CHAPTER 3 Blood specimen collectionElaine M. Keohane* OUTLINE Safety Responsibility of the Phlebotomist in Infection Control Physiologic Factors Affecting Test Results Venipuncture Equipment for Venipuncture Selection of a Vein for Routine Venipuncture Venipuncture Procedure Venipuncture in Children Complications Encountered in Venipuncture Venipuncture in Special Situations Inability to Obtain a Blood Specimen Skin Puncture Collection Sites Precautions with Skin Puncture Equipment for Skin Puncture Skin Puncture Procedure Quality Assurance in Specimen Collection Technical Competence Collection Procedures Anticoagulants and Other Additives Requirements for a Quality Specimen Collection of Blood for Blood Culture Quality Control and Preventive Maintenance on Specimen Processing and Storage Equipment Reasons for Specimen Rejection Specimen Handling Legal Issues in Phlebotomy Objectives After completion of this chapter, the reader will be able to:
CASE STUDIES After studying the material in this chapter, the reader should be able to respond to the following case studies: Case 1 A phlebotomist asks an outpatient, “Are you Susan Jones?” After the patient answers yes, the phlebotomist proceeds by labeling the tubes and drawing the blood. What is wrong with this scenario? Case 2 A patient must have blood drawn for a complete blood count (CBC), potassium level, prothrombin time (PT), and type and screen. The phlebotomist draws blood into the following tubes in this order:
Which of the results will be affected by the incorrect order of draw? Explain. Safety Standard precautions must be followed in the collection of blood, and all specimens must be treated as potentially infectious for bloodborne pathogens. Regulations of the Occupational Safety and Health Administration (OSHA) that took effect on March 6, 1992, outlined in detail what must be done to protect health care workers from exposure to bloodborne pathogens, such as the pathogens that cause hepatitis C, hepatitis B, hepatitis D, syphilis, malaria, and human immunodeficiency virus (HIV) infection.1 Bloodborne pathogens may enter the body through an accidental injury by a sharp object, such as a contaminated needle, a scalpel, broken glass, or any other object that can pierce the skin. Cuts, skin areas with dermatitis or abrasions, and mucous membranes of the mouth, eyes, and nose may also provide a portal of entry. Indirect transmission can occur when a person touches a contaminated surface or object and then touches the mouth, eyes, nose, or nonintact skin without washing the hands. Hepatitis B virus can survive on inanimate or dried surfaces for at least 1 week.2 Hand washing is the most important practice to prevent the spread of infectious diseases. The phlebotomist should wash his or her hands with soap and running water between patients and every time gloves are removed. An alcohol-based hand rub may be used if hands are not visibly contaminated.3 Antimicrobial wipes or towelettes are less effective for hand sanitation.3 Gloves are essential personal protective equipment and must be worn during blood collection procedures. When gloves are removed, no blood from the soiled gloves should come in contact with the hands. Glove removal is covered in detail in Chapter 2. Contaminated sharps and infectious wastes should be placed in designated puncture-resistant containers. The red or red-orange biohazard sign (Figure 2-2) indicates that a container holds potentially infectious materials. Biohazard containers should be easily accessible and should not be overfilled. Responsibility of the phlebotomist in infection control Because phlebotomists interact with patients and staff throughout the day, they potentially can infect numerous people. Phlebotomists should become familiar with and observe infection control and isolation policies. Violations of policies should be reported. A phlebotomist must maintain good personal health and hygiene, making sure to have clean clothes, clean hair, and clean, short fingernails. Standard precautions must be followed at all times, with special attention to the use of gloves and hand washing. Physiologic factors affecting test results Certain physiologic variables under the control of the patient or the phlebotomist may introduce preanalytical variation in laboratory test results. Examples of these factors include posture (supine or erect), diurnal rhythms, exercise, stress, diet (fasting or not), and smoking (Box 3-1). The phlebotomist must adhere to the specific schedule for timed specimen collections and accurately record the time of collection. BOX 3-1 Some Physiologic Factors That Can Contribute to Preanalytical Variation in Test Results Posture Changing from a supine (lying) to a sitting or standing position results in a shift of body water from inside the blood vessels