Supplementary Material for: Glomeruli count and arterial injury in real-time ultrasound-guided needle kidney biopsy specimens: Adequacy of three approaches for pig kidneys

Introduction. Real-time ultrasound-guided percutaneous kidney biopsy is essential for diagnosis and treatment planning; nonetheless, the optimal puncture approach has yet to be established. In vivo, performing different approaches on the same patient at once is not possible. This study aimed to determine the impact of different approaches on the number of obtained glomeruli and their potential to cause arterial injury using pig kidneys, which are similar to humans. Methods. A total of 120 pig kidneys (60 right-sided kidneys and 60 left-sided kidneys) for research were obtained from a slaughterhouse. The specimens were collected from the lower pole on the sagittal plane of the kidney using three different approaches on the same kidney: Caudocranial approach, caudal to cranial; Craniocaudal approach, cranial to caudal; and Vertical approach, through the surface cortex. Five blinded pediatric nephrologists assessed the number of glomeruli and arterial injuries. Results. Overall, 360 specimens were collected from the kidneys through biopsy using a 16-gauge needle (mean vertical kidney length, 11.2 ± 0.7 cm; mean depth, 3.47 ± 0.23 cm). No significant difference in the incidence of arterial injury was observed between the three approaches (Caudocranial vs. Craniocaudal vs. Vertical approaches: 78% vs. 87% vs. 87%, P = 0.14). In contrast, the Vertical approach retrieved significantly more glomeruli than the Caudocranial and Craniocaudal approaches (Caudocranial approach: 7.5 ± 2.8, Craniocaudal approach: 7.8 ± 2.7, and Vertical approach: 8.9 ± 3.3, P < 0.001). Conclusions. Considering its efficacy and safety profile, the Vertical approach may be preferred, as more glomeruli can be obtained without increasing the incidence of arterial injury. Although the results cannot be directly extrapolated to humans due to the differences between species, they still offer important insights into the characteristics of each approach