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D-Dimers

Department of Haematology

Notes

Please see the Trust's Management of Venous Thromboembolic Disease policy

In accordance with Trust Guidelines, D-Dimers will only be performed in the following instances:

  • Low or Intermediate (Wells score) probability DVT
  • Low (BTS) probability PE
  • Investigation of Disseminated Intravascular Coagulation (DIC)

Information on how to perform a probability (Wells) score for suspected DVTs and PEs can be found here (please note, these links are currently only available to Trust users):

Please clearly state the reason for the D-Dimer request, and the associated probability score, on the request form. Without this information, the test will not be performed.

  • Test performed at CGH and GRH

Sample requirements

3ml Trisodium citrate

2ml, 3ml or 3.5ml Trisodium Citrate tube

Full size
Information:

Tubes must be filled to the level of the arrow (frosted line). Short samples give invalid results.

Turnaround Times

  • Clinical emergency: 30 mins
  • Other urgent requests: 60 mins
  • Routine: within 2 hours

Reference Ranges

If D-dimers are used in conjunction with clinical scoring:

For DVT: <500ng/ml: Negative

>500ng/ml:Positive

For PE: Consider following Trust guidance on age related D Dimers:

Patient aged <50: >500ng/ml: Positive

Patient aged >50: >(Age x 10)ng/ml: Positive

Interfering substances

Interfering substances include high levels of lipaemia, haemolysis and bilirubin.

Poor quality samples which are under or overfilled can also lead to errorneous results, so will not be tested.

Add ons

Within 4 hours.

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