to the interstitial spaces. Larger molecules, such as protein, cholesterol, and iron cannot filter into the tissues, and their concentration increases in the blood.4, 5 Diurnal rhythm Diurnal rhythm refers to daily body fluid fluctuations that occur with some constituents of the blood. For example, levels of cortisol, thyroid- stimulating hormone, and iron are higher in the morning and decrease in the afternoon.4, 5 Other test values, such as the eosinophil count, are lower in the morning and increase in the afternoon.4, 5 Exercise Exercise can increase various constituents in the blood such as creatinine, total protein, creatine kinase, myoglobin, aspartate aminotransferase, white blood cell count, and HDL-cholesterol.6 The extent and duration of the increase depend on the intensity, duration, and frequency of the exercise and the time the blood specimen was collected postexercise. Stress Anxiety and excessive crying in children can cause a temporary increase in the white blood cell count.4 Diet Fasting means no food or beverages except water for 8 to 12 hours before a blood draw. If a patient has eaten recently (less than 2 hours earlier), there will be a temporary increase in glucose and lipid content in the blood. In addition, the increased lipids may cause turbidity (lipemia) in the serum or plasma, affecting some tests that require photometric measurement, such as the hemoglobin concentration and coagulation tests performed on optical detection instruments. Smoking Patients who smoke before blood collection may have increased white blood cell counts and cortisol levels.7, 8 Long-term smoking can lead to decreased pulmonary function and result in increased hemoglobin levels. Venipuncture This chapter only covers an overview of blood specimen collection; sources that provide detailed information are listed in the reference section. Equipment for venipuncture Tourniquet A tourniquet is used to provide a barrier against venous blood flow to help locate a vein. A tourniquet can be a disposable elastic strap, a heavier Velcro strap, or a blood pressure cuff. The tourniquet should be applied 3 to 4 inches above the venipuncture site and left on for no longer than 1 minute before the venipuncture is performed.9 Latex-free tourniquets are available for individuals with a latex allergy. Collection tubes The most common means of collecting blood specimens is through the use of an evacuated tube system. The system includes an evacuated tube, which can be either plastic or glass; a needle; and an adapter that is used to secure the needle and the tube. When the needle is inserted into a vein and a tube is inserted into the holder, the back of the needle pierces the stopper, allowing the vacuum pressure in the tube to automatically draw blood into the tube. For safety, OSHA recommends the use of plastic tubes whenever possible. Most glass tubes are coated with silicone to help decrease the possibility of hemolysis and to prevent blood from adhering to the sides of the tube. Evacuated tubes are available in various sizes and may contain a variety of premeasured additives. Manufacturers of evacuated tubes in the United States follow a universal color code in which the stopper color indicates the type of additive contained in the tube. Figure 3-1 provides a summary of various types of evacuated collection tubes. Additives in collection tubes Clot activators. Blood specimens for serum testing must first be allowed to clot for 30 to 60 minutes prior to centrifugation and removal of the serum.10 A clot activator accelerates the clotting process and decreases the specimen preparation time. Examples of clot activators include glass or silica particles (activates factor XII in the coagulation pathway) and thrombin (an activated coagulation factor that converts fibrinogen to fibrin) (Chapter 37). Anticoagulants. An anticoagulant prevents blood from clotting. Ethylenediaminetetraacetic acid (EDTA), citrate, and oxalate remove calcium needed for clotting by forming insoluble calcium salts. Heparin prevents clotting by binding to antithrombin in the plasma and inhibiting thrombin and activated coagulation factor X (Chapter 37). Tubes with anticoagulant must be gently inverted immediately after collection according to the manufacturer’s directions to ensure proper mixing. Tubes with anticoagulant are either tested as whole blood or are centrifuged to yield plasma. Antiglycolytic agent. An antiglycolytic agent inhibits the metabolism of glucose by blood cells. Such inhibition may be necessary if testing for the glucose level is delayed. The most commonly used antiglycolytic agent is sodium fluoride.4.5 Tubes containing sodium fluoride alone yield serum. Tubes containing sodium fluoride and an anticoagulant (such as EDTA or oxalate) yield plasma. Anticoagulated blood can