Welcome to the Exeter Clinical Laboratory International website
NHS logo

UNCERTAINTY OF MEASUREMENT

Cellular Pathology


INTRODUCTION

To comply with UKAS Medical Laboratories it is necessary to determine the uncertainty of results where relevant. Full consideration and awareness of all identifiable components that contribute to the uncertainty of a test will allow valid results to be obtained and may also indicate aspects of a test or procedure which need improvement.

Uncertainty of measurement is normally associated with a quantitative result. Although most results in Cellular Pathology are not quantitative, determining the possible errors during the processing of samples provides information on total error and creates the doubt (uncertainty) of the true validity of the result.

Cellular Pathology uses the evidence from the repeatability or reproducibility of a test where possible to meet this standard.

Please note that a negative cytology report does not exclude the presence of disease.

 

SOURCES OF UNCERTAINTY OF MEASUREMENT

There are two types of uncertainty as defined by the International Organization for Standardization.

Type A is the statistical figures for specific assays and includes:

  • Calibration data
  • Internal Quality Control statistics
  • External Quality Assurance data
  • Verification of data from implementation and evaluations

Type B is the non-statistical measures and can be grouped as:

  • Pre-examination
  • Examination
  • Post-examination

 

FACTORS AFFECTING THE UNCERTAINTY OF MEASUREMENT

The following factors can all affect the quality of results in Cellular Pathology:

  • Specimen collection procedures including sample quality
  • Transportation of samples
  • Storage facilities for samples prior to testing
  • Quality of reagents and consumables
  • Performance of equipment
  • Distribution of normal/abnormal cells in an aliquot of sample
  • Technical competence of staff undertaking the testing
  • Reporting protocols
  • Referral of samples to other laboratories for testing

In order to minimize the uncertainty of measurement, all of these factors must be evaluated, monitored and where possible actions taken to minimize them.

 

MONITORING AND MINIMIZING UNCERTAINTY OF MEASUREMENT IN COMPLIANCE WITH ISO 15189

PRE-EXAMINATION
  LAB ACTIVITY TO MONITOR LAB ACTIVITY TO MINIMIZE
PATIENT STATE & PREPARATION Ensure all relevant clinical information is supplied on EPIC and on request forms from external sources Advice available from http://www.exeterlaboratory.com/ and the laboratory  at 01392 402991

 

 

SAMPLE COLLECTION TIME Lab to note any samples not received promptly in lab As Above
SPECIMEN COLLECTION AND HANDLING Lab to log all sample and/or request form errors (Includes labelling, leakage and missing samples)

As Above

 

SAMPLE TRANSPORT Delays due to transport logged Transport policy on Intranet
THIRD PARTY Ensure third party compliant with any registration or accreditation requirements Annual review of referrals to third parties
SAMPLE & BODY STORAGE Fridge temperature monitoring Procedure in place for logging any incidents or equipment downtime

 

EXAMINATION
  LAB ACTIVITY TO MONITOR LAB ACTIVITY TO MINIMIZE
CALIBRATION Timely calibration of appropriate equipment Ensure companies performing calibration comply with UKAS standards
INSTRUMENT PERFORMANCE  Error logging of equipment downtime Preventative Maintenance and Servicing
REAGENTS IQC & EQA monitored. Logged with lot numbers and expiry dates Use of CE or UKCA marked reagents. All new methods verified prior to use
INTERNAL QUALITY CONTROL

All IQC checks documented in SOPs

Stain quality

Slide quality

 

Ensure all staff trained and competent for IQC

Stain and slide checking for early recognition of any issues

EXTERNAL QUALITY ASSURANCE Ensure laboratory enrolled in EQA or ILC schemes and relevant staff take part Monitor EQA and ILC outcomes
STAFF COMPETENCY Incidents and training issues logged and addressed

Training and competency updates for all staff

Ensure staff comply with CPD requirements

Retain training approval with IBMS

 

CONSUMABLES Inspect and document consumables upon arrival to laboratory. Avoid damaged consumables being used.

 

POST – EXAMINATION
  LAB ACTIVITY TO MONITOR

LAB ACTIVITY TO MINIMIZE

 

REPORT

Avoid transcription errors prior to release of results

Ensure correct patient management

 

Reports checked by qualified staff
INTERPRETATION Ensure meaning of report is unambiguous All reports checked by reporting Pathologist or AP
STORAGE, RETENTION AND DISPOSAL OF CLINICAL SAMPLES Ensure compliance with current RCPath and HTA guidance SOP in place for retention and disposal of clinical samples; audit procedures

 

 

Specimen Labelling Procedure
University of Exeter logo
UKAS Medical logo

8123

Royal Devon University Healthcare logo