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Methodology Guidelines
Haematology
Urine Specimens
102
Manual de operaciones de la Cytospin 4
mixtures of Ficoll and Hypaque. The sample is layered
onto the gradient in a centrifuge tube and then the tube is
centrifuged. The red cells will migrate through the gradient,
and will also be haemolyzed. The remaining cells will stay
on top of the gradient, and can be removed for subsequent
processing.
The primary difference between cytological and
haematological preparations is the routine use of air dried
preparations in haematology. In most cases, haematology
will also have available a specific cell count derived from an
electronic volume sensing instrument. This permits a defined
solution and allows precise control of cell number on the
final Cytospin preparation.
Haematological samples are routinely diluted to obtain
samples of the correct cell concentration. The diluent used
is commonly one of the balanced salt solutions. Thermo
recommend that coated slides are used to increase adhesion
of the cells to the slide, and to avoid the deleterious effects of
the high concentration as the diluent evaporates during the
drying of the slide.
Since haematology specimens are to be air dried, they should
not be flooded with any residual liquid after use of the
Cytospin. For haematology, after the chambers are removed
from the Cytospin sealed head, any residual fluid is allowed
to drain back into the sample chamber. The thumb pad
release lever is then pressed to open the slide support and
remove the slide. The disposable cytochamber is properly
discarded following laboratory safety procedures. The slide
is then air dried. As with all air dried preparations, the more
rapidly drying occurs, the better. Drying may be accelerated
by gentle heating of the slides.
Specimens derived from urine are typically high volume
fluids with few cells or particles. These specimens must
be concentrated by conventional centrifugation prior to
cytological examination. If appropriate, a EZ Megafunnel
can be used. Often urine samples contain particles that are
A78310250ES 5.1ª Edición
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