introduction to phlebotomy
the purpose of phlebotomy is to collect a blood specimen for laboratory analysis. the word phlebotomy is derived from the greek words for "vein" (phlebos) and "incision" (atomy) and literally means "making an incision into a vein". as used in the clinical
phlebotomy encompasses three major areas of blood collection:
- arterial puncture
- venipuncture
- skin puncture
arterial puncture:
is typically performed in an hospital to asses the oxygen level, carbon dioxide level, and acid base balance of arterial blood; medical assistants do not perform arterial punctures.
venipuncture
means the puncturing of a vein for the removal of a venous blood sample
venipuncture is usually performed in the medical office using the following methods:
- vacuum tube method
- butterfly method
vacuums tube method
is the fastest and most convenient method and is used most often. this method relies on the use of an evacuated tube that contains a vacuume. the butterfly method is used for difficult draws, such as when vein is small or sclerosed (hardened). this chapte
General guidelines for venipuncture
general guidelines that are common to both methods of venipuncture include verifying any advance preparation, reviewing specimen collection and handling requirements, identifying the patient, reassuring the patient, assembling equipment and supplies, posi
OSHA
Occupational Safety and Health Administration
patient preparation for venipuncture
fasting involves abstaining from food or fluids (except water) for specified amount of time before the collection of a specimen. (4-6 or 8-12) hours
identification of the patient
it cannot be emphasized enough how important it is to identify the patient using two forms of identification (name & birthdate) before performing venipuncture.
skin puncture devices
regardless of the skin puncture device the puncture must not penetrate deeper than 3.1 mm in adults and 2.0mm in infants (plantar surface of the heel) and children. if the puncture is deeper than this, the bone may be penetrated, which could result in the
puncture sites
the fingertip of the third or fourth finger is the preferred site for a skin puncture in an adult. in the past the earlobe also was recommended as a skin puncture site for an adult. thesis no longer true. blood obtained by puncturing the earlobe has been
skin puncture
a skin puncture is used to obtain a capillary blood specimen and is also called a capillary puncture. laboratory testing of a capillary blood specimen is usually performed at the medical office. examples of such tests are hemoglobin, hemotocratic, blood g
serum separator tubes
the specimen must be allowed to stand in an upright position for 30 to 45 minutes for proper clot formation of the blood cells and must be centrifuged as previously described.
removal of serum
if red-stoppered tube has been used to collect the specimen, the serum is removed from the clot using a pipet and is placed in a separate transfer tube. it is important that proper technique be employed in removing the serum, to avoid disturbing the cell
preparation of the specimen
after the blood specimen has been collected, the red-stoppered tube or SST must be allowed to stand upright at room temperature for 30-45 mins before being centrifuged. a fibrin clot is a spongey substance that occupies space interfering with adequate ser
serum
serum is plasma from which the closing factor fibrinogen has been removed. serum is virally clear in aperance and light yellow to yellow in color. serum contains many dissolved substances such as GLUCOS, CHOLESTROL, SODIUM, POTASSIUM, CHLORIDE, ANTIBODIES
fainting
occasionally a patient experiences dizziness or fainting during or after a venipuncture. should this occur the most immediate concern is to protect the patient from injury for example by preventing the paten from falling
Vasovagal syncope (fainting)
-Caused by unpleasant physical or emotional stimuli such as pain, fright, and the site of blood.
TREATMENT: a person should who is about to faint should be placed in a position that facilities blood flow to the brain and told to breathe deeply. the prefer
collapsing veins
veins are most likely to collapse in individuals that have small veins or veins with thin walls. because better control and less pressure on the vein are possible, the butterfly method of the venipuncture is recommended to obtain the specimen in patients
premature needle withdrawal
patient movement or improper venipunture technique can cause the needle to come out of the vein prematurely, because of the pressure exerted by the tourniquet, blood may be forced out of the puncture site, and immediate action is required to prevent a hem
hematoma
a hematoma is caused by blood leaking from the puncture site of the vein and into the surrounding tissues, resulting into a bruise. a hematoma is caused by a needle that is inserted too far and goes through the vein, a bevel opening that is partially in t
hemolysis
blood cells are fragile and rough handling may cause hemolysis or breakdown of the blood cells. hemolyzed blood specimens produce inaccurate test results. to prevent hemolysis these guidelines should be followed:
1. stop the vacuum tubes at room temperatu