#2697 Predictors of complications in percutaneous kidney biopsy: a single-center experience

Abstract Background and Aims Percutaneous kidney biopsy (PKB) is an invaluable procedure in Nephrology. It is routinely performed guided by real-time ultrasonography (US), and, as an invasive procedure, its benefits must be weighed against its risks, despite being mostly safe. Bleeding is its main complication, usually resulting in hematuria, hematoma and/or pain, according to the affected renal compartment—collector system, perirenal/retroperitoneal or subcapsular space, respectively. Infrequently, arteriovenous fistulas (AVF) can form. In rare cases, major bleeding may occur and warrant percutaneous embolectomy or nephrectomy. Our study aims to evaluate potential risk factors associated with PKB complications. Methods A single center retrospective study was conducted in our Nephrology department, where PKB is performed by nephrologists. Our protocol warrants antiplatelet therapy (APT) and anticoagulation (ACO) suspension prior to PKB. Post PKB, a 24 h-period of strict bed rest is required. In this period, complete blood count is collected at 6 and 24 h, and kidney US is performed at 24 h, with subsequent discharge in the absence of complications. We collected demographic, laboratory, clinical and procedure-related data, including complications and histopathology results (diagnosis and chronicity score, as defined by Sethi et al., 2017) from all patients undergoing native kidney (N-PKB) and renal allograft (G-PKB) from 1 January 2018 to 31 December 2024. Major complications were defined as clinically significant hematoma or hematuria requiring prolongation of hospital stay, blood transfusion and/or radiological or surgical intervention. We used SPSS® software for statistical analysis, performing Chi-squared test for categorical data and Mann-Whitney test for continuous data, and statistical significance was assumed if P < 0.05, with a confidence interval of 95%. Results and Discussion A total of 475 patients were submitted to PKB, of which 60.8% were N-PKB and 39.2% were G-PKB. The mean age of the patients was 52 ± 16 years and 57.9% were male. We observed a 10.1% rate of major complications (n = 48). 4 patients required blood transfusion. 10 developed an AVF, 2 requiring percutaneous embolization. No patient needed surgery or died as a result of the procedure. We observed a statistically significant difference in the number of complications between N-PKB and G-PKB (P = 0.006), with a rate of 13.1% and 5.4%, respectively. The higher rate of complications in N-PKB may be explained by the increased complexity of the procedure when compared to G-PKB. We performed further analysis to look for additional risk factors for complications. Patients submitted to N-PKB had significantly more proteinuria (P = 0.005) and hematuria (P = 0.035), but there were no differences between N-PKB and G-PKB regarding sex, age, serum creatinine [sCr], glomerular filtration rate [GFR], and hypertension or diabetes diagnosis. We further evaluated the subgroup of patients submitted to N-PKB and found a significant negative correlation between complications and sCr (P = 0.019) and GFR (P = 0.023), but not with the number of needle passes (P = 0.300). We found no association with chronicity score in the obtained native kidney tissue samples (P = 0.104). No correlations with previous APT or ACO were found. Conclusion Our results highlight that N-PKB are technically more complex than G-PKB and, therefore, associated with a higher rate of clinically relevant complications. Among these, the degree of kidney impairment also seems to contribute to an increased risk of complications, a finding probably attributable to uremia-associated bleeding diathesis. This suggests that these patients might benefit from dialysis or desmopressin administration prior to PKB. Interestingly, the severity of the pathological chronicity score in N-PKB samples was not associated with increased risk of procedure complications, suggesting that the degree of uremia (which can be due to acute kidney injury) is more relevant, in this regard, than the chronicity of the kidney disease. The absence of association between complications and the use of APT or ACO suggests that the timing for suspension is appropriate.