PMLS 2 Lecture 7: Preanalytical Considerations PDF

PMLS 2 MT TERM 103 02 LECTURE \ ANINON LECTURE 7: PREANALYTICAL CONSIDERATIONS OUTLINE I. REFERENCE RANGES/INTERVALS II. BASAL STATE III. PHYSIOLOGICAL VARIABLES a. Altitude b. Dehydration c. Diet d. Diurnal/Circadian Variations e. Drug Therapy f. Exercise g. Fever h. Gender i. Intramuscular Injecti...

PMLS 2 MT TERM 103 02 LECTURE \ ANINON LECTURE 7: PREANALYTICAL CONSIDERATIONS OUTLINE I. REFERENCE RANGES/INTERVALS II. BASAL STATE III. PHYSIOLOGICAL VARIABLES a. Altitude b. Dehydration c. Diet d. Diurnal/Circadian Variations e. Drug Therapy f. Exercise g. Fever h. Gender i. Intramuscular Injection i. Jaundice j. Position k. Pregnancy l. Smoking m. Stress n. Temperature and Humidity IV.PROBLEM SITES a. Burns, Scars, and Tattoos b. Damaged Veins c. Edema d. Hematoma e. Mastectomy f. Obesity V. VASCULAR ACCESS DEVICES (VADS) AND SITES a. Arterial Line b. Arteriovenous Shunt, Fistula, or Graft c. Blood Sampling Device d. Heparin or Saline Lock e. Intravenous Sites f. Previously Active IV Sites g. Central Vascular Access Devices VI. PATIENT COMPLICATIONS AND CONDITIONS a. Allergies to Equipment and Supplies b. Excessive Bleeding c. Fainting d. Nausea and Vomiting e. Pain f. Petechiae g. Seizures/Convulsion VII. PROCEDURAL ERROR RISKS a. Hematoma Formation b. Iatrogenic Anemia c. Inadvertent Arterial Puncture d. Infection e. Nerve Injury f. Reflux of Additive g. Vein Damage VIII. SPECIMEN QUALITY CONCERNS a. Hemoconcentration b. Hemolysis c. Partially Filled Tubes d. Specimen Contamination e. Wrong or Expired Collection Tube IX. TROUBLESHOOTING FAILED VENIPUNCTURE a. Tube Position b. Needle Position c. Collapsed Vein d. Tube Vacuum OBJECTIVES List and describe the physiological variables that influence laboratory test results and identify the tests most affected by each one List problem areas to avoid in site selection, identify causes for concern, and describe procedures to follow when encountering each. Identify and describe various vascular access sites and devices and explain what to do when they are encountered Identify, describe, and explain how to handle patient complications associated with blood collection. Identify, describe, and explain how to avoid or handle procedural error risks, specimen quality concerns, and reasons for failure to draw blood. OVERVIEW The preanalytical (before analysis) or pre-examination phase of the testing process begins for the laboratory when a test is ordered and ends when testing begins. Numerous factors associated with this phase of the testing process, if not properly addressed, can lead to errors that can compromise specimen quality, jeopardize the health and safety of the patient, and ultimately increase the cost of medical care. Since each blood collection situation is unique, a phlebotomist must have—in addition to the technical skills needed to perform a blood draw—the ability to recognize preanalytical factors and address them, if applicable, to avoid or reduce any negative impact. This chapter addresses physiological variables, problem venipuncture sites, various types of vascular access devices, patient complications and conditions, procedural errors, specimen quality issues, and how to troubleshoot failed venipuncture. REFERENCE RANGES/ INTERVALS Most tests are performed to confirm health or to screen for, diagnose, or monitor disease. To be properly evaluated, test results typically need to be compared with results expected of healthy individuals. Consequently, result values for most tests are established using specimens from normal, healthy individuals. Because results vary somewhat from person to person, the results used for comparison become a range of values with high and low limits, commonly called a reference range or reference interval. Most reference ranges are for healthy fasting individuals. Although less common, some tests have reference ranges for specific situations, such as patients who are ill or those being treated for certain disorders, such as diabetes. TRANS: PREANALYTICAL CONSIDERATIONS o KEY POINT One way a physician evaluates a patient’s test results is by comparing them to reference ranges and, if applicable, previous results on the same patient. If a specimen has been compromised and the results are not valid, a physician could make a decision based upon incorrect information and thus jeopardize the patient’s care. Basal state refers to the resting metabolic state of the body early in the morning after fasting for approximately 12 hours. A basal-state specimen is ideal for establishing reference ranges on inpatients because the effects of diet, exercise, and other controllable factors on test results are minimized or eliminated. Basal state is influenced by a number of physiologic patient variables such as age, gender, and conditions of the body that cannot be eliminated. BASAL STATE FYI Analytes generally take weeks to adapt to high elevations; however, they adapt to a return to sea level within days. Dehydration (decrease in total body fluid), which occurs, for example, with o persistent vomiting or diarrhea, o causes hemoconcentration, a condition in which blood components that cannot easily leave the bloodstream become concentrated in the smaller plasma volume. Blood components affected include o RBCs, o enzymes, o iron (Fe), o calcium (Ca), o sodium (Na), and o coagulation factors. Consequently, results on specimens from dehydrated patients may not accurately reflect the patient’s normal status. In addition, it is often difficult to obtain blood specimens from dehydrated patients. FYI Outpatient specimens are not basal-state specimens and may have slightly different reference ranges (normal values). PHYSIOLOGICAL VARIABLES AGE Values for some blood components vary considerably depending upon the age of the patient. o For example, red blood cell (RBC) and white blood cell (WBC) values are normally higher in newborns than in adults. Some physiological functions such as kidney function decrease with age. ALTITUDE Test results for some blood analytes show significant variation at higher elevations compared with results at sea level. Red blood cell (RBC) counts are a prime example. o RBCs carry oxygen. o Decreased oxygen levels at higher altitudes → cause the body to produce more RBCs to meet the body’s oxygen requirements; the higher the altitude, the greater the increase. o Thus RBC counts and related determinations such as hemoglobin (Hgb) and hematocrit (Hct) have higher reference ranges at higher elevations. o C-reactive protein and uric acid → increase at higher elevations as well o Urinary creatinine (which in turn affects creatinine clearance tests) and plasma renin → analytes that decrease in value at increased altitude For example, creatinine clearance, a measure of kidney function, is directly related to the age of the patient, which must be factored in when test results are being calculated. DEHYDRATION DIET Blood analyte composition can be altered by the ingestion of food and drink. As a result, blood specimens collected soon after a meal or snack are unsuitable for many laboratory tests. Diet effects on analytes are generally temporary and vary depending upon the amount and type of food or drink and the length of time between ingestion and specimen collection. Requiring a patient to fast or follow a special diet eliminates most dietary influences on testing. Patients are typically asked to fast approximately 8 to 12 hours, depending on the test. BSMT-1D | CATANPATAN 2 TRANS: PREANALYTICAL CONSIDERATIONS Fasting is normally done overnight after the last evening meal, with specimens collected the following morning before the patient has eaten. KEY POINT Patients are allowed to drink water during fasting unless they are NPO for another procedure. Refraining from drinking water while fasting can result in dehydration, which can negatively affect test results and also make blood collection more difficult. The following are examples of how some analytes can be significantly affected by the consumption of certain types of food or drink and the excess consumption of some fluids. o Ammonia, urea, and uric acid levels → may be elevated in patients on high-protein diets. o Cortisol and ACTH levels → have been shown to increase with the consumption of beverages containing caffeine. o Glucose (blood sugar) levels → increase dramatically with the ingestion of carbohydrates or sugar-laden substances but return to normal within 2 hours if the patient has normal glucose metabolism. Eating carbohydrates can also increase insulin levels. o o Lipemia can be present for up to 12 hours, which is why accurate testing of triglycerides (a type of lipid) requires a 12-hour fast. In addition, some chemistry tests cannot be performed on lipemic specimens because the cloudiness interferes with the testing procedure. KEY POINT Lipemia in a fasting specimen is rare. When a test requires a fasting specimen but the serum or plasma sample submitted is lipemic, it is a clue that the patient may not have been fasting. o o FYI Malnutrition and starvation also affect the composition of blood analytes. Long-term starvation decreases cholesterol, triglycerides, and urea levels and increases creatinine, ketone, and uric acid level The