QUALITY AND SAFETY OF CT-GUIDED NATIVE KIDNEY BIOPSY – A SINGLE CENTER STUDY

Native kidney biopsy is vital for accurately diagnosing nephropathies and guiding treatment and is traditionally performed under ultrasound (US) guidance. A minimum of 8-10 glomeruli are required for adequate pathological evaluation. Current literature supports the safety of US-guided native kidney biopsies, with post-biopsy rates for blood transfusion and invasive intervention ranging between 0.34-1.60% and 0.30-0.63%, respectively. A CT-guided approach is preferred in cases of complicated anatomy and has gained popularity in interventional radiology, becoming a routine method at our institution. Different from US-guided biopsy, CT-guided approach uses a two-needle system where a larger outer guide needle (coaxial introducer) is placed adjacent to or into the renal capsule, allowing a smaller inner biopsy needle to obtain multiple tissue samples through a single capsular puncture. A recent CT-guided native kidney biopsy study revealed a 9.5% transfusion rate and a 3.2% embolization rate, which is higher than the US-guided method. We aimed to evaluate the quality and safety of CT-guided native kidney biopsy to guide future improvements and optimize patient care.

This study was conducted as a quality improvement project for native kidney biopsies at a university medical center. A total of 150 native kidney biopsies were performed from November 2023 to April 2025, and 6 biopsies were excluded due to missing data or renal mass biopsy cases, resulting in 144 biopsies in this study. All biopsies were done under CT guidance. Complications were documented via manual chart review, including embolization within 4 weeks, surgery within 4 weeks, transfusion within 3 days, and biopsy-related hospitalization within 3 months of biopsy. 

Among 144 CT-guided native kidney biopsies, there were 80 female patients and 64 male patients, with a mean age of 45.9 years, ranging from 18 to 82 years. The biopsy was performed in the inpatient setting for 79 patients; the rest were outpatient procedures. The median number of glomeruli obtained per biopsy was 25, the median number of cores per biopsy was 4, and the median number of glomeruli per core was 6.25. Of 144 cases, 129 (89.6%) had at least 10 glomeruli in the sample. After kidney biopsy, 40 complications occurred among 144 patients, and 15 patients received transfusions for blood loss (10.4%). Embolization was performed in 4 patients (2.8%), of those, 3 (75%) had no history of anticoagulant or antiplatelet agent use, 1 had history of aspirin use. Among 68 patients with acute kidney injury, 3 (4.4%) required embolization whereas 1 (1.3%) out of 75 patients without AKI required the procedure.  Embolization and transfusion rates were higher in the inpatient group. Of the inpatient group, 3.8% required embolization, and 17.7% required transfusion compared to the outpatient group which had a 1.5% embolization and 1.5% transfusion rate.

In our cohort of CT-guided native kidney biopsies, overall tissue samples were considered adequate in approximately 90%. However, the complication rates, such as transfusions and interventions, appeared to be higher in this cohort and a recent CT-guided biopsy study compared with the reported rates for US-guided biopsies. This finding suggests the need for further studies to determine the comparative quality and safety of US-guided versus CT-guided kidney biopsy.