CLINICAL LAB SCIENEC

CHAPTER 7: MEDICAL ECONOMICS AND LABORATORY EQUIPMENT 181
distilled water over resin columns and then filters before qualifying as reagent
grade water. Type I water is the purest grade and is the only type that is used
for preparing standards and controls used in monitoring confidence levels of
laboratory test performance. Type I water is used to reconstitute vials of freezedried
materials so there are no substances that may interfere with the tests being
performed.
Type II water may be used where small numbers of bacteria will not interfere
with test results. Some procedures in hematology, serology, and qualitative
procedures may be performed with the use of Type II water. If Type II
water is used in microbiological procedures, it must be sterilized due to the
presence of bacteria in this grade of water. Type III water is used as a source
for preparing Types I and II water, and for washing and rinsing glassware.
However, Type I or II is required as the final rinse following the washing of
laboratory glassware. Type I water will absorb gases from the air so it should
be used soon after preparation. Types II and III are stored in tightly capped
containers to prevent absorption of gases, but unlike Type I may be stored for
periods of time.
Types of Testing
Manual Testing
With the flexible financing available today, most laboratories, even those that are
quite small, have a significant amount of automation available for tests that are
run in batches on a frequent basis. Manual testing is seldom performed today
except when instruments may have malfunctioned and need extensive repair or
to confirm a result from an automated system when there is doubt as to the veracity
of the result. Many automated instruments take little training to operate. The
skills possessed by medical laboratory technicians and technologists are necessary
to ensure that all the systems are operating properly and to provide adequate
samples that have been properly handled. Some of the instruments will “kick
out” results that do not meet certain parameters, and attention is required from
the technical personnel. Learning the basics of how tests are performed, even by
instruments, is important in the education and training of medical laboratory
workers.
Automated Testing
Most automated instruments operate on the same premises as the manual test
methodology. Some have evolved into more specific and more sensitive procedures,
and instruments have become smaller and simpler to operate. In addition,
it is difficult to duplicate the precision pipetting required for both reagents
and patient samples by the automated systems, when using manual pipettes for
reagents and micropipettes for measuring the patient samples. The most common
automated systems used in even the smaller laboratories are the blood
cell counter and the chemistry analyzer. The blood cell counter enumerates
both red and white cells, and estimates the types of white cells, which is important
in both bacterial and viral infections. The shape and size of the blood
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