Clinical Laboratory Improvement Act
Julie C. Paulson Happel, M.T. (ASCP), M.A.
Photographs by Joel Carl, M.A.
Edited by:
Marian Schwabbauer, Ph.D., CLDir(NCA)
Peer Review Status:
I. Introduction
Quality patient care can be provided only if decisions are based on
valid data. The validity of laboratory data is dependent on
pre-analytical factors just as it is on analytical parameters. These
pre-analytical factors will be discussed in the following text.
The National Committee for Clinical Laboratory
Standards has established standards for the pre-analytical phase.
II. Patient Education and Preparation
The first step is to educate and properly prepare the patient.
If the test requires the patient to be fasting, does the patient understand the requirements? For example, the patient may ask: "Can I have my morning coffee and/or cigarette if I don't eat anything?"
Next, consider which pre-existing patient conditions or habits might influence which test results; exercise, medications, and disease states should be considered.
Additionally, the importance of the time of day (diurnal variation), the timing (tolerance tests, half-life of drug), and the patient's posture (supine or upright) when drawing a blood sample should be considered.
Note: The laboratory performing the test analysis often can provide information regarding pre-analytical requirements as they pertain to test results and reference ranges. Be sure to check with them regarding any questions.
III. Laboratory Requisitions (test orders)
Complete and legible laboratory requisitions must contain the
following:
Note: Incomplete or illegible requisitions may result in delay of patient's test results, an incorrect test being performed, or a test being performed on the wrong patient.
IV. Patient Identification
The identification of the patient is crucial. Briefly greet the
patient, identify yourself, and establish a comfortable rapport with
her/him. This is to help put the patient at ease. The patient being
drawn must be identified as the person designated on the requisition.
The following are suggested scenarios for patient identification for
various clinical situations.
V. The Blood Sample
The integrity of the sample is dependent on using good venipuncture
or skin puncture technique, drawing from an appropriate site, and
avoiding hemolysis or contamination of a sample. When performing a
venipuncture, do not draw above an IV site, from a vein that is
sclerosed, from an area with a hematoma, from an arm with a fistula
or shunt, or from the same side where a patient has had a mastectomy.
When performing a skin puncture, do not use a finger or heel that is
bruised, cold, swollen or cyanotic. Each procedure will include
information on the appropriate site to select.
The following procedures for obtaining a blood sample, whether
performing a venipuncture, fingerstick or heelstick, assume that the
venipuncturist has
(1.)greeted the patient,
(2.)verified the patient's identity,
(3.)interviewed the patient to ascertain if s/he followed any
pre-testing requirements, and
(4.)explained the procedure to the patient and/or guardian.
Note: All patient blood specimens are to be treated with "Universal Precautions" as it is frequently impossible to know which specimens might be infectious. Gloves are to be worn when performing a venipuncture or skin puncture procedure.
Assemble all the equipment you might need in an organized manner.
Venipuncture using evacuated tube/hub system (to be performed
on adults or older children)
1. Check the test ordered and organize the required tubes in the
proper order of draw.
2. Inspect the site. Determine the type of needle and drawing system to be used. Whether to use a hub/vacuum tube, needle/syringe or IV infusion set is determined by the site and vein quality.
3. Assemble the equipment. It is helpful to have an extra tube of each type within reach or in your pocket as a tube might be lacking sufficient vacuum or in case you lose tube vacuum on a difficult stick.
4. Tie the tourniquet. It should be placed approximately 4 inches above the venipuncture site, with the ends pointing upwards, away from the site. Oftentimes a tourniquet must be applied before a person is able to determine the venipuncture site and the type of drawing system to use. The total time a tourniquet may be tied before it affects results by hemoconcentration, becomes uncomfortable for the patient, or causes petechiae to form is 1 to 2 minutes. Release the tourniquet while you assemble the equipment and then re-tie immediately prior to the actual stick for best results.
5. Palpate the vein.
6. Clean the site with 70% isopropyl alcohol. Dry the area with clean gauze or allow to air dry. Alcohol left on the skin can cause hemolysis and an unpleasant stinging sensation for the patient.
