Specimen collection

Question 1

Sample collection

Answer 1

• Blue top tube: Sodium citrate
• Non-wettable, siliconized surfaced glass, or plastic –> not activate factor
• Maintain the stability of coagulant factors (not activation, not interfere), prevent clot formation

Question 2

Sodium citrate

Answer 2

• Prevent clotting: stable for hours, maintain body pH

- Make complex with Ca and can be overcome by adding more Ca

Question 3

The ratio of anticoagulant to whole blood

Answer 3

9 whole blood: 1 anticoagulant (normal Hct)
Underfilled blood = over anticoagulant –> falsely prolonged
Overfilled blood = under anticoagulant –> over add Ca

Question 4

Too low Hct (<20%) vs too high Hct

Answer 4

• Too low Hct: high plasma = overfilled blood (under anticoagulant)
• Too high Hct: low plasma = underfilled blood (over anticoagulant)

Question 5

Sample collection method

Answer 5

• Vacutainer: direct into tube (avoid hemolysis can occur during transfer)
• Syringe size: only when veins are highly collapsible, should be 10cc (no larger than 20cc)
• Needle size: 19-22 for adults, 21-23 for pediatric

Question 6

The problem of sample collected

Answer 6

1. Clotted sample: caused by inadequate mixing
   - Factors activated, consumed.
2. Short sample:
   - Incorrect ration plasma/anticoagulant
3. Hemolyzed sample: caused by trauma puncture
   - Falsely shorten

Question 7

Sample collection errors

Answer 7

• Tourniquet: shouldn’t be longer than 1 -2 min
• Catheter + extension set: short length can cause turbulence
• Syringe size: do not allow more than 1cc air when pulling
• Shaking, draw at the hematoma site (bruise), traumatic stick, massaging of arm, fist-clenching too strong.

Question 8

Processing sample steps

Answer 8

• Check: amount, clot sample
• Centrifuge at 4440 G for 3 min
• Check hemolyzed sample
• Spin once –> remove plasma for next spin
• Spin plasma –> remove upper 3/4 layer for testing
• Freeze sample for later testing
• Avoid contact cell layer when transferring aliquots

Question 9

Storage time & temp

Answer 9

• Frozen samples are quick-thawed at 37C
• Sample frozen at -20C: good for 2 weeks
• Sample frozen at -70C: good for 6 months

Question 10

PRP

Answer 10

Used for PLT aggregometry

• 200k-300k/uL
• Centrifuge 50 G for 30min
• 9-12mL whole blood
• PRP-based light-transmittance aggregometry test: no less than 30 min after centrifuge, within 4 hour of collection

Question 11

PPP

Answer 11

Used for clot-based testing

• Less than 10,000/uL
• Centrifuge at 4440 G for 3 min
• Double spin for special hemostasis test