Clinical laboratory personnel are familiar with the scenario whereby a blood specimen is collected but not delivered immediately to the laboratory for processing until later. This would include speciments that are delayed in processing for various reasons. When such a specimen arrives at the laboratory, the staff needs to decide: (1) whether to accept or reject it: (2) if accepted, whether to perform all of the ordered tests or only those deemed appropriate based on the age of the specimen: and (3) what comments, if any, should be appended to the reported results regarding their reliability and/or unreliability. Such decision-making requires laboratory personnel to be familiar with changes known to occur in blood specimens during exposure. Manufacturers of automated analyzers and published literature often cite that blood specimens, kept at either room temperature or 4 degrees C (refrigerated) for up to 24 hours, generally yield reliable results for complete blood cell counts (CBC) and automated differential leukocyte count (differential).
To identify the changes that occur in various parameters of automated complete blood cell count (CBC) and differential leukocyte count (differential) in blood exposed at room temperature.
Laboratory & Pathology, Jose R. Reyes Memorial Medical Center
A total of 50 EDTA (ethyleneiamineteracaetate) anticoagulated blood specimens will be processed through the Sysmex SE-9500 hematology analyzer for CBC and differential count.
The specimens will be analyzed at four intervals - baseline, 30 minutes, 1 hour and 2 hours. Specimen were kept at room temperature throughout the study.
MAIN OUTCOME MEASURES:
The results were tabulated wherein percent change or absolute difference from the initial value for each parameter for each subsequent interval of the study was calculated.
Among the CBC parameters, hematocrit, red blood cell count, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red cell distribution width and mean platelet volume were stable for the duration of the study. White blood cell count (WBC) was decreased significantly compared to the other parameters, as well as the mean corpuscular volume (MCV). The hemoglobin and platelet count each increased. Among the differential parameters, the relative percentages of lymphocytes, monocytes, and eosinophils tended to increase, whereas those of neutrophils and basophils decreased.
Blood specimens exposed at room temperature for up to 2 hours (or more) were found to be acceptable but considerations should be applied on some parameters, particularly the WBC count, MCV, and neutrophil and basophil percentages.