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http://evolve.elsevier.com/Warekois/phlebotomy CHAPTER 13 Arterial Blood Collection
Plastic
cap
https://t.me/med1917
6. Mix well using the magnet and ea, and trans-
Capillary tube
port the specimen to the laboratory on ice.
203
Plastic
caps
Heparinized
capillary tube
FIGURE 13-3 A metal filing, called a flea, is inserted into the
capillary tube before collection. A magnet is used to stir the sample
after collection.
Metal
flea
Magnet
Metal
flea
Magnet
1. Warm the site to 40° C to 42° C for 5 to 10 minutes before the stick to maximize the arterial
character of the capillary blood.
2. Clean the site with the appropriate antiseptic
swab, using the antiseptic required by your institution. Allow the site to dry for the appropriate
time.
3. Collect the sample in a heparinized glass pipet.
Before collection, insert a metal ling, called a
ea, into the tube. After collection, a magnet is
used to draw the ea back and forth across the
length of the tube to mix the contents with the
heparin (Figure 13-3).
4. Fill the tube completely with blood so that no air
bubbles remain.
5. Seal both ends of the tube with clay or plastic
caps to prevent air contamination.
REVIEW FOR CERTIFICATION
Because of the increased danger of arterial blood
collection, special training is required beyond that
needed for routine venipuncture. Arterial blood
monitoring is ideal for managing oxygen, electrolytes, and acid-base balance. ABGs measure the
gas exchange ability of the lungs and the buffering
capacity of the blood. Arterial blood is collected in
a syringe pretreated with heparin to prevent coagulation. The site is cleansed with both alcohol and
chlorhexidine to minimize the serious risk of infection. Lidocaine is used as an anesthetic. The site is
selected after testing the adequacy of collateral
circulation using the modied Allen test. A rapid
return of color indicates that the site has adequate
collateral circulation and may be used for collection. In adults, the radial artery is the preferred
site. The patient must be in a respiratory steady state
and should be kept calm during the procedure.
The specimen should be delivered immediately or
kept on ice if a delay of more than 5 to 10 minutes
is expected. Complications include arteriospasm,
nerve damage, hematoma, hemorrhage, thrombosis,
and infection. Sampling errors affecting test values
may be introduced from improper cooling, delay in
delivery, too much or too little heparin, insufcient
mixing, exposure of the sample to air, and improper
collection technique. Capillary blood gas testing
is an alternative to ABG testing when arterial
collection is not possible or recommended. A metal
ea and magnet are used to mix the contents with
the heparin.
BI BL IOG R AP H Y
Bishop ML, Fody EP, Schoeff LE: Clinical chemistry: Principles,
procedures, and correlations, ed. 7, Philadelphia, 2013, Lippincott.
Burton GG, Hodgkin JE, Ward JJ: Respiratory care: A guide to
clinical practice, ed 4, Philadelphia, 1997, Lippincott.
CLSI: Procedures for the collection of arterial blood specimens;
Approved standard—fourth edition. CSLI document GP43-A4 (for-
merly H11-A4). Wayne, Pa., 2004, Clinical and Laboratory Standards
Institute.
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
Conover K: Blood gases: Not as complicated as they seem,
Version 1.8, 2010. Retrieved from www.pitt.edu/,mercyres/
Abg-ref.pdf.
Lockshin MBL: Arterial blood gas, 2010. Retrieved from www.
wisc-online.com/objects/ViewObject.aspx?ID5NUR202.
Shapiro BA: Clinical application of blood gases, ed. 5, St. Louis,
1994, Mosby.
204
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CHAPTER 13 Arterial Blood Collection http://evolve.elsevier.com/Warekois/phlebotomy
STUDY QUESTIONS
See answers in Appendix F.
1. Arterial collection is most often used for what type of testing?
2. List four conditions that produce abnormal ABG values.
3. What is a normal blood pH?
4. What is the difference between acidosis and alkalosis?
5. Describe the difference between a syringe used for venipuncture and a syringe used for ABG
collection.
