CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
13. Lock the top of the centrifuge Hct head following the instructions for the instrument
you will be using.
14. Start the centrifuge and operate it for 5 minutes, then turn the machine off. Most
microhematocrit centrifuges have one speed. For those that are adjustable, refer
to the instrument instruction manual to set a proper speed.
15. Wait until the rotor has completely stopped before removing the tube(s). Place
each tube in the slots in the Hct reader and determine the percentage of RBCs in
the whole blood sample.
16. Record the results.
a. List the results by the numbers you assigned each tube.
b. Average the two tubes for each determination. The values of the two should
agree to within ±2% of each other.
c. Repeat the process for any samples that return abnormal results.
17. Discard all supplies used for the procedure in the appropriate containers. A disinfectant
should be used to clean the work surfaces and equipment should be
cleaned and restored to its former position. Gloves should be discarded appropriately
and the hands washed thoroughly in accordance with established policies.
Sources of Error Encountered for the Hematocrit
Improperly mixed specimens that have been allowed to settle in a collection tube will
dramatically affect the results. For specimens collected by capillary puncture, tissue
fluids and perspiration may contribute to the volume of the liquid portion of the blood.
Sometimes an inadequately sealed capillary tube will leak some of the RBCs from the
sealed base of the tube and the results will be drastically affected. Other factors leading
to errors are inadequate volume of specimen; inadequate or improper centrifugation
(e.g., incorrect speed and time); including the buffy coat (WBCs and platelets) in
the reading; and improper use of the reader.
Reporting of Results
Report your findings from the Determining Hematocrit procedure in the Procedure
#3 Report Form or other form supplied by your instructor. Report the average of the
duplicate tests. If the tests are not within ±2% of each other, the sample should be
retested. The averaged results are reported as a percentage of red cells in the sample
of whole blood. If the hemoglobin result is available, normocytic blood will yield a
hemoglobin value that is roughly one-third the value of the hematocrit.
Procedure #3 Report Form: Determining Hematocrit
Patient Name: _____________________ Pt. ID _______________ Date: _____________
Age: _______ Gender (Circle One) M F Physician: ____________________________
Time Requested: ___________ Time Performed: ___________ Time Reported: __________
Examination Requested: Hematocrit Other
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