be centrifuged immediately to obtain plasma for testing, thus decreasing the specimen preparation time. Separator gel. Separator gel is an inert material that undergoes a temporary change in viscosity during the centrifugation process; this enables it to serve as a separation barrier between the liquid (serum or plasma) and cells. Because this gel may interfere with some testing, serum or plasma from these tubes cannot be used with certain instruments or for blood bank procedures. Needles Venipuncture needles are sterile and are available in a variety of lengths and gauges (bore or opening size). Needles used with evacuated tube systems screw into a plastic needle holder and are double pointed. The end of the needle that is inserted into the vein is longer and has a point with a slanted side or bevel. A plastic cap covers this end of the needle and is removed prior to insertion. The end of the needle that pierces the stopper of the evacuated tube is shorter and is covered by a rubber sleeve in multiple-sample needles. The rubber sleeve prevents blood from dripping into the holder when changing tubes (Figure 3-2). Needles used with syringes are discussed below. The gauge number of a needle is inversely related to the bore size: the smaller the gauge number, the larger the bore. Needles for drawing blood range from 19 to 23 gauge.9 The most common needle size for adult venipuncture is 21 gauge with a length of 1 inch. The advantage of using a 1-inch needle is that it provides better control during venipuncture. Needle holders Needles and holders are designed to comply with OSHA’s revised Occupational Exposure to Bloodborne Pathogens Standard (effective April 18, 2001) and its requirement for implementation of safer medical devices.11 Needles and holders have safety features to prevent accidental needle sticks. Needle holders are made to fit a specific manufacturer’s needles and tubes and should not be interchanged. The holders are disposable and must be discarded after a single use with the needle still attached as required by OSHA.12 The following are some examples of safety needles and holders:
Winged blood collection set (butterfly) A winged blood collection set or butterfly consists of a short needle with plastic wings connected to thin tubing (Figure 3-5). The other end of the tubing can be connected to a needle holder for an evacuated tube, a syringe, or a blood culture bottle with the use of special adapters. Winged blood collection sets are useful in collecting specimens from children or other patients from whom it is difficult to draw blood. They also have sheathing devices to minimize the risk of needle stick injury. Examples include MONOJECTTM ANGEL WINGTM Blood Collection Set (Covidien, Mansfield, MA), Vacutainer® Safety-Lok™ and Vacutainer® Push Button Blood Collection Set (BD Medical, Franklin Lakes, NJ), VACUETTE® Safety Blood Collection Set (Greiner Bio-One, Monroe, NC), and Jelco Saf-T Wing® Blood Collection set (Smiths Medical ASD, Norwell, MA). Syringes A syringe consists of a barrel, graduated in milliliters, and a plunger. Syringe needles have a point at one end and an open hub at the other end that attaches to the barrel of the syringe. Syringes are available with different types of needle attachments and in different sizes. It is important to attach the needle securely to the syringe to prevent air from entering the system.Syringes may be useful in drawing blood from pediatric, geriatric, or other patients with tiny, fragile, or “rolling” veins that would not be able to withstand the vacuum pressure from evacuated tubes. With a syringe, the amount of pressure exerted is controlled by the phlebotomist by slowly pulling back the plunger. Syringes may also be used with winged infusion sets. If only one tube of blood is needed, the phlebotomist fills the syringe barrel with blood, removes the needle from the arm, activates the needle safety device, removes and discards the needle in a sharps container, and attaches the hub of the syringe to a transfer device to transfer the blood into an evacuated tube. An example is the BD Vacutainer® Blood Transfer Device with Luer adapter. If multiple tubes are needed, the phlebotomist can use a closed blood collection system such as the Jelco Saf-T Holder® with male Luer adapter with Saf-T Wing®butterfly needle (Smiths Medical ASD) (Figure 3-6). With this system, the butterfly needle tubing branches into a Y shape and attaches to the syringe on one side and an evacuated tube in a holder on the other side. Clamps in the tubing control the flow of blood from the arm to the syringe and then from the syringe to the evacuated tube. To prevent hemolysis when using transfer devices, only the tube’s vacuum (and not the plunger) should be used to transfer the blood from the syringe into the evacuated tube.