levels of many blood components normally exhibit diurnal (happening daily) or circadian (having a 24-hour cycle) variations or fluctuations. Factors that play a role in diurnal variations include o posture, o activity, o eating, o daylight and darkness, o and being awake or asleep. For example, melatonin levels are affected by light; o they increase at night, when it is dark, o decrease during daylight hours. Maximum renin and thyroid-stimulating hormone (TSH) levels → normally occur in the predawn hours of the morning during sleep, Peak cortisol levels → normally occur later in the morning, around 8:00 A.M. Hgb levels → can decrease and electrolyte balance can be altered by drinking excessive amounts of water and other fluids. Lipid levels → increase with ingestion of foods such as butter or margarine, cheese, cream, and some enteral (tube feeding) preparations. ▪ (Lipid is a term meaning fat-soluble; it is used to describe certain fatty substances of animal or vegetable origin.) ▪ Abnormally increased blood lipid content is called lipemia. ▪ Lipids do not dissolve in water and thus high levels of lipids are visible in serum or plasma, causing it to appear milky (cloudy white) or turbid, and the specimen is described as being lipemic Left to right: Lipemic, icteric, and normal specimen Memory Jogger The word root lip means “fat.” To associate lipemic with fat, think “fat lip” or visualize a big fat white cloud, because fats make the specimen appear cloudy white. Some test methods that detect occult (hidden) blood in stool specimens also detect similar substances in meat and certain vegetables. Consequently, a special diet that eliminates these foods must be followed for several days before the specimen is collected. Triglycerides, certain liver enzymes, and other liver function analytes → are increased by chronic consumption or recent ingestion of large amounts of alcohol, which can also cause hypoglycemia. DIURNAL/CIRCADIAN VARIATIONS Other blood components that exhibit diurnal variation with highest levels occurring in the morning include o aldosterone, o bilirubin, o cortisol, o hemoglobin, o insulin, o iron, o potassium, o testosterone, and o RBCs. Blood levels of eosinophils, creatinine, glucose, growth hormone (GH), triglycerides, and phosphate are normally lowest in the morning. Diurnal variations can be large. o For example the levels of cortisol, TSH, and iron can differ by 50% or more between morning and late afternoon. BSMT-1D | CATANPATAN 3 TRANS: PREANALYTICAL CONSIDERATIONS KEY POINT Tests influenced by diurnal variation are often ordered as timed tests; it is important to collect them as close to the time ordered as possible. DRUG THERAPY Some drugs alter physiological functions, causing changes in the concentrations of certain blood analytes. The effect may be desired or an unwanted side effect or sensitivity. Consequently, it is not uncommon for physicians to monitor levels of specific blood analytes while a patient is receiving drug therapy. The following are just a few examples of drugs that can alter physiologic function and the analytes they affect: o Chemotherapy drugs → can cause a decrease in blood cells, especially WBCs and platelets. o Many drugs are toxic to the liver → as evidenced by increased levels of liver enzymes such as aspartate aminotransaminase (AST)—also called serum glutamic-oxaloacetic transaminase (SGOT), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) and decreased production of clotting factors. o Opiates → such as morphine increase levels of liver and pancreatic enzymes. o Oral contraceptives → can affect the results of many tests. ▪ For example, they can elevate the erythrocyte sedimentation rate (ESR) and decrease levels of vitamin B12. o Steroids and diuretics → can cause pancreatitis and an increase in amylase and lipase values. o Thiazide diuretics → can elevate calcium and glucose levels and decrease sodium and potassium levels. Other thiazide-type medications that lower blood volume can increase blood levels of nitrogenous waste such as urea, a condition called azotemia Drugs can also interfere with the actual test procedure, causing false increases or decreases in test results. A drug may compete with the test reagents for the substance being tested, causing a falsely low or falsenegative result, or the drug may enhance the reaction, causing a falsely high or false-positive result. Although it is ultimately up to the physician to prevent or recognize and eliminate drug interferences, this can be a complicated issue that requires cooperation between the physician, pharmacy, and laboratory to make certain that test results are not affected by medications. FYI An acronym for substances that interfere in the testing process is CRUD, which stands for “compounds reacting unfortunately as the desired.” EXERCISE Exercise affects a number of blood components, raising levels of some and lowering levels of others. Effects vary, depending on the patient’s physical condition and the duration and intensity of the activity. However, moderate to strenuous exercise appears to have the greatest effect. Levels typically return to normal soon after the activity is stopped. The following are examples of the effects of exercise on a number of blood components: o Arterial pH and PaCO2 levels are reduced by exercise. o Glucose, creatinine, insulin, lactic acid, and total protein can be elevated by moderate muscular activity. o Potassium (K+) is released from the cells during exercise, increasing levels in the plasma. Levels generally return to normal after several minutes of rest. CAUTION: The simple exercise of pumping the hand (i.e., making and releasing a fist) during venipuncture is enough to erroneously increase potassium levels. o FYI Athletes generally have higher resting levels of skeletal muscle enzymes, and exercise produces less of an increase. o Phlebotomists can play a role in this effort by noting on the requisition when they observe medication being administered just prior to blood collection. KEY POINT According to CAP guidelines, drugs that interfere with blood tests should be stopped or avoided 4 to 24 hours prior to obtaining the blood sample for testing. Drugs that interfere with urine tests should be avoided for 48 to 72 hours prior to the urine sample collection. Skeletal muscle enzyme levels are increased by exercise, with levels of creatine kinase (CK) and lactate dehydrogenase (LDH) remaining elevated for 24 hours or more. Vigorous exercise shortly before blood collection can temporarily increase cholesterol levels by 6% or more. ▪ Levels can remain elevated for up to an hour after the exercise has stopped. ▪ Vigorous or sustained exercise can also affect hemostasis. ▪ For example, an increased number of platelet clumps were seen in a study of runners evaluated immediately after running the Boston marathon. FEVER Fever affects the levels of a number of hormones. Fever-induced hypoglycemia → increases insulin levels, followed by a rise in glucagon levels. Fever also increases cortisol and may disrupt its normal diurnal variation. GENDER A patient’s gender affects the concentration of a number of blood components. Most differences are apparent only after sexual maturity and are reflected in separate normal values for males and females. For example, RBC, Hgb, and Hct normal values are higher for males than for females. BSMT-1D | CATANPATAN 4 TRANS: PREANALYTICAL CONSIDERATIONS o INTRAMUSCULAR INJECTION A recent intramuscular injection can increase levels of creatine kinase (CK) and the skeletal muscle fraction of LDH. Consequently, it is recommended that CK and LDH levels be drawn before intramuscular injection or at least 1 hour after injection. Muscular trauma from injuries or surgery can also increase CK levels. JAUNDICE Jaundice, also called icterus, is a condition characterized by increased bilirubin (a product of the breakdown of RBCs) in the blood, leading to deposits of yellow bile pigment in the skin, mucous membranes, and sclerae (whites of the eyes), giving the patient a yellow appearance The term icteric means relating to or marked by jaundice and is used to describe serum, plasma, or urine specimens that have an abnormal deep yellow to yellowbrown color due to high bilirubin levels The abnormal color can interfere with chemistry tests based on color reactions, including reagent-strip analyses on urine. KEY POINT Jaundice in a patient may indicate liver inflammation caused by hepatitis B or C virus. POSITION Body position before and during blood collection can influence specimen composition. Going from supine (lying down on the back) to an upright sitting or standing position causes blood fluids to filter into the tissues, decreasing plasma volume in an adult up to 10%. Only protein-free fluids can pass through the capillaries; consequently the blood concentration of components that are protein in nature or bound to protein—such as aldosterone, bilirubin, blood cells, calcium, cholesterol, iron, protein, and renin—increases. In most cases the concentration of freely diffusible blood components is not affected by postural changes. Nevertheless, a significant increase in potassium (K􏰌) levels occurs within 30 minutes of standing; this has been attributed to the