Clotting Screen

Pathology category

Haematology

Code

CS

Referral code

Request form

Test information

Must be analysed within 8 hours of collection (due to the APTT)

Guidelines

Pre-analytical

Lipaemic or jaundiced samples may cause issues with testing

Haemolysed, underfilled or clotted samples will be rejected

Sample transport should be at 4-25C and reach the laboratory ASAP

Please note: samples must arrive within 8 hours of collection otherwise they will be rejected by the laboratory

Reference range

Time is reagent dependent

PT Normal ratio (INR) = 0.8 – 1.2

PT Normal Range = 9 – 14 secs

Normal ratio (APTT) = 0.8 – 1.2

APTT Normal Range = 24 – 37 secs

Please note: Reference range is dependant upon clinical condition and medication (e.g. anticoagulation)

Tube type

Tube type info

2.7ml blue top citrate

1.8ml blue top citrate (paediatric bottle)

Special requirements

NA

Minimum volume

1 tube minimum 90% full (to the thick black line on the bottle) – essential to ensure correct 1:9 ratio of anticoagulant:blood

Assay frequency

Routine

TAT Inpatient (urgent)

1 hour

TAT Inpatient

4 hours

TAT GP/Outpatient

4 hours

Referral lab

NA