 0-38). Tissue was considered as adequate for diagnosis in 56 of 57 (98.2%) biopsies. With respect to BANFF 50.9% of the specimen were adequate (>10 glomeruli), 47.4% marginally adequate (1-9 glomeruli) and 1.8% inadequate (no glomeruli). After implementation of real-time assessment all specimen contained glomeruli. One of the fifty-eight (1.8%) procedure-related major complications occurred (hydronephrosis requiring nephrostomy due to gross hematuria). Transfemoral renal transplant biopsy (TFRTB) is feasible and appears to be safe compared to PRB. It offers a useful new alternative for histological evaluation of graft dysfunction in selected patients with contraindications to PRB.

Nephrotic syndrome and autosomal dominant polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited disorder characterized by the development and growth of cysts in the kidneys and other organs. In ADPKD patients, nephrotic range proteinuria is unusual and needs to be investigated further to exclude coexisting glomerular disease. Among the anecdotal case reports of ADPKD associated with nephrotic syndrome, focal segmental glomerulosclerosis occurs most frequently.

METHODS

We report the case of a 26-year-old male with ADPKD and concomitant nephrotic syndrome, in which an ultrasound (US)-guided renal biopsy showed a mesangioproliferative glomerulonephritis. We treated the patient with prednisone 1 mg/kg/day, because of the failure of treatment with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker association.

RESULTS

After 6 months of steroid treatment, we observed a stability of his GFR and a reduction of proteinuria.

CONCLUSION

This case report and other cases of the literature underline the importance of a renal biopsy in patients with ADPKD and nephrotic syndrome in order to make an accurate diagnosis and an appropriate treatment/prevention of renal function deterioration.

Complications of the percutaneous kidney biopsy

Percutaneous kidney biopsy is an integral part of a nephrologist's practice. It has helped to define nephrology as a subspecialty. When indicated, it is a necessary procedure to help patients, as it allows for diagnostic, prognostic, and therapeutic information. Although very safe, this procedure can give rise to complications, mainly related to bleeding. Since its development in the 1950s, modifications have been made to the approach and the technique, which have improved the diagnostic yield while keeping it a safe procedure. Alterations to the standard approach may be necessary if risk factors for bleeding are present. In addition, obesity, pregnancy, and solitary kidney biopsy are all special circumstances that change the procedure itself or the risk of the procedure. Today, kidney biopsy is a vital procedure for the nephrologist: clinically relevant, safe, and effective.

Detection of glomerular complement C3 fragments by magnetic resonance imaging in murine lupus nephritis

One of the challenges of treating patients with glomerulonephritis is to accurately assess disease activity. As renal biopsies are routinely stained for deposits of C3 activation fragments and glomerular C3 deposits are found in most forms of glomerulonephritis, we sought to determine whether a relatively noninvasive measure of C3 fragment deposition in the kidney can serve as a good biomarker of disease onset and severity. We recently developed a magnetic resonance imaging (MRI)-based method of detecting glomerular C3 and used this to track the progression of renal disease in the MRL/lpr mouse model of lupus nephritis using superparamagnetic iron oxide nanoparticles conjugated to complement receptor type 2 as a targeting agent. Quantitative immunofluorescence showed that glomerular C3b/iC3b/C3d deposition progressively increased with disease activity, a finding replicated by the T2-weighted MRI. The T2 relaxation times decreased with disease activity in the cortex and medulla of the MRL/lpr but not in MRL/Mpj control mice. Thus, MRI contrast agents targeted to glomerular C3 fragments can be used to noninvasively monitor disease activity in glomerulonephritis. As therapeutic complement inhibitors are used in patients with renal disease, this method, should it become feasible in humans, may identify those likely to benefit from complement inhibition.

Biopsy of the transplanted kidney

This article describes the current state-of-the-art technique of percutaneous transplant renal biopsy. A brief overview of the history of transplant renal biopsy is given. The indications and contraindications are discussed, including pre- and postprocedure patient management. The technique of the procedure and the devices that are available in the market are described.

Percutaneous ultrasound-guided renal biopsy: A Libyan experience

This study was done to assess the safety and efficacy of ultrasound-guided percutaneous renal biopsy (PRB), to ascertain the risk factors for complications and determine the optimal period of observation. The radiologist (A.M.) at the National Organ Transplant Centre, Central Hospital, Tripoli, Libya, performed 86 PRBs between February 1, 2006, and January 31, 2008, using an automated biopsy gun with 16-gauge needle. Coagulation profile was done in all the patients. All patients were kept on strict bed rest for six hours post-procedure. Eighty six renal biopsies were performed on 78 patients referred from rheumatology department and eight post-kidney transplant recipients; 23 were males with age range 15 – 56 years and 63 females with age range 16 – 66 years. A mean of 17.5 glomeruli were present in each specimen. A glomerular yield of less than five glomeruli was seen in four biopsies. Class I lupus nephritis (LN) was seen in 1 patient, class II lupus nephritis in 7 patients, class III LN in 13 patients and class IV LN in 29 patients. All the eight renal allografts were diagnosed as acute tubular necrosis or acute interstitial rejection. The risk of post-biopsy bleeding was higher in women, older patients and higher PTT. The overall complication rate was 5.8%. Three complications were observed within six hours of biopsy. No late complication was seen. PRB under real-time ultrasound-guidance is a safe and efficacious procedure to establish the histological diagnosis and should be done as out-patient procedure. Observation time of six hours post-biopsy is optimal.

