The Thrombophilia Screen is a detailed blood test that checks for inherited and acquired factors that make blood clot more easily than it should. It is aimed at people who have had an unexplained blood clot, a family history of clotting disorders, or recurrent miscarriage, and who need a thorough assessment. The test costs £987.50, plus a £50 blood-draw fee, with results back in 5 days. You can walk in or book online at 117a Harley Street, seven days a week.
This screen is usually requested after someone has had a blood clot, such as a deep vein thrombosis or pulmonary embolism, that was not clearly explained by an obvious cause like surgery or immobility.
It is also used when there is a strong family history of blood clots, before starting certain hormone treatments in someone with that family history, or after recurrent miscarriage.
Because several of these markers are affected by clotting itself, pregnancy or anticoagulant medication, timing of the test matters and is often best agreed with a doctor first.
Most people do not need to fast before this test, but timing and current medication matter a great deal here. If you have had a recent clot, are pregnant, or are taking anticoagulant medication such as warfarin or a DOAC, several of these results can be affected, so it is important to follow the specific guidance given by your doctor about when to have this test done.
A low level of a protective protein such as Antithrombin III, Protein C or Protein S, or the presence of a gene variant such as Factor V Leiden, can mean your blood is more prone to clotting than average. Having one of these findings does not mean a clot is certain, only that the risk is higher in certain situations.
A positive Lupus Anticoagulant or Cardiolipin Antibody result usually needs to be repeated after several weeks to confirm it, since these can be raised temporarily by illness or infection.
This is a complex panel, and results need to be interpreted together by a doctor, ideally one experienced in clotting disorders, alongside your personal and family history. Arrange a follow-up appointment to go through the full report rather than reading individual results in isolation.
If you would like a doctor to request the right tests for your symptoms or talk the report through, book a private GP consultation at Medical Express Clinic.
Written by Mr Stephen Lingam. Reviewed by Dr Mohammad Bakhtiar (GMC 4694470) on 24/09/2026.
It is generally considered after an unexplained blood clot, with a strong family history of clotting disorders, or after recurrent miscarriage. A doctor can help decide whether it is the right test for your situation.
No, a positive result shows an increased tendency to clot in certain circumstances, not a certainty. Many people with these findings never have a clot, and doctors use the result to guide precautions rather than to predict the future.
Pregnancy and anticoagulant medication can affect several of these results, so timing needs to be discussed with your doctor beforehand. It may be more appropriate to test before starting medication or a set period after stopping it.
It covers a wide range of specialised markers, some of which need specific sample handling, which is why results take around 5 days rather than 1 to 2.