lecture 16 manual cell counting

Question 1

advantages of automated vs manual cell counting

Answer 1

high specimen through put, multi test instruments, smaller volumes, direct to LIS, more accurate/precise

Question 2

how electrical impedance is used to count cells and determine size

Answer 2

aperture set to allow certain size to pass. increases resistance as cells pass equals a pulse

Question 3

how light scatter can differentiate WBC

Answer 3

different cell structures refract, diffract or reflect light at diff angles

Question 4

in what situations is manual count performed

Answer 4

count below detection limit of insurgent, on CSF and synovial fluid, remote 3rd world countries

Question 5

magnification and microscope set up for manual WBC and platelet count

Answer 5

10x objective for WBC. 40x objective for platelets

Question 6

standard dilutions and diluent for WBC, platelet, RBC counts

Answer 6

dimension and volume of WBC counting square

Question 7

what to do if 2 counts differ by more than 15 cells

Answer 7

repeat chamber loading and counting procedure

Question 8

6 errors that affect accuracy/precision of manual count

Answer 8

inadequate specimen/dilution mixing, improper dilution, under fill chamber, leaving WBC in lysing diluent too long, humidified chamber drying out, not using hemocytometer slip, improper counting, uneven distribution of cells

Question 9

formula for cell count

Answer 9

(avg cell count/0.4 uL total volume) * 20 DF * 10^6 ul/L vol correction factor