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

Image-guided renal parenchymal biopsies- how we do it

This paper is a multi-institutional review of image-guided renal parenchymal biopsies. Among the topics covered are indications, preprocedural considerations, biopsy technique, complications, and postprocedural management. Both native kidney and transplant kidney biopsies are considered in this review.

Safety and efficacy of different transplant kidney biopsy techniques: comparison of two different coaxial techniques and needle types

PURPOSE

Percutaneous ultrasound-guided renal biopsy is essential for diagnosing medical renal disorders in transplant kidneys. A variety of techniques have been advocated. The purpose of this study is to evaluate the safety and efficacy of two different coaxial techniques and biopsy devices.

METHODS

This single-center dual-arm, observation study cohort included 1831 consecutive transplant kidney biopsies performed over a 68-month period. Two coaxial techniques were used, distinguished by whether the 17 gauge (G) coaxial needle was advanced into the renal cortex (intracapsular technique; IC) or to the edge of the cortex (extracapsular technique; EC). One of two needle types could be used with either technique: an 18G side-cutting (Bard Max-Core or Mission) or an 18G end-cutting (Biopince Ultra) needle. In all cases, the cortical tangential technique was used to reduce the risk of central artery transgression and unnecessary medullary sampling. Patients were monitored for 30 days post-procedurally and complications were evaluated using the SIR adverse event classification.

RESULTS

Of the 1831 patients included in the study cohort, 13 suffered severe bleeding complications requiring operative intervention. Of these patients, 8 underwent biopsy with side-cutting needle and IC, 2 with side-cutting needle and approach not specified, 2 with end-cutting needle and IC, and 1 with end-cutting needle and EC. There was no statistically significant difference in the risk of bleeding complications between different coaxial techniques and needle types. However, there was a significantly increased chance of inadequate sampling when comparing the side-cutting needle (1.0%) to the end-cutting needle (0.1%).

CONCLUSIONS

Transplant kidney biopsy performed with two different coaxial techniques and needle types did not show differences in bleeding complications. There is an increased risk of inadequate sampling when using side-cutting relative to end-cutting biopsy devices.

Analysis of hemorrhage upon ultrasound-guided percutaneous renal biopsy in China: a retrospective study

PURPOSE

Ultrasound-guided percutaneous renal biopsy (PRB) has been considered as a golden standard for CKD diagnosis and is employed to identify potential therapeutic targets since 1950s. Post-biopsy hemorrhage is the most common complication, while severe bleeding complication might cause nephrectomy or death. Therefore, how to reduce the occurrence of complications while ensuring the success of PRB is always a clinical research topic.

METHODS

This study retrospectively collected and established a renal biopsy database of each patient who underwent ultrasound-guided PRB at a tertiary teaching hospital from September 2017 to December 2020 through the Health Information System. All the data were statistically processed by SPSS software.

RESULTS

A total of 1146 patients underwent PRB for various reasons. The overall rate of post-biopsy hemorrhage was 37.70% (432/1146). Of those bleedings, minor bleeding after PRB was found in 337 (29.41%), middle bleeding 84 (7.33%), major bleeding 11 (0.96%). Besides that, there were 96 patients (8.38%) reported their discomfort symptoms. There was no death. Females were at significantly increased risk of hemorrhagic complication than males (OR = 2.017, CI = 1.531-2.658). While the risk for hemorrhagic complication significantly decreased as BMI and platelet before renal biopsy increased (OR = 0.956, CI = 0.924-0.989; OR = 0.998, CI = 0.996-1.000). As the APTT time prolonged, the risk for hemorrhagic complication significantly increased (OR = 1.072, CI = 1.023-1.123). Those patients whose albumin were higher, also had higher risk for hemorrhagic complication than other patients (OR = 1.020, CI = 1.000-1.041). Specifically, postoperative urination within 4 h increased the risk for hemorrhagic complication (OR = 1.741, CI = 1.176-2.576).

