capillary puncture equipment, principles and procedures

Question 1

What is the primary purpose of capillary puncture?

Answer 1

To obtain drops of blood for testing by puncturing the capillary bed in the dermal layer of the skin using a lancet or other sharp device.

Question 2

What are the terms typically used to describe the technique of capillary puncture?

Answer 2

capillary puncture
dermal puncture
skin puncture

Question 3

What are the two types of devices used for capillary specimen collection?

Answer 3

Devices that puncture the skin.
Devices that make an incision in the skin.

Question 4

What is the common term used for both types of devices used for capillary specimen collection?

Answer 4

Both types are commonly referred to as lancets.

Question 5

What is important to remember when handling lancets?

Answer 5

Lancets are disposable (one-time use only) and must be handled cautiously as they are small.

Question 6

What is the difference between feather lancets and pointed lancets?

Answer 6

Feather lancets have a larger incision.
Pointed lancets have a smaller, sharper point for puncture.

Question 7

it is a small plastic tubes used to collect tiny amounts of blood from capillary punctures.

Answer 7

Microcollection containers
(also called microtubes)

Question 8

What types of microcollection containers are there?

Answer 8

Microcollection containers can be anticoagulant or non-anticoagulant (plain tubes).

Question 9

What is a challenging part of working with microcollection containers?

Answer 9

The labeling of the tube is the challenging part, ensuring proper identification of the specimen.

Question 10

What are microhematocrit tubes used for, and what do they typically hold?

Answer 10

Microhematocrit tubes are used for manual hematocrit (Hct) or packed cell volume (PCV) determinations.
They hold 50 to 75 µL of blood.

Question 11

Why must one end of a microhematocrit tube be sealed?

Answer 11

To prevent the blood from spilling out during handling.

Question 12

What are microhematocrit tubes made of, and how do they fill?

Answer 12

made of disposable, narrow-bore plastic or plastic-clay glass
fill by capillary action.

Question 13

What is the purpose of using glass microscope slides in hematology?

Answer 13

to make blood films for hematology determinations.

Question 14

How do you make a blood smear on a microscope slide?

Answer 14

A drop of blood is placed directly on the slide to make a blood smear.

Question 15

How does warming the site affect blood flow and collection time?

Answer 15

increase blood flow by up to seven times, making the collection process quicker.

Question 16

Why is warming the site especially important when performing heel punctures on newborns?

Answer 16

ncreases blood flow, making the collection process quicker and easier, which is particularly important for newborns who have limited blood volume.

Question 17

How does the composition of capillary blood differ from venous blood?

Answer 17

mixture of arterial, venous, and capillary blood, along with interstitial (tissue fluid) and intracellular fluid (fluid within cells) from the surrounding area.

Question 18

Why is capillary blood not the priority for routine blood samples?

Answer 18

contains interstitial fluid, which can affect the accuracy of the test results.

Question 19

How can the reference values for capillary blood differ from venous blood?

Answer 19

The reference (normal) values may differ because the composition of capillary blood varies, though most differences are minor.
Clinically significant differences in some analytes have been reported.

Question 20

Give an example of an analyte that has a
- higher concentration in capillary blood compared to venous blood.
- have lower concentrations in capillary blood compared to venous blood.

Answer 20

high concentration:
Glucose concentration is typically higher in capillary blood.

lower concentration:
Bilirubin, calcium (Ca2+), chloride, sodium, potassium, and total protein (TP) concentrations are typically lower in capillary blood.

Question 21

Under what circumstances can capillary puncture be an appropriate choice for older children and adults?

Answer 21

Veins are fragile or difficult to access.
Several unsuccessful venipunctures have been performed.
The patient has an intense fear of needles.
The patient is extremely overweight, making veins hard to find.
Point-of-care testing (POCT) is needed, such as for glucose monitoring.

Question 22

Why is capillary puncture the preferred method for infants and very young children?

Answer 22

Small blood volume in infants means venipuncture or arterial puncture can lead to anemia.
Large quantities of blood removed rapidly can cause cardiac arrest.

Question 23

Which tests cannot be collected by capillary puncture due to their requirements?

Answer 23

Erythrocyte sedimentation rate (ESR) methods.
Coagulation studies that require plasma specimens.
Blood cultures and tests that need large volumes of serum or plasma.

Question 24

site selection for capillary puncture

Answer 24

adults and children:
on the 3rd (middle) or 4th (ring) finger on the palmar surface near the fleshy center of the distal segment

infant:
heel on the medial or lateral boarders only

Question 25

What type of slides are used to make a blood smear?

Answer 25

Film slide
Pusher/spreader slide

Question 26

What is the ideal diameter of the blood drop for making a smear, and how does it affect the smear?

Answer 26

The ideal blood drop is 2-3 mm in diameter.

Too large: Results in a long/thick smear.
Too slow: Results in a short/thin smear.

Question 27

What can happen if the spreader slide is moved too slowly?

Answer 27

If the spreader slide is too slow, it may lead to poor WBC distribution.

Question 28

What are the characteristics of an ideal blood smear?

Answer 28

Gradual transition from thick to thin area.
⅔ to ¾ the length of the film slide.
Finger-shaped appearance.
Visible lateral edges.
No irregularities, holes, or streaks.
Feather edge has a rainbow appearance.

Question 29

What is the purpose of a blood smear?

Answer 29

To make cells more visible.
To evaluate cellular morphology.

Question 30

What is used as a fixative for blood smears?

Answer 30

Methanol

Question 31

What are the stains and buffer used in blood smear preparation?

Answer 31

Eosin and Methylene blue are used as stains.
Aged distilled water is used as a buffer.

Question 32

images of cells

Answer 32

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