Clotting is one of the body's most important safety systems. When a blood vessel is damaged, a cascade of proteins works in sequence to seal the leak. A coagulation screen is a blood test that checks how well that machinery is working — neither clotting too slowly nor being affected by medication or an underlying condition.
What the screen includes
A standard coagulation screen measures a handful of related figures, each testing a different part of the clotting process:
- PT (prothrombin time) — how long one pathway of the clotting cascade takes to form a clot.
- INR (international normalised ratio) — a standardised version of the PT, used above all to monitor people taking warfarin.
- APTT (activated partial thromboplastin time) — tests a second clotting pathway, sensitive to different factors and to heparin.
- Fibrinogen — the protein that forms the mesh of a clot; too little can impair clotting.
Why it is done
A coagulation screen is requested in several everyday situations. It gives a baseline before procedures and helps make sense of unexplained bleeding:
- Before surgery or an invasive procedure, to check clotting is normal.
- When someone bruises easily, bleeds for a long time, or has frequent nosebleeds.
- To monitor blood-thinning treatment such as warfarin (via the INR).
- As part of investigating liver problems, since the liver makes most clotting factors.
What abnormal results can mean
A prolonged PT or APTT means one part of the clotting cascade is slower than expected. This can be entirely intentional — for example in someone on warfarin — or it can flag a lack of certain clotting factors, a vitamin K deficiency, or liver disease. A low fibrinogen suggests the clot-forming protein is running short. Because several explanations are possible, results are always read together and in the light of your history and medications.
Check your clotting
Our coagulation screen measures PT, APTT, INR and fibrinogen — a general assessment of how well your blood clots, useful before surgery or when investigating easy bleeding or bruising.
Check your clottingWhat it does not cover
A routine coagulation screen checks whether your blood clots normally, but it is not designed to hunt for a tendency to clot too much. Investigating an inherited or acquired clotting tendency after an unexplained clot needs a broader set of specialist tests, sometimes called a thrombophilia screen, which is a separate assessment.
When to get checked
Consider a coagulation screen if you are due surgery, are being monitored on blood thinners, or have noticed unusual bleeding or bruising. As always, unexpected results are best discussed with a clinician who can look at the full picture and decide whether any further testing is needed.
Check your clotting
Book online with OneMedicine — CQC-registered clinic in Birmingham, or a home visit / local clinic nationwide. Doctor-reviewed results, most within 24 hours.
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Specialist interest: Cardiovascular Medicine · OneMedicine, CQC-registered clinic