Quality

Quality, in pathology, has got a lot of attention lately because there have been high profile screw-ups that lead to significant harm.

Analysis

Overview

Quality issues are examined a number of different ways, e.g. root cause analysis, failure mode and effects analysis (FMEA).

A common way to break down error analysis is:

Errors in pathology

Pre-analytical errors

Analytical errors

Post-analytical errors

Failure-potential analysis

Adapted from Ullman:

1. Identify potential individual failures.
2. Identify the consequences of those failures.
3. Identify how the individual failures can arise.
4. Identify the corrective action.

General error analysis

• Pathology errors happen any time from when the lab gets the specimen until after the report is issued.

When errors happen:

• Work-up the problem.
  • Where did the error occur?
• Talk to the clinician.
  • If it is a critical diagnosis contact the most-responsible physician immediately... if they are unreachable call the physician on-call for the most-responsible physician... if the patient is out-of-town you may have to coordinate with the local emergency department.
• Talk to the chief of pathology.
• Incident report.
• Reconstruct error.
  • Was it a specimen mix-up?
    • Is there another error?
• Amend the report(s).
• Remedy the source of error.

Pre-analytic errors

• Container mix-up - pre-lab & in-lab.
• Block mix-up.
• Slide mix-up - labels wrong.
• Poor quality slides (fixation, processing, staining).
• Lost specimen - can be potentially anywhere in the process.

Analytic errors

• Interpretation wrong.
  • Factors:
    • Difficult case.
    • Technical factors (quality of slides).
    • Lack of clinical history.

Post-analytic errors

• Wrong case signed-out.
• Filing problem/lost report.
• Interpretation of report problem (poorly written report, misinterpretation).

Error reduction

Various strategies can be employed:

• Training of staff - on error handling.
• Computer order entry.
  • Avoid duplication fatigue.
  • Quick correlation with several identifying features.
    • Full name, sex, date of birth -- these all appear when one opens a case.
• Barcode use.
  • Avoid transcription errors.
• Clinical information entry required.
  • Allow correlation with test.
    • The interpretation may differ if the history says "screening coloscopy" versus "large cecal mass, anemia and weight loss".

Other strategies:

• Statistical process control.

Sources of error

• "Human error".
  • Training.
  • Work flow.
• Process gaps.
  • Process control.
  • Lack of redundancy.

Biopsy size

Very small tissue fragments are associated with a decreased diagnostic yield and an increased diagnostic uncertainty.

Immunohistochemistry

Main article: Immunohistochemistry

Work-up of suspected IHC problems:

• Review controls (internal and external).
  • Isolated to case vs. larger problem?
    • Discuss with lab/make other pathologists of the issue.
• Repeat test - to identify the cause.

IHC process:

1. Ischemia time - warm ischemia, preparation of specimen.
2. Fixation - under, over, defective fixative, not enough fixative.
3. Processing prior to antibody binding, usu. heating (antigen retrieval).
4. Antibody-antigen binding.
5. Reporter molecule binding.
6. Counterstaining.
7. Interpretation.

Notes:

• Problems can arise at any step.

Classification of IHC tests

IHC tests are classified in a paper by Torlakovic et al.:

• Class I:
  • Adjunct to histomorphology.
  • Examples: CD45, S-100.
• Class II:
  • Considered independent of the other information in the pathology report; thus, cannot be derived from other information in the report.
  • Used directly for treatment decisions.
  • Examples: ER, PR, HER2.

The implication of irregularies in the different classes are different. Problems in Class II tests are potentially more severe, as there is no internal control.

See also

• Critical values.
• CAP checklists.