Section II. BLOOD SPECIMENS
2-6.
INTRODUCTION
Proper collection and handling of specimens to be examined for blood parasites
are important since inadequate or poor samples may lead to erroneous conclusions. Not
all the organisms usually grouped as blood parasites are diagnosed from blood. In
certain instances, spinal fluid, peritoneal fluid, aspirates, and biopsies of organs and
tissues are also used to diagnose blood parasites.
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COLLECTION OF SPECIMENS
The blood specimens used for clinical testing are obtained using a procedure
called venipuncture. Venipuncture is a minor surgical procedure. Therefore, you must
be aware of the precautions associated with the technique when you perform a
venipuncture. Sometimes, the venipuncture technique is not practical. For example, the
physical condition or age of the patient or the need for only a small volume of blood may
make the venipuncture technique impractical. In these instances, a capillary puncture is
indicated. No matter which method is chosen for blood specimen collection, you must
attempt to reduce the trauma for the patient while you obtain an acceptable specimen for
clinical testing.
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THE VENIPUNCTURE
The venipuncture procedure is employed when more than a few drops of blood are
needed for the performance of the required procedure. Blood collection can be achieved
in two different ways: the use of a syringe and needle or by the use of a vacuum system.
The chosen vein for phlebotomy must be large, easily accessible, and close enough to
the surface to be seen and palpated with the finger. The most common site for
venipuncture is the medial surface of the elbow joint--the antecubital area. The veins of
the hand and foot are also used, but these areas are more painful when punctured and
give discomfort to the patient. Also, they are not anchored as well as those in the
antecubital area. UNDER NO CIRCUMSTANCES SHOULD A TECHNICIAN
WITHDRAW BLOOD FROM A SAGITTAL SINUS, JUGULAR VEIN, OR FEMORAL
VEIN. THE LABORATORY TECHNICIAN SHOULD ALSO AVOID THE USE OF AN
ARTERY. The physician in charge of the patient should be consulted when difficulties
are encountered in performing the phlebotomy procedure. Strict aseptic technique must
be used for venipuncture. That is, care must be exercised to complete the procedure
without contaminating the sample or introducing any foreign material into the patient's
vein.
a. Equipment. Sterility of the appropriate equipment is required.
(1) Alcohol sponges. Gauze pads soaked in 70 percent Isopropyl alcohol are
used to cleanse the site of the venipuncture. Commercially prepared pads can be
purchased for this purpose.
MD0841
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