Bioingeniøren (Jun 2018)
The impact of under-filling of blood collection tubes on automated hematological parameters
Abstract
Correct blood sample drawing is a major preanalytical key to obtain accurate results. In clinical practice, blood from under-filled EDTA-tubes is generally accepted for hematological analysis. The aim of this project was to evaluate the impact on automated hematological parameters by under-filling of blood collection tubes containing K2EDTA as anticoagulant. Phlebotomy was conducted on healthy individuals (n=30) and patients (n=15). Samples were collected in 3,0 mL Vacuette® K2EDTA tubes. Four tubes were collected from each individual. One tube was filled optimally (3,0 mL) and three were under-filled with 1,5 mL blood (50 %), 0,750 mL blood (25 %) and 0,375 mL (12,5 %), respectively. Samples were analyzed in primary blood sample tubes on CELL-DYN Sapphire. Parameter concentrations from under-filled tubes were compared statistically to optimally filled tubes by linear mixed effects-models, to detect systematic differences. Confidence intervals for systematic differences were compared to analytical quality specifications based on biological variation. Results indicate that the hematological parameters are impacted differently by the same level of under-filling. The following under-filling of tubes containing K2EDTA can be accepted for automated hematological analysis: Mean corpuscular volume (MCV): 1,5 mL (50 %), hemoglobin and erythrocytes: 0,750 mL (25 %), leukocytes and thrombocytes: 0,375 mL (12,5 %). The results also indicate that the same levels of under-filling may be accepted for samples collected from healthy individuals and patients.
