In recent years, digital pathology has experienced significant growth. Laboratories have progressively implemented digital workflows based on whole slide imaging (WSI) and image management systems (IMS) to support their diagnostic activities.
However, most organizations still rely on infrastructure-focused metrics, such as scanner utilization, storage consumption, or the number of slides scanned. While these indicators are valuable for technical monitoring, they do not reflect actual clinical use. This article presents five operational KPIs that can help assess adoption and its benefits, workflow efficiency, and the overall maturity of digital pathology organizations.
The Digital Sign-Out Rate measures the proportion of cases that are finalized entirely through a digital workflow, without requiring the use of physical glass slides for routine diagnosis. Digital Sign-Out Rate = Digitally signed-out cases ÷ Total eligible cases × 100
This KPI provides a direct measure of how digital pathology tools are actually used in clinical practice. The number of slides scanned alone is not sufficient to assess the adoption of digital workflows. The Digital Sign-Out Rate indicates whether pathologists are completing their diagnostic work entirely within a digital environment..
A review of 24 studies found that digital pathology delivers diagnostic results comparable to conventional microscopy in 98.3% of cases (1). Diagnostic accuracy is therefore not a major barrier to adoption.
As a result, when the Digital Sign-Out Rate remains low, it is more likely to reflect organizational factors, workflow constraints, or established working habits rather than technical limitations of digital pathology systems.
(1) Williams BJ et al. Diagnostic concordance and discordance in digital pathology: a systematic review and meta-analysis. Journal of Clinical Pathology, 2021 : https://pmc.ncbi.nlm.nih.gov/articles/PMC8223673/
For example, a laboratory may scan 95% of its slides while performing fully digital diagnosis in only 45% of eligible cases. This illustrates that slide digitization alone does not guarantee the adoption of digital workflows in routine clinical practice.
Digital pathology offers significant advantages, including greater flexibility in accessing slides and improved workflow organization compared with conventional microscopy. For this reason, the Digital Sign-Out Rate has become a key indicator for measuring the true level of digital integration within pathology practice.
The Glass Fallback Rate measures the proportion of cases that are initially reviewed digitally but ultimately require consultation of physical glass slides to reach a final diagnosis. It reflects interruptions in the digital workflow during the interpretation phase.
Each return to glass slides introduces additional handling steps and can slow case processing, particularly in high-volume laboratory environments. Although this metric is not always tracked systematically, it can reveal workflow friction points that are not captured by traditional technical indicators.
The Glass Fallback Rate is not consistently reported as a formal KPI in the scientific literature. However, it is closely related to recommendations from the College of American Pathologists (2), which state that digital images should provide access to all the information required to make a diagnosis that would otherwise be available on a physical glass slide.
In practice, fallback to glass slides occurs most frequently in challenging cases or when pathologists are still gaining experience with digital workflows. As users become more familiar with digital pathology and workflows mature, these situations tend to become less common. Avec l’expérience et l’amélioration des workflows, ces situations deviennent moins fréquentes.
(2) Evans AJ et al. Validating Whole Slide Imaging for Diagnostic Purposes in Pathology: Guideline Update from the College of American Pathologists (CAP). Archives of Pathology & Laboratory Medicine, 2021 : https://pmc.ncbi.nlm.nih.gov/articles/PMC7240346/
During the early stages of digital pathology deployment, it is common to observe high slide digitization rates alongside occasional returns to glass slides. This is particularly true for specific case types, such as hematopathology specimens, rare tumors, or complex inflammatory lesions. Over time, digital review typically becomes more consistent and fully integrated into routine practice. At that stage, glass slide fallback is more likely to highlight workflow optimization opportunities than fundamental technological limitations of digital pathology.
The Rescan Rate measures the proportion of slides that must be scanned a second time due to image quality issues: rescanned slides ÷ Total slides scanned × 100
Rescanning increases workload consumes scanner capacity, and can extend turnaround times. As such, it is an important indicator of the robustness of both the digitization process and the upstream pre-analytical workflow. Monitoring the Rescan Rate helps laboratories assess the overall efficiency and reliability of their digital pathology operations.
Guidelines from the College of American Pathologists (3) emphasize that image quality depends on both slide preparation and scanning conditions. Variations at either stage can result in images that are unsuitable for diagnosis and require rescanning.
