Feasibility and Safety of Percutaneous Kidney Biopsy in Small Kidneys: Breaking the Paradigm

The percutaneous kidney biopsy (PKB) is an essential tool in nephrology; small kidney size has been a relative contraindication to PKB and there is limited data on the safety and utility of performing PKB in this setting. Our aim was to describe the complications of PKB in small kidneys and to assess if kidney biopsy results have an impact on medical decisions and outcomes.

This was a retrospective, descriptive, and observational study. Patients older than 16 years of age with a decreased kidney size (≤8 cm) and undergoing PKB of native kidneys from July 2019 to December 2022 were included.

Twenty-five patients were included, 19 women and 6 men. The mean age was 42.3 ± 18.04. The mean kidney length was 7.56 ± 0.33 and the mean width was 4.2 cm. All patients received only 1 puncture, obtaining an average of 12 glomeruli. The mean blood urea nitrogen and serum creatinine were 36 mg/dL and 1.94 mg/dL, respectively and the mean Hgb (hemoglobin) was 12.87 ± 2.81 g/dL. Minor complications occurred in 5 patients, perirenal hematoma in 3 patients, hematuria in 1 patient, and hematoma plus hematuria in 1 patient. Histological examination showed FSGS, lupus nephritis, other Glomerular disease, crescentic glomerulonephritis, and tubulointerstitial nephritis in 36%, 20%, 16%, 16%, and 12% of the cases, respectively. Biopsy resulted in management modification in 64% of cases. In a bivariate analysis, kidney size was not associated with higher complication rates.

PKB in small kidneys is a feasible and safe procedure when properly planned, providing an adequate sample in all cases, with an insignificant number of minor complications, and that is clinically relevant.