The formula is as follows:
Average number of chambers (2) WBCs counted X dilution (20)
WBCs per cu mm =
Cells counted in
in each square
158 WBCs counted
162 WBCs counted
Average of the 2 chamber counts. Total the amount and divide by 2:
320 - = 160 WBCs
60 X 20 =8,000 WBCs
e. Sources of Error.
Improper collection of blood specimens causes variable results.
Wet or dirty pipets.
(3) Poor condition or inaccurate calibration of pipets. Pipets must be in
good condition and calibrated to have maximum error of + or -1percent.
(4) Poor pipetting technique causes high or low counts. Poor pipetting
(a) Undershooting desired line with blood or diluting fluid.
(b) Overshooting desired line with blood or diluting fluid.
Air bubbles in the column on bulb.
(d) Failure to wipe tip free of blood.