Implementing Westgard QC Rules in a Healthcare LIS: A Practical Guide

How to encode Westgard quality control rules with traceable audit trails in laboratory information systems used in regulated environments.

Why this matters

LIS quality control is not just a technical feature. It is a patient safety requirement and a regulatory requirement.

Rule groups commonly implemented

• 1_2s as warning rule
• 1_3s, 2_2s, R_4s as reject rules
• 4_1s and 10x for trend detection

QC decision flow

Implementation notes

• keep instrument raw values immutable
• evaluate rules per analyte and control level
• capture who approved override, why, and when
• expose QC timeline in auditor-friendly format

SQL query used for audit extraction

SELECT run_id, analyte, rule_code, decision, approved_by, approved_at
FROM qc_decisions
WHERE run_date >= CURRENT_DATE - INTERVAL '30 day'
ORDER BY run_date DESC, analyte;

Final takeaway

A compliant LIS implementation combines deterministic rule evaluation with complete auditability and controlled override workflow.