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Coagulation Screen (Diagnostic)

Blood Sciences Test


Sodium citrate tube

Minimum sample volume

1.8 mL adult or 1.3 mL paediatric.

For Neonates we can prepare half volume paediatric tubes, which will require 0.65 mL blood (filled to the black line). Please contact the Coagulation Section on extension 2916 before 1600 weekdays if you require these tubes.

Special Instructions

The tube must be filled correctly (filled to line on tube). It must be received in the laboratory on the same day.

For specific coagulation factor assay requests, please contact the laboratory


INR for oral anticoagulant control

APTR for unfractionated heparin


Prothrombin Time (PT)

D Dimer

Lupus Anticoagulant

Thrombophilia screening

Factor Assays For Clotting Factors

Clotting Factor inhibitor assays : Please discuss with the laboratory

Factors affecting results

Haemolysed or clotted samples cannot be tested. To avoid haemolysis and clotted samples mix tube gently by inversion, do not shake.

Patients on anticoagulants will have abnormal results.

Reference Ranges


  • PT: 11-14 sec
  • INR : 0.9 – 1.2 (ratio)
  • APTR : 0.87 – 1.13 (ratio)
  • From: Williams M, Chalmers E,Gibson B  British Journal of Haematology 2002 119: 295 – 309,Andrew M et al Blood 1992 80: 1998 – 2005
  • Fibrinogen (Clauss) 2.0 – 4.0 g/L
  • From: Toulon P, Berruyer M, et al Coagulation & Fibrinolysis 2016 116 p 9-16
  • Ranges for other age groups available from laboratory and are automatically adjusted on the report


In house

STAT availability


Turnaround times

1 hr – STAT samples

4 hr – routine samples

Clinical Advice

Clinical advice is available from the Haematology Medical team (contact RD&E switchboard on 01392 411611)

Specimen Labelling Procedure
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