release of intracellular potassium from muscle. Other examples of the effects of posture changes include the following: o A change in position from lying to standing can cause up to a 15% variation in total and high-density lipoprotein (HDL) cholesterol results. KEY POINT The National Cholesterol Education Program recommends that lipid profiles be collected in a consistent manner after the patient has been either lying down or sitting quietly for a minimum of 5 minutes. o Plasma aldosterone and renin change more slowly but can double within an hour. ▪ Consequently patients are required to be recumbent (lying down) for at least 30 minutes prior to aldosterone specimen collection, and plasma renin-activity levels require documentation of the patient’s position during collection. The RBC count on a patient who has been standing for approximately 15 minutes will be higher than a basal-state RBC count on that patient. KEY POINT Calling outpatients into the drawing area and having them sit in the drawing chair while paperwork related to the draw is readied can help minimize effects of postural changes on some analytes. PREGNANCY Pregnancy causes physiologic changes in many body systems. Consequently results of a number of laboratory tests must be compared with reference ranges established for pregnant populations. For example, increases in body fluid, which are normal during pregnancy, have a diluting effect on the RBCs, leading to lower RBC counts. SMOKING A number of blood components are affected by smoking. The extent of these effects depends upon the number of cigarettes smoked. Patients who smoke prior to specimen collection may have increased cholesterol, cortisol, glucose, growth hormone, and triglyceride levels as well as WBC counts. Chronic smoking often leads to decreased pulmonary function and increased RBC counts and hemoglobin levels. Smoking can also affect the body’s immune response, typically lowering the concentrations of immunoglobulins IgA, IgG, and IgM but increasing levels of IgE. FYI Skin-puncture specimens may be difficult to obtain from smokers because of impaired circulation in the fingertips. Emotional stress such as anxiety, fear, or trauma can cause transient (short-lived) elevations in WBCs. o For example, studies of crying infants have demonstrated marked increases in WBC counts, which returned to normal within 1 hour after the crying stopped. o Consequently CBC or WBC specimens on an infant are ideally obtained after the infant has been sleeping or resting quietly for at least 30 minutes. If they are collected while an infant is crying, this should be noted on the report. FYI: Studies in psychoneuroimmunology (PNI)—a field that deals with the interactions between the brain, the endocrine system, and the immune system—have demonstrated that receptors on the cell membrane of WBCs can sense stress in a person and react by increasing cell numbers. Stress is also known to decrease serum iron levels and increase adrenocorticotropic hormone (ACTH), catecholamine, and cortisol levels. Other hormones that can be affected include aldosterone and TSH, and GH in children. STRESS BSMT-1D | CATANPATAN 5 TRANS: PREANALYTICAL CONSIDERATIONS TEMPERATURE AND HUMIDITY Environmental factors such as temperature and humidity can affect test values by influencing the composition of body fluids. Acute heat exposure causes interstitial fluid to move into the blood vessels, increasing plasma volume and influencing its composition. Extensive sweating without fluid replacement, on the other hand, can cause hemoconcentration. Environmental factors associated with geographic location are accounted for when reference values are established. FYI Temperature and humidity in the laboratory are closely monitored to maintain specimen integrity and ensure proper functioning of equipment. KEY POINT Phlebotomists on early-morning rounds in hospitals or nursing homes are often the first ones to notice edema from infiltrated IVs and should alert the appropriate personnel to the problem. A hematoma is a swelling or mass of blood (often clotted) that can be caused by blood leaking from a blood vessel during or following venipuncture. A large bruise eventually spreads over the surrounding area. Venipuncture through an existing hematoma is painful and can result in collection of a specimen that is contaminated with hemolyzed blood from outside the vein and unsuitable for testing. Venipuncture in the area surrounding a hematoma may also be painful. In addition, obstruction of blood flow by the hematoma and the effects of the coagulation process may lead to inaccurate test results on the specimen. HEMATOMA PROBLEM SITES BURNS, SCARS, AND TATTOOS Avoid burned, scarred, or tattooed areas. Veins are difficult to palpate or penetrate in these areas. Healed burn sites and other areas with extensive scarring may have impaired circulation and can therefore yield erroneous test results. Newly burned areas are painful and also susceptible to infection. Tattooed areas can have impaired circulation, may be more susceptible to infection, and contain dyes that can interfere with testing. KEY POINT If you have no choice but to draw in an area with a tattoo, try to insert the needle in a spot that does not contain dye. Some patients’ veins feel hard and cord-like and lack resiliency because they are occluded or obstructed. These veins may be sclerosed (hardened) or thrombosed (clotted) from the effects of inflammation, disease, or chemotherapy drugs. Scarring caused by numerous venipunctures—as occurs in regular blood donors, persons with chronic illnesses, and illegal IV drug users—can also harden veins. Damaged veins are difficult to puncture, yield erroneous (invalid) test results because of impaired blood flow, and should be avoided. CAUTION: Never perform venipuncture through a hematoma. If there is no alternative site, perform the venipuncture distal to the hematoma to ensure the collection of free-flowing blood. KEY POINT Choose another site if possible; otherwise draw below (distal to) damaged veins. Edema is swelling caused by the abnormal accumulation of fluid in the tissues. It sometimes results when fluid from an IV infiltrates the surrounding tissues. Specimens collected from edematous areas may yield inaccurate test results owing to contamination with tissue fluid or altered blood composition caused by the swelling. In addition, veins are harder to locate, the tissue is often fragile and easily injured by tourniquet and antiseptic application, and healing may be prolonged in these areas. Another site should be chosen if possible. Blood should never be drawn from an arm on the same side as a mastectomy (surgical breast removal) without first consulting the patient’s physician. Lymph node removal, which is typically part of the procedure, causes lymphostasis (obstruction or stoppage of normal lymph flow). Impaired lymph flow makes the arm susceptible to swelling, called lymphedema, and to infection. Applying a tourniquet to the arm can cause injury. Effects of lymphostasis can also change blood composition in that arm and lead to erroneous test results. DAMAGED VEINS EDEMA MASTECTOMY KEY POINT When a mastectomy has been performed on both sides, the patient’s physician should be consulted to determine a suitable site. Generally, the side of the most recent mastectomy is the one avoided. BSMT-1D | CATANPATAN 6 TRANS: PREANALYTICAL CONSIDERATIONS OBESITY Obese (extremely overweight) patients often present a challenge to the phlebotomist. Veins on obese patients may be deep and difficult to find. Proper tourniquet selection and application is the first step to a successful venipuncture. Conventional tourniquets may be too short to fi t around the arm without rolling and twisting. A long length of new Penrose drain tubing or a long Velcro closure strap often works better than a latex or vinyl strap. A blood pressure cuff can also be used. Check the antecubital area first. Obese patients often have a double crease in the antecubital area with an easily palpable median cubital vein between the two creases. If no vein is easily visible or palpable on tourniquet application, ask the patient what sites have been successful for past blood draws. Most patients who are “difficult draws” know what sites work best. If the patient has never had blood drawn before or does not remember, another site to try is the cephalic vein. To locate the cephalic vein, rotate the patient’s arm so that the hand is prone. In this position, the weight of excess tissue often pulls downward, making the cephalic vein easier to feel and penetrate with a needle VASCULAR ACCESS DEVICES (VADS) AND SITES ARTERIAL LINE An arterial line is a catheter that is placed in an artery. It is most commonly placed in a radial artery and is typically used to provide accurate and continuous measurement of a patient’s blood pressure. It may also be used to collect blood gas and other blood specimens and for the administration of drugs such as dopamine. Only specially trained personnel should access arterial lines. Never apply a tourniquet or perform venipuncture on an arm with an arterial line. ARTERIOVENOUS SHUNT, FISTULA, OR GRAFT An arteriovenous (AV) shunt, fistula, or graft is the permanent surgical connection