FBC Flashcards
What are the FBC parameters?
WBCs Hb RBCs Haematocrit Mean Cell Volume Mean Cell Haemoglobin Mean Corpuscular Haemoglobin Concentration p platelets
Additional parameters of an FBC are…
RC distribution width RDW
Immature granulocyte count
Nucleated RBC count
Reticulocyte count
What are the main reasons for doing an FBC?
Diagnosis Monitoring of a disease Defensive medicine Reassurance Well person screening
When doing a manual cell count, the device used is a
haemocytometer slide, used to count RBC, WBC and Platelets
What is the calculation for packed cell volume (%) ?
height of RBC column
—————————————– X 100
total height of blood column
Haemoglobinopathy is
where a capillary use is sealed at one end and filled with blood and centrifuged
What are the benefits of an automated blood count?
- capacity - manual count takes ~10mins
- cost - employing enough people
- time - count required quickly
- precision - manual is less precise compared to a machine
- Accuracy - also improved with automation
There are two principle methods to an automated count these are:
- Aperture impedance
- Optical
both can be used in combination
Aperture impedance is also known as
Coulter principle
Describe the aperture impedance
principle developed in the 1950s, count salmon farming. Have a pot containing electrolytic diluent, electrode dipped in glass tube with an aperture in the tube, another electrode inside the glass tube. current is passed between the electrodes, suction in the tube is applied. As a particle passes through the hole it displaces the electric current.
In aperture impedance principle each cell displaces it’s ____________ of diluent as it passes through the orifice.
own volume
number of impedance pulses =_______________
= number of cells
Magnitude of pulses = _________________
Volume of cells
the size of the aperture in aperture impedance is?
50-100um
What are the disadvantages/problems with aperture impedance?
- Vortex behind aperture
- Detection zone extends either side of aperture
- Sizing influenced by cell orientation
- Shear forces near aperture deform cells
- Cannot count sub populations