7. Anchor the vein. Using gentle pressure, place your index finger just below the insertion point. (Some phlebotomists prefer to hold the vein both above and below the insertion point.) Holding the skin taut helps to anchor the vein.
8. Insert the needle with the bevel facing up. The needle should
be at a 15 to 20 degree angle, and be placed in the same direction as
the vein. If you need to palpate the vein one more time before
inserting the needle, you must clean your gloved finger just as you
did the venipuncture site.
9. Engage the evacuated tube. Be sure to hold the needle/hub steady or you may lose the vein or cause pain or injury to the patient. The hand holding the needle/hub may be steadied by lightly resting your hand on the patient's arm. With your other hand, hold onto the hub flange and gently engage the tube. If you do not see blood being pulled into the tube as soon as you engage the tube, you may need to adjust the position of the needle slightly. If multiple tubes are to be drawn, mix each tube when you remove it from the needle/hub assembly; engage the next tube and etc., until you have drawn all the required tubes. You must follow the correct tube draw order to prevent a risk of contamination between tube types.
10. Release the tourniquet.
11. Remove the needle/hub assembly and apply pressure to the venipuncture site. Ask the patient to hold the gauze in place for you.
12. Discard the needle in a puncture resistant biohazard sharps container.
13. Again gently invert the tubes and label them.
14. Check the patient's arm and apply a bandage as necessary.
15. Ensure the patient is feeling fine before allowing the patient to stand and/or leave the area.
Note: If the patient is feeling queasy or faint, follow your lab's protocol for a fainting patient.
Venipuncture using a syringe
Syringes typically are used when the patient's veins are small or
fragile and the evacuated tube suction could cause the vein to
collapse. Using a syringe allows the venipuncturist to control the
amount of suction applied to the vein.
The venipuncture procedure using a syringe follows the same steps as the evacuated tube system procedure. It differs slightly in equipment preparation and assembly, pulling the blood into the syringe, and transferring of blood into evacuated tubes.
The entry into the skin and the vein is exactly the same as with
the evacuated tube system. 
Once you feel that the needle
is in the vein, pull back gently on the syringe plunger while holding
the syringe barrel securely to keep the needle in place in the vein.
Use the syringe flange to brace against as you pull back on the
plunger just as you do when changing tubes using a needle/hub system.
Fill the syringe with the desired amount of blood, release the
tourniquet and complete the procedure exactly as you would using an
evacuated tube system. (See needle
re-directing when using a syringe.)
To transfer the blood from the syringe to the appropriate tubes, remove the needle from the syringe and replace it with an 18 gauge needle. Using a large bore needle will help prevent hemolysis of the blood and maintain the integrity of the sample. Since there is the possibility of the formation of micro clots, the blood should be transferred in the appropriate order as quickly as possible into the tubes containing anticoagulant and mixed immediately.
Again, label the tubes and check the status of the patient before allowing the patient to stand or leave.
Venipuncture Using an IV Infusion Set:
An IV infusion set (butterfly) is used for venipuncture when you draw
from a hand or foot vein or from a very small or fragile vein; when
the angle of needle entry is awkward, e.g. when a patient is in bed
and repositioning of her/his arm is difficult or painful, or when the
patient's vein is difficult to find or draw. If a small child must
have blood drawn using the venipuncture procedure, a 23 gauge IV
infusion set attached to a 1 ml or 3 ml syringe is typically used.
This allows for good control and helps prevent excessive suction from
the syringe if the blood is drawn slowly and carefully.
The butterfly's needle and plastic "wings" are attached to a length of flexible tubing which is, in turn, attached to either a syringe or luer adapter/hub assembly. The butterfly is lighter and less cumbersome than either the other two assemblies. Thus, it allows better control and "feel" when drawing a patient. Additionally, as soon as the needle is in the vein, blood is visible in the tubing rather having to wait and see as when using the either of the other two methods.
The venipuncture procedure using an IV infusion set follows the same steps stated previously in the evacuated tube system procedure. The IV infusion set differs slightly in a lower angle of needle entry and equipment preparation and assembly. Whether the set is attached to a syringe or to a hub/tube assembly will determine if you will need to transfer the blood to tubes or if they were drawn directly into tubes.
