A partial thromboplastin time (PTT) test is a blood test that measures how long it takes for blood to make a clot). The test is used to check for problems with a specific group of blood clotting factors, which are involved in the coagulation cascade). The PTT test is used to:

• Find the cause of too much bruising or bleeding.
• Find the cause of clotting problems.
• Monitor patients who are taking heparin, a blood thinner).

During the test, a healthcare professional will take a blood sample from a vein in your arm using a small needle). The test usually takes less than five minutes, and you may feel a little sting when the needle goes in or out). You dont need any special preparations for a PTT test). The results of the test are usually given as a number of seconds, which shows how much time it took for your blood to clot). A PTT test is often ordered along with another blood test called a prothrombin time (PT) test, which measures other clotting factors that a PTT test doesnt check). Your healthcare provider will usually compare the results of both tests to understand how your blood is clotting)[[4]](https://my.clevelandclinic.org/health/dia...