=====5.6.3     Interlaboratory comparisons=====
====5.6.3.1    Participation====

The laboratory shall participate in an interlaboratory comparison programme(s) (such as an external quality assessment programme or proficiency testing programme) appropriate to the examination and interpretations of examination results. The laboratory shall monitor the results of the interlaboratory comparison programme(s) and participate in the implementation of corrective actions when predetermined performance criteria are not fulfilled.\
===NOTE===
The laboratory should participate in interlaboratory comparison programmes that substantially fulfil the relevant requirements of ISO/IEC 17043.\\
The laboratory shall establish a documented procedure for interlaboratory comparison participation that includes defined responsibilities and instructions for participation, and any performance criteria that differ from the criteria used in the interlaboratory comparison programme.\\
Interlaboratory comparison programme(s) chosen by the laboratory shall, as far as possible, provide clinically relevant challenges that mimic patient samples and have the effect of checking the entire examination process, including pre-examination procedures, and post-examination procedures, where possible.\\
====5.6.3.2     Alternative approaches====
Whenever an interlaboratory comparison is not available, the laboratory shall develop other approaches and provide objective evidence for determining the acceptability of examination results.\\
Whenever possible, this mechanism shall utilize appropriate  materials.\\
===NOTE===
Examples of such materials may include:
  -certified reference materials
  -samples previously examined;
  -material from cell or tissue repositories;
  -**exchange of samples with other laboratories;**
  -control materials that are tested daily in interlaboratory comparison programmes.
====5.6.3.3     Analysis of interlaboratory comparison samples====
The laboratory shall integrate interlaboratory comparison samples into the routine workflow in a manner that follows, as much as possible, the handling of patient samples.\\
Interlaboratory comparison samples shall be examined by personnel who routinely examine patient samples using the same procedures as those used for patient samples.\\
The laboratory shall not communicate with other participants in the interlaboratory comparison programme about sample data until after the date for submission of the data.\\
The laboratory shall not refer interlaboratory comparison samples for confirmatory examinations before submission of the data, although this would routinely be done with patient samples.\\
====5.6.3.4     Evaluation of laboratory performance====
The performance in interlaboratory comparisons shall be reviewed and discussed with relevant staff.When predetermined performance criteria are not fulfilled (i.e. nonconformities are present), staff shall participate in the implementation and recording of corrective action. The effectiveness of corrective actionshall be monitored. The returned results shall be evaluated for trends that indicate potential nonconformities and preventive action shall be taken.\\