Kidney biopsy adequacy and complications in children - does technique matter?

Optimization of Pediatric Kidney Biopsy: Impact of Needle Size and Passes

PURPOSE

This study evaluated the impact of needle size and the number of passes on complication rates and glomerular yield in pediatric native kidney biopsies performed under real-time ultrasound (US) guidance, aiming to determine the optimal biopsy approach.

MATERIALS AND METHODS

Pediatric native kidney biopsies performed between March 2019 and February 2022 at a single tertiary-care children's hospital were included. Biopsies were done with a semi-automated 16 G needle until December 2020, then with an 18 G needle, with varying numbers of passes. US examinations were conducted 24 h post-biopsy to assess complications. Patients were categorized into six subgroups using needle size and the number of passes and compared for complication rates, glomerular yield, and diagnostic adequacy.

RESULTS

A total of 145 pediatric patients (59.3% female, 40.7% male) with a mean age of 10.74 (±4.69) years were included. An 18 G needle was used in 76 (52.4%) cases and a 16 G needle in 69 (47.6%) cases. Minor complications occurred in 56 (38.6%) cases, with no major complications. Complication rates were not significantly different between 18 G and 16 G (p=0.088) but increased with the number of passes (p<0.001). Mean glomerular yield was higher with 16 G than 18 G (34.6 vs. 22.6, p<0.001), though not significantly affected by the number passes (p=0.123). The 18 G needle was associated with inadequate sampling (p=0.024). The optimal scenario was a 16 G needle with one or two passes.

CONCLUSION

Real-time US-guided pediatric kidney biopsy is safe. A 16 G needle with one or two passes optimizes glomerular yield without increasing complications. Three or more passes should be avoided.

Current and potential methods to assess kidney structure and morphology in term and preterm neonates

After birth, the kidney structure in neonates adapt to the functional demands of extrauterine life. Nephrogenesis is complete in the third trimester, but glomeruli, tubuli, and vasculature mature with the rapidly increasing renal blood flow and glomerular filtration. In preterm infants, nephrogenesis remains incomplete and maturation is slower and may be aberrant. This structural and functional deficit has life-long consequences: preterm born individuals are at higher risk for chronic kidney disease and arterial hypertension later in life. This review assembles the literature on existing and potential methods to visualize neonatal kidney structure and morphology and explore their potential to longitudinally document the developmental deviation after preterm birth. X-rays with and without contrast, fluoroscopy and computed tomography (CT) involve relevant ionizing radiation exposure and, apart from CT, do not provide sufficient structural details. Ultrasound has evolved into a safe and noninvasive high-resolution imaging method which is excellent for longitudinal observations. Doppler ultrasound modes can characterize and quantify blood flow to and through the kidneys. Microvascular flow imaging has opened new possibilities of visualizing previously unseen vascular structures. Recent advances in magnetic resonance imaging display renal structure and function in unprecedented detail, but are offset by the logistical challenges of the imaging procedure and limited experience with the new techniques in neonates. Kidney biopsies visualize structure histologically, but are too invasive and remain anecdotal in newborns. All the explored methods have predominantly been examined in term newborns and require further research on longitudinal structural observation in the kidneys of preterm infants.

Puncture approaches for ultrasound-guided kidney biopsy specimens: a pediatric model study using piglet kidneys

BACKGROUND

The optimal puncture approach for real-time ultrasound-guided native kidney needle biopsy in children remains undetermined due to insufficient evidence. This study evaluated various puncture approaches for glomeruli count and arterial injury in the small kidneys of piglets.

METHODS

A total of 144 kidneys sourced from a slaughterhouse were examined. On each kidney, three puncture approaches were performed on the lower pole using a 16-gauge needle: Caudocranial, Craniocaudal, and Vertical. Blinded pediatric nephrologists assessed core length, glomeruli count, and arterial injury.

RESULTS

The kidneys had a mean vertical length of 9.31 ± 0.59 cm. Of 432 punctures, no punctures traversed the kidney. The Vertical approach yielded a significantly shorter core length than other methods (P < 0.001), but the glomeruli count was consistent across approaches (P = 0.41). Over 60% of the biopsies resulted in arterial injury, with the Caudocranial approach showing significantly higher injury rates (P < 0.03).

CONCLUSIONS

This study focused on puncture techniques in a pediatric model, suggesting that the Craniocaudal and Vertical approaches are advantageous for selective glomerular sampling without increasing the arterial injury risk. Although further research on smaller kidneys is necessary, these findings offer valuable guidance for biopsy approaches to small kidneys, particularly in pediatric patients.

