Abstract

BACKGROUND

Preanalytical mistakes in coagulation assays to a great extent affect diagnostic results. K 2EDTA contamination is one of the preanalytical mistakes that significantly interferes with assays of prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and thrombin time (TT).

OBJECTIVE

To assess how different levels of K 2EDTA contamination influence coagulation test results and to evaluate the effectiveness of clot waveform analysis in identifying such contamination in citrated blood samples.

METHODS

Contamination was introduced at varying concentrations (5%, 13%, 17%, 29%, 33%, 43%, and 100%) in citrated whole blood samples from 36 healthy volunteers. Coagulation assays for aPTT, PT, fibrinogen, and TT were performed using the Sysmex CN 6000 analyzer. Clot waveform analysis was used to detect contamination.

RESULTS

The results revealed significant differences from the reference ranges for aPTT at contamination above 17% K 2EDTA and at 29% in PT and fibrinogen. As far as TT is concerned, significant changes were found from a contamination of 33%. Notably, fibrinogen second-derivative graphs showed min2 values above 0.31, with a sensitivity of 80.3%, specificity of 99.3%, and an area under the curve (AUC) of 0.94. These changes indicated a high likelihood of K 2EDTA contamination.

CONCLUSIONS

K 2EDTA contamination above 17% can significantly alter coagulation test results, potentially leading to diagnostic inaccuracies. Clot waveform analysis, particularly fibrinogen second-derivative graphs, can detect contamination, and proper sample collection guidelines are crucial for accuracy.

MeSH

Partial Thromboplastin Time, Thrombin Time, Blood Coagulation Tests, Hematology, Blood, Thrombin, Fibrinogen, Hemostasis, Pre-Analytical Phase