Clotting Time (CT) in Dehradun

What is a Clotting Time (CT)?

The clotting time measures how long a sample of whole blood takes to form a clot under standard conditions. Like the bleeding time it is an old bedside test still widely included in Indian pre-operative panels, and like it, its limitations need stating plainly. It is insensitive: it only becomes abnormal with severe deficiencies of clotting factors, so someone with a clinically important but moderate bleeding disorder, including many patients with haemophilia carriers or von Willebrand disease, will have an entirely normal clotting time. It is also poorly standardised between operators. The tests that replaced it are the prothrombin time with INR and the APTT, which assess the two arms of the clotting cascade separately, are properly standardised, and identify which specific part of the system is at fault. A normal clotting time therefore provides very limited reassurance, and it should never be the basis for concluding that someone's clotting is normal before surgery or a procedure.

Why take this test?

Clotting time is usually performed because it forms part of a standard pre-operative package rather than because it answers a specific question. Where clotting needs genuine assessment, the appropriate tests are a prothrombin time with INR and an APTT, together with a platelet count, interpreted alongside a careful bleeding history. That history is the single most valuable element: easy bruising, prolonged bleeding after dental work or minor injury, recurrent nosebleeds, heavy menstrual periods, bleeding after previous surgery, or a family history of a bleeding disorder each warrant proper investigation regardless of what a clotting time shows. If you take an anticoagulant, this test is not the way to monitor it; warfarin requires INR, and the direct oral anticoagulants require no routine monitoring at all. Disclose any bleeding history and all medicines to your surgeon and anaesthetist rather than relying on a normal result.

• Commonly included in pre-operative screening packages
• Detects only gross, severe clotting factor deficiencies
• Superseded by prothrombin time with INR and APTT
• Not adequate to assess clotting before surgery on its own
• Not a way to monitor any anticoagulant
• A bleeding history warrants proper testing regardless of the result

Normal reference ranges

Ranges are indicative for adults. Your report carries the lab-specific reference range and is reviewed by a LabONE pathologist; always interpret results with your doctor.

FAQs: Clotting Time (CT) in Dehradun