6. Besides alcohol, which other antiseptic must be used for arterial puncture?
7. What local anesthetic may be used to numb the site?
8. What safety precautions must be taken by the phlebotomist when collecting blood from an artery?
9. What gauge needle is most often used for blood gas collection?
10. Dene collateral circulation, and state which test is used to determine whether this is present.
11. For an arterial collection, at what angle is the needle inserted into the artery?
12. How long must pressure be applied to the puncture site after an arterial collection?
13. Dene arteriospasm.
14. List ve ABG sampling errors.
15. Name ve reasons that ABG specimens may be rejected.
16. In which population is capillary blood gas testing most commonly performed, and on what part of
the body is this procedure usually done?
17. Why is capillary blood not as desirable as arterial blood for testing blood gases?
CERTIFICATION EXAMINATION PREPARATION
See answers in Appendix F.
1. Arterial blood collection monitors all of the
following except
a. ammonia.
b. glucose.
c. lactic acid.
d. blood gases.
2. A normal blood pH is
a. 7.35.
b. 7.00.
c. 7.60.
d. 7.75.
3. The ABG syringe is coated with
a. sodium citrate.
b. sodium uoride.
c. EDTA.
d. heparin.
4. A typical needle gauge for ABG collection is
a. 16.
b. 20.
c. 22.
d. 18.
5. Which artery is most frequently used for ABG
collection?
a. Brachial
b. Femoral
c. Dorsalis pedis
d. Radial
6. Which of the following is not an ABG
sampling error?
a. Delivery of an un-iced sample to the
laboratory 15 minutes after collection
b. Use of the anticoagulant EDTA
c. Air bubbles in the syringe
d. Use of a gas-impermeable plastic syringe
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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205
7. The modied Allen test determines
a. Po2.
b. Pco2.
c. collateral circulation.
d. pH.
8. In an arterial collection, the needle should be
inserted at a ______ degree angle.
a. 90
b. 45
c. 30
d. 70
9. If lidocaine is injected before an arterial
blood collection, wait ______ minutes for
the anesthetic to begin working.
a. 1 to 2
b. 2 to 3
c. 3 to 4
d. 4 to 5
10. The modied Allen test is performed on the
______ and ______ arteries.
a. ulnar, brachial
b. brachial, radial
c. ulnar, radial
d. radial, femoral
11. Which of the following is not a complication
of ABG collection?
a. Petechiae
b. Arteriospasm
c. Thrombosis
d. Hematoma
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
CHAPTER 14 Special Collections
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and Procedures
206
lthough routine venipuncture is the most com-
A
mon procedure you will perform as a phlebotomist, special collecting or handling procedures are
needed in many situations for samples that involve
one or more special circumstances. Fasting specimens, timed specimens, blood cultures, and blood
donor specimens all require collection procedures
OU TL I NE
Fasting Specimens and the
Basal State
Timed Specimens
2-Hour Postprandial Test
Glucose Tolerance Test
Other Tolerance Tests
Diurnal Variation
Therapeutic Drug Monitoring
Blood Cultures
Types of Collection Containers
Timing
Multiple Sites
Sample Collection
Procedure 14-1: Blood Cul-
ture Collection
Blood Donor Collection
Collection Procedure
Autologous Donation
Therapeutic Phlebotomy
Special Specimen Handling
Cold Agglutinins
Cryofibrinogen and Cryoglob-
ulin
Chilled Specimens
OB J E CT IV E S
specic to the sample being collected. A variety
of samples require special handling, which may
involve keeping the sample warm, cool, or away
from light, or providing immediate delivery or legal
documentation. In this chapter, you will learn when
and why these special procedures are needed and
the details of how to perform them.
Light-Sensitive Specimens
Time-Sensitive Specimens
Legal and Forensic Specimens
Legal Alcohol Collection
Blood Smears
Blood Smear Preparation
Procedure 14-2: Blood
Smear Preparation
Malaria Smears
Review for Certification
After completing this chapter, you should be able to:
1. Define basal state.
2. Define and explain the uses of:
a. Fasting specimens
b. Timed specimens
c. 2-hour postprandial specimens
3. Describe the procedure for performing the various
tolerance tests.
4. Define diurnal variation, and list the blood
constituents that may be affected by it.