FIGURE 3-6 A, Jelco closed blood collection system. (Courtesy Smiths Medical ASD, Norwell, MA.) B, Device for transferring blood from syringe to vacuum tube. (1) Draw blood with syringe. (2) Close clamp. (3) Insert tube to transfer blood from syringe to tube. To fill additional tubes, open clamp, draw blood with syringe again, close clamp, and transfer. Source: (Courtesy Smiths Medical ASD, Norwell, MA.) Solutions for skin antisepsis The most common skin antiseptic is 70% isopropyl alcohol in a commercially prepared pad. The phlebotomist cleans the phlebotomy site in a circular motion, beginning in the center and working outward. The area is allowed to air-dry before the venipuncture is performed so that the patient does not experience a burning sensation after needle insertion and to prevent contamination of the specimen with alcohol. The phlebotomist must use a non-alcohol-based antiseptic to collect blood for a legal blood alcohol level.9 When a sterile site is prepared for collection of specimens for blood culture, a two-step procedure with a 30- to 60-second scrub is used in which cleansing with 70% isopropyl alcohol is followed by cleansing with 1% to 10% povidone-iodine pads, tincture of iodine, chlorhexidine compounds, or another isopropyl alcohol prep.9 Some health care facilities use a one-step application of chlorhexidine gluconate/isopropyl alcohol or povidone-70% ethyl alcohol.9 Whatever method is used, the antiseptic agent should be in contact with the skin for at least 30 seconds to minimize the risk of accidental contamination of the blood culture. Selection of a vein for routine venipuncture The superficial veins of the antecubital fossa (bend in the elbow) are the most common sites for venipuncture. There are two anatomical patterns of veins in the antecubital fossa4, 9 (Figure 3-7). In the “H” pattern, the three veins that are used, in the order of preference, are (1) the median cubital vein, which connects the basilic and cephalic veins in the antecubital fossa; (2) the cephalic vein, located on the outside (lateral) aspect of the antecubital fossa on the thumb side of the hand; and (3) the basilic vein, located on the inside (medial) aspect of the antecubital fossa. In the “M” pattern, the order of preference is the (1) median vein, (2) accessory cephalic vein, and (3) the basilic vein. The cephalic and basilic veins should only be used if the median cubital or median veins are not prominent after checking both arms. The basilic vein is the last choice due to the increased risk of injury to the median nerve and/or accidental puncture of the brachial artery, both located in close proximity to the basilic vein.9 If necessary, the phlebotomist should have the patient make a fist after application of the tourniquet; the veins should become prominent. The patient should not pump the fist because it may affect some of the test values. The phlebotomist should palpate (examine by touching) the vein with his or her index finger to determine vein depth, direction, and diameter. If a vein cannot be located in either arm, it may be necessary to examine the veins on the dorsal surface of the hand. The veins in the feet should not be used without physician permission. The policy in some institutions is to request that a second phlebotomist attempt to locate a vein in the arm or the hand before a vein in the foot is used. The veins in the inner wrist should never be used due to the high risk of injury to tendons and nerves in that area.9 Venipuncture procedure The phlebotomist uses standard precautions, which include washing hands and applying gloves at the beginning of the procedure and removing gloves and washing hands at the end of the procedure. The Clinical and Laboratory Standards Institute (CLSI) recommends the following steps:9
BOX 3-2 Order of Draw for Venipuncture9
EDTA, ethylenediaminetetraacetic acid Note: Compare the labeled tube with the patient’s identification bracelet or have the patient verify that the information on the labeled tube is correct whenever possible.
The most crucial step in the process is patient identification. The patient must verbally state his or her full name, or someone must identify the patient for the phlebotomist. In addition, at least one additional identifier needs to be checked such as the address, birth date, or the unique number on the patient’s identification bracelet (for hospitalized patients). The phlebotomist must match the patient’s full name and unique identifier with the information on the test requisition. Any discrepancies must be resolved before the venipuncture can continue. Failure to confirm proper identification can result in a life-threatening situation for the patient and possible legal ramifications for the facility. The phlebotomist must also label all tubes immediately after the blood specimen has been drawn, with the label attached to the tube, before leaving the patient’s side. Coagulation testing If only a light blue stopper coagulation tube is to be drawn for determination of the prothrombin time or activated partial thromboplastin time, the first tube drawn may be used for testing. It is no longer necessary to draw a 3-mL discard nonadditive tube before collecting for routine coagulation testing. The phlebotomist must fill tubes for coagulation testing to full volume (or to the minimum volume specified by the manufacturer) to maintain a 9:1 ratio of blood to anticoagulant. Underfilling coagulation tubes results in prolonged test values. When a winged blood collection set is used to draw a single light blue stopper tube, the phlebotomist must first partially fill a nonadditive tube or another light blue stopper tube to clear the