Abstract: TH-PO1063
Kidney Biopsy Adequacy as a Quality Metric: Effect of Glomerular Yield on Diagnostic Reliability
Session Information
- Pathology and Lab Medicine
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1700 Pathology and Lab Medicine
Authors
- Thomas, Serena C., University of Illinois Chicago College of Medicine, Chicago, Illinois, United States
- Caza, Tiffany, Arkana Laboratories, Little Rock, Arkansas, United States
- Kallarackel, Rosemary, Advocate Christ Medical Center, Oak Lawn, Illinois, United States
- Lerma, Edgar V., University of Illinois Chicago College of Medicine, Chicago, Illinois, United States
- Thomas, Abraham, Nephrology Associates, Evergreen Park, Illinois, United States
Background
Kidney biopsy is a high-stakes diagnostic procedure in which inadequate tissue sampling can lead to nondiagnostic results, repeat procedures, delayed treatment, and increased costs. Although KDIGO guidelines define biopsy adequacy as ≥ 8 glomeruli on light microscopy, this threshold is not routinely monitored as a quality metric. We evaluated glomerular yield and its relationship to diagnostic adequacy to identify a target for quality improvement.
Methods
As a part of a quality assessment initiative, we retrospectively reviewed 381 consecutive native kidney biopsies processed at a single renal pathology laboratory between January 2021 and June 2023. The number of glomeruli identified on light microscopy was recorded from pathology reports. Biopsies with fewer than eight glomeruli were classified as inadequate per KDIGO guidelines. The primary outcome was diagnostic failure, defined as the inability to establish a definitive pathological diagnosis. Diagnostic yield was then compared across groups stratified by glomerular count.
Results
Nearly one-quarter of biopsies (23.9%, n=91) failed to meet KDIGO adequacy criteria, representing a substantial quality gap. Diagnostic failure occurred in 51.6% of inadequate biopsies, compared with 1.4% of adequate biopsies. A clear dose–response relationship was observed between glomerular yield and diagnostic reliability: nondiagnostic rates were 61.9% for biopsies with fewer than four glomeruli, 26.5% for those with 4–7 glomeruli, and fell below 2% for biopsies with eight or more glomeruli. Diagnostic performance stabilized at higher yields, with little benefit beyond approximately 10–12 glomeruli.
Conclusion
Inadequate glomerular sampling remains common in contemporary kidney biopsy practice and is strongly associated with diagnostic failure. Glomerular yield represents a modifiable, measurable quality metric with direct clinical consequences. Based on these findings, we are implementing a quality improvement intervention consisting of standardized biopsy adequacy targets, real-time communication of glomerular yield from pathology to proceduralists, and periodic operator-level feedback, with the goal of reducing inadequate biopsies and improving diagnostic reliability. Incorporating biopsy adequacy monitoring into routine practice may improve patient outcomes while reducing repeat procedures and downstream costs.