Phlebotomy

LEARNING OBJECTIVES	PROCEDURES
Venipuncture
1. List and describe the general guidelines that should be followed when performing a venipuncture. 2. Explain how each of the following blood specimens is obtained: Clotted blood Serum Whole blood Plasma 3. List the layers the blood separates into when an anticoagulant is added to the specimen. 4. List the layers the blood separates into when an anticoagulant is not added to the specimen. 5. List the OSHA safety precautions that must be followed during venipuncture and when separating serum or plasma from whole blood. 6. State the additive content of each of the following vacuum tubes, and list the types of blood specimens that can be obtained from each: red, lavender, gray, light blue, green, royal blue. 7. Identify and explain the order of draw for the vacuum tube and butterfly methods of venipuncture. 8. List and describe the guidelines for use of evacuated tubes. 9. Identify possible problems during a venipuncture. 10. List four ways to prevent a blood specimen from becoming hemolyzed. 11. Explain how the serum separator tube functions in the collection of a serum specimen.	Perform a venipuncture using the vacuum tube method. Perform a venipuncture using the butterfly method.
Skin Puncture
12. Explain when a skin puncture would be preferred over a venipuncture. 13. Describe each of the following skin puncture devices: disposable semiautomatic lancet and reusable semiautomatic lancet. 14. List and describe the guidelines for performing a finger puncture.	Obtain a capillary blood specimen using a disposable semiautomatic lancet. Obtain a capillary blood specimen using a reusable semiautomatic lancet.

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” (otomy) and literally means making an incision into a vein. As used in the clinical laboratory sciences, phlebotomy is defined generally as the collection of blood. An individual who collects a blood sample is a phlebotomist.

Some blood specimens are tested in the medical office, and others are picked up and taken to an outside laboratory for testing. The latter specimens need to be placed in a biohazard specimen bag along with a laboratory request (Figure 31-1), so that laboratory personnel know what type of test the physician desires. The medical assistant may be responsible for completing the laboratory request form either on the computer or manually. The request form includes the physician’s name and address; the patient’s name, address, age, and gender; the date and time of collection of the specimen; the International Classification of Diseases (ICD) code of the clinical diagnosis; and a mark next to the type of test or tests to be performed.

Figure 31-1 Specimen in a biohazard specimen bag along with the laboratory request form.

Phlebotomy encompasses three major areas of blood collection:

• Arterial puncture

• Venipuncture

• Skin puncture

An arterial puncture is typically performed in a hospital to assess the oxygen level, carbon dioxide level, and acid-base balance of arterial blood; medical assistants do not perform arterial punctures. In the medical office, medical assistants perform venipunctures and skin punctures. This chapter focuses on these two ways to obtain blood.

Venipuncture

Venipuncture means the puncturing of a vein for the removal of a venous blood sample. In the medical office, a venipuncture is performed when a large blood specimen is needed for testing. Venipuncture can be performed by the following two methods:

• Vacuum tube method

• Butterfly method

The vacuum tube method is the fastest and most convenient of the three methods and is used most often. This method relies on the use of an evacuated tube, which is a closed glass or plastic tube that contains a vacuum. The butterfly method is used for difficult draws, such as when a vein is small or sclerosed (hardened). This chapter presents the theory and procedure for both methods.

The medical assistant must be sure to label each blood tube. An unlabeled specimen is a cause for rejection of the specimen by an outside laboratory. Two unique identifiers should be used to label the specimen. A unique identifier is information that clearly identifies a specific patient, such as the patient’s name and date of birth. A specimen can be labeled by attaching a computerized bar code label to the specimen (Figure 31-4, A). The bar code label includes (at least) two unique patient identifiers. A specimen can also be labeled by handwriting the information on the label, which should include the patient’s name and date of birth (two unique identifiers), the date and time of collection, the medical assistant’s initials, and any other information required by the laboratory (Figure 31-4, B). The information should be printed legibly, and the medical assistant should be certain that the information is accurate to avoid a mix-up of specimens. The medical assistant must also complete a laboratory request form to accompany the blood specimen. (NOTE: The medical assistant should follow the medical office policy as to when the tubes should be labeled. Some offices prefer the tubes be labeled before the specimen is drawn; other offices want the tubes to be labeled right after the specimen is obtained.)