of an artery and vein by direct fusion (fistula), resulting in a bulging vein, or with a piece of vein or tubing (graft) that creates a loop under the skin. It is typically created to be used for dialysis, commonly joins the radial artery and cephalic vein above the wrist on the underside of the arm, and has a distinctive buzzing sensation called a “thrill” when palpated. A temporary shunt with tubing on the surface of the skin can also be created. BLOOD SAMPLING DEVICE A needleless closed blood sampling device is sometimes connected to an arterial or central venous catheter for the purpose of collecting blood specimens. These devices are said to reduce the chance of infection, prevent needlesticks, and minimize waste associated with line draws. BLOOD SAMPLING DEVICE 1) Squeeze and hold flexures raise plunger slightly to facilitate flow of priming solution 2) With shut-off valve in open position (parallel to the tubing), hold sampling site above the VAMP reservoir ate a 45 degree angle 3) Provide flow by pulling Snap-Tab of the pressure transducer BSMT-1D | CATANPATAN 7 TRANS: PREANALYTICAL CONSIDERATIONS 4) Slowly deliver priming solution to remove air. Close the plunger and connect to patient’s catheter 9) Gently remove the tube holder from the port by pulling straight out 10) Open the shut-off valve by turning the handle parallel to the tubing 5) Firmly squeeze the flexures and slowly draw the reservoir open over 3 to 5 seconds 11) Smoothly and evenly, over 3 to 5 seconds, depress the plunger until flexures lack in place in the fully closed position and all fluid has been reinfused into the line 6) Close shut-off valve by turning handle perpendicular to tubing 12) Flush the VAMP system clear by pulling the Snap-Tab on the transducer. Swab the sampling site to remove any excess blood on the sampling port 7) Swab sample port and push tube holder onto it HEPARIN OR SALINE LOCK 8) Collect required tubes of blood via the tube holder A heparin or saline lock is a catheter or cannula connected to a stopcock or a cap with a diaphragm (thin rubber-like cover) that provides access for administering medication or drawing blood. It is often placed in a vein in the lower arm above the wrist and can be left in place for up to 48 hours. BSMT-1D | CATANPATAN 8 TRANS: PREANALYTICAL CONSIDERATIONS To keep it from clotting, the device is flushed and filled with heparin or saline. A saline lock is sometimes flushed with heparin also. Heparin readily adheres to surfaces; therefore it is difficult to remove all traces of it. Consequently a 5-mL discard tube should be drawn first when blood specimens are collected from either type of device. Drawing coagulation specimens from either type is not recommended because traces of heparin or dilution with saline can negatively affect test results. Only specially trained personnel should draw blood from heparin and saline locks. Many specimens (e.g., CBCs) can easily be collected this way. A specimen that cannot be collected by capillary puncture (e.g., a coagulation specimen) may be collected below the IV (never above) following the steps PERFORMING VENIPUNCTURE BELOW AN IV STEPS EXPLANATION/ RATIONALE 1) Ask the patient’s nurse to A phlebotomist is not turn of the IIV for at qualified to make IV least 2 minutes prior to adjustments. Turning off the collection IV for 2 minutes allows IV fluids to dissipate from the area. 2) Apply the tourniquet Avoid disturbing the IV distal to the IV INTRAVENOUS SITES 3) Select a venipuncture site distal to the IV 4) Perform the venipuncture in a different vein than the one with the IV if possible. Intravenous (IV) means “of, pertaining to, or within a vein.” An intravenous line, referred to simply as an IV, is a catheter inserted in a vein to administer fluids. It is preferred that blood specimens not be drawn from an arm with an IV, as they can be contaminated or diluted with the IV fluid, causing erroneous test results. This is especially true if the specimen is drawn above the IV. When a patient has an IV in one arm, blood specimens should be collected from the other arm. If a patient has IVs in both arms or the other arm is also unavailable for some reason, it is preferred that the specimen be collected by capillary puncture. 5) Ask the nurse to restart the IV after the specimen has been collected. 6) Document that the specimen was collected below an IV, indicate the type of fluid in the IV, and identify Venous blood flows up the arm toward the heart. Drawing below an IV affords the best chance of obtaining blood that is free of IV fluid contamination IV fluids can be present below an IV because of backflow and may still be there after the IV is shut off because of poor venous circulation. IV flow rates must be precise, and starting or adjusting them is not part of a phlebotomist's scope of practice. This aids laboratory personnel and the patient's physician in the event that test results are questioned. PREVIOUSLY ACTIVE IV SITES Previously active IV sites present a potential source of error in testing. Blood specimens should not be collected from a known previous IV site within 24 to 48 hours of the time the IV was discontinued. Follow facility protocol. BSMT-1D | CATANPATAN 9 TRANS: PREANALYTICAL CONSIDERATIONS CENTRAL VASCULAR ACCESS DEVICES o o A central vascular access device (CVAD), also called an indwelling line, consists of tubing inserted into a main vein or artery. CVADs are used primarily for administering fluids and medications, monitoring pressures, and drawing blood. Having a CVAD is practical for patients who need IV access for an extended time and is especially beneficial for patients who do not have easily accessible veins. Most CVADs are routinely flushed with heparin or saline to reduce the risk of thrombosis. To help ensure that the specimen is not contaminated with the flush solution, a small amount of blood must be drawn from the line and discarded before a blood specimen can be collected. The amount of blood discarded depends upon the deadspace volume of the line. Two times the dead-space volume is discarded for noncoagulation tests and six times (normally about 5 mL) is generally recommended for coagulation tests, although it is preferred that specimens for coagulation tests not be drawn from CVADs. Three main types of CVADs are described; they are as follows: surgically tunneled under the skin to a site several inches away in the chest. One or more short lengths of capped tubing protrude from the exit site which is normally covered with a transparent dressing. Implanted port → a small chamber attached to an indwelling line that is surgically implanted under the skin and most commonly located in the upper chest or arm. The device is located by palpating the skin and accessed by inserting a special needle through the skin into the self-sealing septum (wall) of the chamber. The site is not normally covered with a bandage when not in use. Peripherally inserted central catheter (PICC) → a line inserted into the peripheral venous system (veins of the extremities) and threaded into the central venous system (main veins leading to the heart). It does not require surgical insertion and is typically placed in an antecubital vein just above or below the antecubital fossa. PATIENT COMPLICATIONS AND CONDITIONS ALLERGIES TO EQUIPMENT AND SUPPLIES Occasionally patients are encountered who are allergic to one or more of the supplies or equipment used in blood collection. Examples include the following. ADHESIVE ALLERGY Some patients are allergic to the glue used in adhesive bandages. One solution is to place a clean, folded gauze square over the site and wrap it with self-adherent bandaging material such as Coban. Care must be taken not to wrap it too tightly, and the patient should be instructed to remove it in 15 minutes. If the patient is alert, mentally competent, and willing, another alternative is to instruct him or her to hold pressure for 5 minutes in lieu of applying a bandage. ANTISEPTIC ALLERGY Occasionally, a patient is allergic to the antiseptic used in skin preparation prior to blood col- lection. (For example, many individuals are allergic to povidone–iodine.) Alternate antiseptics should be readily available for use in such cases. LATEX ALLERGY o Central venous catheter (CVC) or central venous line → a line inserted into a large vein such as the subclavian and advanced into the superior vena cava, proximal to the right atrium. The exit end is Increasing numbers of individuals are allergic to latex. Most latex allergies are seemingly minor and involve irritation or rashes from physical contact with latex products such as gloves. O ther allergies are so severe that being in the same room where latex materials are used can set off a lifethreatening reaction. There should be a warning sign on the door to the room of any patient known to have a severe latex allergy, and it is vital that no items made of latex be brought into the room. BSMT-1D | CATANPATAN 10 TRANS: PREANALYTICAL CONSIDERATIONS This means that the phlebotomist must wear nonlatex gloves, use a nonlatex tourniquet, and use nonlatex bandages when in the room, whether collecting blood from the patient or a roommate. KEY POINT Patients with known allergies often wear special armbands