When you are ready to perform the venipuncture, grasp the wings
between your thumb and index or middle finger, hold the skin and vein
taut with your other hand, and enter the skin with the needle.
As soon as you see blood in the tubing, you may pull
back on the syringe plunger or engage the vacuum tube. If you do not
see blood on the tubing you will need to
redirect the needle. When the
needle is well anchored in the vein, you may release the butterfly
"wings"; otherwise continue to gently hold the "wings" during the
procedure. If using a syringe, fill it with the desired amount of
blood, release the tourniquet, remove the needle and complete the
procedure exactly as you would using a syringe. If using a needle/hub
assembly, fill the tubes and complete the procedure as you would
drawing directly into evacuated tubes. Again, be sure to check the
status of the patient before allowing the patient to stand or to
leave.
Note: To prevent accidental re-stick with the butterfly set needle, hold the base of the needle or the wings as you remove the needle and do NOT let go of the needle base until it is being placed in the biohazard sharps container.
Skin Punctures:
Blood obtained from a skin puncture is a mixture of arterioles,
venules and capillaries and contains interstitial and intracellular
fluids. There is more of the arterial blood than venous blood due to
pressure differences in the capillaries. Also, the venous blood in
the skin more closely resembles arterial blood than in the other
parts of the body. This is especially true when the puncture site has
been warmed. Warming the skin primarily
increases the arterial blood flow.
Because of the differences in the blood concentration of certain analytes in capillary versus venous or arterial blood, the blood collection technique and site both should be noted on the reports form. This allows the physician to consider the collection technique used when interpreting the results.
The key to obtaining a good skin puncture sample (finger or heel)
is performing a puncture that results in free flowing blood. This is
dependent upon accessing the capillaries, veins, and arteries of the
dermis and subcutaneous tissues. Manufacturers have developed varied
types and sizes of skin puncture devices to safely access this
juncture. The devices are usually designed specifically for
(1.) heelstick: on a pre-term baby
(2.) heelstick on a full-term baby
(3.) finger puncture on a pediatric patient
(4.) finger puncture on an adult patient.
These devices vary in the depth and
width of the cut or puncture.
Preventing hemoylsis is also often technique dependent. Be sure the site is wiped dry from alcohol before performing the puncture. Residual alcohol may cause red blood cell lysis Also, if blood flow is inadequate or begins to decrease, do not excessively squeeze the adjacent tissue; rather, perform a second skin puncture using all new equipment. Never re-stick the same site or re-use a lancet. Allow tube to fill by capillary action. Do not scrape the tube against the site as this may cause mechanical lysis of the RBCs. Technique is even more important when performing a skin puncture on an infant. Infants often have high packed cell volumes and increased red blood cell fragility.
The Finger Puncture Procedure
A finger puncture procedure is performed instead of the venipuncture
or heelstick when the patient is a small child older than six months,
or the specimen was unattainable by venipuncture. The finger puncture
procedure is not to be performed on infants as the distance from the
skin surface to the bone at the thickest portion of the distal
phalanx of a newborn is between 1.2 to 2.2 mm. The available lancets
cutting or puncture depth is .85 to 4.5 mm and thus could easily
cause injury to the bone.
The finger puncture is typically used for lower sample volume
tests that can be placed into special micro-sized tubes.
These tests include CBC, white blood cell
differential, hemoglobin, hematocrit, and limited chemistry tests,
e.g. Na, K, Cl, CO2, BUN, creatinine, and glucose. Fingersticks are
also frequently used in public health screening events, e.g.
cholesterol, HDL and glucose self-monitoring at home.
Again, this procedure assumes that patient education and preparation, test request verification, patient identification, and procedure explanation have occurred.
The steps for the finger puncture are:
1. Select skin puncture site. You may use either hand but the less dominant hand is usually not as callused. Use the palmar surface of the distal phalanx of the middle or ring finger (3rd or 4th digit). The only finger that should not be used is the last finger (5th digit).
2. Warm the site if necessary.
3. Organize equipment.
4. Clean the site with 70% isopropyl alcohol. Dry the site completely using sterile gauze.
5. Puncture the site with a disposable lancet. Hold the finger and
hand firmly to immobilize the finger as some patients's response is
to pull away as you perform the skin puncture. This often
necessitates repeating the procedure in order to obtain the sample.