Figure 31-4 A, Computerized bar code label. B, Hand-labeled blood tube.

Reassuring the Patient

Venipuncture is often a frightening experience for the patient. For many patients, the anticipation of the procedure is worse than the actual drawing of the blood. The medical assistant should take time to explain the procedure to the patient in an unhurried and confident manner. This helps to alleviate the patient’s fears, which relaxes the patient’s veins. Relaxed veins make venipuncture easier to perform and result in less pain for the patient.

Instruct the patient to remain still during the procedure. Explain to the patient that a small amount of pain is associated with a venipuncture, but it is brief. Never tell the patient that the venipuncture will not hurt. Just before inserting the needle, tell the patient that he or she will “feel a small stick.” This prevents startling the patient, which could cause the patient to move. Movement causes pain for the patient, and it may damage the venipuncture site.

Patient Position for Venipuncture

The patient position for venipuncture is especially important to the successful collection of a blood specimen. Proper positioning allows easy access to the vein and is more comfortable for the patient. The patient position depends on the vein to be used. The most common site for venipuncture is the antecubital space, and the information presented next refers to this site.

The patient should be seated comfortably in a chair. The arm should be extended downward to form a straight line from the shoulder to the wrist with the palm facing up; the arm should not bend at the elbow. The arm should be well supported on the armrest by a rolled towel or by having the patient place the fist of the other hand under the elbow (Figure 31-5).

Figure 31-5 Patient position for obtaining a blood specimen from the antecubital veins.

A venipuncture should never be performed with the patient sitting on a stool or standing. The patient may faint and injure himself or herself. If the patient appears nervous or has fainted in the past from a venipuncture, it is best to place the patient in a semireclining position (semi-Fowler position) on the examining table. A pillow or a cushion should be placed under the patient’s arm to support the arm in a straight line from the shoulder to the wrist.

Although unusual, it is possible for blood to flow from the evacuated tube back into the patient’s vein during the procedure. This condition is known as venous reflux. Venous reflux could cause the patient to have an adverse reaction to a tube additive, particularly if the additive in the tube is ethylenediaminetetraacetic acid (EDTA). Venous reflux can occur only if the contents of the evacuated tube are in contact with the tube stopper while the specimen is being drawn. Venous reflux is prevented by keeping the patient’s arm in a downward position so that the evacuated tube remains below the venipuncture site and fills from the bottom up.

Application of the Tourniquet

An important step in the venipuncture procedure is the application of the tourniquet. The tourniquet makes the patient’s veins stand out so that they are easier to palpate. The tourniquet acts as a “dam,” which causes the venous blood to slow down and pool in the veins in front of the tourniquet. This pooling of blood makes the veins more prominent so that they are more visible and can be palpated.

When applying a tourniquet, it is important to obtain the correct tourniquet tension. The tourniquet should be applied with enough tension to slow the venous flow without affecting the arterial flow. A tourniquet that is too tight obstructs both venous blood flow and arterial flow, which may result in a specimen that produces inaccurate test results. A tourniquet that is too loose fails to cause the veins to stand out enough to be palpated. A correctly applied tourniquet should fit snugly and not pinch the patient’s skin.

Putting it All into Practice

My name is Dori Glover, and I work in a very busy, fast-paced family practice office for two physicians. I love my job. The physicians are great, with very different styles; the pace is fast; and the time flies by. I am constantly challenged, learning new things, meeting and helping people, and being a part of a team that works well together.

While performing a venipuncture for a routine blood chemistry profile (a procedure I have performed many times), I accidentally stuck myself. I could see the blood inside my glove, and I could see the patient’s blood clinging to the point of the needle—my heart sank. I placed the needle and holder in the sharps container and tried to keep my cool and not alarm the patient. I mentally assessed the patient. He was an older man from a rural community, but I know you cannot always judge a book by its cover.

I excused myself and immediately proceeded to wash my hands thoroughly with soap and water and rinse, rinse, rinse! I then notified the physician. The physician questioned the patient regarding operations he had had in the previous year. He had undergone bypass surgery and had received 2 units of blood. Although blood is effectively screened, I thought about that one-in-a-zillion chance that it could have been contaminated. Thankfully, I had received the hepatitis B immunization series, but there was still concern regarding hepatitis C and, of course, HIV.