dead air space in the tubing before collecting the tube to be used for coagulation testing. For special coagulation testing, however, a second-drawn light blue stopper tube may be required.9 Chapter 42 covers specimen collection for hemostasis testing in more detail. Venipuncture in children Pediatric phlebotomy requires experience, special skills, and a tender touch. Excellent interpersonal skills are needed to deal with distraught parents and with crying, screaming, or frightened children. Ideally, only experienced phlebotomists should draw blood from children; however, the only way to gain experience is through practice. Through experience, one learns what works in different situations. Smaller gauge (22- to 23-gauge) needles are employed.9 Use of a syringe or winged blood collection set may be advantageous for accessing small veins in young children. The child’s arm should be immobilized as much as possible so that the needle can be inserted successfully into the vein and can be kept there if the child tries to move. Use of special stickers or character bandages as rewards may serve as an incentive for cooperation; however, the protocol of the institution with regard to their distribution must be followed. Complications encountered in venipuncture Ecchymosis (bruise) Bruising is the most common complication encountered in obtaining a blood specimen. It is caused by leakage of a small amount of blood in the tissue around the puncture site. The phlebotomist can prevent bruising by applying direct pressure to the venipuncture site with a gauze pad. Bending the patient’s arm at the elbow to hold the gauze pad in place is not effective in stopping the bleeding and may lead to bruising. Hematoma A hematoma results when leakage of a large amount of blood around the puncture site causes the area to rapidly swell. If swelling begins, the phlebotomist should remove the needle immediately and apply pressure to the site with a gauze pad for at least 2 minutes. Hematomas may result in bruising of the patient’s skin around the puncture site. Hematomas can also cause pain and possible nerve compression and permanent damage to the patient’s arm. Hematomas most commonly occur when the needle goes through the vein or when the bevel of the needle is only partially in the vein (Figure 3-8, B and C) and when the phlebotomist fails to remove the tourniquet before removing the needle or does not apply enough pressure to the site after venipuncture. Hematomas can also form after inadvertent puncture of an artery. Fainting (syncope) Fainting is also a common complication encountered. Before drawing blood, the phlebotomist should always ask the patient whether he or she has had any prior episodes of fainting during or after blood collection. The CLSI does not recommend the use of ammonia inhalants to revive the patients because they may trigger an adverse response that could lead to patient injury.9 The phlebotomist should follow the protocol at his or her facility. If the patient begins to faint, the phlebotomist should remove and discard the needle immediately, apply pressure to the site with a gauze pad, lower the patient’s head, and loosen any constrictive clothing. The phlebotomist should also notify the designated first-aid providers at the facility. The incident should be documented. Hemoconcentration Hemoconcentration is an increased concentration of cells, larger molecules, and analytes in the blood as a result of a shift in water balance. Hemoconcentration can be caused by leaving the tourniquet on the patient’s arm for too long. The tourniquet should not remain on the arm for longer than 1 minute. If it is left on for a longer time because of difficulty in finding a vein, it should be removed for 2 minutes and reapplied before the venipuncture is performed.9 Hemolysis The rupture of red blood cells with the consequent escape of hemoglobin—a process termed hemolysis—can cause the plasma or serum to appear pink or red. Hemolysis can occur if the phlebotomist used too small a needle during a difficult draw; drew the blood through an existing hematoma; pulled back too quickly on the plunger of a syringe; forced blood into a tube from a syringe by pushing the plunger; mixed a tube too vigorously; or contaminated the specimen with alcohol or water at the venipuncture site or in the tubes. Hemolysis also can occur physiologically as a result of hemolytic anemias. Hemolyzed specimens can alter test results, such as levels of potassium, lactate dehydrogenase, and aspartate aminotransferase, which can result in patient treatment errors.10 Petechiae Petechiae are small red spots indicating that small amounts of blood have escaped into the skin. Petechiae indicate a possible hemostasis abnormality and should alert the phlebotomist to be aware of possible prolonged bleeding. Allergies Some patients may be allergic to skin antiseptic substances and adhesive bandages and tape. The phlebotomist should use hypoallergenic tape or apply pressure manually until the bleeding has stopped completely. The phlebotomist should also determine if the patient has a latex sensitivity before the phlebotomy procedure. Nerve damage The phlebotomist must select the appropriate veins for venipuncture and should not blindly probe the arm with the needle or try to laterally relocate the needle. If a nerve has been affected, the patient may complain about shooting or sharp pain, tingling, or numbness in the arm. The phlebotomist should immediately remove and discard the needle, apply pressure with a gauze pad, and collect the blood from the other arm. Seizures Patients occasionally experience seizures because of a preexisting condition or as a