Real-Time Kidney Biopsy Adequacy Assessment Using Built-In Smartphone Macrophotography

Background: Assessing bedside biopsy adequacy is essential for a successful kidney biopsy procedure. Recent advancements in smartphone optical technology have enabled high-resolution macro imaging through built-in camera modules. We hypothesized that nephrologists could visually assess specimen adequacy with the assistance of a modern smartphone’s built-in macro camera. Methods: A prospective cohort study was conducted with consecutive adult patients who underwent ultrasound-guided native kidney biopsies performed by two nephrologists between February and May 2025 at a tertiary referral academic hospital in Korea. Macro photography of each biopsy core was manually captured using the built-in macro photography mode of the Galaxy S25 Ultra (Samsung) immediately after each procedure. Adequacy determinations made via smartphone macro imaging were compared to those made by pathology technicians using standard light microscopy (Olympus, BX40). Statistical agreement between the two methods was assessed using Cohen’s kappa coefficient. Results: Among 29 kidney biopsy patients, a total of 111 kidney core samples were obtained. 89 (80.2%) cores were considered adequate by both smartphone macro imaging and standard microscopy, while 19 (17.1%) cores were deemed inadequate by both methods. One sample (0.9%) was classified as adequate by smartphone macro imaging but inadequate under microscopy, and two samples (1.8%) were considered inadequate by smartphone macro imaging but adequate under microscopy. The smartphone macro photography-based assessment demonstrated a positive adequacy agreement rate of 97.8% and a negative adequacy agreement of 95.0%, with an overall agreement rate of 97.3% (Cohen’s kappa: 0.91, 95% CI 0.79–1.00). The mean number of glomeruli included in final pathology results was 28.4±10.9, and all biopsies led to a definite pathologic diagnosis. Conclusion: Bedside assessment of ultrasound-guided kidney biopsy samples using smartphone-based macro photography showed excellent agreement with standard microscopic evaluation. This approach provides a cost-effective, accessible, and time-efficient alternative for assessing biopsy adequacy and holds promise for reducing nondiagnostic results in real-world clinical practice.