5. Define therapeutic drug monitoring (TDM),
describe the differences among a random level
and peak and trough levels, and explain how TDM
samples are collected.
6. Describe the reasons and procedures for collecting
blood for culture.
7. Explain the steps in collecting blood from donors
for transfusion.
206
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
8. Define and explain the uses of autologous
donation and therapeutic phlebotomy.
9. Explain how samples to be tested for or
suspected of containing cold agglutinins,
cryofibrinogen, or cryoglobulin should be handled.
10. List samples that should be chilled until tested.
11. List samples that are light sensitive, and explain
how they should be handled.
12. Describe the precautions to be taken when
collecting legal or forensic specimens.
13. List samples that are time sensitive, and explain
how they should be handled.
14. Explain how to prepare blood smears, describe
features of unacceptable smears, and list the
possible causes.
15. Explain how to prepare smears to be examined
for malaria.
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KE Y TE R M S
207
aerobic bacteria
agglutination
anaerobic bacteria
bacteremia
basal state
blood culture (BC)
chain of custody (COC)
cold agglutinins
cryofibrinogen
cryoglobulin
differential count (diff)
diurnal variation
epinephrine tolerance test
fasting specimen
feathered edge
fever of unknown
origin (FUO)
gestational diabetes
glucagon tolerance test
glucose tolerance test (GTT)
half-life
hemochromatosis
hyperglycemia
hypoglycemia
lactose tolerance
test (LTT)
oral glucose tolerance
test (OGTT)
peak level
polycythemia
sepsis
sodium polyanethole
sulfonate (SPS)
therapeutic drug
monitoring (TDM)
therapeutic phlebotomy
trough level
2-hour postprandial test
AB BR E VI AT IO NS
AABB American Association of Blood Banks
ACTH adrenocorticotropic hormone
BC blood culture
COC chain of custody
DNA deoxyribonucleic acid
FDA Food and Drug Administration
FUO fever of unknown origin
GTT glucose tolerance test
HIV human immunodeficiency virus
LTT lactose tolerance test
NIDA National Institute on Drug Abuse
OGTT oral glucose tolerance test
RBCs red blood cells
SPS sodium polyanethole sulfonate
stat short turnaround time
TDM therapeutic drug monitoring
WHAT WO ULD YOU DO?
After you have had 2 months on the job at City General Hospital, your supervisor is ready to let you
collect blood culture specimens. She asks your coworker, Tom, to go along with you in case you have
any problems. You perform your rst draw awlessly, although it took longer than expected, and Tom
has started looking at his watch. You begin prepping your second patient, hoping to do this one a bit
faster, but as you are about to insert the needle, your gloved nger grazes the site. Oh no! Is the site
contaminated? Do you need to start all over again? You look at Tom. “Don’t worry,” he says. “You can
just go ahead and draw. It’ll be ne. The lab is OK with that kind of thing.” What would you do?
FASTING SPECIMENS AND THE
BASAL STATE
As detailed in Box 14-1, many factors inuence
the composition of blood. Diurnal variation refers
to the normal daily uctuations in body chemistry
related to hormonal cycles, sleep–wake cycles, and
other regular patterns of change.
In Chapter 18, you will learn more about factors that affect test
results and how to avoid making errors in your collection and
transport.
To minimize the variations introduced by normal
uctuations in blood composition, reference ranges
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
FLASH FORWARD
BOX 14-1 Factors That Influence Blood
Composition
• Age
• Altitude
• Body position
• Dehydration
• Diet
• Diurnal variation
• Drugs
• Environment
• Exercise
• Gender
• Pregnancy
• Smoking
• Stress
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CHAPTER 14 Special Collections and Procedures http://evolve.elsevier.com/Warekois/phlebotomy
for blood tests are based on healthy patients in what
is known as the basal state. The basal state is
dened as the body’s state after 8 to 12 hours of
fasting and abstention from strenuous exercise.
Routine phlebotomy rounds are scheduled for the
early morning, because most patients are in the
basal state at that time.