There are two basic types of lancets. One type has an exposed blade
with that will penetrate the skin to a pre- determined depth. When
using this type of lancet, perform a quick puncture to the
pre-determined depth of the lancet, perpendicular to the fingerprints
and at a 90 degree of angle. The second type is a semi-automatic
lancet. This type has either a plunger or button to push to perform a
puncture or an incision. To use these, again immobilize the finger
and hold the lancet at a 90 degree angle to the finger, perpendicular
to the lines of the fingerprint. Using moderate pressure, depress the
plunger completely, then release the plunger and remove the lancet.
6. Wipe away the first drop of blood using sterile gauze. This drop of blood contains the highest concentration of tissue fluids.
7. Collect the specimen by allowing the drops of blood to fill the collection tube by capillary action. When drawing hematology and chemistry tests, always draw the hematology tests first. Immediately mix the hematology micro-collection tubes at least 8-10 times to ensure adequate mixing of the small volume. One manufacturer suggests mixing their micro-collection EDTA tube 20 times. If the blood flow becomes inadequate or stops, repeat the skin puncture using a different site and a new lancet.
8. Apply pressure to the puncture site using sterile gauze.
9. Discard the lancet in a puncture resistant biohazard sharps container.
10. Label the tubes.
11. Apply a band-aid as necessary. Do not apply a band-aid on a small child as s/he may swallow the band-aid. Colorful stickers may bring a smile to an older child after the procedure is done.
12. Check the status of the patient before allowing the patient to stand or leave.
The Heelstick Procedure
Skin puncture of the heel is frequently the least problematic method
for obtaining a blood sample from an infant. The puncture is
performed on the most medial or lateral portion of the plantar
surface of the heel. Do not perform a puncture on the central area of
the foot, the arch of the foot, nor the posterior curvature of the
heel. See the shaded portion on diagram.
Also, do not puncture a previously used site which
may be infected. The National Committee for Clinical Laboratory
Standards states that the puncture depth should be no more than 2.4
mm. Studies indicate that for certain infants, including premature
infants, even this depth may be excessive.
The heel puncture procedure follows the same steps as the finger puncture procedure. Some of the disposable lancets are specifically designed for heelsticks.
1. Select the heel puncture site.
2. Warm the site for three to ten minutes, if necessary.
3. Organize your equipment.
4. Clean the with 70% alcohol and wipe dry with sterile gauze or allow to air dry.
5. Perform heel puncture. Firmly hold the heel, place the lancet
perpendicular to the heel, and quickly perform puncture.
If, for any reason you are using a lancet that will enter at a depth greater than 2.4 mm, do NOT enter the skin at a perpendicular angle. The risk of hitting a bone is too great. Place the lancet almost parallel to the heel, facing toward the toes, and enter at a shallow angle. You need only to access the capillary bed. It is never recommended to use a lancet that will puncture the heel at a depth of greater than 2.4mm. Good technique and the appropriate lancet should negate any reason for exceeding the recommended maximum depth of 2.4 mm.
6. Collect specimens. The order of draw is the same as for the finger punctures.
7. Apply pressure to the site. Apply a bandaid only if there is no danger of the infant getting it into her/his mouth.
8. Discard the lancet into a biohazard sharps container.
9. Label the tubes. Tubes too small to be labeled, such as hematocrit tubes, can be placed in a plain (red top) tube and the tube can be labeled.
10. Check the site and the patient again before allowing the patient to leave.
VI. Specimen Handling and Transportation
Once a sample is drawn properly, it must be processed, stored,
assayed and/or transported correctly or the results may be invalid.
Certain blood samples must be placed on ice, others kept at body
temperature, and some centrifuged and frozen immediately. If you are
sending samples drawn in your office to an outside laboratory for
analysis, make sure your specimen collection, handling, and
transportation procedures meet the guidelines set by the reference
laboratory.
Test for Pre-Analytical Factors Affecting Laboratory Results Emphasis : Phlebotomy
Practice test for Pre-Analytical Factors Affecting Laboratory Results Emphasis : Phlebotomy
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