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CHAPTER 11
Blood Cultures, GGT, ABGs,
and Urine Samples
Blood Cultures
• Collected from patients who have fevers of unknown origin (FUO)
• During the course of a bacterial infection, bacteremia or septicemia may result.
• Blood cultures aid in identifying the specific bacterial organism causing the infections.
Blood Culture Collection
• Possible Interfering Factors
– Blood culture specimens must be collected first.
– Do not scrape the needle across the skin.
– Fill anaerobic blood culture vial first except when using the butterfly assembly.
– Culture vials with resin beads.
Blood Cultures Procedural Steps
– Read the manufacturer’s directions about blood culture vials before using them.
– Place each bottle on a flat surface and then use a marker to mark a “fill-to line.”
Safety Syringe Blood Culture Collection
• Prepare and assemble supplies.
• Identify the patient properly. Briefly explain the test to the patient.
• Wash or sanitize your hands with an alcohol hand rinse, then put on gloves.
• Locate the vein.
• Loosen the tourniquet.
• Scrub the site of the venipuncture with 70% isopropyl alcohol for 60 seconds.
• Scrub with iodine tincture(chlorhexidine gluconate for patients sensitive to iodine or for infants older
than 2 months) for 30 seconds.
• Initially place the iodine swab at the site of needle insertion and then move it outward in concentric
circles to a diameter of 2.5 inches.
• After the collection of the blood into the syringe, activate the safety-needle cover.
• Aseptically dispose of the needle into the sharps container without touching the needle.
• Place a blunt-tipped cannula(connector) on the syringe tip and attach the blunt-tipped connector
to the direct-draw holder/adapter.
• Start with the vial labeled “an aerobic microbiology vial” and place it in an upright position.
• Place the blood-transfer device on the vial.
• Fill to the desired amount.
• Remove the syringe with the blood-transfer device from this vial.
Safety Syringe Blood Culture Collection Con’t
• Fill the aerobic vial after the an aerobic vial.
• Fill other blood collection tubes according to the “order of draw.”
• NEVER push on the syringe plunger.
• Allow the vacuum in the microbiology vials to pull the blood into the vials.
• If the amount of blood collected is only3 mL or less, place the entire amount in the aerobic vial.
• For infants and small children, only 1 to5 mL of blood can usually be collected
for bacterial culture.
• Use blood culture bottles that are designed specifically for the pediatric patient.
• Discard the syringe, safety blood-transfer device, and needle in the sharps container with biohazard
label.
• Discard blood-soaked gauze sponges, grossly contaminated items, and gowns or gloves used in
isolation rooms in biohazard waste containers.
• Dispose of gowns and gloves that are not from isolation rooms in the regular trash.
• Wash or sanitize your hands.
• Deliver the sample immediately to the laboratory.
Safety Butterfly Assembly—Blood Culture Collection
• Prepare and assemble supplies.
• Identify the patient properly.
• Briefly explain the test to the patient.
• Wash or sanitize your hands with an alcohol hand rinse, then put on gloves.
• Use a safety butterfly assembly for insertion of the butterfly needle into the venipuncture site after the
appropriate skin preparation.
• Place a strip of tape over the butterfly wings to keep the needle in place.
• Transfer the blood to the microbiology vials via a direct draw adapter that fits directly over the blood
culture vial.
• Transfer the blood to the aerobic vial first.
• Discard the safety butterfly assembly and safety blood-transfer device in the sharps container with
biohazard label.
• Discard blood-soaked gauze sponges, grossly contaminated items, and gowns or gloves used in
isolation rooms in biohazard waste containers.
• Dispose of gowns and gloves that are not from isolation rooms in the regular trash.
• Wash or sanitize your hands.
• Deliver the sample immediately to the laboratory.
After Blood Culture Collection
• After collecting the blood, remove the iodine from the patient’s skin.
• Initial the patient identification labels, indicate the time and date of collection on the
labels, and attach a label to each vial or tube.
• Document the: a) date and time specimen obtained and b) site of specimen collection.
• Changing needles should not occur.
Glucose Tolerance Test (GTT)
• An effective diagnostic tool for patients who have symptoms suggesting problems in carbohydrate
metabolism, such as diabetes
• Complete Instructions to Patient for Preparation
– Eat normal, balanced meals for at least 3 days before the test.
– Fast for 8 to 12 hours.
– Drink water and not tea, coffee, or other beverages.
– Do not smoke, chew tobacco, or chew gum.
• Obtain a fasting blood specimen.
• If the result is normal, then the patient can be given a standard load of glucose.
• Obtain subsequent blood and urine samples at intervals, usually during a 2 to 3 hour period.