response to the needle stick. If a seizure occurs, the phlebotomist should immediately remove and discard the needle, apply pressure with a gauze pad, and notify the nurse or designated first-aid providers at the facility. The phlebotomist should also ensure the patient’s safety by preventing injury from nearby objects. Vomiting If the patient begins vomiting, the phlebotomist should provide the patient an appropriate container and tissues, notify the nurse or designated first-aid providers at the facility, and ensure the patient’s head is positioned so that he or she does not aspirate vomit. Venipuncture in special situations Edema Swelling caused by an abnormal accumulation of fluid in the intercellular spaces of the tissues is termed edema. The most common cause is infiltration of the tissues by the solution running through an incorrectly positioned intravenous catheter. Edematous sites should be avoided for venipuncture because the veins are hard to find and the specimens may become contaminated with tissue fluid. Obesity In obese patients, veins may be neither readily visible nor easy to palpate. Sometimes the use of a blood pressure cuff can aid in locating a vein. The cuff should not be inflated any higher than 40 mm Hg and should not be left on the arm for longer than 1 minute.9 The phlebotomist should not probe blindly in the patient’s arm because nerve damage may result. Burned, damaged, scarred, and occluded veins Burned, damaged, scarred, and occluded veins should be avoided because they do not allow the blood to flow freely and may make it difficult to obtain an acceptable specimen. Intravenous therapy Drawing blood from an arm with an intravenous (IV) infusion should be avoided if possible; the phlebotomist should draw the blood from the opposite arm without the IV. If there is no alternative, blood should be drawn below the IV with the tourniquet also placed below the IV site. Prior to venipuncture, the phlebotomist should ask an authorized caregiver to stop the infusion for 2 minutes before the specimen is drawn. The phlebotomist should note on the requisition and the tube that the specimen was obtained from an arm into which an IV solution was running, indicating the arm and the location of the draw relative to the IV.4, 9 The phlebotomist should always follow the protocol established at his or her facility. Mastectomy patients The CLSI requires physician consultation before blood is drawn from the same side as a prior mastectomy (removal of the breast), even in the case of bilateral mastectomies.9 The pressure on the arm that is on the same side as the mastectomy from a tourniquet or blood pressure cuff can lead to pain or lymphostasis from accumulating lymph fluid. The other arm on the side without a mastectomy should be used. Inability to obtain a blood specimen Failure to draw blood One reason for failure to draw blood is that the vein is missed, often because of improper needle positioning. The needle should be inserted completely into the vein with the bevel up and at an angle of less than 30 degrees.9 Figure 3-8ncture is made on the palmar surf shows reasons for unsatisfactory flow of blood. It is sometimes possible to reposition the needle in the vein by slightly withdrawing or advancing the needle, but only an experienced phlebotomist should attempt this. The phlebotomist should never attempt to relocate the needle in a lateral direction because such manipulation can cause pain and risk a disabling nerve injury to the patient. Occasionally an evacuated tube has insufficient vacuum, and insertion of another tube yields blood. Keeping extra tubes within reach during blood collection can avoid a recollection when the problem is a technical issue associated with the tube. Each institution should have a policy covering the proper procedure when a blood specimen cannot be collected. If two unsuccessful attempts at collection have been made, the CLSI recommends that the phlebotomist seek the assistance of another practitioner with blood collection expertise.9 Another individual can make two attempts to obtain a specimen. If a second person is unsuccessful, the physician should be notified. Patient refusal The patient has the right to refuse to give a blood specimen. If gentle urging does not persuade the patient to allow blood to be drawn, the phlebotomist should alert the nurse, who will either talk to the patient or notify the physician. The phlebotomist must not force an uncooperative patient to have blood drawn; it can be unsafe for the phlebotomist and for the patient. In addition, forcing a patient of legal age and sound mind to have blood drawn against his or her wishes can result in charges of assault and battery or unlawful restraint. If the patient is a child and the parents offer to help hold the child, it is usually acceptable to proceed. Any refusals or problems should be documented for legal reasons. Missing patient For hospitalized patients, if the patient is not in his or her room, the absence should be reported to the nursing unit so that the nurses are aware that the specimen was not obtained. Skin puncture Skin puncture is the technique of choice to obtain a blood specimen from newborns and pediatric patients. In adults skin puncture may be used in patients who are severely burned and whose veins are being reserved for therapeutic purposes; in patients who are extremely obese; and in elderly patients with fragile veins. Blood obtained from skin puncture is a mixture of blood from venules, arterioles, capillaries, and interstitial and intracellular fluids.9 After the puncture site is warmed, the specimen more closely resembles arterial blood. The phlebotomist should note