The patient was gracious and complied with our request to be tested for hepatitis and HIV. The physician and I discussed the situation, and we determined the risk to be low, but he nonetheless offered me the option of getting the HIV postexposure prophylactic treatment. This treatment is very toxic and is not something you want to receive needlessly. I declined and proceeded to wait in agony for the patient’s test results. The word relief hardly describes how I felt when the patient’s laboratory results came back negative!

This incident confirmed the importance of getting the hepatitis B immunization and paying attention to good technique when performing procedures involving blood.

Guidelines for Applying the Tourniquet

The following guidelines help to ensure successful application of the tourniquet:

1. Do not apply the tourniquet over sores or burned skin.

2. Place the tourniquet 3 to 4 inches above the bend in the elbow. This allows adequate room for cleansing the site and performing the venipuncture without the tourniquet getting in the way.

3. Apply the tourniquet so that it is snug, but not so tight that it pinches the patient’s skin or is otherwise painful to the patient.

4. When applying the tourniquet, ask the patient to clench his or her fist. This pushes blood from the lower arm into the veins and makes them easier to palpate. You can ask the patient to clench and unclench the fist a few times; however, vigorous pumping should be avoided because it could lead to hemoconcentration, which could produce inaccurate test results.

5. Never leave the tourniquet on for longer than 1 minute because this would be uncomfortable for the patient. In addition, prolonged application of the tourniquet causes the venous blood to stagnate, or pool in one place too long—a condition known as venous stasis. When venous stasis occurs, the plasma portion of the blood filters into the tissues, causing hemoconcentration. Hemoconcentration is an increase in the concentration of nonfilterable blood components in the blood vessels, such as red blood cells, enzymes, iron, and calcium, as a result of a decrease in the fluid content of the blood. This can result in inaccurate results for a variety of laboratory tests.

6. Ideally, you should remove the tourniquet as soon as a good blood flow is established; however, this may not be practical when you are first learning the venipuncture procedure. Removing the tourniquet may cause the needle to move such that no more blood can be obtained, and the blood has to be redrawn. When you are learning the venipuncture procedure, it is better to wait until just before the needle is removed to remove the tourniquet.

7. Always remove the tourniquet before removing the needle from the patient’s arm. If the needle is removed first, the pressure of the tourniquet causes blood to be forced out of the puncture site and into the surrounding tissue, resulting in a hematoma. A hematoma is defined as a swelling or mass of coagulated blood caused by a break in a blood vessel.

8. After use, wipe a tourniquet thoroughly with a disinfectant such as alcohol. Disposable tourniquets are available that are thrown away after one use.

Types of Tourniquets

The most common tourniquets are the rubber tourniquet and the Velcro-closure tourniquet. The type of tourniquet used is a matter of individual preference.

Rubber Tourniquet

The rubber tourniquet consists of a flat, soft band of rubber approximately 1 inch (2.5 cm) wide and 15 to 18 inches (38 to 45 cm) long. Rubber tourniquets are commercially available in latex or nonlatex rubber. They offer the advantage of being easily removable with one hand. The technique for applying a rubber tourniquet is described next and is illustrated in Figure 31-6.

Procedure: Rubber Tourniquet

1. Hold each end of the tourniquet with one hand. Position the tourniquet 3 to 4 inches (7.5 to 10 cm) above the bend in the elbow, making sure that the tourniquet lies flat against the patient’s skin. Pull the ends away from each other to create tension (see Figure 31-6, A).

2. Bring the ends of the tourniquet toward each other and cross one over the other at the point of your grasp, with enough tension so that the tourniquet is snug but is not pinching the patient’s skin (see Figure 31-6, B).

3. Tuck a portion of the top length into the bottom length, forming a loop between the tourniquet and the patient’s arm. This allows for a one-handed release of the tourniquet when pulled on one end. Make sure the flaps are directed upward so that they do not dangle into the working area (see Figure 31-6, C).

Velcro-Closure Tourniquet

The Velcro-closure tourniquet consists of a band of rubber or elastic material with Velcro attached at the ends. This type of tourniquet is easier to apply and is more comfortable for the patient than the rubber tourniquet. The disadvantage of the Velcro-closure tourniquet is that it is more difficult to remove with one hand than the rubber tourniquet. In addition, this type of tourniquet may not fit around the arms of extremely obese patients. The technique for applying a Velcro-closure tourniquet is described next and is illustrated in Figure 31-7.