• Send each specimen to the laboratory for immediate testing.
• Venous blood is the preferred specimen.
• If serum samples are collected, use the serum separator tube.
• The grey-topped tubes have a preservative and can be used for this procedure.
metabolism tests(such as a GTT or Hemoglobin A1c) areneeded.
• Possible Interfering Factor with GTT
– Nausea and vomiting may occur early during the GTT.
– If the patient vomits within the first 30 minutes, discontinue the test and reschedule for
another day.
– If the patient vomits or becomes faint later in the test, have them lie down and complete
the testing if possible.
• Used to screen patients for diabetes
• Patient placed on a high carbohydrate diet 2 to 3 days before the 2-hour test
• The day of the test, the patient should eat a breakfast of orange juice, cereal with sugar,
toast, and milk to provide an approximate equivalent of 75 g of glucose.
• A blood specimen is taken 2 hours after the patient finishes eating breakfast.
• The glucose level is then determined, and the physician can decide whether further
carbohydrate metabolism tests(such as a GTT or Hemoglobin A1c) are needed.
Point-of-Care Testing
• Demand for point-of-care testing(POCT) is increasing because rapid turn around of laboratory test
results is necessary.
• Other Terms for POCT
– Decentralized laboratory testing
– On-site testing
– Bedside testing
– Near-patient testing
– Patient-focused testing
• Examples of POC Tests
– Glucose testing instruments
– Hemoglobin A1c
– Hemoglobin
– Influenza A and B
– Cholesterol
Obtaining Blood Specimen for Glucose Testing (Skin Puncture)
• Gather equipment:
safety automatic lancet
• Identify the patient properly. Briefly explain the test to the patient.
• Clean your hands.
• Don gloves.
• Select the site and cleanse with antiseptic (especially the side of a finger).
• Cleanse skin with alcohol wipe and allow skin to dry.
• Gently massage the finger five or six times from base to tip to aid blood flow.
• Decide on which side of the finger to make the incision.
• Remove the safety lancet from the protective paper, hold the patient’s finger firmly with one hand, make a swift, deep
puncture with the retractable safety puncture device.
• Wipe the first three drops of blood away with clean gauze.
• Gently massage the finger from base to tip to obtain the needed drop of blood. Do not squeeze the fingertip.
• Apply the test strip to the drop of blood.
• The correct volume is drawn into the cuvette by capillary action
• Wipe off any excess blood from the sides of the cuvette.
• The laboratory test result is displayed automatically.
• Discard the safety automatic lancet in the sharps container with biohazard label.
• Discard the gauze, alcohol wipes, and gloves in biohazard waste containers.
• Wash or sanitize your hands.
Quality in Point-of-Care Testing(POCT)
• Instruments calibrated with glucose standards
• Values monitored with quality control material
• Electronic quality control (EQC) to test electronics
Control material should be analyzed so that the mean and standard deviation can be
calculated.
• Calculations on 20 to 30 control values.
• The control value is plotted on a chart under the appropriate date, and the daily plots are
joined with a straight line.
• Reproducibility of the Results
– Purchasing the reagent strips and controls in quantities to enable healthcare workers to use
constant pools of the same lot number.
– Preventive maintenance of each instrument is critical for accurate results.
Blood Coagulation Monitoring
• Provides immediate results used in monitoring bleeding or clotting disorders in patients
• CoaguChek XS System
– Used to monitor long-term anticoagulation therapy
– Immediate test results allow rapid dose adjustments
– Calibrated to use the first drop of blood in skin puncture
• Instrument to Monitor Anticoagulation Therapy during Cardiac Procedures and Dialysis:
– Actalyke XL Activated Clotting Time Test(ACT) System
• The INRatio2 Meter is used to measure prothrombin time (PT)INR for maintenance of proper anticoagulation therapy.
Hematocrit, Hemoglobin, and Other Hematology Parameters
• Hematocrit (Hct, packed cell volume[PCV], or Crit)
– Represents the volume of circulating blood that is occupied by red blood cells(RBCs)
– It is expressed as a percentage.
– Values are obtained to aid in the diagnosis and evaluation of anemia.
– Blood collection usually occurs by skin puncture.
– Plastic micro capillary tubes are used.
• Hemoglobin Test
– Aids in the diagnosis and evaluation of anemia and other blood abnormalities
– More accurate than hematocrit test
– Safer method to detect anemia
Cannulas and Fistulas
• A cannula is a tubular instrument that is used in patients with kidney disease to gain access
to venous blood for dialysis or blood collection.
• Blood should be collected only by specially trained personnel, because the procedure
requires special techniques and experience.
