(e) Too slow manipulation following the withdrawal of the specimen
thus, allowing some of the blood specimen to coagulate.
Failure to mix the blood and diluent properly.
(5) Failure to expel 2 or 3 drops in the pipet tips before charging the
(6) Overfilling the chamber of the hemacytometer, which causes
erroneously high counts.
Wet or dirty cover glasses and hemacytometers.
Uneven distribution of cells in the counting chamber causes erroneous
Inaccuracy or carelessness in marking counts.
(10) Diluent that which is cloudy or contains debris.
(11) Failure to mix anticoagulated blood thoroughly before use.
(1) The available error when four large squares are counted is +20 percent.
Counting eight large squares decreases the error to +15 percent.
(2) The importance of clean, dry diluting pipets cannot be stressed too much
as the greatest source of error in the counting of WBC is the use of wet and/or dirty
(3) The counting chamber must be scrupulously clean and free of debris
that might be mistaken for cells.
(4) The minimum blood sample recommended for performing routine white
blood cell counts is that obtained using one pipet and counting two chambers as
(5) In cases where the WBC count is exceptionally high, as in leukemia, the
dilution should be made in the red blood cell diluting pipet. The blood is drawn to the
"1.0" mark and the diluting fluid is drawn to the "101" mark. The resulting dilution is
(6) In cases of leukopenia, the white pipet should be filled to the "1.0" mark
and diluted to the "11" mark with 2 percent acetic acid. The resulting dilution is 1:10.