Procedure: Velcro-Closure Tourniquet

1. Hold each end of the tourniquet with one hand. Position the tourniquet 3 to 4 inches (7.5 to 10 cm) above the bend in the elbow.

2. Wrap the tourniquet around the arm, and secure it with the Velcro fastener. The tourniquet should be applied with enough tension so that it is snug but is not pinching the patient’s skin.

Site Selection for Venipuncture

For most patients, the best site to use is the veins in the antecubital space (Figure 31-8). If the patient has large, visible antecubital veins, drawing blood is easy. If the patient has small veins or veins that cannot be palpated, obtaining a blood specimen can be quite a challenge, even for the most experienced medical assistant.

The antecubital space is the surface of the arm in front of the elbow. The antecubital veins generally have a wide lumen and are close to the surface of the skin, which makes them easily accessible. In addition, these veins typically have thick walls, making them less likely to collapse. Using the antecubital space spares the patient unnecessary pain because the skin is less sensitive there than at other sites, such as the back of the hand. The medical assistant should not be misled by the presence in some patients of many small, very blue “spidery” veins that lie close to the surface of the skin. These veins are not suitable for performing a venipuncture. The antecubital veins lie beneath these veins.

The best vein to use in the antecubital space is the median cubital. The median cubital is a prominent vein in the middle of the antecubital space and does not roll (see Figure 31-8). At times, however, the median cubital vein cannot be used, for example, when it lies deep in the tissues and cannot be palpated or is scarred from repeated venipunctures.

The cephalic and basilic veins are located on opposite sides of the antecubital space and provide an alternative site when the median cubital vein is unavailable. The cephalic vein is located on the thumb side of the antecubital space, and the basilic vein is located on the little finger side of the antecubital space. The disadvantage of these “side” veins is that they tend to roll or move away from the needle, escaping puncture. To prevent rolling, firm pressure should be applied below and to the side of the vein to stabilize it as the needle is inserted.

The brachial artery also is located in the antecubital space, but it lies deeper in the tissues. This is the artery that is used to measure blood pressure. Before performing a venipuncture, palpate for the presence of this artery. In contrast to a vein, an artery pulsates, is more elastic, and has a thicker wall than a vein. If the brachial artery is inadvertently punctured, the patient feels more than the usual amount of pain, and the blood is bright red and comes out in pulsing movements. If this situation occurs, the tourniquet should be removed and then the needle. Pressure with a gauze pad should be applied for 4 to 5 minutes.

Guidelines for Site Selection

Specific guidelines should be followed to facilitate the selection of a good vein:

1. Ensure that the lighting is adequate. Good lighting facilitates inspection of the veins.

2. Ensure that the veins “stand out” as much as possible. Before locating a venipuncture site, always apply the tourniquet, and have the patient make a fist. This combination makes the veins more prominent.

3. Examine the antecubital veins of both arms. The best site to perform a venipuncture varies with each individual. The patient may have larger veins in one arm than in the other. It is advisable to ask the patient whether he or she has had a venipuncture before. Most adults have had previous venipunctures and know which of their veins are best to use and which should be avoided. Listen to and evaluate information offered by the patient.

4. Use inspection and particularly palpation to select a vein. A vein does not have to be seen to be a good selection. If you cannot see a vein, palpation alone can be used to locate it. A vein feels like an elastic tube that “gives” under the pressure of the fingertips.

5. Always palpate for the median cubital vein (middle vein) first. It usually is bigger, is anchored better, bruises less, and poses the smallest risk of injuring underlying structures (e.g., nerves and arteries) than the other veins. Because of this, if the patient’s median cubital vein cannot be seen but still can be palpated, it should be used as the first choice when selecting a vein. If the median cubital vein is good in both arms, select the one that appears the fullest. The cephalic vein located on the thumb side is the next best vein choice because it does not roll and bruise as easily as the basilic vein. The basilic vein, located on the little finger side of the antecubital space, is the least desirable venipuncture site in the antecubital space. Branches of the median nerve may lie close to this vein in some individuals. In addition, the basilic vein lies in close proximity to the brachial artery. Both of these conditions pose a risk of injury to underlying structures when blood is drawn from the basilic vein.

