The capillary tube
uses capillary action to draw the blood into the micro tube
thereby eliminating the tendency for scooping. Because the capillary tube is also coated with anticoagulant, the blood sample mixes with it immediately to prevent clotting.
How is capillary puncture done?
The puncture must be on the palm-up surface of the distal segment (fingertip) of the middle or ring finger (a). The puncture should be made across the fingerprint, not parallel to it (b). The puncture must be
performed on the side of the fingertip
where tissue depth is sufficient to prevent bone injury.
What is the order of collection for capillary tubes?
The order of draw is based on
CLSI Procedures
and Devices for the Collection of Capillary Blood Specimens; Approved Standard – Sixth Edition, September 2008. This standard recommends that EDTA tubes be drawn first to ensure good quality specimen, followed by other additive tubes and finally, serum specimen tubes.
What is the purpose of capillary puncture?
Capillary blood sampling is becoming a common
way to minimize the amount of blood drawn from a patient
. The 10 or 20 microliters can be used to look for anemia, check blood sugar or even to evaluate thyroid function. The procedure is easier and less painful than traditional venipuncture which draws blood from a vein.
What finger is not allowed in capillary collection?
The thumb (1) is
to be avoided because it has a pulse. The index finger (2) tends to be more calloused, which would make collection of the specimen more difficult. This area is also more sensitive for the patient. The pinky finger (5) does not have sufficient tissue depth to prevent injury.
What tests Cannot be performed on capillary blood?
Certain tests cannot be performed on capillary blood due to the large volume they require or the possibility of contamination. These include the following:
Westergren erythrocyte sedimentation rate (ESR) test
, due to large blood volume required.
What capillary blood test should be collected first?
Take laboratory samples in the order that prevent cross-contamination of sample tube additives. As described above for adult patients, collect the
capillary haematology specimen first
, followed by the chemistry and blood bank specimens.
What is the correct order of blood draw tubes?
The draw order for specimen tubes is as follows:
Red No Gel
.
Gold SST
(Plain tube w/gel and clot activator additive) Green and Dark Green (Heparin, with and without gel) Lavender (EDTA)
What is the correct order of blood draw?
The correct order of draw follows:
Blood culture tube or bottle
.
Sodium citrate tube
(eg, blue closure) Serum tubes, including those with clot activator and gels (eg, red, red-speckled, gold closures)
What are the errors in capillary puncture?
Mistakes made in obtaining capillary blood include
inadequate warming of the site
, which results in inadequate arterialization of the blood; excessive squeezing, which causes contamination with venous blood or interstitial fluid; and exposure of blood to air during collection.
How much blood does a capillary tube hold?
| Female: 36-48% | Male: 40-52% |
|---|
What tests can be done with capillary blood?
- Blood smears for manual white blood cell count.
- Complete blood count (CBC)
- Hemoglobin & hematocrit (H&H)
- Electrolytes.
- Neonatal blood gasses.
- Neonatal bilirubin.
- Neonatal screening.
- Glucose.
Why is it important to wipe the first drop of blood?
The first drop of blood from a lancing site contains
a greater volume of platelets
, which could make the lancing site seal up before enough blood was obtained for the test, and the dual wipe ensured a longer, larger flow of blood.
Which finger is used for pricking?
Prick your finger with the lancing device at the sides of the finger as there are less nerve ending here than at the tips or the ‘pads’. Recommended finger: the World Health Organisation recommends
the middle or ring fingers
are used for blood glucose tests (second and third fingers).
Which site should you avoid for venipuncture?
Do not use the
tip of the finger
or the center of the finger. Avoid the side of the finger where there is less soft tissue, where vessels and nerves are located, and where the bone is closer to the surface. The 2nd (index) finger tends to have thicker, callused skin.
What is the difference between venous blood and capillary blood?
The differences between capillary and venous blood in most cases
are minimal
. However, there are some discrepancies in hemoglobin and hematocrit values and in platelet counts. It is well known that capillary blood has higher hemoglobin and hematocrit values than venous blood.
