Page 691 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 32 ■ Laboratory Manual: Manual Procedures in Hematology 675

HEMATOLOGY PROCEDURES (continued)

Note: When taking rea ings, be sure that the bottom o the 2. Conventional microscope an lens paper

packe cell column is line up correctly to the zero mark. Do 3. ra itional hemocytometer an coverslip or isposable

not inclu e the bu y coat in rea ing the packe erythrocyte hemocytometer*

column. Do not allow the tubes to remain in the centri uge Note: T e improve Neubauer hemocytometer consists o two

or more than 10 minutes because the inter ace between the raise counting chambers. A specif cally weighe coverslip or

plasma an the cells will become slante an an inaccurate the hemocytometer is place over the chambers or cell count-

rea ing will result.
ing. T e f ve mi le squares are use or RBC counting.

Reporting Results Quality Control

Te PCV is pre erentially expresse as a ecimal raction, A normal control specimen shoul be counte .
such as 0.45 L/L, rather than as 45%. In current practice, the

percentage expression is commonly use . Re erence values: Procedure
males, 41.5% to 50.5%; emales, 36.0% to 45.0%. 1. Prepare the ilution (1:200) an f ll the counting chamber

Procedure Notes ollowing the manu acturer’s instructions.

Sources of Error 2. Allow the hemocytometer to sit or at least 3 minutes (it
may be covere with a Petri ish cover). During this time,
Erroneous results can be cause by inclusion o the bu y the erythrocytes will settle in the chamber.

coat in rea ing the packe column, hemolysis o the speci- 3. Place the hemocytometer on the microscope stage an

men, an ina equate mixing. I the centri ugation time is too ocus with the 10× objective (low power) on the large cen-

short or the spee is too low, an increase in trappe plasma tral re cell counting area (Fig. 32.1). T is central area is

(1% to 3%) will occur in normal bloo . Increase amounts rule o into 25 small squares; the 4 corner squares an 1

o trappe plasma can pro uce errors in cases in which an mi le square are use or the erythrocyte count (Fig. 32.3).

erythrocyte abnormality exists, such as sickle cell anemia. 4. Switch to the 43 to 44× objective (high power) an begin

Other sources o error inclu e prolonge tourniquet stasis counting the appropriate cells in the f ve squares esig-

an excess ED A, which cause cells to shrink an pack more nate with Rs. T e number o cells counte in each o the

tightly than they shoul .
f ve small squares shoul not vary by more than 10 cells.

Clinical Applications It is important to note that the istribution o cells shoul

Te PCV is use or etecting anemia, polycythemia, hemo- be roughly equivalent, an no clumps o cells shoul be

ilution, or hemoconcentration. seen. I clumping is seen, another ilution must be ma e.
Count the erythrocytes on the other si e o the hemo-

cytometer. T is total shoul be within 20 to 30 cells o
BIBLIOGRAPHY the other si e. T e total erythrocytes counte on each

si e are a e together an ivi e by 2 to obtain the
Provi e on this book’s companion Web site at http://thepoint. average.
lww.com/ urgeon6e. 5. Soak the hemocytometer in a bleach solution to isin ect.

RED BLOOD CELL TOTAL COUNT

Erythrocyte Count

Principle

A specimen containing orme cellular elements, such as

erythrocytes an leukocytes, is ilute in specif c volumes.

Te isotonic iluting ui will not lyse erythrocytes, which

acilitates enumeration. Manual eterminations o erythro-

cytes may be per orme i an automate cell counter is not

available or in cases o extremely low erythrocyte counts. Counted

Not counted
Specimen

Anticoagulate whole bloo or capillary bloo can be use .

ED A is the pre erre anticoagulant. A hemolyze speci-

men is inappropriate or an accurate erythrocyte count.

Reagents, Supplies, and Equipment

1. Disposable Ery- IC capillary pipette an Ery- IC iluent

vial FIGURE 32.3 RBC counting square.

(continued)