or have allergy-specific warning signs posted in their hospital rooms. The medical term for fainting is syncope (sin’ko-pea), described as a loss of consciousness and postural tone resulting from insufficient blood flow to the brain. It can last for as little as a few seconds or as long as half an hour. Any patient has the potential to faint before, during, or immediately following venipuncture. Some patients become faint at just the thought or sight of their blood being drawn, especially if they are ill or have been fasting for an extended period. Other contributing factors include anemia, dehydration, emotional problems, fatigue, hypoglycemia, hyperventilation, medications, nausea, needle phobia, and poor compromised breathing. Sudden faintness or loss of consciousness due to a nervous system response to abrupt pain, stress, or trauma is called vasovagal (relating to vagus nerve action on blood vessels) syncope. A patient with a history of fainting should be asked to lie down for the procedure. Patients who feel faint just before or even after venipuncture should be asked to lie down until recovered. Inpatients, who typically are already lying down, rarely faint during blood draws. Outpatients are more likely to faint because they are usually sitting up during venipuncture. Blood collection personnel should routinely ask patients how they are doing during a draw, watch for signs of fainting, and be prepared to protect them from falling. Signs to watch for include o pallor (paleness), o perspiration, and o hyperventilation or an indication from the patient that he or she is experiencing vertigo (a sensation of spinning), o dizziness, o light-headedness, or nausea. Fainting can occur without any warning, so never turn your back on a patient. When a patient who has fainted regains consciousness, he or she must remain in the area for at least 15 minutes. The patient should be instructed not to operate a vehicle for at least 30 minutes. It is important for the phlebotomist to document the incident (following institutional policy) in case of future litigation. EXCESSIVE BLEEDING CAUTION: Never apply a pressure bandage instead of maintaining pressure, and do not leave or dismiss a patient until bleeding has stopped or the appropriate personnel have taken charge of the situation. CAUTION: The use of ammonia inhalants to revive patients can have unwanted side effects such as respiratory distress in asthmatic individuals and is not recommended Normally, a patient will stop bleeding from the venipuncture site within a few minutes. Some patients, particularly those on aspirin or anticoagulant therapy, may take longer to stop bleeding. Pressure must be maintained over the site until the bleeding stops. If the bleeding continues after 5 minutes, the appropriate personnel should be notified. STEPS TO FOLLOW IF A PATIENT STARTS TO FAINT DURING VENIPUNCTURE STEP ESPLANATION/ RATIONALE 1. Release the tourniquet Discontinuing the draw and and remove and discard the discarding the needle needle as quickly as protects the phlebotomist possible and patient from injury should the patient faint. 2. Apply pressure to the site Pressure must be applied to while having the patient prevent bleeding or lower the head and breathe bruising. Lowering the head deeply and breathing deeply helps get oxygenated blood to the brain FAINTING 3. Talk to the patient 4 Physically support the patient. Diverts patient's attention, helps keep the patient alert, and aids in assessing the patient's responsiveness Prevents injury in case of collapse, 5. Ask permission and explain what you are doing if it is necessary to loosen a tight collar or tie. Avoids misinterpretation of actions that are standard protocol to hasten recovery. 6. Apply a cold compress or wet washcloth to the forehead and back of the neck Part of the standard of care 7.Have someone stay with the patient until recovery is complete. Prevents patient from getting up too soon and possibly causing self-injury. 8. Call first aid personnel if the patient does not respond Emergency medicine is not in the phlebotomist's scope of practice 9. Document the incident according to facility protocol. Legal issues could arise, and further documentation is essential at that time. NAUSEA AND VOMITING It is not unusual to have a patient experience nausea before, during, or after a blood draw. The patient may state that he or she is feeling nauseous or show signs similar to fainting, such as becoming pale or having beads of sweat appear on the forehead. BSMT-1D | CATANPATAN 11 TRANS: PREANALYTICAL CONSIDERATIONS A blood draw should not be attempted until the experience subsides. A blood draw that is in progress should be discontinued. KEY POINT If the patient vomits during venipuncture, the procedure must be terminated immediately. The patient should be reassured and made as comfortable as possible. A feeling of nausea often precedes vomiting, so it is a good idea to give the patient an emesis basin or wastebasket to hold as a precaution. Ask the patient to breathe slowly and deeply. Apply a cold, damp washcloth or other cold compress to the patient’s forehead. If the patient vomits, provide tissues or a washcloth to wipe the face and water to rinse the mouth. If the patient is NPO for surgery, other procedures, or otherwise not allowed to have water, advise him or her to spit the water out after rinsing and not swallow any. Notify the patient’s nurse, physician, or appropriate firstaid personnel of the incident. SEIZURES/CONVULSION Seizures have been known to occur during venipuncture, although there is no evidence that they can be caused by venipuncture. In the rare event that a patient has a seizure or goes into convulsions during blood specimen collection, it is important to discontinue the draw immediately. Hold pressure over the site without overly restricting the patient’s movement. Do not attempt to put anything into the patient’s mouth. Try to protect the patient from self-injury without completely restricting movement of the extremities. Notify the appropriate first-aid personnel. PAIN A small amount of pain is normally associated with routine venipuncture and capillary puncture. Putting patients at ease before blood collection helps them relax and can make the procedure less painful. Warning the patient prior to needle insertion helps avoid a startle reflex. A stinging sensation can be avoided by allowing the alcohol to dry completely prior to needle insertion. Excessive, deep, blind, or lateral redirection of the needle is considered probing. It can be very painful to the patient; risks injury to arteries, nerves, and other tissues; and should never be attempted. Marked or extreme pain, numbness of the arm, a burning or electric-shock sensation, or pain that radiates up or down the arm during a venipuncture attempt indicates nerve involvement and requires immediate removal of the needle. If pain persists after needle removal, the patient’s physician or other appropriate personnel should be consulted and the incident documented. Application of an ice pack to the site after needle removal can help prevent or reduce inflammation associated with nerve involvement. Follow your healthcare facility’s protocol. PROCEDURAL ERROR RISKS Hematoma formation is the most common complication of venipuncture. It is caused by blood leaking into the tissues during or following venipuncture and is identified by rapid swelling at or near the venipuncture site. SITUATIONS THAT CAN TRIGGER HEMATOMA FORMATION Excessive or blind probing is used to locate the vein. Inadvertent arterial puncture. The vein is fragile or too small for the needle size. The needle penetrates all the way through the vein. The needle is only partly inserted into the vein. The needle is removed while the tourniquet is still on. Pressure is not adequately applied following venipuncture. PETECHIAE Petechiae are tiny, nonraised red spots that appear on the patient’s skin when a tourniquet is applied. The spots are minute drops of blood that escape the capillaries and come to the surface of the skin below the tourniquet, most commonly as a result of capillary wall defects or platelet abnormalities. They are not an indication that the phlebotomist has used incorrect procedure. However, they are an indication that the venipuncture site may bleed excessively. HEMATOMA FORMATION CAUTION: A rapidly forming hematoma may indicate that an artery has been inadvertently hit. Discontinue the draw immediately and apply direct forceful pressure to the puncture site for a minimum of 5 minutes until active bleeding ceases. A hematoma is painful to the patient and often results in unsightly bruising it can also cause compression injuries to nerves and lead to lawsuits. Continuing to draw blood while a hematoma is forming risks injury to the patient and collection of a specimen contaminated with hematoma blood that has mixed with tissue fluids from outside the vein. Such a specimen has a high probability of being hemolyzed and of being rejected for testing. Even if it is not hemolyzed, it can still produce inaccurate test results. The presence of a hematoma makes the site unacceptable for subsequent venipunctures. If a hematoma forms during blood collection, the phlebotomist should