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HEMA 1 > Specimen Collection Pt. II > Flashcards

Specimen Collection Pt. II Flashcards

1
Q

what to do after cleaning the puncture site?

A

Reapply tourniquet

  • perform puncture
  • DO NOT TOUCH SITE WITH UNCLEAN FINGERS
  • ask patient to remake fist
      • instruct not to pump/continuously clench fist (to prevent hemoconcentration)
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2
Q

after anchoring the vein, insert the needle smoothly & swiftly at _________

A

15-30 degree angle; bevel up

- brace fingers against arm to prevent movement of needle when changing tubes

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3
Q

T/F:

once blood flow is observed, release the tourniquet & ask patient to open fist

A

TRUE

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4
Q

T/F:

for ETS, the prints on the tubes should face up when filling them with blood

A

FALSE

  • prints should face down to allow blood flow to be seen
  • once full, remove the tube gently, invert & fill the next tube (according to the order of draw)
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5
Q

once the tubes are all filled, cover the puncture site, remove the needle swiftly & smoothly, and ______________

A

Ask patient to apply pressure

  • arm should be straight or raised
  • for 2-5 minutes
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6
Q

T/F:

it is okay to leave the patient right away after collection

A

FALSE

  • verify info for labelling
  • examine puncture site for bleeding or hematoma
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7
Q

specimens should be transported to the lab within ________

A

45 minutes - 2 hours

- do not forget to thank the patient, clean the area, and perform hand hygiene before transport

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8
Q

sites that may be used when collecting venous blood in infants

A
  • dorsal hand veins
  • cord blood
  • external jugular vein
      • DOCTORS ONLY
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9
Q

veins in the antecubital fossa are the best choice for _____________

A

children > 2 years old

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10
Q

dorsal hand veins

A
  • those used for IV therapy
  • can be used for children < 2 years old
  • PROS:
      • sample is collected from superficial hand veins directly into microcontainers
      • more blood is collected than heelstick
      • there is less chance of hemolysis & contamination with tissue fluids
  • CONS:
      • requires additional training
      • an institutional decision (saving veins for IV therapy may be preferred)
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11
Q

sample obtained only at the time of delivery

A

Cord blood

  • placental segment is allowed to drain into a test tube, OR
  • umbilical vein is aspirated with needle & syringe
  • admixture of cord jelly must be avoided
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12
Q

cord jelly

A

“Wharton’s jelly”

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13
Q

procedure in which only the doctors are allowed to perform

A

External jugular vein

  • infant is wrapped in sheet (to immobilize infant)
  • infant is placed on his/her back on the table with the head hanging over the edge (head should be supported)
  • infant is turned to the side
  • when child cries, EJV becomes visible
      • running the angle of the mandible to midclavicular area
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14
Q

method of choice for collecting blood from infants & children younger than 2 years old

A

Skin (dermal) puncture

  • locating large, superficial veins are difficult
  • available veins may be reserved for IV therapy
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15
Q

total blood volume of a 2-pound infant

A

approx. 150mL

- drawing excessive amounts can rapidly cause anemia

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16
Q

complications that may arise from using deep veins in infants

A
  • cardiac arrest
  • venous thrombosis
  • hemorrhage
  • damage to surrounding tissues & organs
  • infection
  • reflex arteriospasm –> resulting gangrene
  • injury to the child (restraining)
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17
Q

certain tests that require capillary blood from newborn & infants

A
  • newborn screening tests
  • neonatal bilirubin
  • capillary blood gases
  • POCT
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18
Q

conditions where dermal puncture may be preferred over venipuncture in adults

A
  • burned/scarred patients
  • patients receiving chemotherapy
  • patients with thrombotic tendencies
  • geriatric patients; those with very fragile veins
  • patients with inaccessible veins
  • obese patients
  • apprehensive patients
  • patients requiring home glucose monitoring
  • POCT
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19
Q

why is dermal puncture preferred in patients receiving chemotherapy?

