Quality

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

General

The keys to quality are understanding the:

1. Needs of the stakeholders (surgeons, oncologists, patients, other pathologists, the public at large).
2. Processes.
3. Developing measures of quality.
4. Tracking the measures of quality.
5. Understanding the causes of failures/adverse events in the context of the processes.

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" versus "breast cancer".

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 aware 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 problem.
   • Epitope cross-reactions - expected (e.g. CMV & HSV), unexpected/unknown.

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.