chapter 10

microcollection containers

small plastic tubes used to collect tiny amounts of blood from capillary punctures

microcollection containers are also referred to as

bullets

Capillary blood gas equipment

• CBG collection tube

• Stirrer

• Magnet

• Plastic cap

purpose of warming devices?

facilitates blood collection by promoting vasodilation

indications of capillary puncture

• Available veins are too fragile/difficult to access

• Several unsuccessful venipuncture attempts

• Burns/scars at typical venipuncture site

• Intense fear of needles

• Thormobotic/clot forming tendencies

• No accessible veins

Tests that cannot be collected via capillary puncture:

• erythrocyte sedimentation rate methods

• coagulation studies requiring plasma

• blood cultures

• tests that require large amounts of serum/plasma

order of draw for capillary puncture (by category)

1. blood gas specimens

2. EDTA specimens

3. Other additive specimens

4. Serum specimens

Bilirubin specimens are collected on infants via…

heel stick

kernicterus

brain dysfunction caused by toxic levels of bilirubin

jaundice treatment

phototherapy

Purpose of blood spot screening in newborns

To check for rare but serious genetic, metabolic, hormonal, and functional disorders

Common NBS test

• PKU (phenylketonuria)

• Hypothyroidism

• Galactosemia

Phenylketonuria (PKU)

rare metabolic disorder where the body can't break down phenylalanine, causing it to build up to toxic levels in the blood

Galactosemia

disorder where the body can't break down galactose into glucose for energy, causing it to build up to toxic levels

true or false: blood smears should be collected first to avoid effects of platelet clumping

true

which of the following tests requires an arterialized specimen if collected by capillary puncture:
A. bilirubin
B. blood gases
C. glucose
D. Electrolytes

B

capillary puncture blood contains…

arterial blood, venous blood, and interstitial fluids

The concentration of this substance is higher in capillary blood than in venous blood

glucose

If collected by capillary puncture, which test specimen is collected first?
a. CBC
b. electrolytes
c. glucose
d. phosphorus

A

According to CLSI a heel puncture lancet should puncture no deeper than

2mm

When making a routine blood smear, the "pusher slide" is normally used at an angle of how many degrees?

30º

The blood specimen for this test is placed in circles on special filter paper

PKU

Capillary action is a term used to describe how

Blood fills a microhematocrit tube

fluid in the spaces between cells is called

interstitial fluid

Strong repetitive pressure such as squeezing or milking a site during capillary specimen collection may…

hemolyze and contaminate specimens

In an infant's heel, the primary blood supply is located how deep

between 0.35 and 1.6mm deep

using capillary puncture collection, what should be drawn first, according to CLSI recommendations?

blood gas specimens

what type of tube is primarily used for manual Hct determinations

microhematocrit

the capillary bed in the ______ of the skin is where blood for laboratory testing is obtained

dermis

a 6 months infant who weights 6.5 kg needs her blood drawn. What is the percentage of total blood volume of a 10 mL blood draw?

1.6%

what is the preferred position of the patient for a specimen collection using a heel capillary puncture for an infant?

Supine with the foot lower than the torso

A blood film is required to perform which type of test:
a. EDTA
b. Galactosemia
c. Cystic fibrosis

C

Why is the first drop of blood wiped away during specimen collection?

It prevents contamination of the specimen with excess tissue fluid

What additive should a phlebotomist use when performing a peripheral blood smear for a WBC count

EDTA

A phleb tech is collecting blood culture from an infant who weighs 6.6 lbs (3 kg) What is the total blood volume for this infant?

240-330mL

how to find total blood volume in infants

Total Blood Volume (mL)=Weight (kg)×80mL/kg

Optimal time to perform neonatal screening test

between 24-72 hours after birth

A phleb tech is collecting a peripheral blood smear from a patient. The tech should identify that this collection technique is used for which test?

WBC differential test

Collection of a blood specimen in a special thin capillary tube that is sealed with clay and spun is what kind of test?

packed cell volume

Order of draw for capillary puncture by color

1. Lavender

2. Green

3. Light green

4. Gray

5. Yellow

6. Red