A

they require frequent tests & their veins must be reserved for therapy

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20
Q

blood collected by dermal puncture comes from ___________, ____________, __________

A

capillaries, arterioles, & venules

  • a mixture of arterial & venous blood
  • may contain small amounts of interstitial & intracellular fluids
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21
Q

T/F:
because of arterial pressure, the composition of capillary blood more closely resembles arterial rather than venous blood

A

TRUE
- warming the site before collection increases blood flow by 7x –> producing a sample very close to arterial blood composition

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22
Q

dermal puncture devices

A
  • skin puncture devices (lancets)
  • microcontainers
  • glass slides
  • heel warmer
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23
Q

T/F:

to prevent contact with the bone, the depth of the puncture is critical

A

TRUE

  • should not exceed 2mm (CLSI recommendation)
  • length of lancet & spring release mechanisms control the puncture depth (automatic devices)
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24
Q

major vascular area of the skin

A

Dermal subcutaneous junction

  • newborn: 0.35-1.6mm below the skin
  • adults: max. 3mm
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25
Q

sufficient blood flow should be obtained from incision widths __________

A

not greater than 2.5mm

  • widths vary from needle stabs - 2.5mm
  • number of severed capillaries depends on the incision width
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26
Q

the type of device selected depends on the following factors:

A
  • age
  • amount of blood sample required
  • collection site
  • puncture depth
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27
Q

lancets approved by the FDA for adults & children older than 5 years old

A

Laser lancets

  • available for clinical & home use
  • eliminates the risks of accidental punctures & the need for sharps containers
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28
Q

depth at which laser lancets penetrate the skn

A

1-2mm

  • vaporizes water in the skin
  • smaller wound is created
  • pain & soreness associated with capillary puncture is reduced
  • allows up to 100uL of blood to be collected
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29
Q

microcontainers

A

Microsample containers

  • microcollection tubes
  • capillary tubes
  • micropipettes
30
Q

frequently referred to as microhematocrit tubes

A

Capillary tubes

  • used to collect approx. 30-75uL of blood
  • primary purpose: for microhematocrit tests
  • 2 types:
      • plain = blue band
      • heparinized = red band (ammonium heparin)
31
Q

heel warmers

A

a. warm washcloths
- heating at 42C & applying for 3-5 minutes
- site should not be warmed for more than 10 minutes –> false results
- be careful not to burn the patient

b. commercial heel warmer
- sodium thiosulfate & glycerin
- produces heat when mixed together (gentle squeezing the packet)

32
Q

puncture site for dermal puncture

A
  • off center
  • 3rd or 4th finger, palmar side (nondominant hand)
  • perpendicular to the (ridges of the) fingerprint
33
Q

position of puncture site

A

palmer surface facing up, finger pointing down

34
Q

T/F:

after puncturing, the first drop of blood is wiped away

A

TRUE

  • to prevent contamination
  • the first drop may contain alcohol residue & tissue fluid
35
Q

sample should be collected within ________ to prevent clotting

A

2 minutes

36
Q

number of inversions for microcontainers

A

5-10 times

  • or as recommended by the manufacturer
  • containers may be gently tapped to mix blood & anticoagulant
37
Q

T/F:

it is okay to apply bandage for children younger than 2 years old after puncture

A

FALSE

- it can cause choking to the infant

38
Q

T/F:

punctures should never be made through previous puncture sites

A

TRUE

- can easily introduce microorganisms into the puncture –> allowing them to reach the bone

39
Q

where to collect blood when patient has had mastectomy?

A

Opposite to the side of the mastectomy

  • inform health-care provider first
  • aside from breast tissue, lymph nodes are also removed in mastectomy
      • there is greater chance of acquiring infections
40
Q

site used for dermal punctures on infants younger than 1 year old

A

Heel puncture site

  • contains more tissue than the fingers
  • has not yet been calloused from walking
  • acceptable areas: MEDIAL & LATERAL AREAS OF THE PLANTAR SURFACE (bottom) OF THE HEEL
      • distance between the skin & calcaneus (heel) bone is greatest
41
Q

punctures performed in other areas aside from the acceptable areas may cause _____________

A

damage to nerves, tendons, cartilage

42
Q

heel puncture vs. finger puncture

A

a. heel puncture
- medial & lateral areas of the plantar surface of the heel
- for children younger than 1 year old

b. finger puncture
- 3rd & 4th finger of the nondominant hand
- for adults & children over 1 year old

43
Q

why should finger punctures be off center & perpendicular to the fingerprint?

A
  • wound easily opens up
  • collect more (rounded) blood
  • tip & sides of the finger contain only about 1/2 tissue mass of the central area –> possibility of bone injury is increased
44
Q

problems associated with the use of other fingers for puncture

A

a. thumb & index fingers
- possible calluses

b. index finger
- increased nerve endings

c. fifth finger
- decreased tissue

45
Q

effect of puncturing a swollen site

A

increased tissue fluid –> contamination of blood sample

46
Q

heel stick procedure

A
  • same basic steps as venipuncture
  • hold the foot with a firm grip
      • grasp the heel with the thumb placed below the site & index finger placed over the arch
  • puncture at a 90 degree angle parallel to the heel
  • use a quick continuous motion
47
Q

when is warming the site required?