Predictors of complication after percutaneous ultrasound-guided kidney biopsy in HIV-infected individuals: possible role of hepatitis C and HIV co-infection

BACKGROUND AND OBJECTIVES

HIV-infected patients often undergo kidney biopsy. The risks of percutaneous ultrasound-guided kidney biopsy in this population are not well established.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a case-control, single-center study of 1116 (243 with HIV infection and 873 without) consecutive ultrasound-guided biopsies from 1024 patients. The primary outcome was any major or minor complication. Major complications included biopsy-associated bleeding that required transfusion, angiography, or surgery; hypotension that required intervention; and death. Minor complications included development of a hematoma or gross hematuria. The odds of complication was assessed with logistic regression.

RESULTS

Overall complication rates (8.6 versus 7.2%) did not significantly differ between HIV-infected and noninfected individuals. HIV-positive status did not predict complication. In the entire cohort, hepatitis C infection was associated with a 2.08 (95% confidence interval [CI] 1.47 to 2.93) increased odds of complication, and each 10,000-cells/mm(3) decrease in prebiopsy platelet count a 1.05 (95% CI 1.02 to 1.08) increased odds of complication. In addition, prebiopsy hematocrit <30% and estimated GFR <30 ml/min per 1.73 m(2) were associated with major complication. Whereas the association of prebiopsy platelet count was not modified by HIV infection, hepatitis C/HIV co-infection was associated with a 5.71 (95% CI 1.89 to 17.2) increased odds of complication as compared with 1.27 (95% CI 0.73 to 2.19) in hepatitis C-positive/HIV-negative individuals.

CONCLUSIONS

Ultrasound-guided percutaneous kidney biopsy is a relatively safe, well-tolerated procedure in the HIV-infected population. HIV-infected individuals who are co-infected with hepatitis C seem to be at greatest risk.

The renal biopsy

CONTEXT

The first renal biopsy was carried out more than a century ago, but its widespread introduction into clinical use, beginning in the 1950s, helped develop nephrology into the powerful subspecialty of internal medicine that it is today. In the past 25 years, the use of the spring-loaded biopsy gun, in combination with newer visualization techniques, including ultrasound and computed axial tomography scanning, has led to greater tissue yield and to a much lower risk of complication. During this same time, our understanding of renal pathology has increased many fold. Correct fixation and processing of renal biopsy tissue is critical, and the laboratory must be skilled with renal biopsy light microscopy, immunohistochemistry, and transmission electron microscopy preparation.

OBJECTIVES

To provide an overview of the renal biopsy, including the techniques and its complications, and to summarize proper laboratory methods for processing renal biopsy tissue.

DATA SOURCES

This article is based on a review of the literature and on the experience of the author.

CONCLUSIONS

The experienced nephropathologist, knowledgeable in both renal medicine and pathology and thus able to correlate subtle tissue-derived information with appropriate clinical data, remains the most important key to the development of an accurate clinicopathologic diagnosis.

Focal segmental glomerulosclerosis complicating solitary kidney

A 78-year old woman with complicating solitary kidney had nephrotic syndrome. Renal biopsy specimens showed focal segmental glomerulosclerosis (FSGS). First, the patient was treated with angiotensin receptor blocker (ARB) and angiotensin converting enzyme inhibitor (ACEI). Proteinuria decreased from 10 to 6 g/day, but overall the nephrotic syndrome did not improve. Additional treatment with prednisolone and cyclosporine reduced proteinuria to less than 1.0 g/day. We report that combination therapy with ARB, ACEI, prednisolone, and cyclosporine was successful for FSGS complicating solitary kidney.

Safety and diagnostic yield of transjugular renal biopsy

PURPOSE

To evaluate the safety and tissue acquisition with transjugular renal biopsy (TJRB) by using the Quick-Core method in patients who were at high risk for complications with percutaneous renal biopsy.

MATERIALS AND METHODS

This was a retrospective study, and indication for the transjugular route, complications, clinical and laboratory data, and adequacy of samples were abstracted from patient records. TJRB was performed when the patient had thrombocytopenia or coagulopathy and was at high risk for bleeding from percutaneous renal biopsy. Follow-up images were available in 25 patients; nine underwent abdominal ultrasonography (US) and 17 underwent computed tomography (CT) (one patient underwent both US and CT). The hemoglobin level, prothrombin time, international normalized ratio (INR), partial thromboplastin time, platelet count, and serum creatinine level were obtained before and after biopsy, and these findings were correlated with clinical outcomes.

