The effect of anticoagulant, storage temperature and dilution on cord blood hematology parameters over time.

The objective of the study was to determine whether selected hematologic parameters measured on umbilical cord blood samples using an automated hematology analyzer (Sysmex XE-2100) were affected by (i) anticoagulant (the specimens were collected in EDTA vs. sodium heparin), (ii) temperature (the specimens were maintained at 4 degrees C vs. room temperature for up to 72 h) and (iii) 1 : 5 dilution vs. undiluted using the manufacturer's diluting solution. Use of heparin, instead of EDTA, had little effect on the hematologic results (n = 8) except for lower platelet and progenitor cell counts. Results were remarkably stable for 72 h at either room temperature or 4 degrees C except for modest red blood cell swelling at 24 h. Specimens of blood diluted at 1 : 5 had an immediate small, but significant change on white cell count (+13.3%), reticulocyte count (-11.2%) and reticulocyte hemoglobin content (-19.6%). Diluted samples did not change further over 4 h at room temperature. With a 1 : 5 dilution, analysis of 40 microl of cord blood stored for 3 days at room temperature may provide useful hematologic information with little phlebotomy loss.