Ultrasound-guided renal parenchymal biopsy: a retrospective comparison of coaxial and noncoaxial techniques

Percutaneous renal biopsy is essential for diagnosing kidney disease, yet the optimal technical approach remains debated. This study aimed to compare coaxial and noncoaxial techniques for ultrasound-guided percutaneous renal parenchymal biopsy in terms of complication rates and to evaluate patient-related clinical and laboratory factors associated with complications. This single-center retrospective comparative study included 336 biopsies performed between November 1, 2022, and November 1, 2025. Of 365 consecutive patients screened, 336 met the inclusion criteria and were assigned to noncoaxial ( n = 168) or coaxial ( n = 168) groups according to the technique used. Demographic, clinical, and laboratory data were collected retrospectively. All biopsies were ultrasound-guided and performed by two interventional radiologists. Complications were graded according to Society of Interventional Radiology criteria. Between-group comparisons and univariate analyses were performed. The study was not powered to test equivalence, and between-group comparisons were regarded as descriptive. The mean age was 49.5 ± 16.2 years, and 198 patients (58.9%) were male. Complications occurred in 9 of 336 patients (2.7%). Rates were 3.6% in the noncoaxial group and 1.8% in the coaxial group ( p = 0.50). Major complications occurred in three noncoaxial and two coaxial cases. Five patients underwent selective embolization, and one of them subsequently required nephrectomy. Hemoglobin decline did not differ significantly between groups. Among 13 patients biopsied below institutional eligibility thresholds after multidisciplinary review and analyzed separately, no major complication occurred. In univariate analyses, INR was higher in patients with complications ( p = 0.01), platelet count showed a borderline association ( p = 0.07), and no complication occurred in transplant recipients ( p = 0.03). In this retrospective cohort, no statistically significant difference in clinically recognized complication rates was observed between coaxial and noncoaxial techniques. Given the small number of events, baseline imbalances between groups, and the sequential adoption of the two techniques, these findings should be interpreted with caution and do not establish equivalence.