that the specimen was obtained by skin puncture because those specimens may generate slightly different test results.13 For example, higher glucose values are found in specimens obtained by skin puncture compared with those obtained by venipuncture, and this difference can be clinically significant.13 It is especially important to note the specimen type when a glucose tolerance test is performed or when glucometer results are compared with findings from venous specimens. Collection sites The site of choice for skin puncture in infants under 1 year of age is the lateral (outside) or medial (inside) plantar (bottom) surface of the heel (Figure 3-9, A). In children older than 1 year of age and in adults, the palmar surface of the distal portion of the third (middle) or fourth (ring) finger on the nondominant hand may be used.13 The puncture on the finger should be made perpendicular to the fingerprint lines (Figure 3-9, B). Fingers of infants should not be punctured because of the risk of serious bone injury. Warming the site can increase the blood flow sevenfold.13 The phlebotomist should warm the site with a commercial heel warmer or a warm washcloth to a temperature no greater than 42° C and for no longer than 3 to 5 minutes.13 The phlebotomist should clean the skin puncture site with 70% isopropyl alcohol and allow it to air-dry. Povidone-iodine should not be used because of possible specimen contamination, which could falsely elevate levels of potassium, phosphorus, or uric acid.13 Precautions with skin puncture The finger or heel must be securely immobilized. Heel punctures in infants should not be made more than 2 mm deep because of the risk of bone injury and possible infection (osteomyelitis).13 In premature infants, a puncture device that makes an incision with even less depth is preferred. The phlebotomist should not puncture an area that is swollen, bruised, infected, or already has been punctured. In addition phlebotomists should not perform skin puncture in patients with edema, dehydration, or poor peripheral circulation because specimen integrity and test accuracy may be compromised. The first drop of blood should be wiped away with a clean gauze pad to prevent contamination of the specimen with tissue fluid and to facilitate the free flow of blood.13 Equipment for skin puncture Devices for skin puncture contain sterile lancets that puncture or sterile blades that make a small incision in the skin. The lancet or blade is spring-loaded in the device, and when activated by the phlebotomist, pierces the skin. Devices are single-use, disposable, and have retractable blades in compliance with OHSA safety standards.11 Devices are available for newborns, children, and adults that produce punctures or incisions of varying depths in the skin. Containers for collecting blood from skin puncture include capillary tubes and microcollection tubes.13 Capillary tubes of various sizes are available with or without heparin. OSHA recommends the use of plastic tubes or Mylar-coated glass tubes to avoid injury by broken glass and exposure to bloodborne pathogens. Microcollection tubes are preferred and are available with or without additives. The cap colors on microcollection tubes correspond with the color coding system for evacuated tubes. The order of draw, however, is different for microcollection tubes (Box 3-3). The EDTA microcollection tube should be filled first to ensure adequate volume and accurate hematology results, especially for platelets, which tend to aggregate at the site of puncture.13 Skin puncture specimens should be labeled with the same information as required for evacuated tubes. Examples of skin puncture equipment are shown in Figure 3-10.
FIGURE 3-10 Examples of equipment used for skin puncture. A, Various puncture devices. B, Various microcollection tubes. Source: (A, B Courtesy Dennis J. Ernst, MT[ASCP], Director, Center for Phlebotomy Education, Inc.) BOX 3-3 Order of Draw for Skin Puncture13
EDTA, ethylenediaminetetraacetic acid Skin puncture procedure The phlebotomist uses standard precautions that include washing hands and applying gloves at the beginning of the procedure and removing gloves and washing hands at the end of the procedure. CLSI recommends the following steps:13
Preparation of peripheral blood films Peripheral blood films can be made directly from skin puncture blood or from a tube of EDTA-anticoagulated venous blood. With a skin puncture, the phlebotomist must remember to wipe away the first drop of blood and use the second drop to make the blood film. Chapter 16 covers preparation of blood films in detail. Quality assurance in specimen collection To ensure accurate patient test results, it is essential that the blood collection process, which includes specimen handling, be monitored. Patient diagnosis and medical care are based on the outcomes of these tests. The following areas should be monitored. Technical competence The individual performing phlebotomy should be trained properly in all phases of blood collection. Certification by an appropriate agency is recommended. Continuing education is required to keep current on all the changes in the field. Competency should be assessed and documented on an annual basis for each employee performing phlebotomy. Collection procedures Periodic review of collection procedures is essential to maintaining the quality of specimens. This includes a review of policies on the allowable number of blood collection attempts for unsuccessful blood draws, procedures for what to do when the patient is unavailable for a blood draw, or when the patient refuses a draw. Proper patient preparation and correct patient identification are crucial. The correct tube or specimen container must be used. Anticoagulants and other additives The phlebotomist must follow the manufacturer’s instructions with regard to mixing all tubes with additives to ensure proper specimen integrity and prevent formation of microclots in the anticoagulated tubes. All tubes should be checked for cracks, expiration dates, and discoloration or cloudiness, which could indicate contamination. New lot numbers of tubes must be checked to verify draw and fill accuracy. When blood is collected in the light blue stopper tube for coagulation, a 9:1 ratio of blood to anticoagulant must be maintained to ensure accurate results. Specimens must be stored and handled properly before testing. Requirements for a quality specimen Requirements for a quality specimen are as follows:
Collection of blood for blood culture Each facility should monitor its blood culture contamination rate and keep that rate lower than 3% as recommended by the CLSI and the American Society for Microbiology.14, 15 Higher blood culture contamination rates should prompt an investigation of the causes and implementation of the appropriate corrective action. False-positive blood culture results lead to unnecessary testing and treatment for patients and increased costs for the institution.14, 15 A 2012 CDC-funded Laboratory Medicine Best Practices systematic review and meta-analysis concluded that the use of well-trained phlebotomy teams and proper venipuncture technique was an effective way to reduce blood culture contamination rates.15 Quality control and preventive maintenance for specimen processing and storage equipment Thermometers used in refrigerators and freezers in which specimens are stored should be calibrated annually, or only thermometers certified by the National Bureau of Standards should be used. Centrifuges should be maintained according to the manufacturer’s instructions for cleaning and timing verification. Reasons for specimen rejection A laboratory result is only as good as the integrity of the specimen provided. Specimens are rejected for conditions that may result in identification errors or inaccurate results. Box 3-4lists some reasons for specimen rejection. BOX 3-4 Reasons for Specimen Rejection
*Lipemic specimens cannot be used for certain tests; however, the phlebotomist has no control over this aspect. Collection of a specimen after patient fasting may be requested to try to reduce the potential for lipemia. Specimen handling Proper handling of specimens begins with the initiation of the test request and ends when the specimen is tested. Accurate test results depend on what happens to the specimen during that time. This pretesting period is called the preanalytical phase of the total testing process (Chapter 5). Blood collected into additive tubes must be inverted to mix the additive and blood according to manufacturer’s instructions. Shaking can result in hemolysis of the specimen and lead to specimen rejection or inaccurate test results. Specimens should be transported in an upright position to ensure complete clot formation and reduce agitation, which can also result in hemolysis. Exposure of the blood specimen to light can cause falsely decreased values for bilirubin, beta-carotene, vitamin A, and porphyrins.9 For certain tests, the specimens need to be chilled, not frozen, and should be placed in an ice-water bath to slow down cellular metabolism. Examples of these tests include ammonia, lactic acid, parathyroid hormone, and gastrin.9 Other tests, such as the cold agglutinin titer, require that specimens be kept warm to ensure accurate results. If the specimen is refrigerated before the serum is removed, the antibody in the serum will bind to the red blood cells, thus falsely decreasing the serum cold agglutinin titer. To ensure accurate results, cells and serum must be separated within 2 hours of collection for tests such as those measuring glucose, potassium, and lactate dehydrogenase.10 The CLSI provides recommendations to laboratories for the maximum time uncentrifuged specimens are stable at room temperature for various tests based on studies in the literature.10 Legal issues in phlebotomy There are many daily practices in health care that, if performed without reasonable care and skill, can result in a lawsuit. Facilities have been and will continue to be held legally accountable for the actions of those who collect blood for diagnostic testing. Two areas of particular concern to phlebotomists are breach of patient confidentiality and patient misidentification. Unless there is a clinical need to know or a patient has given written permission, no one has a right to patient information. A patient will not be misidentified if correct procedures for specimen collection are followed. Phlebotomists often are called to testify in court in cases involving blood alcohol levels. The phlebotomist is asked about patient identification procedures and skin antisepsis. Only alcohol-free antiseptics should be used for skin antisepsis in such cases. Soap and water may be used if no other cleaners are available. To minimize the risk of legal action, the phlebotomist should do the following:
Summary
Now that you have completed this chapter, go back and read again the case studies at the beginning and respond to the questions presented. Review questions Answers can be found in the Appendix.
References
*The author extends appreciation to Carole A. Mullins, whose work in prior editions provided the foundation for this chapter. |
What is the minimum number of evacuated tubes required to collect a CBC and a PT when using a winged infusion set?
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