6. Thoroughly assess the patient’s veins. To assess a vein as a possible site for venipuncture, place one or two fingertips (index and middle fingers) over it and press lightly, then release pressure. Do not use your thumb to palpate the vein because it is not as sensitive as the index finger. To be suitable for a venipuncture, the vein should feel round, firm, elastic, and engorged. When you depress and release an engorged vein, it should spring back in a rounded, filled state.

7. Determine the size, depth, and direction of the vein. When a suitable vein has been located, it should be palpated thoroughly and carefully to determine the direction of the vein and to estimate the size and depth of the vein. Palpate and trace the path of the vein several times by rolling your index finger back and forth over the vein to determine its size. Inspect and palpate the vein for problems. Some veins that appear suitable at first sight feel small, hard, bumpy, or flat when palpated.

8. Map the location of the site. After locating an acceptable vein, mentally “map” the location of the puncture site on the patient’s arm with “skin marks.” This technique is particularly helpful if the vein cannot be seen, but only palpated. The puncture site may be located on or next to a skin mark, such as a freckle, a small wrinkle, or a pigmented area.

9. Do not leave the tourniquet on for longer than 1 minute. When first learning the venipuncture procedure, you may need to perform numerous assessments of the patient’s arms to locate the best vein. After each assessment, remove the tourniquet for approximately 2 minutes to allow normal circulation of the blood to occur. This prevents patient discomfort and hemoconcentration, which can lead to inaccurate results for a variety of laboratory tests.

10. If a good vein cannot be found, the following techniques can be employed to make the veins more prominent:

Remove the tourniquet, and have the patient dangle the arm over the side of the chair for 1 to 2 minutes.

Tap the vein site sharply a few times with your index finger and second finger.

Gently massage the arm from the wrist to the elbow.

Apply a warm, moist washcloth to the area for 5 minutes.

Alternative Venipuncture Sites

If it is impossible to locate a suitable vein in the antecubital space, alternative sites are available, including the inner forearm, the wrist area above the thumb, and the back of the hand (Figure 31-9). These alternative veins are smaller and have thinner walls than the antecubital veins and should be used for venipuncture only when all possibilities for obtaining the blood specimen at the antecubital site have been considered. If the medical assistant is able to palpate a small vein in the antecubital space, it may be possible to obtain blood there using the butterfly method of venipuncture.

The hand veins, in particular, should be used only as a last resort. The veins of the hand have a tendency to roll because they are not supported by much tissue and are close to the surface of the skin. This makes them more difficult to stick. In addition, an abundant supply of nerves is present in the hands, which makes this procedure more uncomfortable for the patient. Hand veins tend to have thin walls, which makes them more susceptible to collapsing, bruising, and phlebitis. In some patients, however, especially the obese and the elderly, the hand veins may be the only accessible site.

Types of Blood Specimens

The type of blood specimen required depends on the type of test to be performed. Serum is required for most blood chemistry studies, whereas whole blood is required for a complete blood count. The various types of blood specimens that the medical assistant would be required to obtain through the venipuncture procedure are as follows:

1. Clotted blood. Clotted blood is obtained from a tube that does not contain an anticoagulant. A tube without an anticoagulant causes the blood cells to clot.

2. Serum. Serum is obtained from clotted blood by allowing the specimen to stand and then centrifuging it. Centrifuging a blood specimen that does not contain an anticoagulant causes the blood to separate into the following layers (Figure 31-10, A):

Figure 31-10 Layers into which the blood separates when there is no anticoagulant **(A)** and when an anticoagulant is present **(B).**

Top layer—serum

Bottom layer—clotted blood cells

3. Whole blood. Whole blood is obtained by using a tube that contains an anticoagulant. An anticoagulant is a substance that inhibits blood clotting. It is important to mix the anticoagulant with the blood by gently inverting the tube back and forth 8 to 10 times after collection.