A
  • for patients with very cold (cyanotic) fingers
  • for heel sticks to collect multiple samples
  • for collection of capillary blood gases
      • BVs are dilated –> arterial blood flow is increased
48
Q

_____________ may also increase blood flow to the area

A

Massaging the puncture area

- do not squeeze when collecting sample

49
Q

presence of air bubbles in the sample

A

Interferes with blood gas determinations

- bubbles limit the amount of blood that can be collected

50
Q

how to prevent air bubbles?

A

hold capillary tubes horizontally while being filled (capillary action)
- do not remove the tube while collecting

51
Q

what to do when tubes are filled?

A

Seal

  • sealant clay
  • designated plastic caps
  • place the end of the tube (with no band) into the clay
      • remove with a slight twisting action
      • be careful not to break the tube
52
Q

effect of using adhesives as bandage

A
  • skin irritation

- tear sensitive skin (part. fragile skin)

53
Q

how to label microcollection tubes

A

The same info required for venipuncture samples

  • wrap around a number of microcollection tubes
  • place in a large tube for transport
      • the outside of the capillary pipettes may be contaminated with blood
      • prevents breakage
54
Q

order of draw for dermal puncture

A
  1. blood gas (?)
  2. blood smear
  3. EDTA tubes
    - pink/lavender
    - HEMA tubes
  4. heparin tubes
    - light/dark green
    - tests requiring plasma
    - K, Glu, chem tests
  5. red/gold tubes
    - tests requiring serum
    - K, Na, bilirubin, chem tests, blood bank
55
Q

veins in antecubital fossa used for venipuncture

A
  1. Median cubital
    - most well-anchored
    - largest, superficial
    - most preferred
  2. Cephalic
    - well-anchored
  3. Basilic
    - least well-anchored
    - surrounded by nerves
    - least preferred
56
Q

sources of error for skin puncture

A

a. hemolysis
- most common
- infants’ RBCs are more fragile than adults’

b. failure to dry site completely
c. failure to wipe away 1st drop of blood
d. vigorous massaging/milking
e. accidental capturing of air bubbles into tubes

*“skin puncture” should be noted in requisition slip - lab values may differ

57
Q

coagulation of blood can be prevented by:

A

a. removing (chelating) calcium
- oxalates
- citrates
- EDTA

b. inactivating thrombin & thromboplastin
- heparin

c. removing fibrin

58
Q

too little anticoagulant

A

partial clotting; interferes with:

    • WBC, RBC, platelet cts.
    • ESR, etc.
59
Q

interferes with K assay

A

potassium salts of EDTA

60
Q

interferes with BUN determinations

A

ammonium oxalate

61
Q

affects white cell morphology

A

oxalates

- affects peripheral blood smear

62
Q

diluted blood samples interfere with ____________

A

quantitative determinations

63
Q

sodium citrate

A
  • used for many coagulation studies
  • anticoagulant of choice for PT, PTT
      • factor V is relatively stable
64
Q

concentration of sodium citrate for coagulation studies

A
  1. 8%
    - light blue top tube
    - 3.8g sodium citrate to 100mL dist. H2O
65
Q

black top tube sodium citrate concentration

A
  1. 2%

- used for ESR (Westergren)

66
Q

potassium salt of EDTA

A
  • preparation of choice
  • commercial name: Sequester Solution
  • used as anticoagulant for platelet counts, function tests & most hematological tests
67
Q

optimal concentration of EDTA

A
  1. 5mg EDTA/mL blood
    - does not cause cell distortion if read within 2 hours
    - excessive amounts induce red cell shrinkage –> decreased Hct, ESR values
68
Q

heparin

A
  • powerful anticoagulant: anti-thrombic & anti-thromboplastic
  • NOT USED FOR COAGULATION STUDIES
  • anticoagulant of choice for osmotic fragility test (unless defibrinated blood is used)
69
Q

appearance of blood & bone marrow smears prepared from heparinized blood

A
  • light bluish background (Wright-Giemsa stain)
  • causes morphologic distortions of platelets, WBCs
  • causes errors in automated cell counting
70
Q

effect of oxalates when used alone

A

a. potassium oxalate
- shrinks RBC
- “potaSHRINK oxalate”
- 0.8g

b. ammonium oxalate
- causes swelling of cells
- “ammonium oxSWELLate”
- 1.2g

*when combined, they do not affect cell shape –> Hct not affected

HEMA 1 (12 decks)

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