Historical vs. New Mitigations in a FMEA

One of the things that I often encounter when looking at FMEAs is failure to distinguish between what’s already in place and what is new because of the FMEA activity (1).

Consider an example. In a clinical laboratory it is standard practice to check each sample for hemolysis (because hemolyzed samples give misleading results for some analytes such as potassium).

A FMEA table might list a cause for an error, “hemolysis in the sample”, and the mitigation as “check the adequacy of the sample.” There is nothing wrong with this FMEA but one should be aware that nothing new has been added. This check in the process is already in place. Thus, it would be helpful in the FMEA to distinguish between items that are already in place and new items.

If every mitigation in the FMEA is already in place, then there is cause for alarm regarding the FMEA. To continue with the example, one could postulate a new error; that the check for adequacy of the sample fails meaning that the sample is hemolyzed but the check to detect it failed – causing the same error of misleading results. Perhaps, a cause for this error is postulated as “non cognitive error” meaning that for any task, a “slip” may occur. The mitigation suggested is a double check. There is another possibility – that after considering the severity and probability and perhaps other factors – the mitigation column for this error might read – “no mitigation required.”

This FMEA now thus considered new items – not just what is already in place. Note that all new, proposed mitigations will not be implemented as in , “no mitigation required” but they have been considered.

In summary, an important step in conducting a FMEA is the historical listing of mitigations. If the FMEA stops at this stage, it is not useful.


  1. Ten tips to improve risk assessment. Krouwer JS. IVD Technology 2008; 14;16-23. See http://www.devicelink.com/ivdt/archive/08/03/010.html

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