HNY Policy and Pathway Repository - North Yorkshire

Blood clotting tests should be performed when there is a suspicion of an underlying bleeding disorder. Screening in the absence of symptoms rarely detects significant abnormalities but may detect insignificant problems prompting unnecessary referral and further testing. It should be remembered that abnormal clotting tests usually do not indicate a bleeding disorder and that not all bleeding disorders produce abnormal clotting results (e.g. some von Willebrand disease, mild factor deficiencies, platelet disorders, vascular disorders, factor XIII deficiency, fibrinolytic disorders...).

Local audit of "routine" pre-operative coagulations screens found an abnormal PTr in 5.7% of samples and abnormal APTTr in 7.4% of samples, however, on further testing, only 0.7% of patients were felt to have a potentially significant disorder.

Isolated prolonged prothrombin time (PT) or PT > APTT	Isolated prolonged activated partial thromboplastin time (APTT) or APTT > PT	Prolonged PT and APTT
Warfarin, rivaroxaban, apixaban, edoxaban Vitamin K deficiency Liver disease (early) Inherited – FVII deficiency	Lupus anticoagulant Heparin Dabigatran Inherited FXII, FXI, FIX or FVIII deficiency	Liver disease (late) Disseminated intravascular coagulation (DIC) Inherited Fibrinogen, FX, FV or prothrombin deficiency.

None provided

Examination:

• Evidence of bleeding disorder (e.g. unexplained bruising or bleeding).
• Features of liver disease

Baseline investigations:

• FBC, PT, APTT, thrombin time, fibrinogen, U+E, LFT

Any further relevant coagulation tests (e.g. mixing studies) may be performed automatically by the laboratory if enough sample is available and if the clinical details suggest bleeding symptoms.

If unexplained consistently prolonged PT then repeat sample after a trial dose of 10mg oral vitamin K.

If unexplained consistently prolonged APTT then initially screen for a lupus anticoagulant, especially if mixing studies do not show complete correction.

If unexplained consistently prolonged APTT with complete correction on mixing then consider coagulation factor assays, especially if personal or family history of abnormal bleeding.

Referral:

• Haematology referral if suspicion of inherited or acquired bleeding disorder regardless of clotting test results (see protocol on easy bruising for more specific details).
• Abnormal results can also be discussed via our Advice & Guidance service.
• Not for haematology referral if a non-haematological cause is apparent, e.g. liver disease.

Haematology Handbook - South Tees Hospitals NHS Foundation Trust

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