It is essential to distinguish between internal Quality Control (QC) and External Quality Assurance (EQA).


  • QC ensures an analytical run produces results that are consistent with results from previous internal runs. The laboratory sets the QC range and confirms the consistency of the laboratory’s results.
  • While remaining an important part of a laboratory’s quality activities, QC does not guarantee the correct result.


  • EQA provides assurance that a laboratory’s results are comparable with other laboratories doing the same test using the same methodology and/or instrument. An external proficiency organisation provides samples, and laboratory results are evaluated and compared to peers.
  • EQA provides independent external evaluation of a laboratory’s performance.
  • EQA is an investment in reducing the risk of reporting incorrect results and minimising potential harm to patients and laboratories.
  • EQA can help meet regulatory compliance; laboratories that participate in EQA may be preferred by their referring clinicians over those that do not.
  • EQA is a check on internal QC as well as the competency of laboratory staff.