Common causes include tissue folds, staining artifacts, air bubbles, incomplete tissue capture, or focus-related issues. For this reason, rescanning is an integral part of the quality control process. Tracking the Rescan Rate enables laboratories to analyze the root causes of scanning failures and identify opportunities to improve slide preparation, scanning procedures, and workflow efficiency.
(3) Evans AJ et al. Validating Whole Slide Imaging for Diagnostic Purposes in Pathology: Guideline Update from the College of American Pathologists (CAP). Archives of Pathology & Laboratory Medicine, 2021 : https://pmc.ncbi.nlm.nih.gov/articles/PMC7240346/
A laboratory processing 5,000 slides per day with a Rescan Rate of 5% would perform approximately 250 rescans daily. Even relatively small changes in this metric can therefore have a significant operational impact on staffing, scanner availability, and turnaround times. Regular monitoring of the Rescan Rate helps identify problem areas early and supports continuous improvement of both slide preparation and digitization processes.
Turnaround Time (TAT) refers to the total time elapsed between case accessioning and diagnostic sign-out. In digital pathology, it encompasses the entire diagnostic process, from slide preparation and digitization through to the final pathology report.
TAT has a direct impact on patient management and clinical decision-making. Digital pathology can help reduce turnaround times by enabling remote access to cases and supporting more flexible workflows. However, the actual benefits depend largely on laboratory organization and the level of integration between digital pathology systems and the broader diagnostic workflow.
Comparative studies have consistently demonstrated that digital pathology provides diagnostic performance equivalent to conventional microscopy, confirming that it can effectively replace traditional workflows without compromising diagnostic quality.
Large-scale implementation studies (4) have also shown that early challenges are primarily related to system integration and organizational transition. Once workflows are fully integrated, digital pathology can streamline the diagnostic pathway through instant access to slides, reduced dependence on physical slide handling, and the ability to review cases remotely. These advantages contribute to improved turnaround times across a wide range of specimen types, including both biopsies and surgical pathology cases.
(4) Hanna MG et al. (2019). Whole Slide Imaging equivalency and efficiency study. Modern Pathology : https://doi.org/10.1038/s41379-019-0205-0
In a conventional workflow, glass slides must be physically transported, sorted, and often batched before review, introducing delays between slide preparation and diagnosis. In a digital pathology environment, slides can be automatically routed and made available for review as soon as scanning is completed. This reduces waiting times and improves case circulation throughout the laboratory.
As a result, TAT is a valuable KPI for comparing overall process performance between traditional and digital pathology environments, highlighting efficiency gains achieved through the elimination of physical constraints and the optimization of workflow management.
This KPI measures differences in digital pathology usage among pathologists within the same laboratory. It highlights variations in adoption levels across members of the same team and provides insight into how consistently digital workflows are being used in routine practice.
Even in well-equipped digital pathology environments, the use of digital tools often remains uneven. Some pathologists work primarily in a digital environment, while others continue to rely on glass slides for certain case types. This variability can affect workflow organization, reduce process standardization, and limit the full benefits of digital pathology adoption across the laboratory.
Studies consistently show that digital pathology adoption is driven primarily by human and organizational factors rather than technological limitations. Usage patterns can vary depending on user experience, established work habits, confidence with digital tools, and case complexity.
Implementation studies also emphasize the importance of training and change management programs in supporting the transition to digital workflows and promoting consistent adoption across pathology teams (5).
(5) Niazi et al., Digital pathology and AI : https://pmc.ncbi.nlm.nih.gov/articles/PMC8711251
In this context, structured support from our specialized teams can help secure deployment and accelerate the maturity of digital pathology adoption. Teams can contact us for guidance and assistance throughout this process.
These five KPIs provide a better understanding of the real-world use of digital pathology beyond traditional technical indicators. They offer a more operational view of workflows and user practices. Taken together, they help assess the maturity of digital pathology environments and identify opportunities to improve efficiency.
Monitoring each of these indicators is useful for progressively optimizing workflows and improving productivity. Because the transition to digital pathology is gradual, it is normal to observe differences and variations depending on the context and level of adoption.
Whether your laboratory has already begun its digital transformation or is still considering a digital pathology project, our teams are available to support you, answer your questions, and help structure both training and deployment initiatives.