ISO 15189:2022 is the standard against which medical laboratories are accredited worldwide, and it is specific about quality control. This page sets out which clauses govern internal QC and external quality assessment, what assessors expect to see, and how CAP accreditation relates to the standard.
The core sits in clause 7.3.7, “ensuring the validity of examination results”, supported by the clauses on measurement uncertainty, point-of-care testing and corrective action. The table summarises them in our own words; the binding text is the standard itself.
| Clause | Topic | What it means in practice |
|---|---|---|
| 7.3.7.1 | General | A planned procedure for monitoring the validity of results, with data recorded so that trends become visible. |
| 7.3.7.2 | Internal quality control | Suitable control material, risk-based frequency, rules that prevent the release of results after a failure, review of affected results. Details |
| 7.3.7.3 | External quality assessment | Participation for every examination, including POCT; alternative comparisons where no programme exists; review of results and corrective action. Details |
| 7.3.7.4 | Comparability | Where one measurand is examined on several analysers, methods or sites, the results have to be shown to agree. |
| 7.3.4 | Measurement uncertainty | Evaluated for quantitative examinations and reviewed regularly; internal QC data are the usual starting point. |
| 8.7 | Nonconformities and corrective action | Failed QC and unacceptable EQA results are handled as nonconformities, with root-cause analysis and a check that the action worked. |
| Annex A | Point-of-care testing | POCT under the laboratory’s quality management, including training of non-laboratory operators. |
Where ISO 15189:2022 speaks about QC and EQA
Boxes with an arrow open the matching page of this guide
Three changes matter most for quality control. The standard is now built around risk to the patient, so QC frequency and the choice of controls have to be justified by risk rather than by habit. The point-of-care requirements that used to stand in ISO 22870 are part of ISO 15189 itself, which brings POCT run under the laboratory’s governance into its quality management system. And the structure follows ISO/IEC 17025:2017, so management-system requirements are leaner and the technical ones carry more weight.
The transition period for accredited laboratories ended in December 2025; since then only the 2022 edition is recognised under the ILAC arrangement. National adoptions carry their own year: DIN EN ISO 15189:2024 in Germany and GOST R ISO 15189-2024 in Russia have the same content.
QC frequency and controls justified by the risk to the patient.
The former ISO 22870 requirements are now part of ISO 15189.
Leaner management requirements, more weight on the technical ones.
That the laboratory takes part for every examination it offers and acts on the results. In an assessment that usually comes down to six points:
CAP accreditation is a laboratory-medicine programme run by the College of American Pathologists. It is built on discipline-specific checklists, inspects the whole pre-analytical, analytical and post-analytical process, and is recognised in the United States under CLIA. Laboratories outside the United States and Canada have to take part in a CAP proficiency testing / EQA programme for at least six months before they can apply. The CAP also offers CAP 15189, open only to laboratories already accredited under the CAP Laboratory Accreditation Program.
| Aspect | CAP laboratory accreditation | ISO 15189 accreditation |
|---|---|---|
| Who accredits | The College of American Pathologists, worldwide | The national accreditation body (for example DAkkS in Germany) |
| Requirements | Checklists per discipline, updated every year | One international standard, applied by each body |
| Depth | Procedure-level, with examples of compliance evidence | Process-level; detail depends on the assessment body |
| Inspectors | Practising laboratory professionals (peers), matched to the disciplines | Assessors and technical experts of the body |
| Entry condition for EQA | Six months of CAP PT before the application | EQA for every examination in the scope |
According to the CAP (2026), more than 8,400 laboratories in 60 countries hold CAP accreditation. Details of the process, the checklists and the inspection are on CAP accreditation; where your laboratory stands today shows the CAP readiness assessment.
No. Accreditation checks that a QC system exists and is followed; it does not design the rules. In the 2025 Great Global QC Survey by Westgard QC, 29 % of the ISO 15189-accredited laboratories were out of control every day, against 44 % of the US CLIA laboratories. At the same time, more than 15 % of the ISO laboratories overrode a failed QC run (CLIA laboratories: about 6 %), and 11 % still did not calculate measurement uncertainty.
Source: Westgard QC, 2025 Great Global QC Survey: ISO and CLIA laboratories. Survey results of self-selected respondents, not market statistics; Central Asia is not reported separately. More in ISO 15189, CAP or CLIA: does accreditation improve QC?
ISO 15189 and CLIA laboratories compared
Share of responding laboratories
Source: Westgard QC, 2025 Great Global QC Survey: ISO and CLIA laboratories. Survey results of self-selected respondents; Central Asia is not reported separately.
The records that show how QC decisions are made. Before an assessment or a CAP self-inspection, check that these exist and agree with each other:
Depending on the country and the type of laboratory, further rules set the framework. In Germany the RiliBÄK guideline of the German Medical Association makes internal QC and regular participation in external quality assessment (Ringversuche) mandatory for medical laboratories. Testing laboratories outside medicine — food, environment, pharmaceutical quality control — are accredited to ISO/IEC 17025:2017, which requires proficiency testing or interlaboratory comparison where available and appropriate. In the United States, CLIA sets acceptance limits for regulated analytes. Which of these apply to a new laboratory is part of the regulatory notes in our investment memorandum.
