Proficiency testing in immunohematology in Ontario, Canada, 1975-1977

Area of Science:

• Medical Laboratory Science
• Transfusion Medicine
• Clinical Pathology

Background:

• Laboratory proficiency assessment in immunohematology began in Ontario in April 1975.
• While most tests involve basic ABO and Rh(D) typing, complex cases present challenges.

Purpose of the Study:

• To assess the proficiency of laboratories performing immunohematology tests in Ontario.
• To identify error rates and specific challenges in various immunohematology procedures.
• To evaluate the impact of proficiency testing on laboratory practices and education.

Main Methods:

• Proficiency testing surveys were conducted using various immunohematology test samples.
• Error rates were calculated for ABO typing, Rh(D) grouping, direct antiglobulin tests, alloantibody detection, and complex antigen-antibody interpretations.
• Data collected from multiple surveys since 1975 were analyzed.

Main Results:

• Error rates included: ABO typing (1.3/1,000), Rh(D) grouping (6.6/1,000), false-negative direct antiglobulin tests (36/1,000), and false-positive direct antiglobulin tests (1.4/1,000).
• Significant errors occurred in detecting strong alloantibodies (up to 19.7/1,000) and interpreting ABO discrepancies (up to 189/1,000) with A2B/A2 cells and anti-A1.
• Laboratories also struggled with Rh(D) typing of cells with positive antiglobulin tests.

Conclusions:

• Proficiency testing effectively identifies laboratories with suboptimal performance.
• These assessments influence laboratory practices and reveal knowledge gaps in immunohematology.
• The surveys provide a crucial stimulus for ongoing professional development and education in the field.