discontinue the draw immediately BSMT-1D | CATANPATAN 12 TRANS: PREANALYTICAL CONSIDERATIONS and hold pressure over the site for a minimum of 2 minutes. A small amount of blood under the skin is relatively harmless and generally resolves on its own. If the hematoma is large and causes swelling and discomfort, the patient should be offered a cold compress or ice pack to relieve pain and reduce swelling. Follow facility protocol. Iatrogenic is an adjective used to describe an adverse condition brought on by the effects of treatment. Blood loss as a result of blood removed for testing is called iatrogenic blood loss. Removing blood on a regular basis or in large quantities can lead to iatrogenic anemia in some patients, especially infants. FYI A primary reason for blood transfusion in neonatal ICU patients is to replace iatro- genic blood loss. Blood loss to a point where life cannot be sustained is called exsanguination. Signs of inadvertent arterial puncture include a rapidly forming hematoma and blood filling the tube very quickly. In the absence of these clues, arterial blood can be recognized by the fact that it spurts or pulses into the tube or by its bright red color if the patient’s pulmonary function is normal. If arterial puncture is suspected, terminate the venipuncture immediately and apply direct forceful pressure to the site for at least 5 minutes and until bleeding stops. KEY POINT If you think a specimen might be arterial blood, check with laboratory personnel to deter mine if a suspected arterial specimen is acceptable for testing, as opposed to redrawing more blood from the patient. If testing is permitted, identify the specimen as possible arterial blood, since some test values are different for arterial specimens. Although a rare occurrence, infection at the site following venipuncture does happen. The risk of infection can be minimized by the use of proper aseptic technique, which includes the following: o Do not open adhesive tape or bandages ahead of time or temporarily tape them to your lab coat cuffs or other contaminated objects. o Do not preload needles onto tube holders to have a supply for many draws ready ahead of time. The sterility of the needle is breached once the seal is broken. o Before or during needle insertion, do not touch the site with your finger, gauze, or any other nonsterile object after it has been cleaned. o Try to minimize the time between removing the needle cap and performing the venipuncture. o Remind the patient to keep the bandage on for at least 15 minutes after specimen collection. Poor site or improper vein selection, inserting the needle too deeply or quickly, movement by the patient as the needle is inserted, excessive or lateral redirection of the needle, or blind probing while attempting venipuncture can lead to injury of a main nerve (such as the median cutaneous), the risk of permanent damage, and the possibility of a lawsuit. Follow national guidelines for site selection, vein selection, and venipuncture technique to minimize the risk of problems. If initial needle insertion does not result in successful vein entry and slight forward or backward redirection of the needle or use of a new tube does not result in blood flow, the needle should be removed and venipuncture IATROGENIC ANEMIA Life is threatened if more than 10% of a patient’s blood volume is removed at one time or over a short period of time. Coordination with physicians to minimize the number of draws per patient, following quality assurance procedures to minimize redraws, collecting minimum required specimen volumes, especially from infants, and keeping a log of draws can help reduce iatrogenic blood loss. INADVERTENT ARTERIAL PUNCTURE Inadvertent arterial puncture is rare when proper venipuncture procedures are followed. It is most often associated with deep or blind probing, especially in the area of the basilic vein, which is in close proximity to the brachial artery. If an inadvertent arterial puncture goes undetected, leakage and accumulation of blood in the area can result in compression injury to a nearby nerve. Such injuries are often permanent and can lead to lawsuits. INFECTION NERVE INJURY BSMT-1D | CATANPATAN 13 TRANS: PREANALYTICAL CONSIDERATIONS attempted at an alternate site, preferably on the opposite arm. CAUTION: Extreme pain, a burning or electric-shock sensation, numbness of the arm, and pain that radiates up or down the arm are all signs of nerve involvement, and any one of them requires immediate termination of the venipuncture. Application of an ice pack to the site after needle removal can help prevent or reduce inflammation associated with nerve involvement. REFLUX OF ADDITIVE In rare instances, it is possible for blood to reflux (flow back) into the patient’s vein from the collection tube during the venipuncture procedure. Some patients have had adverse re- actions to tube additives, particularly EDTA, that were attributed to reflux. Reflux can occur when the contents of the collection tube are in contact with the needle while the specimen is being drawn. To prevent reflux, the patient’s arm must be kept in a downward position so that the collection tube remains below the venipuncture site and fills from the bottom up. This prevents the tube-holder end of the needle from contacting blood in the tube. Back-and-forth movement of blood in the tube should also be avoided until the tube is removed from the evacuated tube holder. An outpatient can be asked to lean forward and extend the arm downward over the arm of the drawing chair to achieve proper positioning. Raising the head of the bed, extending the patient’s arm over the side of the bed, or supporting the arm with a rolled towel can be used to help achieve proper positioning of a bedridden patient. FYI Sometimes, when venipuncture is performed using a butterfly, blood initially flows into the tubing, but then some of it starts to disappear back into the vein before the tube is engaged. This is an example of reflux; however, since the tube is not engaged, there is no danger of additive reflux. VEIN DAMAGE FYI Cholesterol levels can increase up to 5% after 2 minutes of tourniquet application and up to 15% after 5 minutes. Massaging or squeezing the site, probing for veins, longterm IV therapy, drawing blood from sclerosed or occluded veins, and vigorous hand pumping (making and releasing a fist) can also result in the collection of specimens affected by hemoconcentration. KEY POINT Hand or fist pumping can increase blood potassium levels up to 20%. It is reported to be responsible for a third of all elevated potassiums and may also increase lactate and phosphate levels. Test results on hemoconcentrated specimens may not accurately reflect the patient’s true status, so it is important to try to avoid them. Properly performed, an occasional venipuncture will not impair the patency of a patient’s vein. Numerous venipunctures in the same area over an extended period of time, however, will eventually cause a buildup of scar tissue and increase the difficulty of performing subsequent venipunctures. Blind probing and improper technique when redirecting the needle can also damage veins and impair patency. WAYS TO HELP PREVENT HEMOCONCENTRATION DURING VENIPUNCTURE Ask the patient to release the fist upon blood flow. Choose an appropriate patent vein. Do not allow the patient to pump the fist. Do not excessively massage the area in locating a vein. Do not probe or redirect the needle multiple times in search of a vein. Release the tourniquet within 1 minute. SPECIMEN QUALITY CONCERNS The quality of a blood specimen can be compromised by improper collection techniques. A poor-quality specimen will generally yield poor-quality results, which can affect the patient’s care. Because it is not always apparent to the phlebotomist or testing personnel when the quality of a specimen has been compromised, it is very important for the phlebotomist to be aware of the following pitfalls of collection. HEMOCONCENTRATION Tourniquet application causes localized venous stasis, or stagnation of the normal venous blood flow. (A similar term for this is venostasis, the trapping of blood in an extremity by compression of veins.) In response, some of the plasma and filterable components of the blood pass through the capillary walls into the tissues. This results in hemoconcentration, a decrease in the fluid content of the blood with a subsequent increase in nonfilterable large molecule or protein-based blood components such as red blood cells. Other abnormally increased analytes include o albumin, o ammonia, o calcium, o cholesterol, o coagulation factors, o enzymes, o iron, o potassium, and o total protein. Changes that occur within 1 minute of tourniquet application are slight; however, prolonged tourniquet application can lead to marked changes. HEMOLYSIS Hemolysis results when RBCs are damaged or destroyed and the hemoglobin they contain escapes into the fluid portion of the specimen. The red color of the hemoglobin makes the serum or plasma appear pink (slight hemolysis), dark pink to light red (moderate hemolysis), to dark red (gross hemolysis), and the specimen is described as being “hemolyzed” BSMT-1D | CATANPATAN 14 TRANS: PREANALYTICAL CONSIDERATIONS PARTIALLY