PTD - 5

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Test Directory -  D-Dimer

Synonyms

DDIM, DD, FDP's, XDP's

Clinical Indications

To aid in exclusion of VTE in association with a pre-test clinical score.
To aid in the investigation of DIC.

Part of Profile

A coagulation screen should be requested if anticoagulation is contemplated.

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

On request.

Specific Criteria

A pre-test clinical score should be undertaken before requesting D-dimer for exclusion of VTE (Both PE & DVT)
GP request should only be to exclude PE, suspected DVT should be referred to the DVT Assessment Clinic.

Turnaround Time

2 hours

Specimen

Citrated Blood  

Volume

Collection tube must be filled to 'fill mark' on side of bottle. This is critical.

Container

Blue top (sodium citrate) tube

Collection

Haemolysis or stasis during venepuncture should be avoided.

Lab. Handling

Samples should be processed within 4 hours of collection.

Causes for Rejection

Unlabelled . incorrectly labelled sample
Not meeting specific criteria for analysis. 
Delay in sample reaching laboratory
Underfilled, clotted or haemolysed samples. 

Limitations

Short testing window (2 hours after bleeding).

Reference Range

For investigation of DVT and PE, a cut off value of <500ng/ml FEU should be used, but should only be interpreted when there is a low clinical suspicion or score.
If the clinical suspicion of DVT is moderate / high then the D-Dimer result is not diagnostically helpful.

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 Version 1.0 / December 2012