Parkview Laboratory: Test Directory

If a Blue Top Tube is collected utilizing a butterfly, a Blue Discard Tube must be drawn first to remove air from the line. If this is not done, the Blue Top Tube will not be filled properly due to the vacuum in tube and a redraw will be required

Note: Collection of blood for coagulation testing through intravenous lines that have been previously flushed with heparin should be avoided, if possible. 
If the blood must be drawn through an indwelling catheter, possible heparin contamination and specimen dilution should be considered. 
When obtaining specimsn from indwelling lines that may contain heparin, the line should be flushed with 5mL 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.

In excluding deep vein thrombosis (DVT) and pulmonary (PE): In a non-high clinical probability population, using a cutoff of 0.5 mg/L FEU, a normal (<0.5 mg/L FEU) result excludes deep vein thrombosis (DVT) and pulmonary (PE) effectively. (Negative predictive value is 96-100% and 97.5-100% respectively)