FILLED TUBES ETS tubes should be filled until the normal amount of vacuum is exhausted. Failing to do so results in a partially filled tube, referred to as a short draw. Short-draw serum tubes such as red tops and SSTs are generally acceptable for testing as long as the specimen is not hemolyzed and there is sufficient specimen to perform the test. Underfilled anticoagulant tubes and most other additive tubes, → may not contain the blood-to-additive ratio for which the tube was designed. Left to right: Normal serum specimen, specimen with slight hemolysis, and grossly hemolyzed specimen. Hemolyzed specimens can result from patient conditions such as hemolytic anemia, liver disease, or a transfusion reaction, but they are more commonly the result of procedural errors in specimen collection or handling that damages the RBCs. Hemolysis can erroneously elevate ammonia, catecholamines, creatine kinase and other enzymes, iron, magnesium, phosphate, and potassium levels; it can also decrease RBC counts. Consequently a specimen that is hemolyzed as a result of procedural error will most likely have to be redrawn. PROCEDURAL ERRORS THAT CAN CAUSE SPECIMEN HEMOLYSIS Drawing blood through a hematoma or from a vein with a hematoma Failure to wipe away the first drop of capillary blood, which can contain alcohol residue Forceful aspiration of blood during a syringe draw Forcing the blood from a syringe into an evacuated tube Frothing of blood caused by improper fit of the needle on a syringe Horizontal transport of tubes, which lets the blood slosh back and forth Mixing additive tubes vigorously, shaking them, or inverting them too quickly or forcefully Partially filling a normal-draw sodium fluoride tube Pulling back the plunger too quickly during a syringe draw Rough handling during transport Squeezing the site during capillary specimen collection Syringe transfer delay in which partially clotted blood is forced into a tube Using a large-volume tube with a small-diameter butterfly needle Using a needle with a diameter that is too small for venipuncture KEY POINT A common procedural error by nursing personnel that causes hemolysis is drawing blood through an IV valve. IV valves are designed to prevent backflow of IV solution by allowing fluid to move in only one direction. Consequently the force required to pull blood through a valve in the opposite direction can hemolyze the specimen. CAUTION: Never pour two partially filled additive tubes together to fill one tube, as this will also affect the bloodto-additive ratio. Although in some cases underfilled additive tubes may be accepted for testing, the specimens can be compromised. For example: o Excess EDTA in underfilled lavender-top tubes can shrink RBCs, causing erroneously low blood cell counts and hematocrits and negatively affecting the morphological ex- amination of the RBCs on a blood smear. It can also alter the staining characteristics of the cells on a blood smear. o Excess heparin in plasma from underfilled green-top tubes may interfere with the testing of some chemistry analytes. o Excess sodium fluoride in underfilled gray-top tubes can result in hemolysis of the specimen. o Underfilled coagulation tubes do not have the correct blood-to-additive ratio and will produce erroneous results. Inadvertent (unintentional) short draws are usually the result of difficult draw situations in which blood flow stops or vacuum is lost during needle manipulation. Phlebotomists some- times underfill tubes on purpose when it is inadvisable to obtain larger quantities of blood, as when drawing from infants, children, or severely anemic individuals. CAUTION Some phlebotomists underfill tubes to save time. This practice is never recommended Partial-vacuum tubes are available that are the same size as some standard-fill tubes but designed to contain a smaller volume of blood. These tubes can be used in situations where it is difficult or inadvisable to draw larger amounts of blood. They are sometimes referred to as “short-draw” tubes, but when they are filled properly, the blood-to-additive ratio is correct even though they contain less blood. Some manufacturers’ short-draw tubes have a line or arrow on the label to indicate the proper fill level BSMT-1D | CATANPATAN 15 TRANS: PREANALYTICAL CONSIDERATIONS SPECIMEN CONTAMINATION Specimen contamination is typically inadvertent and generally the result of improper technique or carelessness, such as o Allowing, alcohol, fingerprints, glove powder, baby powder, or urine from wet diapers to contaminate newborn screening forms or specimens, leading to specimen rejection. o Getting glove powder on blood films (slides) or in capillary specimens, resulting in mis- interpretation of results. Calcium-containing powders can affect calcium results. o Unwittingly dripping perspiration into capillary specimens during collection or any specimen during processing or testing. The salt in sweat, for example, can affect sodium and chloride levels. o Using the correct antiseptic but not following proper procedure. For example, improperly cleaning bloodculture bottle tops or the collection site, touching the site after it has been prepped (cleaned), or inserting the needle before the antiseptic on the arm or bottle tops is dry. (Traces of the antiseptic in the culture medium can inhibit the growth of bacteria and cause false-negative results.) Performing capillary puncture before the alcohol is dry can cause hemolysis of the specimen and lead to inaccurate results or rejection of the specimen by the lab. o Using the wrong antiseptic to clean the site prior to specimen collection. For example, using alcohol to clean the site can contaminate an ethanol (blood alcohol) specimen. Using povidone–iodine (e.g., Betadine) to clean a skin puncture site can contaminate the specimen and cause erroneously high levels of uric acid, phosphate, and potassium. TUBE POSITION Tube position is important. Check the tube to see that it is properly seated and the needle in the tube holder has penetrated the tube stopper. Reseat the tube to make certain that the needle sleeve is not pushing the tube off the needle. NEEDLE POSITION Insertion of the venipuncture needle so that the bevel is correctly positioned within the vein is critical to the success of venipuncture. If the needle or bevel is incorrectly positioned, blood may not flow into the tube or syringe properly or at all. If blood flow is not established or the rate of flow is not normal, use visual cues to help determine if the needle is correctly positioned in the vein. Some problems are harder to discern than others. Eliminate any that you can and try the remedy for the others to see if one works. All needle adjustments must be made slowly and precisely to avoid injuring the patient. Correct position is shown below WRONG OR EXPIRED COLLECTION TUBE Drawing a specimen in the wrong tube can affect test results and jeopardize patient safety if the error is not caught before testing. The error may not be caught if the phlebotomist is also the one who processes the specimen, as it is impossible to visually tell serum from plasma or one type of plasma from another if the specimen has been removed from the cells and transferred to an aliquot tube. A phlebotomist who is not certain of the type of tube required for a particular test must consult the procedure manual before collecting the specimen. Additives in expired tubes may not work properly. For example, expired anticoagulant may allow the formation of microclots. Expiration dates of tubes must be checked routinely and expired tubes discarded. NEEDLE NOT INSERTED FAR ENOUGH TROUBLESHOOTING FAILED VENIPUNCTURE Failure to initially draw blood during a venipuncture attempt can be caused by a number of procedural errors. Being aware of these errors and knowing how to correct them may determine whether you obtain blood on the first try or have to repeat the procedure. If you fail to obtain blood, remain calm so that you can clearly analyze the situation and check the following: If the needle is not inserted far enough, it may not penetrate the vein at all. This can happen if the vein is located more deeply than normal (e.g., if the patient is extremely overweight). In this case there will be no blood flow at all. To correct this problem, slowly advance the needle forward until blood flow is established. CAUTION: One must be very certain that needle depth is the issue before advancing the needle, as the deeper a needle goes, the greater the chance of injuring a nerve, artery, or other tissue BSMT-1D | CATANPATAN 16 TRANS: PREANALYTICAL CONSIDERATIONS CAUTION: Continuing the draw while a hematoma is forming increases the risk of injury to the patient and the collection of blood from outside the vein; this blood would be contaminated with tissue fluids and is very likely to be hemolyzed. BEVEL PARTIALLY OUT OF THE SKIN If the needle bevel is not completely under the skin after it is inserted the tube will lose its vacuum when engaged and fail to fill with blood even if the bevel is mostly in the vein. This can happen with arm veins that are close to the surface of the skin as well as hand veins, especially if the angle of needle entry is too steep. BEVEL PARTIALLY THROUGH THE VEIN Tube vacuum can