Prolong Storage of Blood in EDTA Has an Effect on the Morphology and Osmotic Fragility of Erythrocytes

Abstract

Blood for various laboratory analyses are commonly kept in ethylenediamine tetra-acetic acid (EDTA). EDTA can however cause morphological and fragility changes in blood cells particularly erythrocytes (RBCs) if the storage is prolonged. This can affect erythrocytes viability and hence their analytical results. The timing between blood sampling and analysis is therefore very important in achieving reliable results. The objective of this study was to investigate the storage effects of EDTA on erythrocytes morphology and osmotic fragility over a period of 4 days. A total of twenty- four (24) consenting, apparently healthy blood donors who passed the pre-donation screening were recruited for the study. Blood samples were collected into EDTA tubes and analysed for changes in erythrocyte morphology and osmotic fragility in 24 hour interval over the four day period. On Day 1(control), sample analysis were done within four hours after collection, they were then stored refrigerated (4 – 8oC) and re-analysed from Day 2 to Day 4. Morphological changes observed in erythrocytes over time include echinocytosis, spherocytosis, sphero-echinocytosis and increase in rouleaux formation. Mean percentage haemolysis of erythrocytes increased from Day 1 to Day 4 (p>0.05). Again, the osmotic fragility curves of the RBCs exhibited a rightward shift suggestive of decrease in RBC membrane stabilization. Analysis of blood samples for haematological parameters should therefore be carried out as soon as possible, preferably within 4 hours after their collection to ensure clinically reliable results.