IMPACT

Kidney biopsy is essential for establishing diagnosis and determining treatment strategies; however, there is no consensus on the puncture approach in children who have the additional risk factor of small-sized kidneys. This study compared between biopsy specimens from piglet models of pediatric kidneys to clarify the best puncture approach based on pediatric characteristics. Although the same number of glomeruli were sampled using all approaches, the Caudocranial approach exhibited a significantly higher incidence of arterial injury. In kidney biopsy that considers the characteristics of children with small kidneys, the Craniocaudal or Vertical approaches may improve the safety and quality of biopsy specimens.

Computed tomography-based delta-radiomics analysis for preoperative prediction of ISUP pathological nuclear grading in clear cell renal cell carcinoma

BACKGROUND

Nuclear grading of clear cell renal cell carcinoma (ccRCC) plays a crucial role in diagnosing and managing the disease.

OBJECTIVE

To develop and validate a CT-based Delta-Radiomics model for preoperative assessment of nuclear grading in renal clear cell carcinoma.

MATERIALS AND METHODS

This retrospective analysis included surgical cases of 146 ccRCC patients from two medical centers from December 2018 to December 2023, with 117 patients from Hospital and 29 from the *Hospital Affiliated to University of **. Radiomic features were extracted from whole-abdomen CT images, and the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm was used for feature selection. The Multi-Layer Perceptron (MLP) approach was employed to construct five predictive models (RAD_NE, RAD_AP, RAD_VP, RAD_Delta1, RAD_Delta2). The models were evaluated using area under the curve (AUC), accuracy, sensitivity, and specificity, while clinical utility was assessed through Decision Curve Analysis (DCA).

RESULTS

A total of 1,834 radiomic features were extracted from the three phases of the CT images for each model. The models demonstrated strong classification performance, with AUC values ranging from 0.837 to 0.911 in the training set and 0.608 to 0.869 in the test set. The Rad_Delta1 and Rad_Delta2 models demonstrated advantages in predicting ccRCC pathological grading.The AUC value of the Rad_Delta1 is 0.911in the training set and 0.771 in the external verifcation set.The AUC value of the Rad_Delta2 is 0.881 in the training set and0.608 in the external verifcation set. DCA curves confirmed the clinical applicability of these models.

CONCLUSION

CT-based delta-radiomics shows potential in predicting the pathological grading of clear cell renal cell carcinoma (ccRCC).

Noninvasive assessment of pediatric glomerular disease: multimodal ultrasound

Background

Traditional 2-dimensional (2D) ultrasound is a noninvasive method in the assessment of glomerular disease. Ultrasound elastography shows promise in evaluating renal fibrosis, which plays a key role in glomerular disease progression. However, research in pediatric cohorts is limited. This study aimed to assess the diagnostic efficacy of multimodal ultrasound in pediatric patients with glomerular disease.

Methods

Pediatric patients undergoing kidney elasticity examination were recruited. Participants were categorized into a control group, nephritic group, and nephrotic group based on clinical presentation and pediatric nephrologist diagnosis. The nephritic group included cases with hematuria, proteinuria, kidney function impairment, and potentially edema or hypertension. The nephrotic group included cases with nephrotic syndrome. All participants underwent multimodal ultrasound of the right kidney to obtain 2D parameters, hemodynamic parameters, and elasticity values. Sound touch quantification (STQ) is a new shear wave elastography (SWE) technology that has been used in clinical applications in recent years. In this study, it was used to obtain kidney elasticity values. The diagnostic efficacy of multimodal ultrasound was evaluated through receiver operating characteristic (ROC) curve analysis. Logistic regression was further utilized to investigate the combined diagnostic efficacy of multiple parameters.

Results

This study included 154 females and 187 males with ages ranging from 4 to 16 years (mean age: 9.78±3.20 years). Cortical STQ and medullary STQ exhibited lower sensitivity but higher specificity. In logistic regression modeling, multimodal ultrasound showed good diagnostic performance. Between the nephritic group and the control group, the ROC curve yielded an area under the curve (AUC) of 0.71 [95% confidence interval (CI): 0.64-0.77]; sensitivity, 58.10%; specificity, 76.26% (P<0.01). Between the nephrotic group and the control group, the ROC curve yielded an AUC of 0.75 (95% CI: 0.69-0.82); sensitivity, 75.26%; specificity, 62.59% (P<0.01).

Conclusions

Ultrasound elastography demonstrates potential in detecting glomerular disease. Multimodal ultrasound can serve as a noninvasive approach for assessing glomerular disease, exhibiting good diagnostic performance.

Percutaneous Ultrasound-Guided Renal Biopsy in Greek Children: 15 Years of Experience at a Single Center

BACKGROUND

Percutaneous ultrasound-guided renal biopsy (PRB) is a key element for diagnosis and management of several renal pathologies. We aimed to lay out the experience of our pediatric nephrology unit performing PRBs. The rationale and findings of these biopsies, safety issues and considerations of the extracted data are going to be analyzed.

