Platelet count assessment from peripheral blood smear (PBS).
OBJECTIVE
To visually count platelets in a peripheral blood smear and compare with an automated machine platelet count.


METHODS
Thirty-five peripheral blood smears were made from blood specimens counted on an automated blood cell machine: twenty-three thrombocytopenic specimens, 1 with high platelet count and 11 with normal counts. Ten and 25 high-power fields were microscopically averaged and then multiplied by 15,000 and 20,000 to arrive at a platelet count in 1,000 per microliter. Comparisons between visual and machine counts were drawn.


RESULTS
There was fair concordance in 27 specimens. In three specimens underestimation was found, overestimation in five. A 15,000 multiplier gave slightly better results than 20,000. Average in 10 high-power fields was as good as 25. Abnormal counts could be assessed as well as normal.


CONCLUSIONS
Average in 10 high-power field on a blood film microscopically and multiplying by 15,000 gives a platelet count reasonably close to automated machine counts in thousands per microliter.
Katmai Oncology Group, 3260 Providence Drive, Suite 352, Anchorage, Alaska 99508, USA.
Dale I
DI
Webb
Lisa
L
Parker
Kendal
K
Webb
D001331:Automation / Q000379:methods; D001791:Blood Platelet Disorders / Q000097:blood / Q000175:diagnosis; D006801:Humans; D010976:Platelet Count / Q000379:methods*; D012016:Reference Values; D012680:Sensitivity and Specificity