Some test results are more affected than others
when a patient has not been scrupulously fasting for
12 hours. Glucose and triglycerides are especially
affected. For this reason, a fasting specimen may
be requested that is drawn after a 12-hour complete
fast. Caffeine and nicotine are also prohibited
during the fasting period, as these are metabolic
stimulants. If a fasting specimen is requested, the
phlebotomist must ask the patient if he or she
has had anything to eat or drink other than water,
or has had any caffeine or nicotine, within the past
12 hours. It is better to ask the question in this form
than to ask, “Have you been fasting for 12 hours?”
because some patients may not consider an evening
snack or morning juice to be a violation of their fast.
If the patient has violated the fast, you can still draw
the sample, but make a note on the requisition. You
may also contact your supervisor to see whether the
physician should be notied before the draw. Often,
the physician will reschedule the lab work, particu-
larly if a lipid prole is ordered.
Timed Specimens
Timed specimens are taken to determine changes in
the level of some substance of interest over time.
Timed specimens are most often used to monitor:
• Medication levels (e.g., digoxin for heart disease
or levodopa for Parkinson disease).
• Changes in the patient’s condition (e.g., a decrease
in hemoglobin level).
• Normal diurnal variation in blood levels at
different times of the day (e.g., cortisol or other
hormones).
• Cardiac enzymes, used to diagnose or rule out
myocardial infarction (heart attack); these are
tested at admission and then twice more at
8-hour intervals.
patients will have returned to the fasting level. After
the phlebotomist has obtained a fasting specimen, the
patient is instructed to eat a full meal and then return
to the lab 2 hours after eating for collection of the
second specimen.
Glucose Tolerance Test
The glucose tolerance test (GTT), also called the
oral glucose tolerance test (OGTT), tests for both
diabetes mellitus and other disorders of carbohydrate metabolism. Hyperglycemia, or abnormally
elevated blood sugar, is most commonly caused by
diabetes; hypoglycemia, or abnormally lowered
blood sugar, may be due to one of several endocrine
disorders or other metabolic disruptions. Hyperglycemia is detected with a 3-hour GTT, and hypoglycemia is detected with a 5-hour GTT. Longer testing
periods are sometimes used as well to identify a
variety of metabolic disorders. The GTT has fallen
out of general use for the diagnosis of diabetes mellitus, and has been replaced by either a fasting glu-
cose sample (at least 8 hours without caloric intake)
or a random glucose sample.
Glucose tolerance testing is still widely used in
pregnant women, to diagnose gestational diabetes.
Gestational diabetes is insulin-resistant diabetes
that develops in almost 20% of women late in pregnancy. The initial screen is a 1-hour GTT, performed
without fasting. The patient drinks an intensely
sweetened liquid, and a sample is taken 1 hour later.
Elevated glucose in the sample indicates potential
gestational diabetes. That nding usually prompts
the physician to order a fasting GTT.
Patients will be instructed by their physicians
regarding pretest preparation, which includes eating
high-carbohydrate meals for several days and then
fasting for 12 hours immediately before the test.
Testing begins between 0700 (pronounced “ohseven-hundred”) and 0900 (7 am to 9 am), with the
collection of a fasting blood specimen and sometimes a urine specimen. These specimens should be
tested before the GTT proceeds. In the event that the
glucose level is severely elevated, the physician
may decide not to proceed with the test.
2-Hour Postprandial Test
The 2-hour postprandial test is used to test for dia-
betes mellitus. It compares the fasting glucose level
with the level 2 hours after consuming glucose, either
by eating a meal or by ingesting a measured amount
of glucose (postprandial means “after a meal”). In
patients with diabetes mellitus, the glucose level will
be higher than normal, whereas the level in normal
CLINICAL TIP
Times are given in military time. To get clock time, subtract
1200 for times of 1300 or later. Example: 1430 5 2:30
pm.
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209
The patient then drinks a standardized amount of
glucose solution within 5 minutes. Timing for the
rest of the procedure begins after the drink is nished. The phlebotomist makes a collection schedule. The rst collection is 1 hour after glucose
ingestion. The second collection is 2 hours after
glucose ingestion, and so on, for the number of
hours the physician has indicated. Note that some
procedures may call for collection of the rst sample
at 30 minutes after ingestion of the glucose solution,
followed by another collection 30 minutes later at
the 1 hour mark, and then hourly samples after
that. Follow the protocol of your facility. The phlebotomist gives the patient the collection schedule
and instructs the patient to return to the collection
station at the appropriate times (Table 14-1). Patients
also should be instructed to continue to fast and
drink plenty of water so that they remain adequately
hydrated throughout the test.
