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Lab Test Dictionary

Activated PTT

Methodology

Mechanical

Synonyms

Activated Partial Thromboplastin Time, APTT

Specimen Type

Plasma

Performing Lab

RCHSD Coagulation

Epic ID

LAB325

Lab Test Days

As Received

Standard TAT

4 hours

Stat TAT

1 hour

Collection Information

Specimen Required

1.8 mL or 2.7 mL Sodium Citrate

Container Type

Light Blue (Sodium Citrate)

Collection Instructions

1. The preferred method of specimen collection for coagulation studies is a properly performed VENIPUNCTURE. The specimen may be collected directly into 1.8 or 2.7 mL vacutainer or into a syringe and then transferred immediately into a 1.8 or 2.7 mL vacutainer. 2. The vacutainer tube MUST contain the EXACT amount of blood. It is essential that LT blue top tubes are PROPERLY FILLED. Volume is CRITICAL and the blood (9 parts) to liquid anticoagulant (1 part) must remain intact for correct results. 3. The specimen should be transported to the Laboratory within one hour of collection. 4. SPECIAL INSTRUCTIONS FOR SPECIMENS COLLECTED FROM A LINE: If collecting specimens for coagulation studies from an indwelling line that may contain heparin, it is recommended that the line should be flushed with 5 mL of saline and the first 5 mL of blood or 6-times the line volume (dead space volume of the catheter) be drawn off and discarded before the coagulation tube is filled. For those samples collected from a normal saline lock (capped off venous port) twice the dead space volume of the catheter and extension set should be discarded. 5. Stability - Specimens are stable for 4 hours following collection.6. If patient's hematocrit is greater than 55%, contact hematology lab to request a light blue tube with adjusted anticoagulant amount.

Processing Information - Lab Use Only

Transport Temperature

Ambient-Only

Specimen Stability

Room Temp: 4 hrs

Test Volume Required

1.8 mL or 2.7 mL in light blue top

Minimum Test Volume

1.8 ml in light blue top

Processing Instructions

Centrifuge within one hour of collection

Included Tests

aPTT

Comments

Blood volume draw is critical as the specimen is diluted with an anticoagulant (9:1). Incorrect volumes drawn contribute to over dilution or concentrated specimens. Either case will cause erroneous results.