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Coagulation studies at WRH for thrombophilia screening may include assays for Protein C, Free Protein S, Anti-Thrombin III ,Activated Protein C Resistance and a Lupus Anticoagulant screen
The following factors should be considered before requesting thrombophilia screen:
- The single biggest predictor of recurrence is spontaneity i.e. no obvious underlying predisposing factor. This is irrespective of thrombophilia result.
- Patients who have a history of recurrent VTE (venous thromboembolism) are candidates for indefinite anticoagulation irrespective of thrombophilia result.
- Testing in the setting of an acute VTE, warfarin treatment within the past 4 weeks and pregnancy or OCP usage in the past 3 months is unhelpful as protein levels are low and repeat testing will be required.
- Multiple repeat of testing often occurs in cases with borderline results with ultimately no change in management of the patient.
Situations where thrombophilia testing may be appropriate, although not always definitely indicated are the following:
- Patients presenting with thrombosis at a young age (<40 yrs)
- Individuals from thrombosis prone families (> 2 members)
- Thrombosis at unusual site
- Recurrent (>3) first trimester miscarriages
- Late miscarriage
- Foetal death
- Warfarin-induced skin necrosis/neonatal purpura fulminans
The following are not indications for heritable thrombophilia testing and will no longer be processed:
- Less than 3 first trimester miscarriages
- Asymptomatic relatives with low risk thrombophilias (Factor V Leiden, Prothrombin gene mutation).
- Asymptomatic women with first degree relatives with history of VTE.
- Retinal vein occlusion
- Patients with arterial events (testing for antiphospholipid syndrome may be appropriate)
- Infertility testing.
- Screening prior to infertility treatments
Testing prior to infertility treatment causes tremendous difficulty for GPs and the laboratory while causing great stress for patients who are informed that the result is a prerequisite before embarking on infertility treatments. This is more likely to be requested by clinics abroad. There is no evidence base for thrombophilia testing in this setting. To avoid delays and difficulties testing will no longer be offered in this setting.
The Laboratory policy is:
- samples with definite indications will be tested
- samples where indication is not specified on the form will be frozen with a supplementary form sent out to determine the indication. If testing is not indicated the requesting Clinician will be informed. The sample will be discarded when the Clinician is satisfied that testing is not indicated or within three months if no response is received.
As with all haematology results cases can be discussed with Consultant Haematologist and referral to haematology OPD may be appropriate