4. Plasma. Plasma is obtained from whole blood that has been centrifuged. Centrifuging a blood specimen that contains an anticoagulant causes the blood to separate into the following layers (Figure 31-10, B):

• Top layer—plasma

• Middle layer—buffy coat (contains white blood cells and platelets)

• Bottom layer—red blood cells

OSHA Safety Precautions

The OSHA Bloodborne Pathogens Standard presented in Chapter 17 must be carefully followed during the venipuncture procedure to avoid exposure to bloodborne pathogens. The following OSHA requirements apply specifically to the venipuncture procedure and to separation of serum from whole blood (see later):

1. Wear gloves when it is reasonably anticipated that you will have hand contact with blood.

2. Avoid hand-to-mouth contact, such as eating, drinking, or applying makeup, while working with blood specimens.

3. Wear a face shield or mask in combination with an eye protection device whenever splashes, spray, splatter, or droplets of blood may be generated.

4. Perform all procedures involving blood in a manner so as to minimize splashing, spraying, splattering, and generating droplets of blood.

5. Bandage cuts and other lesions on the hands before gloving.

6. Sanitize hands as soon as possible after removing gloves.

7. If your hands or other skin surfaces come in contact with blood, wash the area as soon as possible with soap and water.

8. If your mucous membranes (e.g., eyes, nose, mouth) come in contact with blood, flush them with water as soon as possible.

9. Do not bend, break, or shear contaminated venipuncture needles.

10. Do not recap a contaminated venipuncture needle.

11. Locate the sharps container as close as possible to the area of use. Immediately after use, place the contaminated venipuncture needle (and plastic holder) in the biohazard sharps container.

12. Place blood specimens in containers that prevent leakage during collection, handling, processing, storage, transport, and shipping.

13. Handle all laboratory equipment and supplies properly and with care as indicated by the manufacturer. For example, wait until the centrifuge comes to a complete stop before opening it.

14. Do not store food in refrigerators where testing supplies or specimens are stored.

15. If you are exposed to blood, report the incident immediately to your physician-employer.

What Would You Do? What Would You Not Do?

Case Study 1

Angela Castillo is 21 years old and comes to the office at 9:00 AM to have her blood drawn for a CBC and a thyroid profile. She has brought a friend along with her. Angela seems nervous, and her voice is shaking. She says this is the first venipuncture she has ever had. Angela asks whether her friend could stay with her to give her moral support while her blood is being drawn. Angela says that the blood has to be taken out of her left arm. She says she is right-handed and has a softball game this evening. When the veins of Angela’s left arm are examined, a suitable vein cannot be located; however, she has a good median cubital vein in her right arm. Angela then wants to know whether the blood could be drawn from her left hand like they do on hospital television shows.

Vacuum Tube Method of Venipuncture

The vacuum tube method is frequently used to collect venous blood specimens. This method is considered ideal for collecting blood from normal healthy antecubital veins that are adequate in size to withstand the pressure of the vacuum in the evacuated tube. Procedure 31-1 outlines the venipuncture vacuum tube method. The vacuum tube system consists of a collection needle, a plastic holder, and an evacuated tube (Figure 31-11). One commercially available vacuum tube system is the Vacutainer System (Becton Dickinson, Franklin Lakes, NJ).

Procedure 31-1 Venipuncture—Vacuum Tube Method

Outcome

Perform a venipuncture using the vacuum tube method.

• Double-pointed needle

• Plastic holder

• Evacuated tubes with labels

• Sterile 2 × 2 gauze pad

• Adhesive bandage

• Biohazard sharps container

• Biohazard specimen bag

• Laboratory request form

1. Procedural Step. Review the requirements for collecting and handling the blood specimen as ordered by the physician. Sanitize your hands.

2. Procedural Step. Greet the patient and introduce yourself. Identify the patient by asking the patient to state his or her full name and date of birth. Compare this information with the demographic data in the patient’s chart. If the patient was required to prepare for the test (e.g., fasting, medication restriction), determine whether he or she has prepared properly. If the patient has not followed the patient preparation requirements, notify the physician for instructions on handling this situation.

Principle. It is important to confirm that you have the correct patient to avoid collecting a specimen on the wrong patient. The patient must prepare properly to obtain a high-quality specimen that would lead to accurate test results.

