Puncture approaches for ultrasound-guided kidney biopsy specimens: a pediatric model study using piglet kidneys

Background: The optimal puncture approach for real-time ultrasound-guided native kidney needle biopsy in children remains undetermined due to insufficient evidence. This study evaluated various puncture approaches for glomeruli count and arterial injury in the small kidneys of piglets. Methods: A total of 144 kidneys sourced from a slaughterhouse were examined. On each kidney, three puncture approaches were performed on the lower pole using a 16-gauge needle: Caudocranial, Craniocaudal, and Vertical. Blinded pediatric nephrologists assessed core length, glomeruli count, and arterial injury. Results: The kidneys had a mean vertical length of 9.31 ± 0.59 cm. Of 432 punctures, no punctures traversed the kidney. The Vertical approach yielded a significantly shorter core length than other methods (P < 0.001), but the glomeruli count was consistent across approaches (P = 0.41). Over 60% of the biopsies resulted in arterial injury, with the Caudocranial approach showing significantly higher injury rates (P < 0.03). Conclusions: This study focused on puncture techniques in a pediatric model, suggesting that the Craniocaudal and Vertical approaches are advantageous for selective glomerular sampling without increasing the arterial injury risk. Although further research on smaller kidneys is necessary, these findings offer valuable guidance for biopsy approaches to small kidneys, particularly in pediatric patients. Impact: Kidney biopsy is essential for establishing diagnosis and determining treatment strategies; however, there is no consensus on the puncture approach in children who have the additional risk factor of small-sized kidneys. This study compared between biopsy specimens from piglet models of pediatric kidneys to clarify the best puncture approach based on pediatric characteristics. Although the same number of glomeruli were sampled using all approaches, the Caudocranial approach exhibited a significantly higher incidence of arterial injury. In kidney biopsy that considers the characteristics of children with small kidneys, the Craniocaudal or Vertical approaches may improve the safety and quality of biopsy specimens.