CONCLUSION

Our analysis finds that the incidence of post-biopsy bleeding complication is 37.70%, and its risk is associated with female, lower BMI, lower platelet before renal biopsy, prolonged APTT, higher albumin, and postoperative urination within 4 h. The findings highlighted the importance of perioperative management for renal biopsy, including adequate risk assessment, tailored careful observation after PRB. And medical staff should pay more attention to fluid management after ultrasound-guided PRB.

Utilization of Re-VASC, the Novel Retroperitoneal Neovascularity Scoring System, for Characterization of T1a Small Renal Masses

Purpose: Early characterization of small (T1a, <4 cm) renal masses is imperative for patient care and treatment planning. Renal biopsy is a sensitive and specific procedure that can accurately differentiate small renal masses as malignant or benign. However, it is an invasive procedure with a nonnegligible complication rate and is not performed routinely at most institutions. In this study, we sought to apply the Retroperitoneal Vascularity Assessment and Scoring in Carcinoma (Re-VASC) scoring system to T1a renal masses and analyzed whether it could differentiate these masses as benign or malignant. Methods: We obtained Institutional Review Board approval to retrospectively examine the records of all patients who presented to our single, urban academic referral center for surgical treatment of renal cell carcinoma (RCC). For the malignant group, patients with a diagnosis of T1a RCC from pathologic evaluation were included. Additionally, patients with a histopathological diagnosis of a T1a nonmalignant renal mass (fat poor-angiomyolipoma or oncocytoma) were included in our benign group. Results: This study includes 57 benign and 69 malignant T1a renal tumors. Average size for benign and malignant masses were 2.47 and 2.63, respectively (p = 0.267). Analysis demonstrated no significant difference between both groups in terms of sex, laterality, or size. The average Re-VASC score of benign and malignant masses was 0.175 and malignant masses was 0.784, respectively (p < 0.001). Additionally, the Re-VASC score was independently associated with malignancy with an odds ratio of 2.223 (p = 0.0109). Conclusion: The Re-VASC scoring system exhibits significantly greater values for malignant T1a renal masses when compared to benign masses. As a result, it shows promise as an adjunctive tool to renal biopsy for clinical decision-making. Further assessment of Re-VASC's true efficacy as a diagnostic marker will include prospective evaluation of a larger multicenter population.

Bleeding Risk of Acupuncture for Patients with Hematological Malignancies Accompanying Thrombocytopenia: A Retrospective Chart Review

Introduction: In recent years, it has been reported that acupuncture is useful for alleviating the symptoms of patients with hematological malignancies, but the safety of acupuncture for such patients has not been established. This study evaluated the risk of bleeding from acupuncture in patients with hematological malignancies accompanying thrombocytopenia. Methods: The authors performed a retrospective investigation of the medical records of patients with hematological malignancies who received acupuncture during hospitalization at the hematology department of a single medical center in Japan. The bleeding risk at the acupuncture site was evaluated in the following four groups according to the platelet count measured on the day of acupuncture treatment: (1) <20 × 103/μL, (2) 20-49 × 103/μL, (3) 50-99 × 103/μL, and (4) 100 × 103/μL or more. Occurrence of grade 2 or higher bleeding according to the Common Terminology Criteria for Adverse Events, version 5.0, within 24 h from the acupuncture session or before the next session was defined as an event, and the risk of occurrence of bleeding was examined in each group. Results: Of 2423 acupuncture sessions conducted on 51 patients with hematological malignancies, 815 were included in the analysis. Ninety sessions were performed in the <20 × 103/μL platelet count group, 161 in the 20-49 × 103/μL group, 133 in the 50-99 × 103/μL group, and 431 in the 100 × 103/μL or more group. No bleeding event according to the authors' definition occurred in any of these groups. Conclusions: This study is the largest to date to assess the bleeding risk of acupuncture in patients with hematological malignancies accompanying thrombocytopenia. The authors considered that acupuncture could be safely performed without causing serious bleeding for patients with hematological malignancies accompanying thrombocytopenia.