• A fistula is an artificial shunt in which the vein and artery have been fused through surgery.
• Only specialized personnel can collect blood from a fistula.
• Use extreme caution and avoid using the arm with fistula.
Donor Room Collections
• Donor Interview and Selection
– Date and time of donation
– Name
– last, first, and middle initial
– Address
– Telephone number
– Gender
– Age and date of birth
–Written consent form signed by the donor
– A record of reasons for deferrals, if any
– Social security number or driver’s license number
– Name of patient or group to be credited
– Race (not mandatory)
– Unique characteristics about a donor’s blood
Donor Room Collections
• Donor Interview and Selection Con’t
• Brief Physical Examination
–Weight
– Temperature
– Pulse
– Blood pressure
– Skin lesions
– General appearance
– Hematocrit or hemoglobin values
– Extensive medical history
• Collection of Donor’s Blood
– Blood should be collected by using aseptic technique; a sterile, closed system; and a single venipuncture.
– The health care worker should be well versed in donor reactions, equipment safety precautions, first-aid techniques, and location of first-aid
equipment incase it is needed in the course of donation.
• Therapeutic Bleeding
– Blood obtained through therapeutic bleeding may be used for homologous transfusion if the unit is deemed suitable by the director of the blood
bank.
– The recipient’s physician must agree to use the blood from his/her patient.
– Keep a record of the agreement.
– The label must indicate that the blood is the result of a therapeutic bleed and must include the patient’s diagnosis.
Arterial Blood Gases
• Provide useful information about the respiratory status and the acid–base balance of
patients with pulmonary(lung) disease or disorders.
• Arterial blood is used rather than venous blood.
• Radial Artery Puncture Site
– Located on the thumb side of the wrist.
Arterial Blood Gases
• Brachial Artery Puncture Site
– An alternative site for blood collection for ABG analysis
– Located in the cubital fossa of the arm
• Femoral Artery Site
– Located in the groin area of the leg, lateral to the femur bone
– Lacks collateral circulation
– Choice of site for patients with cardiovascular disorders
– Last choice of site for an arterial puncture
Radial ABG Procedure
• Gather and organize the necessary equipment and supplies.
• Properly identify and inform the patient of the arterial puncture procedure.
• Determine that the patient has been in a stable state for at least the previous 30 minutes.
• Attempt to calm the patient before collecting the specimen if the patient appears anxious.
• Before proceeding, determine if patient is on anticoagulant therapy, or allergic to iodine or
lidocaine.
• Record the patient’s temperature, oxygen concentration, and respiratory rate.
• Wash your hands, put on gloves, a facial mask, and a protective laboratory coat and palpate the
radial artery in the forearm.
• The radial artery in the patient’s non dominant hand is usually the best choice.
• With the forefinger or first two fingers, press at this site to find the artery.
• Never use the thumb for palpating because there is a pulse in the thumb that may be confused with
the patient’s pulse.
• Avoid any site that has a hematoma or that was previously used for an arterial puncture.
• Position the patient’s arm with the wrist slightly extended and rotated.
• Check for adequate collateral circulation using the modified Allen test.
Modified Allen Test
• Perform before using the radial artery for blood collection for ABG analysis
• Makes certain that the ulnar and radial arteries are providing collateral circulation
• Compress both arteries with your index and middle fingers, and ask the patient to tightly
clench his/her fist.
• Ask the patient to open his/her hand, and release the pressure on the ulnar artery.
• The Allen test is positive when hand fills with blood within 5 to 10 seconds.
• If color does not return to the hand after 5 to 10 seconds, the Allen test is negative.
• A negative Allen test indicates the inability of the ulnar artery to supply blood to the hand
adequately and shows a lack of collateral circulation.
• The radial artery should not be used in a negative Allen test.
Radial ABG Procedure
•Once the radial artery site is chosen, clean the area well with tincture of iodine.
•If a local anesthetic is desired by the patient
– Fill a 1 mL syringe with lidocaine.
– Inject the lidocaine with the 25- to 26-gauge needle subcutaneously around the anticipated puncture site.
• No tourniquet is required because the artery has its own strong blood pressure.
• Use a prefilled heparinized safety syringe (1 to 5 mL) with a needle to withdraw the sample.
• Hold the syringe or collection device in one hand as one would hold a dart.
• Pull the skin taut with a finger of the other hand over the artery and pierce the pulsating artery at a high angle, usually an angle of 30 to 45 degrees against the blood stream.
• Little or no suction is needed, because the blood pulsates and flows quickly into the syringe under its own pressure.
• Completing Arterial Blood Gas Collection.