RESULTS

Thirty-nine patients underwent 39 TJRB procedures and comprise the current study population. The procedure was technically successful in 38 of the 39 patients (97%). Twenty-four of 39 patients (63%) had a platelet count of less than or equal to 75 x 10(9)/L, 11 (29%) had an elevated INR of more than 1.4, and seven received therapeutic anticoagulation. Patients with a platelet count of less than or equal to 75 x 10(9)/L or those with an elevated INR of more than 1.4 after transfusion were not at increased risk of hematoma formation (P = not statistically significant). The mean serum creatinine level at biopsy was 283 mumol/L +/- 150. A mean of 1.8 cores +/- 1.1 were obtained, with 5.0 glomeruli +/- 3.8, 2.1 glomeruli +/- 2.8, and 2.4 glomeruli +/- 3 at light, immunofluorescence, and electron microscopy, respectively. The renal tissue was sufficient for diagnosis in 92% of patients. Major complications occurred in one patient (2.6%). Minor complications-primarily renal hematoma-occurred in 52% of the patients. Contrast medium-induced nephropathy occurred in three patients (7.8%), two of whom also had renal hematomas.

CONCLUSIONS

TJRB is a relatively safe and effective diagnostic tool in high-risk patients with coagulopathy and thrombocytopenia who require renal tissue for accurate diagnosis.

Transjugular renal biopsy: our experience and technical considerations

The purpose of this study was to describe the indications for and technique of transjugular renal biopsy (TJRB) and evaluate the efficacy and complications of this method. We performed a retrospective review of 59 patients who underwent TJRB using the Quick-core needle biopsy system (Cook, Letchworth, UK) over a 4-year period. The indications for obtaining renal biopsy included acute renal failure, chronic renal failure, nephrotic syndrome, and proteinuria with or without other associated disease. Indications for the transjugular approach included coagulopathy, biopsy of a solitary kidney or essentially single functioning kidney, simultaneous renal and hepatic biopsy, morbid obesity, and failed percutaneous biopsy. All but four cases were performed via the right internal jugular vein. The right, left, or both renal veins were cannulated in 41, 14, and 4 cases, respectively. Combined liver and renal biopsies were obtained in seven cases. Diagnostic biopsy specimens were obtained in 56 of 59 patients (95%). The number and size of tissue cores ranged from 1 to 9 mm and from 1 to 20 mm, respectively. The mean numbers of glomeruli per procedure on light microscopy and electron microscopy were 10.3 and 2.6, respectively. Specimens for immunohistology were acquired in 49 cases, of which 40 were adequate. Of the 56 successful TJRB procedures, 34 (61%) were associated with isolated capsular perforation (19), contained subcapsular leak (10), isolated collecting system puncture (1), and concurrent collecting system and capsular perforation (4). There was a significant increase in capsular perforation with six or more needle passes, although no significant correlation was seen between number of needle passes and complication. Six patients had minor complications defined as hematuria or loin pain. Seven patients developed major complications, of whom five received blood transfusion alone. Two required intervention: in one an arteriocalyceal fistula was embolized and the patient was temporarily dialyzed; the remaining patient required ureteric stenting. In conclusion, TJRB provides an adequate yield for diagnosis. Complication rates are relatively high, but patients are also at high risk from the conventional percutaneous approach. Patient selection and optimization are critical to avoid major complications.

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

BACKGROUND

Although renal biopsy is largely employed, even in old patients with systemic diseases, few clinical studies have addressed its risk management. We aimed to obtain a comprehensive assessment of safety/utility ratio of percutaneous renal biopsy.

PATIENTS AND METHODS

Retrospective review of all the 1387 patients who consecutively underwent renal biopsy in a single centre over three decades (1973-2002) was made, with calculation of complications, multivariate logistical analyses to evaluate risk factors of complications, and rate of alteration of clinical hypotheses by pathological diagnosis.

RESULTS

There were no deaths and five major complications, (0.36%). One nephrectomy (0.07%), two surgical revisions (0.1%) and two arterial-venous fistulae (0.1%). There were also 337 minor bleeding complications (24.2%) (16.4% gross haematuria and 7.8% clinically relevant haematomas needing at least prolonged bed rest). Multivariate analyses demonstrated that the risk for complications was significantly increased by systemic autoimmune diseases with odds ratio (OR) 2.06, 95% confidence interval (CI)=1.40-3.01, end-stage kidney/acute-tubular necrosis (OR 2.96, 95% CI=1.19-7.30), and prolonged bleeding time test (BTT) (OR 1.87, 95% CI=1.17-2.83). Among the 1288 cases in which a clinical hypothesis before renal biopsy was recorded, renal pathology changed previous diagnoses in 423/1,288 (32.8%) of cases.

CONCLUSIONS

Risk assessment demonstrates that renal biopsy is a useful procedure with a low incidence of serious complications. Platelet function is the only modifiable factor significantly related to bleeding complications, suggesting the need for a more standardized alternative to the BTT. Platelet function should be evaluated to select low-risk patients for renal biopsy as 'a day case procedure', in order to build adequate risk management strategies.