Some patients do not tolerate the test well.
Any vomiting should be reported to the physician
ordering the test. If the patient vomits shortly after
the test begins, the procedure will have to be
started again.
All collections should be made on time and using
the same collection method (i.e., venipuncture or
dermal puncture) and anticoagulant for each sample. A urine specimen may be collected at the same
time. Samples should be labeled with the time from
test commencement (1 hour, 2 hours, and so
rine, glycogen is converted to glucose and released
into the bloodstream. The test begins with a fasting
specimen, followed by the epinephrine injection
administered by the physician. Specimen collection
begins 30 minutes later. The glucagon tolerance
test is identical in purpose and procedure, except
that the hormone glucagon is injected instead of
epinephrine.
The lactose tolerance test (LTT) determines
whether the lactose-digesting enzyme lactase is
present in the gut. A 3-hour GTT is performed rst
to produce a baseline glucose uptake graph. The
following day a lactose tolerance test is performed.
The procedure is identical to the GTT except that
lactose is consumed and a tourniquet may not be
used. Be sure to follow the protocol for your facility. Because lactose is broken down into glucose
and galactose, the timed samples should produce an
identical glucose uptake graph. Lower glucose levels indicate a problem with lactose metabolism.
Lactose intolerance can also be determined using
the hydrogen breath test, which does not require
a blood sample. In this test, the patient drinks a
lactose solution and then exhales into a collection
bag. Hydrogen in the breath is a sign of undigested
lactose in the gut.
A stool acidity test may be ordered for patients
and children who are unable to undergo the other
tests. Lactic acid and other acids from undigested
forth).
lactose can be detected in a stool, or fecal, sample.
FLASH FORWARD
Urine specimen collection is covered in Chapter 15.
Other Tolerance Tests
You will learn about fecal samples in Chapter 15.
Diurnal Variation
Similar procedures are used for other tolerance
tests. The epinephrine tolerance test determines
the patient’s ability to mobilize glycogen from the
liver. In response to a dose of the hormone epineph-
BOX 14-2 Representative Blood Constituents
That Show Marked Diurnal Variation
TABLE 14-1 Collection Schedule for Oral
Glucose Tolerance Tests
Test Schedule
2-Hr glucose tolerance
test (GTT)
3-Hr GTT Fasting, 1 hr, 2 hr, and 3 hr
5-Hr GTT Fasting, 1 hr, 2 hr, 3 hr, 4 hr,
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
Fasting, 1 hr, and 2 hr
and 5 hr
• Cortisol
• Estradiol
• Glucose
• Hormones
• Progesterone
• Serum iron
• Testosterone
• White blood cells (eosinophils show especially
pronounced variation)
FLASH FORWARD
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Many substances in the blood (especially hormones)
show diurnal variation, or regular changes throughout the day (Box 14-2). Cortisol, for instance,
is usually twice as high in the morning as in the
late afternoon. The time for the draw is usually
scheduled for the diurnal peak or trough. Cortisol is
usually drawn at 1000 or 1600, for instance.
Therapeutic Drug Monitoring
Patients differ greatly in the rate at which they me-
tabolize or excrete medications. In addition, the
“margin of safety,” or the difference between the
level at which a drug is therapeutic and the level at
which it becomes toxic, may be narrow. To maintain
constant therapeutic plasma drug levels and ensure
that the drug does not reach toxic levels, a patient
may require timed specimens to measure the levels
of the medication. This is known as therapeutic
drug monitoring (TDM). Results of TDM are used
by the pharmacy to adjust drug dosing. Table 14-2
lists some commonly monitored drugs. The rate of
metabolism is often given in terms of the drug’s
half-life, the time for half of the drug to be metabo-
lized. Drugs with long half-lives, including digoxin,
often require only one timed specimen. Drugs with
short half-lives, such as the aminoglycoside antibiotics (including gentamicin, tobramycin, and vancomycin) require the most careful monitoring.