also be lost if the bevel backs out of the skin slight) during a draw; for example, if the holder is not held securely when the tube is removed from it. A short hissing sound is often heard as the vacuum is lost, and there may be a spurt of blood into the tube before blood flow stops. Discard the tube and advance the needle slowly until the bevel is under the skin before engaging a new tube. A hand vein may require you to thread the needle bevel within the lumen vein slightly. If the needle is inserted too deeply, too quickly, or at an angle that is too steep part of the bevel may penetrate the lower wall of the vein. If this is not corrected quickly, blood can leak into the tissue below the vein and result in hematoma formation, which may not be apparent until long after the draw is completed. If the needle appears to be inserted deeply and blood fills the tube slowly, this may be the case. Pull the needle back slightly until normal blood flow is established. If it appears that a hematoma has already formed, discontinue the draw immediately, and hold pressure over the site. If the angle is too steep and the vein is small, the bevel may go through the vein before it is completely under the skin, in which case the venipuncture will have to be terminated and a new site chosen. FYI A patient who hears the hissing sound when the tube vacuum is lost during a draw may be alarmed and need reassurance that nothing harmful has happened. CAUTION: Blood that pools beneath a vein can put pressure on underlying nerves, causing pain and the possibility of nerve damage BEVEL COMPLETELY THROUGH THE VEIN BEVEL PARTIALLY INTO THE VEIN If the needle is not inserted deeply enough, the bevel may be beneath the skin but only partly through the upper vein wall, resulting in the blood filling the tube very slowly. Correct blood flow should be established by gently pushing the needle forward into the vein. If not corrected quickly, partial needle insertion can cause blood to leak into the tissue and form a hematoma. If this occurs, discontinue the draw immediately and hold pressure over the site. If the needle has gone in too deep, the bevel may penetrate all the way through the vein. In this case, there may be a small spurt of blood into the tube as the bevel goes through the vein, or there may be no blood flow at all. This can happen on needle insertion, especially if the needle angle is too steep, or as a tube is pushed onto the needle if the tube holder is not held steady. To correct this problem, slowly withdraw the needle until blood flow is established. BSMT-1D | CATANPATAN 17 TRANS: PREANALYTICAL CONSIDERATIONS If the needle position is not corrected quickly, blood may leak out around the needle into the tissues and form a hematoma. Even after correction, blood may still leak out of the opening caused by the needle, especially if the tourniquet is left on throughout the draw. This too can result in a hematoma that is not apparent until long after the draw is completed. If a hematoma is visible, discontinue the draw. (Rotating the bevel slightly may also help.) Advance the tube back onto the needle. If blood flow is established, the problem most likely was an issue with the bevel and the vein wall. CAUTION: Tube vacuum may hold the vein wall against the needle bevel. Do not rotate the bevel of the needle without first removing the tube and pulling the needle back slightly or the vein may be injured. NEEDLE BESIDE THE VEIN BEVEL AGAINST A VEIN WALL Blood flow can be impaired if the needle bevel is up against the upper or lower wall of the vein. This can happen if the needle angle is wrong. Vein walls are sometimes tough, and if a vein is not anchored well with the thumb, it may roll (move away) slightly and the needle may slip to the side of the vein instead of into it. Often the needle ends up beside the vein and slightly under it as well. (This is often the case with the basilic vein, which is not well anchored in the tissue to begin with.) If this happens, disengage the tube to preserve the vacuum, withdraw the needle slightly until just the bevel is under the skin, anchor the vein securely, redirect the needle into the vein, and re-engage the tube. If redirection is unsuccessful, discontinue the draw and choose a new site. Do not search or probe for the vein or move the needle in a lateral (sideways) direction to find it. For example, an angle that is too shallow can cause the needle bevel to contact the upper wall. This can also happen if the needle is inserted near a bend in the vein or at a point where the vein goes deeper into the skin. An angle that is too steep, or inserting the needle with the bevel down, can cause the needle to contact the lower wall. FYI When phlebotomists “miss” veins, they often tell patients that they have “veins that roll.” This leads patients to mistakenly believe that there is a problem with their veins, when more than likely the problem is the phlebotomist’s technique. UNDETERMINED NEEDLE POSITION Most of these situations are hard to detect. Remove the tube from the needle in the holder to release vacuum pull on the vein and pull the needle back slightly. If you cannot determine the position of the needle and the above solutions do not help, you may have to use your finger to relocate the vein. Remove the tube from the holder needle and withdraw the needle until the bevel is just under the skin. Clean your gloved finger with alcohol and palpate the arm above the point of needle insertion to try to determine needle position and vein location. Be careful not to feel too close to the needle, as this would cause pain. Once you have relocated the vein, pull the skin taut and redirect the needle into it. If you cannot relocate the vein BSMT-1D | CATANPATAN 18 TRANS: PREANALYTICAL CONSIDERATIONS (or if access to it would require lateral redirection of the needle), discontinue the draw and select a new site. CAUTION: Do not blindly probe the arm in an attempt to locate a vein. Probing is painful to the patient and can damage nerves or lead to inadvertent puncture of an artery. NEEDLE POSITION A. Correct needle position → blood can flow freely into the needle. B. Needle not inserted far enough → needle does not enter vein. C. Needle bevel partially out of the skin → tube vacuum will be lost. D. Needle bevel partially into the vein → causes blood leakage into tissue. E. Needle bevel partially through the vein → causes blood leakage into tissue. F. Needle bevel completely through the vein → no blood flow obtained. G. Needle bevel against the upper vein wall prevents blood flow. H. Needle bevel against the lower vein wall prevents blood flow. Needle beside the vein → caused when a vein rolls to the side. Collapsed vein prevents blood flow despite correct needle position, COLLAPSED VEIN A vein can collapse despite correct needle position. When a vein collapses, the walls draw together temporarily, shutting off blood flow. This can happen if the vacuum draw of a tube or the pressure created by pulling on a syringe plunger is too much for the vein. A vein can also collapse if the tourniquet is tied too tightly or too close to the venipuncture site. In this case, blood cannot be replaced as quickly as it is withdrawn, causing the vein to col- lapse. In addition, veins sometimes collapse when the tourniquet is removed during the draw. This is often the case in elderly patients, whose veins are fragile and collapse more easily. and a slight adjustment is needed to re-establish blood flow. A clue that a normally visible vein has collapsed is that it disappears as soon as the tube is engaged or when the tourniquet is removed. If the ends of the tourniquet are lying over the arm, grasp them with your free hand and twist them together to reintroduce pressure. That may be enough to re-establish blood flow. If the tourniquet cannot be retightened, use your finger to apply pressure to the vein several inches above the needle. Remove the tube from the needle and wait a few seconds for the blood flow to re-establish itself before re-engaging it. Try using a smaller- volume tube or pull more slowly on the plunger if you are using a syringe. If the blood flow is not re-established, discontinue the venipuncture and attempt a second venipuncture at another site. TUBE VACUUM A tube can lose its vacuum during a venipuncture if the needle bevel is not completely under the skin. Tubes can also lose vacuum during shipping and handling, when they bump one another in trays, if they are dropped, or if they are pushed too far onto the needle prior to venipuncture. If you suspect that a tube has lost its vacuum, try using a new one. If you fail to establish blood flow during a draw and repositioning the needle doesn’t help, try using a new tube before giving up on the draw, as it could be a vacuum problem. KEY POINT Tube vacuum problems at the start of a draw may be a sign that the tube is cracked or has been dropped. Cracked tubes present a safety hazard because they may leak or break with further handling. Never use a tube that has been dropped. Discard it instead FYI Stoppage of blood flow upon tourniquet removal does not necessarily mean that the vein has collapsed. It may be that the needle is no longer positioned properly BSMT-1D | CATANPATAN 19