Risk and Timing of Major Bleeding Complications Requiring Intervention of the Percutaneous Kidney Biopsy With a Short Observation Protocol: A Retrospective Chart Review

Background

We previously published a retrospective study of kidney biopsies performed in a tertiary care hospital in London, Ontario from 2012 to 2017. This study resulted in a change of practice in our institution to shorter postbiopsy monitoring for outpatients as well as the development of a risk calculator to predict serious bleeding complications.

Objective

The primary objective of this study was to determine whether this shorter monitoring time is adequate in the outpatient setting. A secondary objective was to validate the bleeding risk calculator in both inpatients and outpatients.

Design

This was a retrospective chart review.

Setting

This study was performed at a tertiary academic hospital in London, Ontario, Canada.

Participants

This was a retrospective study of 400 adult patients who underwent kidney biopsy between April 30, 2018 and February 25, 2022 at a tertiary academic hospital in London, Canada.

Methods

We retrospectively assessed frequency and timing of major bleeding complications in patients who underwent kidney biopsy. In secondary analyses, we examined the prediction performance of the risk calculator in discrimination and calibration.

Results

Major bleeding occurred in 7 patients (1.8%). Five of these patients required blood transfusions (1.3%) and 2 required embolization (0.5%). In the outpatient setting, any major bleeding events were identified immediately (1 patient) or on the routine 2-hour ultrasounds (1 patient). The risk calculator showed good discrimination (C-statistic, 0.91, 95% confidence interval [CI] = [0.84 to 0.95]) and calibration (slope, 1.10, 95% CI = [0.47 to 1.74]; intercept, 95% CI = -0.02 [-0.79 to 0.75]), but with much uncertainty in the estimates.

Limitations

The occurrence of only a few major bleeding events limits the reliability of our assessment of our risk calculator.

Conclusions

There appears to be little yield in extending observation beyond 2 hours after an outpatient kidney biopsy with the use of immediate and 2-hour postbiopsy ultrasounds. The bleeding risk calculator (http://perioperativerisk.com/kbrc) warrants further validation.

Nontargeted Native Renal Biopsy Adequacy: Preintervention Data From a Province-Wide, Multicentre, and Interdepartmental Audit

Background

Nontargeted renal biopsy is essential to diagnosis, classification, and prognostication of medical renal disease. Inadequate biopsies delay diagnosis, expose the patient to repeated biopsy, and increase costs.

Objective

The purpose of this project is to characterize nontargeted renal biopsy specimen adequacy and identify areas for improvement.

Design

This project was designed as a clinical audit of specimen adequacy rates of nontargeted renal biopsies from 13 hospitals, as well as a questionnaire of radiology and pathology department staff regarding current practices surrounding renal biopsies.

Setting

Retrospective analysis of 2188 adult native renal biopsies was performed from January 1, 2018, to September 9, 2021, across 13 hospitals.

Patients

Adult patients with medical renal disease undergoing a nontargeted renal biopsy were included.

Methods

Retrospective analysis of 2188 adult native renal biopsies was performed from January 1, 2018, to September 9, 2021, across 13 hospitals. Adequacy was divided into 4 categories based on number of glomeruli received: ideally adequate (≥25 glomeruli), minimally adequate (15-24), suboptimal (<15 and diagnosis rendered), and inadequate (<15 and no diagnosis rendered). Two targets were chosen; target 1, to achieve a combined suboptimal and inadequate rate ≤ 10%, and target 2, to attain an ideally adequate rate ≥80%. Radiology department heads in the province were surveyed on biopsy equipment, technique, technologist support, and feasibility of possible interventions to enhance biopsy adequacy. Pathology department staff were surveyed on their education and experience.

Results

Adequacy was as follows: ideally adequate 64.7%, minimally adequate 26.0%, suboptimal 7.9%, and inadequate 1.4%. The province (and 8/13 hospitals) met target 1 for native biopsies (9.3%). Two hospitals achieved target 2 for native biopsies. A key finding was that the 2 hospitals with the lowest target 1 scores did not have a technologist present at biopsy.

