A basic knowledge of clinical laboratory pro-
cedures is required of all hospital corpsmen, par-
ticularly those working at small dispensaries and
isolated duty stations without the supervision of
a medical officer. The patients complaint may
be of little value by itself, but coupled with the
findings of a few easily completed laboratory
studies, a diagnosis can usually be surmised and
Hospital corpsmen who can perform blood
and urine tests and interpret the results are bet-
ter equipped to determine the cause of illness or
to request assistance, since they can give a more
complete clinical picture. Consequently, their pa-
tients can get treated sooner.
In this chapter we will discuss blood collec-
tion, the microscope, and step-by-step procedures
for the complete blood count and basic urinalysis.
The two principal methods of obtaining blood
samples are finger puncture and venipuncture.
Both methods have their advantages and disad-
vantages, but for most clinical examinations,
blood is best obtained from a vein.
The finger puncture is used when a patient is
burned severely or is bandaged so that the veins
are either covered or inaccessible. It is also used
when only a small amount of blood is needed.
. Sterile gauze pads (2 x 2)
. 70 percent isopropyl alcohol pad or Povi-
. Blood lancets
. Capillary tubes
Arrange your equipment in an orderly man-
ner and have it within easy reach. As with many
other laboratory procedures, wash your hands
prior to the procedure.
Using the middle or ring finger, massage
or milk the finger down towards the
fingertip. Repeat this milking five or six
Cleanse the fingertip with an alcohol pad
or Povidone-iodine solution and let dry.
Take a lancet and make a quick deep stab
on the side of the finger (off-center). To
obtain a large rounded drop, the puncture
should be across the striations of the finger-
tip (fig. 6-1).
Wipe away the first drop of blood to avoid
dilution with tissue fluid. Avoid squeezing
the fingertip to accelerate bleeding as this
tends to dilute the blood with excess tissue
fluid, but gentle pressure some distance
Figure 6-1.Finger puncture.