RISK MANAGEMENT


or 9, as they may not be detected until someone identifies an inconsistency.


n Applying FMEA in clinical laboratories


Failure mode and effects analysis is particularly valuable for identifying and preventing common laboratory errors, such as: n Sample mislabelling, leading to incorrect patient results.


n Instrument calibration drift, affecting assay accuracy.


n Reagent stability issues, resulting in unreliable results.


n Delays in reporting critical values.


For instance, an FMEA analysis of blood sample processing might identify that improper sample storage increases the likelihood of haemolysis, affecting potassium test results. The laboratory could then implement corrective actions, such as: n Reinforcing sample transport temperature controls.


n Introducing additional staff training on sample handling.


n Implementing pre-analytical checks to detect haemolysis before analysis.


These are all addressed before patient results are affected.


n Continuing the coffee analogy: FMEA in everyday life Continuing the coffee-making analogy from process mapping, FMEA can be applied to proactively identify risks in making coffee before they result in a poor cup.


Failure modes in coffee preparation n Failure mode: coffee is too weak. n Severity: mild inconvenience (S = 2). n Occurrence: common if incorrect coffee-to-water ratio is used (O = 7).


n Detectability: easily noticed by taste before serving (D = 2).


n RPN calculation: 2 × 7 × 2 = 28 (low priority).


n Failure mode: coffee machine leaks, causing electrical hazard.


n Severity: potential safety risk (S = 9). n Occurrence: rare but possible due to wear-and-tear (O = 3).


n Detectability: hard to detect until leakage becomes obvious (D = 8).


n RPN calculation: 9 × 3 × 8 = 216 (high priority, needs urgent intervention).


Fault tree analysis: a root cause investigation tool


n Origins and evolution of FTA in industry


Fault tree analysis (FTA) is a top-down, 30


retrospective risk assessment method used to investigate why failures occur. Unlike FMEA, which is proactive, FTA systematically traces root causes after an adverse event.


Developed in the 1960s by Bell Laboratories for the US Air Force, FTA was designed to evaluate missile system safety. By the 1970s, NASA adopted it to create fail-safe space missions, and the aviation industry used it to analyse aircraft failures and prevent crashes. Fault tree analysis later expanded into manufacturing, including automotive, nuclear, and electronics sectors, to trace defects and reduce systemic failures. By the 1990s, healthcare and laboratory medicine integrated FTA to investigate errors in medical devices, clinical testing, and patient safety protocols, ensuring compliance with regulatory standards.


n Theoretical basis of FTA Fault tree analysis is used retrospectively to investigate why a failure event has occurred. Instead of examining failure modes individually, as in FMEA, FTA starts with a specific adverse event and systematically traces its underlying causes.


n Structure of an FTA diagram An FTA diagram is built in a hierarchical format, with:


1. The top-level failure event – The adverse event that has already occurred (eg incorrect laboratory results reported). 2. Intermediate contributing events – Factors that contributed to the failure (eg calibration error, incorrect reagent handling). 3. Basic failure causes – The root-level sources of failure (eg expired reagents, LIS software malfunction, inadequate staff training).


Logical AND and OR gates are used to illustrate how multiple failures interact. n AND gate – The failure occurs only if all conditions below it occur.


n OR gate – The failure occurs if any one of the conditions below it occurs.


This structure helps pinpoint the root cause(s) of the failure and determine the most effective corrective actions to prevent recurrence.


n Application of FTA in medical laboratories


Fault tree analysis is particularly useful in retrospective failure analysis, making it an essential tool in quality control in particular, but also other aspects of regulatory compliance. Common applications in laboratories include those shown in Table 1.


n Continuing the coffee analogy: FTA in everyday life Continuing our coffee-making analogy, FTA can help us troubleshoot why a cup of coffee turned out poorly. Imagine you make a cup of coffee, take a sip, and it tastes terrible. You need to trace back the cause using an FTA approach. We may find that the water temperature was too low, leading to under-extraction of coffee grounds, or that the milk was expired, creating an unpleasant taste.


Integrating FTA with FMEA for comprehensive risk management FMEA and FTA are complementary tools in laboratory risk management: n FMEA proactively identifies risks before they occur, allowing for preventive controls.


n FTA investigates failures after they happen, ensuring corrective actions address the true cause.


By integrating both approaches, laboratories can: 1. Prevent critical errors before they occur. 2. Investigate failures thoroughly when they do happen.


3. Strengthen quality assurance measures. 4. Reduce diagnostic variability and improve patient safety.


Conclusions Structured risk assessment is fundamental to ensuring high-quality laboratory operations. Process mapping provides the foundation for understanding workflow vulnerabilities, while FMEA and FTA offer structured approaches to risk identification and mitigation.


By applying these tools, laboratories can optimise workflow efficiency, improve clinical decision-making, and enhance patient safety. As risk- based quality management becomes the standard in laboratory medicine, integrating process mapping, FMEA and FTA will be essential for ensuring compliance with ISO 15189 and ISO 22367 while fostering a culture of continuous improvement. In the next article, we will explore how these methodologies integrate with laboratory quality control strategies, further reinforcing their role in safeguarding patient safety.


Dr Stephen MacDonald is Principal Clinical Scientist, The Specialist Haemostasis Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0QQ.


+44 (0)1223 216746. APRIL 2025 WWW.PATHOLOGYINPRACTICE.COM


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