Preanalytical Sedimentation Effects on Hematological Tests

Specimens suspected of errors related to low hemoglobin or changes in hemoglobin beyond that of clinically explained variations during hospital stays are frequently redrawn under the auspices that they are contaminated. When lack of an indwelling IV eliminates contamination as a possibility, evaluation of the specimen between the time of collection and testing should occur.

As part of a quality improvement project, we investigated the impact of sedimentation on collected blood specimens not immediately transferred to their respective tubes from a syringe. Each syringe of blood was allowed to stand in a vertical position on the transfer device. After 10 min, each syringe was divided into a bottom half and top half into fresh blood tubes, with half of the samples inverted prior to division. Samples were then analyzed for complete blood count.

These results indicate that implementing an inversion of collected specimens prior to transferring will effectively eliminate variations related to sedimentation of blood.

Results highlight the importance of specimen handling after collection, including appropriate mixing to avoid erroneous results caused by erythrocyte sedimentation. Mixing syringes before transferring blood to collection tubes ensures a uniform sample and accurate result.