• When approximately 1 mL of blood is collected, withdraw the needle carefully to avoid introducing bubbles into the syringe.
• Apply gauze and direct manual pressure on the site for at least 5minutes.
• Engage the safety syringe cover to cover the needle exposure.
• Gently mix the blood in the syringe with the heparin and label the syringe.
• Mix the blood gently by inverting the syringe at least 5 minutes.
• Before leaving the patient, clean the puncture site with an alcohol pad to remove the excess iodine solution; leave a pressure bandage on.
• If bleeding from the site persists, apply more manual pressure and ring for assistance from the patient’s primary nurse.
• Never leave a patient who is bleeding, particularly after an arterial puncture.
• Notify the primary nurse after an arterial puncture is performed so that the area may be checked frequently for deep or superficial bleeding.
• Ideally, the specimen should be analyzed within 10 minutes of collection.
• Transport the specimen immediately to the laboratory.
• Discard the syringe and needle in the sharps container with biohazard label.
• Discard blood-soaked gauze, grossly contaminated items, and gowns or gloves used in isolation rooms in biohazard waste containers.
• Dispose of gowns and gloves that are not from isolation rooms in the regular trash.
• Wash or sanitize your hands.
Urine Collections
• Collecting and transporting urine and other body fluid specimens
• Many of the body fluids are difficult to obtain.
• The quality of the test result is only as good as the specimen that is collected.
• Adhere to standard precautions.
• The laboratory request slip must accompany the specimen.
• Labels Must Include
– The patient’s name
– The patient’s identification number
– The date
– The time of collection
– The type of specimen
– The attending physician’s name
• The label should be affixed on the container, not on the lid.
• Routine Urinalysis (UA)
– Includes a physical, chemical, and sometimes microscopic analysis of the urine sample
– The physical properties include color, transparency vs. cloudiness, odor, and concentration as detected through a
specific gravity measurement.
• Chemical Analysis
– Determined by using plastic reagent strips impregnated with color-reacting substances that test for the presence of
glucose, protein, blood (red blood cells[RBCs] and hemoglobin), white blood cells (WBCs), ketones, bacteria, bilirubin,
and other constituents
• Single Specimen Collection
– The preferred urine specimen for most analyses is the first voided urine of the morning, when urine is the most
concentrated.
– The specimen should be transported to the UA section promptly for analysis within two hours after the patient voids.
– If transportation or analysis cannot occur within this time period, the urine should be refrigerated.
• Urine Culture and Sensitivity (C&S)
– Clean-catch midstream urine collection
– The patient is instructed to void approximately one half of the urine in tothe toilet, collect a portion in a readily available
sterile container, and allow the rest to pass into the toilet.
– Used to detect the presence or absence of infecting organisms
– Transport to the microbiology section promptly.
• Timed Collections
– For creatinine clearance tests, protein and hormone studies, 24-hour (or other timed period) urine specimens must be
obtained.
– Be aware of the protocol for collecting a24-hour urine specimen to be able to assist with the prevention of collection
errors.
Collecting a 24-Hour Urine Specimen
• Explain the whole procedure to the patient and also provide written directions.
• Explain the importance of hand washing for the urine collection.
• Give the patient the container and lid.
• Add any required preservatives to the container before giving it to the patient.
• Write the preservative and any precautions on the collection container label.
• Place the label on the container, not on the lid.
• Include the Following Information on the Label:
– Patient’s name
– Patient’s identification number
– Starting collection date and time
– Ending collection date and time
– Name of the requested laboratory test
• Instruct the patient verbally.
• Give them written instructions that the collection of the 24-hour urine specimen begins with emptying the bladder and discarding the first urine passed.
• This first step in the collection process should start between 6 and 8 a.m.
• The exact time should be written on the container label.
• Except for the first urine discarded, all urine should be collected during the next 24-hour period.
• Remind the patient to urinate at the end of the collection period and to include this urine in the 24-hourcollection.
• Tell the patient to urinate before having a bowel movement
• Instruct the patient to refrigerate the entire specimen after adding each collection during the 24-hour period.
• Warn the patient of any preservatives in the container.
• Inform the patient not to add anything except urine to the container and not to discard any urine during the collection period.
• A normal intake of fluids during the collection period is desirable unless otherwise indicated by the physician.
• Some laboratory assays require special dietary restrictions; give these instructions to the patient.
• If possible, discontinue medications for48 to 72 hours prior to urine collection.
• Transport the 24-hour urine specimen to the clinical laboratory as soon as possible.
• Place the specimen in an insulated bag or a portable cooler to maintain their cool temperature.