Limitations

Survey data was used to assess biopsy technique at each hospital, and specific technique for each biopsy was not recorded. As such, a multivariate statistical analysis of specimen adequacy rates was not feasible. Data on complications was not collected.

Conclusions

Preintervention the province was at target for limiting inadequate and suboptimal native biopsies. There was a substantial shortfall in the ideally adequate rate from the proposed target. Using insight from survey data, interventions with the greatest expected impact were identified and those that are feasible given limited resources will be implemented to improve sample adequacy.

Trial Registration

Not registered.

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

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A newly developed image fusion algorithm between CECT image and CT image: A feasibility study

Cancer cases have been on the rise over the world. Cancer treatment can benefit from an early accurate diagnosis. Percutaneous needle biopsy under the guidance of CT images is the most common method to obtain tumor samples for accurate diagnosis. However, due to the lack of vascular information in the CT images, the biopsy procedure is at great risk, especially for the tumor surrounded by vessels. In this study, a biomechanical model and surface elastic registration-based fusion algorithm were developed to map the vessels from contrast-enhanced CT images of the liver and lung to the corresponded CT image. Radiologists could observe vessels in the CT images during the biopsy procedure so that the risk can be decreased. The developed algorithm was tested through 20 groups of lung data and 16 groups of liver data. The results show that the fusion errors (mean ± standard deviation) were 2.35 ± 0.85, 2.08 ± 0.41, 2.31 ± 0.49, and 2.37 ± 0.62 mm for portal vein, hepatic vein, pulmonary artery, and pulmonary vein, respectively. The accuracy of this method was satisfied in clinical application

Predictors of hematoma as a complication in pediatric kidney biopsies

BACKGROUND

Kidney biopsies are crucial in the diagnosis of kidney diseases but they carry the risk of various complications, most commonly hematoma. Here we tried to identify the predictors of hematomas as a complication of kidney biopsies and we constructed an algorithm to stratify the risk.

METHODS

The present report retrospectively reviewed 118 pediatric percutaneous kidney biopsies of native kidneys in 102 children (59 females) with the median age of 9 years (range: 1-19 years) at Kumamoto University Hospital between August 2008 and October 2019. We defined hematoma size using the hematoma index: the short axis of the hematoma/major axis of the kidney on ultrasonography. The inclusion criteria for a hematoma as a complication of a kidney biopsy were hematoma index ≥0.1 and the presence of concomitant, post-kidney biopsy fever or flank pain.

RESULTS

Eight patients presented with a hematoma as a complication. All had hematoma index ≥0.1 and age ≥6 years. On univariate logistic analysis, these patients had a larger hemoglobin (Hgb) decrease on post-biopsy day 1, which was unrelated to a Hgb decrease 2 h after the biopsy, than the patients with no hematoma. All eight patients with a hematoma presented with a fever or flank pain on post-biopsy days 5 to 7, underscoring the need to observe patients with decreased Hgb carefully for about 1 week after a biopsy.

CONCLUSION

Predictors of hematoma as a complication in children after a kidney biopsy were hematoma index ≥0.1, age >6 years, and Hgb decrease ≥15% on post-biopsy day 1.

Safety and Efficacy of Percutaneous Image-Guided Mediastinal Mass Core-Needle Biopsy

Objective

To retrospectively evaluate the safety and efficacy of percutaneous image-guided mediastinal mass core-needle biopsy.

Patients and Methods

Retrospective review of an institutionally maintained biopsy registry identified 337 computed tomography- or ultrasound-guided percutaneous mediastinal mass core needle biopsies between October 2002 and August 2017 in a single quaternary referral center. Mean patient age was 51 (range, 18 to 93) years. Procedural techniques, anticoagulation/antiplatelet therapy, and tumor anatomical characteristics were reviewed. Classification and gradation of complications was based on the Clavien-Dindo system. Diagnostic yield was defined as the ratio of diagnostic biopsy to all biopsies performed.

