[LAB] Hemostasis Lab Testing (Part 1) Flashcards
What type of plasma is used for the hemostasis procedure whereby platelet count is less than 10,000/ μL prepared from whole venous blood collected by venipuncture?
Platelet-poor plasma (PPP)
What type of plasma is used for light transmittance platelet aggregometry whereby platelet count is approximately 200,000/μL?
Platelet-rich plasma (PRP)
Hemostasis testing begins in ____ and ____.
bleeding and thrombosis risk assessment
Patients under drug therapies and dietary supplements are instructed to discontinue nonprescription drugs ____ prior to blood collection.
at least a week
If the patient has multiple bruises, mention a tendency to bleed, or possesses a high-risk BAT score, the phlebotomist should extend the time for observing the venipuncture site from the usual 1 minute to _____ and should apply a pressure bandage before dismissing the patient.
5 minutes
Patients are advised to avoid caffeine and exercise for ____ before collection.
2 hours
Patients are advised to avoid smoking for ____ before collection.
30 minutes
What is the usual gauge size for hemostasis collection on adults with good veins?
20-21 gauge
What gauge size will you use in the case of small, scarred, or fragile veins?
23-gauge
When transferring blood from a syringe to tube, what is the preferred needle gauge?
19-gauge
What is the top color of the collection tube used for the hemostasis specimen?
blue-top
What is the anticoagulant used for most hemostasis testing?
buffered 3.2% sodium citrate
What is the mechanism of a sodium citrate anticoagulant?
binds calcium ions to prevent coagulation
What is the purpose of the buffer?
stabilize specimen pH
What is the ratio of anticoagulant and blood?
9:1 (9 parts whole blood to 1 part anticoagulant)
What is the usual concentration of the anticoagulant and blood collected in evacuated plastic collection tubes?
0.3 mL of anticoagulant
2.7 mL of whole blood
What is the final citrate concentration following the ratio?
10.5-10.9 mM
The formula for computing the amount of anticoagulant.
C = (1.85 X 10^–3) (100-HCT) V
What is the mechanism of EDTA?
irreversibly chelates calcium ions
True or False.
EDTA is one of the anticoagulants used for hemostasis testing.
False.
(Laboratory practitioners do not use EDTA for clot-based coagulation testing because EDTA irreversibly chelates calcium ions)
Identify the anticoagulant.
- produce accurate platelet counts in cases of platelet satellitosis (satellitism) as a substitute for specimens collected in EDTA.
Heparin (green)
Identify the anticoagulant.
- suppress in vitro platelet or coagulation activation for specialty assays
Citrate theophylline adenosine dipyridamole (CTAD, blue closure)
True or False.
If a series of evacuated tubes is to be filled from a single venipuncture site, the hemostasis specimen must be collected before a nonadditive tube.
False.
(hemostasis specimen must be collected first or immediately after a nonadditive tube)
What is the minimum required volume of blood during collection?
90%
True or False.
The smaller the collection tube, the narrower the tolerance for short draws.
True
How many times should a phlebotomist invert the collection tube?
at least 3 times
What refers to excessive specimen agitation?
cocktail shaking
Before specimen collection from the vascular access device, the line must be flushed with _____.
5mL of Saline
How much blood is discarded first during collection on VAD?
5mL
True or False.
The blood collector may flush with heparin.
False.
The blood collector must not flush with heparin.
Where is the usual site of collection for capillary punctures?
third (middle) finger or fourth (ring) finger
What is the function of collection tube seals?
minimizes CO2 diffusion
Sodium citrate-anticoagulated whole blood specimens are placed in a rack and allowed to stand in a _____.
vertical position
What is the temperature range to maintain the specimens?
15-25℃
What temperature activates factor VII, activates platelets, and precipitates large VWF multimers?
1-6℃
PT specimens at 15° C to 25° C are tested within ____ of the time of collection.
24 hours
PTT specimens at 15° C to 25° C are tested within ____ of the time of collection.
4 hours
If a patient is receiving unfractionated heparin (UFH) therapy, PTT specimens must be centrifuged within ____ of the time of collection to avoid depletion of the heparin.
1 hour
Specimens may be stored at –20° C for up to ___.
2 weeks
Specimens may be stored at –70° C for up to ___.
6 months or so
What are the methods used for testing whole-blood specimens?
- lumiaggregometry
- thromboelastography (TEG)
- thromboelastometry (ROTEM)
What is the instrument used for testing PRP?
Light-transmittance (optical) platelet aggregometer
What is the method used for testing PPP with a platelet count of less than 10,000/μL?
Clot-based plasma coagulation tests
What is the method used for testing PPP with a platelet count of less than 5,000/μL?
Double-spin approach
Identify the settings for the centrifuge.
- Light-transmittance (optical) platelet aggregometer for PRP
50 X g RCF for 30 minutes
Identify the settings for the centrifuge.
- Clot-based plasma coagulation tests for PPP
1500 X g RCF for 15 minutes
Identify the settings for the centrifuge.
- HemoCue StatSpin for PPP
4400 X g RCF for 3 minutes
