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Updated: Aug 30, 2025
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In Vitro Thrombosis Test for Ventricular Assist Devices
Published on: March 21, 2025
757
An international study on activated partial thromboplastin time prolongation. Part 1: Analytical results
Josep Miquel Bauça1, Éva Ajzner2, Janne Cadamuro3
1Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Spain.
Summary
Methodological diversity in European labs did not significantly impact activated partial thromboplastin time (APTT) mixing test results. However, accurate classification of causes for prolonged APTT requires improved training and standardized protocols.
Area of Science:
- Hematology
- Clinical Chemistry
- Laboratory Medicine
Background:
- Prolonged activated partial thromboplastin time (APTT) necessitates mixing tests to identify causes.
- Methodological variations in performing these tests may influence outcomes.
Purpose of the Study:
- To evaluate the impact of diverse laboratory methodologies on activated partial thromboplastin time (APTT) mixing test results.
- To assess the accuracy of sample categorization based on these tests.
Main Methods:
- European laboratories received lyophilized plasma samples with known heparin contamination or factor VIII deficiency.
- Participants performed APTT measurements and mixing tests, reporting methodology, results, and sample classification.
Main Results:
- High concordance in prolonged APTT results and mixing test outcomes for heparin contamination.
- Heterogeneity observed in mixing tests for factor VIII deficiency, though factor deficiency was correctly identified by most.
- Inconsistent categorization of causes for prolonged APTT, particularly for heparin contamination.
Conclusions:
- Most laboratories achieve valid APTT and mixing test results despite methodological differences.
- Accurate classification of APTT prolongation causes needs improvement.
- Harmonized protocols, training, and periodic evaluations are recommended for better classification.