Monitoring for these rapidly metabolized antibiotics is done with a pair of specimens, known as a
peak and a trough.
Collection is usually timed to coincide with
either the trough or the peak serum level. The
trough level is the lowest serum level and occurs
immediately before the next dose of medicine is
given. The requisition will specify the actual collection time, which is usually 30 minutes before the
dose. The peak level, or highest serum level, occurs sometime after the dose is given; exactly when
depends on the characteristics of the drug, the
TABLE 14-2 Commonly Monitored
Therapeutic Drugs
Drug Name Therapeutic Purpose
Dilantin and valproic acid Anticonvulsant
Gentamicin Antibiotic
Procainamide and digoxin Heart medication
Theophylline Antiasthmatic
Tobramycin Antibiotic
Vancomycin Antibiotic
patient’s own metabolism, and the method of administration. The tube should be labeled with
the draw time in all cases. Careful attention to
the correct timing of draw, and accurate labeling, is
vital to the patient’s health. TDM results are needed
promptly, because the pharmacy is usually waiting
for the results to determine both the timing and the
concentration of the next dose of drug. By properly
timing the administration of medications, the doc-
tor can have the maximum benecial effect with
the fewest side effects. Most drugs need to be
collected in a red top tube because the gel in a
serum separator tube interferes with the analysis
of the drugs.
AVOID THAT ERROR!
When phlebotomist Thomas Jordan picks up the stack of
requisitions waiting for him in the laboratory at City General
Hospital, he notices that the one for Leonard Brisco, in room
311, calls for a chem panel as well as a peak-level test for
valproic acid, an epilepsy drug, to be drawn at 11
arrives at 10:55 am, prepares the patient, and begins the draw
precisely at 11, filling a gold-top Hemogard tube, inverting it five
times after the draw. He thanks the patient, labels the tube, and
heads off to his next patient. What did he do wrong? What should
he have done, and what should he do now?
am. Thomas
BLOOD CULTURES
A blood culture (BC) is ordered to test for the pres-
ence of microorganisms in the blood, a potentially
life-threatening situation. Such microorganisms in-
clude bacteria, fungi, and protozoa. Bacteremia
refers specically to the presence of bacteria in the
blood. Bacteria occasionally enter the bloodstream,
for instance through the gut or from excessively
vigorous toothbrushing, which breaks capillaries.
These rarely cause illness. Septicemia is a lifethreatening infection caused by rapid multiplication
of pathogens in the bloodstream. When microorganisms in the blood trigger a systemic inammatory
response, it is called sepsis. Patients with symptoms
of chills and fever, or fever of unknown origin
(FUO), may require a BC. BCs are ordered as short
turnaround time (stat) or timed specimens.
Isolating pathogenic organisms from blood
is difcult because the number of organisms may
be low (leading to false-negative results) and the
potential for sample contamination is high (leading
to false-positive results). To increase the likelihood
of nding pathogens and decrease the number of
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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211
false positives, collection is performed at timed
intervals and from multiple sites. Aseptic collection
technique is critical for meaningful results. Drawing
the correct volume is also critical, because the ratio
of blood to culture media depends on the system
used. Always check your institution’s guidelines.
Volumes for pediatric patients differ from those
for adults.
Types of Collection Containers
There are three basic types of containers for
collecting BCs:
1. A long-necked bottle, which accepts a BD Vacutainer needle and tube holder.
2. A shorter bottle, which accepts a winged infusion device, such as a BD Bactec, using a special
adapter.
3. A standard evacuated tube with sodium poly-
anethole sulfonate (SPS) anticoagulant.
Figure 14-1 shows these three types of collection
containers.
Timing
The number of organisms in the bloodstream is
often highest just before a spike in the patient’s
temperature. By frequently recording the temperature, these spikes can often be predicted and collection scheduled accordingly. In other situations,
collection may be timed at regular intervals, often
hourly or just before antibiotic administration.