3. Procedural Step. Assemble the equipment. Select the proper evacuated tubes for the tests to be performed. Check the expiration date on the tubes. Label each tube using one of the following methods: (a) attaching a computer bar code label to each tube to be drawn and labeling it with your initials, or (b) manually labeling each tube with the patient’s name and date of birth, the date, and your initials. If the specimen is to be tested at an outside laboratory, complete a laboratory request form. (NOTE: Follow the medical office policy as to when the tubes should be labeled. Some offices prefer that tubes be labeled before the specimen is drawn; other offices want the tubes to be labeled right after the specimen is drawn.)

Principle. Outdated tubes may no longer contain a vacuum, and, as a result, they may not be able to draw blood into the tube. Proper labeling of blood specimens avoids a mix-up of specimens.

4. Procedural Step. Prepare the vacuum tube system. Remove the cap from the posterior needle using a twisting and pulling motion. Insert the posterior needle into the small opening on the plastic holder. Screw the plastic holder onto the Luer adapter, and tighten it securely.

Principle. An unsecured needle can fall out of its plastic holder.

5. Procedural Step. Open the sterile gauze packet, and lay it flat to allow the gauze pad to rest on the inside of its wrapper. Position the evacuated tubes in the correct order of draw. If the evacuated tube contains a powdered additive, tap the tube just below the stopper to release any additive adhering to the stopper.

Principle. If an additive remains trapped in the stopper, erroneous test results may occur.

6. Procedural Step. Place the first tube loosely in the plastic holder.

7. Procedural Step. Explain the procedure to the patient, and reassure the patient. Perform a preliminary assessment of both arms to determine the best vein to use. It also is helpful to ask the patient which arm has been used in the past to obtain blood.

Principle. Venipuncture is often a frightening experience for the patient, and reassurance should be offered to reduce apprehension.

8. Procedural Step. Apply the tourniquet. Position the tourniquet 3 to 4 inches above the bend in the elbow. The tourniquet should be snug but not tight. Ask the patient to clench the fist of the arm to which the tourniquet has been applied.

Principle. The combined effect of the pressure of the tourniquet and the clenched fist should cause the antecubital veins to stand out so that accurate selection of a puncture site can be made.

9. Procedural Step. With a tourniquet in place, thoroughly assess the veins of first one arm and then the other to determine the best vein to use.

10. Procedural Step. Position the patient’s arm. The arm with the vein selected for the venipuncture should be extended and placed in a straight line from the shoulder to the wrist with the antecubital veins facing anteriorly. The arm should be supported on the armrest by a rolled towel or by having the patient place the fist of the other hand under the elbow.

Principle. This position allows easy access to the antecubital veins.

11. Procedural Step. Thoroughly palpate the selected vein. Gently palpate the vein with the fingertips to determine the direction of the vein and to estimate its size and depth. Never leave the tourniquet on an arm for longer than 1 minute at a time. (NOTE: If you need to perform several assessments to locate the best vein, the tourniquet must be removed and reapplied after a 2-minute waiting period.)

Principle. Leaving the tourniquet on for longer than 1 minute is uncomfortable for the patient and may alter the test results.

12. Procedural Step. Remove the tourniquet and cleanse the site with an antiseptic wipe. Cleansing should be done in a circular motion, starting from the inside and moving away from the puncture site. Allow the site to air-dry; after cleansing, do not touch the area, wipe the area with gauze, or fan the area with your hand. Place the remaining supplies within comfortable reach of your nondominant hand.

Principle. Using a circular motion helps carry foreign particles away from the puncture site. The site must be allowed to air-dry to allow the alcohol enough time to destroy microorganisms on the patient’s skin. Residual alcohol entering the blood specimen can cause hemolysis, leading to inaccurate test results. In addition, residual alcohol causes the patient to experience a stinging sensation when the puncture is made. Touching or fanning the area causes contamination of the puncture site, and the cleansing process must be repeated. Items used during the procedure should be positioned so that you do not have to reach over the patient and possibly move the needle, resulting in pain, injury, or both.

13. Procedural Step. Reapply the tourniquet. Apply gloves. If you are using a needle with a safety shield, rotate the shield backward toward the holder (refer to Figure 31-13, A). Remove the cap from the needle using a twisting and pulling motion. Hold the vacuum tube system by placing the thumb of the dominant hand on top of the plastic holder and the pads of the first three fingers underneath the holder and evacuated tube. The needle should be positioned with the bevel facing up. Position the evacuated tube so that the label is facing down.