Calculating the number of high power fields (40x or 50x objective) under a coverslip:
(1) diameter of high power microscopic field in mm
(2) area of microscopic field in square mm = π * ((diameter in mm) / 2)^2)
(3) area of coverslip in square mm = (width in mm) * (length in mm)
(4) number of high power fields per coverslip = (area of coverslip) / (area of microscopic field)
Calculating concentration of urine sediment:
(1) initial volume of urine in mL prior to centrifugation
(2) final volume of urine sediment after decanting of supernatant in mL
(3) concentration of sediment = (original volume in mL) / (final volume in mL)
Calculating number of high power fields per mL urine:
(1) volume of sediment placed under the coverslip in mL.
(2) equivalent volume of original unspun urine in mL = (volume under slip) * (concentration of sediment)
(3) number of high power fields per mL urine = (number of high power fields under coverslip) / (equivalent volume of original urine in mL)
concentration of formed element per mL urine =
= (number of formed elements per high power field) * (number of high power fields per mL urine)