Multiple Sites
Contamination of the sample by skin bacteria is a
frequent complication of BC collection. However,
distinguishing contaminants from true pathogens
can be difcult because some contaminants can
grow on indwelling devices, causing infection in the
patient. To reduce errors caused by this contamination, a known skin contaminant must be cultured
from at least two different sites to be considered a
blood pathogen. It is even better to collect two pairs
of samples from two different sites. This helps
detect contamination of samples by skin bacteria.
The physician should be consulted about the exact
sites and timing of the two sets.
Sample Collection
Procedure 14-1 outlines the steps in BC collection.
As noted earlier, samples are collected either directly
into a bottle containing culture media or indirectly
into a sterile anticoagulated tube for later transfer to
culture media in the laboratory. The ratio of blood
to culture media is crucial to the culture, so be sure
to collect the sample size indicated on the bottle. In
addition to culture media, some tubes contain activated charcoal, which absorbs antibiotics from the
patient’s blood so that they do not inhibit growth of
the bacteria in the culture tube. Also, some bacteria,
called anaerobic bacteria, cannot tolerate oxygen,
while others, called aerobic bacteria, use it. Some
samples you collect will exclude oxygen and will be
used to grow anaerobic bacteria. Other samples you
collect will include oxygen and will be used to grow
aerobic bacteria.
For direct collection into culture media, two
samples, one aerobic and one anaerobic, are col-
lected from each site. When using a syringe, collect
the anaerobic sample rst and the aerobic sample
second, since the second sample will be more likely
to have been exposed to air. The transfer must
be performed with the appropriate transfer safety
device. When using a buttery, the opposite order is
used: Collect the aerobic sample rst, since there is
FIGURE 14-1 Examples of culture systems used in the collection
of blood cultures (BCs). A, Adult blood culture collection container. B, Pediatric blood culture collection container.
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
air inside the buttery tube, and then collect the
anaerobic sample. Be sure to label the samples to
reect their order of collection.
For anticoagulated tube collections, only one
tube is collected per site. At the laboratory, the
specimen is cultured onto the appropriate media.
BA
CLINICAL TIP
Aerobic bacteria use oxygen to grow; anaerobic bacteria are killed
by exposure to oxygen.
212
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CHAPTER 14 Special Collections and Procedures http://evolve.elsevier.com/Warekois/phlebotomy
PROCEDURE 14-1
Blood Culture Collection
1. Prepare the site.
Proper site preparation is critical to obtain a valid
blood culture (BC) specimen. After identifying
the site, scrub it vigorously with alcohol to clean
1½ to 2 inches beyond the intended puncture site.
Scrub vigorously with 2% iodine or a povidone–
iodine swab stick. Using a new swab stick,
clean the site, moving outward in a concentric
circle. An alternative is to use a one-step
Medi-ex ChloraPrep applicator instead
of the two steps outlined here.
Allow the site to dry for 1 minute. This ensures
enough time for the iodine to kill surface bacteria.
Avoid touching the site once it has been cleaned.
If you must touch it, reclean the site afterward.
2. Prepare your collection equipment.
Clean the tops of collection bottles with iodine
or alcohol, depending on your institution’s
protocol (rubber tops are usually cleaned
with alcohol). Place a clean alcohol pad on
top of each bottle until it is inoculated.
Immediately before inoculation, wipe the
top with the pad to prevent iodine
contamination of the sample. Be sure
not to touch the bottle tops directly.
3. Collect the sample.
Reapply the tourniquet, and perform the
venipuncture. Collect two samples. Label
one “anaerobic” and the other “aerobic,” and
indicate the site of the puncture. (Remember
that for a syringe collection the rst sample
is anaerobic and the second is aerobic. For a
buttery collection, the rst sample is aerobic
and the second is anaerobic.)
4. Attend to the patient.
After collection, remove the iodine from the
patient’s arm with alcohol. Do not touch the
puncture site because this could cause stinging
for the patient at that site.
Check the puncture site to be sure bleeding has
stopped.
Apply a bandage, using a fresh adhesive bandage
or placing adhesive tape over the gauze square.
Raise the bed rail if you lowered it.
Dispose of all contaminated materials in a
biohazard container.
Copyright 2016, 2011, 2007, 2002 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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