METHODS

A retrospective study was conducted from 2008 to 2023 based on the review of the medical records of pediatric patients who underwent PRBs. In total, 216 kidney biopsies in 206 patients were performed: 115 (53.2%) during the 2008-2015 period and 101 (46.8%) during the 2016-2023 period.

RESULTS

The most frequent clinical indication for PRBs was nephritic syndrome followed by nephrotic syndrome, observed in 84 (40.8%) and 72 (34.9%) patients, respectively. The predominant diagnosis was minimal change disease (MCD) (23.3%), followed by focal segmental glomerulosclerosis (FSGS) (15%) equal to lupus nephritis (LN) (15%), and immunoglobulin A nepropathy (10.2%). Minor complications, such as subcapsular hematomas were observed in approximately 15% of patients while no therapeutic intervention was needed.

CONCLUSIONS

This report is the first review of pathohistological data covering a pediatric population over a 15-year period in Greece and one of the largest in southeastern Europe, especially in the Balkan region. The main indication for a PRB was nephritic syndrome; however, MCD was the main histological diagnosis. This study emphasis the fact that PRBs constitute a safe and reliable method of diagnostic approach to kidney diseases in childhood and offers important information on therapeutic approaches as well as the prognosis of these patients.

Controversy between biopsy and risk in children with proteinuria: is there a paradigm war?

BACKGROUND

Proteinuria is a prevalent symptom of pediatric nephrology, while kidney biopsy remains the gold standard for kidney tissue analysis, and it is currently controversial. We report the rare case that the mutation in the AMN gene was considered to cause chronically isolated proteinuria and also suggest that renal biopsy should be chosen with caution in children with chronic isolated non-nephrotic levels of proteinuria and that genetic testing may be feasible for the early precise diagnosis.

CASE PRESENTATION

A 35-month-old boy presented with excessive urine foaming for more than half a month; his proteinuria was considered non-nephrotic range and urine protein electrophoresis was suggestive of mixed proteinuria; other than that, the investigations are non-specific. Given the child's chronic isolated proteinuria and good renal function, we chose to refine the genetic test rather than a renal biopsy; a compound heterozygous variant was found in the AMN gene of this child which was caused by a point mutation in the father, and a partial chromosomal deletion in the mother.

CONCLUSIONS

Cubilin(encoded by CUBN), amnionless(encoded by AMN), and megalin form a multiligand receptor complex; CUBN or AMN gene variants have been implicated as a hereditary cause of megaloblastic anemia, proteinuria, and neurological impairment. In the past few decades, chronic isolated proteinuria caused by CUBN gene variants is benign, non-progressive, and has normal renal function. However, the child is the first reported case of isolated proteinuria of AMN gene mutation, indicating that the earlier diagnostic genetic sequencing in an otherwise well, not nephrotic proteinuria child may be a convenient, cost-effective, and harmless option, challenging the traditional paradigm.

Clinicopathological Pattern of Renal Biopsies in Children with Nephrotic Syndrome

Background: A renal biopsy is essential for the identification and management of renal disorders. Although considered an invasive operation, it is necessary for a definitive diagnosis and treatment of many renal diseases. The primary goal of this study was to assess the clinicopathological aspect of renal diseases undergoing biopsy in children receiving tertiary care.Patients and Methods: Children (≤18 years) hospitalized with nephrotic syndrome were the subjects of this cross-sectional study, and comprehensive assessments confirmed the need for a kidney biopsy. Included were 277 children who met the inclusion and exclusion criteria. Data on patient outcomes, biopsy indications, complications, histopathologic results, and demographic information were documented.Results: Of the 277 patients who underwent renal biopsy, 63.2% were male, and 36.8% were female. Average age of the patients was 15 ± 2.9 years, with age distribution ranging from 3 to 18 years. The most frequent indication for renal biopsy was atypical age of <1 and >10-years-old (91.7%), steroid-resistant (5.1%), asymptomatic hematuria (21.3%), abnormal glomerular filtration rate (16.2%), and proteinuria (14.8%). The most common histopathological findings were focal segmental glomerulosclerosis (FSGS) (36.5%), followed by minimal change disease (MCD) (13.4%), membranoproliferative glomerulonephritis (MPGN) (10.5%), membranous glomerulonephritis (MGN) (7.94%), IgA nephropathy (IGAN) (7.58%), non-proliferative glomerulonephritis (NPGN) (7.58%), diffuse proliferative glomerulonephritis (DPGN) (6.9%), crescentic GN (5.8%), and systemic lupus erythematosus (SLE) (3.97%). The high frequency of positive samples was seen in SLE, followed by DPGN, MPGN, IGAN, and MGN. In contrast, MCD, crescentic GN, and NPGN showed negativity in all differential item functioning (DIF) parameters.Conclusion: Renal biopsy is a safe and effective procedure in the diagnosis and treatment of in children with nephrotic syndrome. FSGS had the highest frequency in examined biopsies.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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