Results

Mean tumor size was 59.2 (range, 10 to 180) mm with 89.9% (n=303) of lesions located in the prevascular (anterior) mediastinum. There was a single major complication (0.3%) of a symptomatic pneumothorax requiring intervention. There were seven (2.1%) minor complications, including three bleeding complications. A transpleural approach was the only variable associated with an increased complication rate (P<.01). Forty-one (12.2%) patients had a biopsy performed while taking an antiplatelet/anticoagulant agent within the therapeutic window, with a single case (0.3%) associated with a minor bleeding complication. Of 18 (5.3%) procedures performed without cessation of anticoagulant/antiplatelet therapy, there were no bleeding complications. Of all 337 biopsies, 322 (95.5%) were diagnostic. None of the analyzed variables were significantly associated with a nondiagnostic biopsy.

Conclusion

Image-guided percutaneous core-needle biopsy of mediastinal masses is a safe procedure with high diagnostic yield. Further prospective studies are required to assess the complication profile in higher risk patients.

Bleeding Complications of Percutaneous Kidney Biopsy: Does Gender Matter?

The incidence of bleeding complications after percutaneous kidney biopsies is low.Female sex may be associated with a greater risk for bleeding complications after percutaneous kidney biopsies.This association and the plausible mechanisms require further evaluation in prospective study.

Preservation of Renal Function after Major Bleeding Events due to Ultrasound-Guided Parenchymal Renal Biopsy

The clinical outcomes of major bleeding events following ultrasound-guided native and allograft parenchymal renal biopsy were evaluated. Forty-eight bleeding complications after biopsy (Society of Interventional Radiology adverse event grade ≥ 2) from 2002 to 2018 were identified. The primary outcome assessed was renal function. The clinical outcomes and interventions performed, including blood transfusion, angiography with or without embolization, nephrostomy tube placement, surgery, nephrectomy, hospitalization, intensive care unit admission, dialysis, and survival, were noted. Renal function may be moderately diminished in the short-term periprocedural setting. None of the patients studied died or required nephrectomy or the initiation of dialysis as a result of a major bleeding complication after the renal biopsy.

Kidney biopsy in the elderly: diagnostic adequacy and yield

PURPOSE

The number of kidney biopsies (KB) performed in elderly patients has been increasing. Safety and usefulness of elderly KB have been well established, whereas much less is known about diagnostic adequacy and yield in this patient population.

METHODS

We performed a retrospective study of KBs in 428 patients from April 2015 to December 2017 at an academic institution. We compared KB from 50 patients aged over 64 (elderly) with KB from 378 patients aged between 18 and 64.

RESULTS

Gender ratio, body mass index, systolic and diastolic BP, creatinine values, incidences of AKI at the time of biopsy, INR/aptt values, and platelets were similar between the two groups. eGFR and number of transplant biopsies were lower in the elderly biopsy group. The glomerular yield was similar between the two groups (22 ± 14 vs. 22 ± 13, p = 0.869). The likelihood of obtaining more than ten glomeruli was 87% and 88%, respectively, without a significant difference. Inadequate samples were encountered in 6% of the elderly and 5.6% of the non-elderly KB, again without a significant difference. Samples taken by nephrologist had higher glomerular yield for both groups (25 ± 13 vs. 18 ± 12 overall, 26 ± 14 vs. 18 ± 14 for elderly, p < 0.001 both). Inadequate biopsies were lower in the nephrologist group when all patients were considered (3% vs. 9%, p = 0.025). Results were numerically similar for the elderly patients, but the difference was not statistically significant (2% vs. 8%, p = 0.322). No deaths occurred in both arms. Minor complications were not different for each group (4.5% vs. 4%). There were no major complications in elderly patients. However, the difference did not reach statistical significance.

CONCLUSION

The world is aging, leading to an increased number of KB in older patients. KB in the elderly is a safe, effective, and an indispensable tool for the nephrologist. This study suggests there is no need to fear lower diagnostic adequacy in the decision making of a KB for an elderly patient.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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