(4) If difficulty is experienced in entering the vein or a hematoma begins to
form, release the tourniquet and promptly withdraw the needle and apply pressure to
(5) Vigorous pulling on the plunger of the syringe can collapse the vein,
produce hemolysis of the blood specimen, or cause air to enter the syringe.
(6) When repeated venipunctures have to be performed on one patient, it is
advisable to select different sites for blood withdrawal.
(7) Remove the tourniquet as early as possible once a good flow of blood
has been established. Prolonged application of the tourniquet results in partial stasis of
blood and changes many quantitative values of blood components.
(8) Blood drawn by venipuncture is often stored for a period of time before it
is analyzed. For this reason, certain general precautions must be followed in order to
ensure a valid analysis. Before withdrawing blood from its container, make sure the
blood sample is thoroughly but gently mixed. Blood containers should Be tightly
stoppered at all times to prevent drying or contamination. Store the blood specimen in
the refrigerator. Blood counts should be done within 3 hours after collection. Under no
circumstances should blood taken for hematological examinations be stored overnight.
a. Site. Several different sites are suitable for capillary puncture. Because it is
the most accessible, the palmer or lateral surface of the tip of the finger (preferably ring
finger) is the most common site in adults. However, certain problems can be
encountered such as heavy calloused areas or excessive tissue fluids (edema) that
tend to result in non-representative samples. The lobe of the ear can be used for
capillary puncture. However, differences in cell concentration do occur when blood is
obtained from this site, primarily because of higher lymphocyte concentrations in the ear
lobe. Because of the small amount of tissue on the fingers of infants, preferred site is
the heel or big toe. A modification of the normal technique that has proven quite
satisfactory when working with the heel of infants is to make two incisions in a
crisscross fashion or "T".
To be a valid report, work done on capillary blood must be from a FREE-
FLOWING puncture wound.
Gauze pads 2 x 2 inches.
(3) Glass slides, heparinized capillary tubes, and other devices to receive