IQC vs EQAS: Key Differences & Relationship in Medical Laboratories | ISO 15189 & NABL Guide
Published 1 Aug 2026
IQC & EQAS Relationship in a Medical Laboratory
Internal Quality Control (IQC) and External Quality Assessment Scheme (EQAS) are different but complementary quality assurance tools. Together, they ensure that laboratory test results are both accurate and reliable, as required by ISO 15189:2022 and NABL guidelines.
IQC vs EQAS Relationship
| IQC (Internal Quality Control) | EQAS (External Quality Assessment) |
|---|---|
| Performed daily or with every analytical run | Performed periodically (monthly, quarterly, etc.) |
| Monitors the day-to-day performance of laboratory instruments and test methods | Compares your laboratory's performance with other laboratories using the same sample |
| Detects random and systematic errors before patient results are released | Verifies the overall accuracy and competence of the laboratory |
| Uses control materials with known target values | Uses unknown samples provided by an external agency |
| Immediate corrective action can be taken | Helps identify long-term performance issues and benchmarking |
How They Work Together
- IQC ensures consistency every day.
- EQAS confirms that your results are accurate compared with other laboratories.
- A laboratory may have good IQC performance but poor EQAS results, indicating issues such as calibration bias, incorrect methodology, or reference interval problems.
- Similarly, good EQAS results do not replace IQC, because errors can still occur between EQAS cycles.
IQC - Internarnal Quality Control
EQAS - External Quality Assessment Scheme
Quality Control (QC)
│
├── Internal Quality Control (IQC)
│ • Performed inside the laboratory
│ • Daily monitoring
│ • Uses control materials
│
└── External Quality Control (EQC/EQA/PT)
• Conducted by an external provider
• Compares your laboratory's results with other laboratories
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