PTT stands for partial thromboplastin time, which is a blood test that calculates the time it takes for a patient’s blood to clot, says WebMD. Partial thromboplastin time is performed to determine the reason for abnormal bleeding, to evaluate how the liver is functioning, and to discover blood clotting issues.
The PTT uses a needle to take a sample of blood, and the patient may receive a bandage to stop any bleeding, says MedlinePlus. Prothrombin time, or PT, is also a test that measures the time for blood to clot. It is normally performed at the same time as a PTT. Blood thinners may affect the time it takes for blood to clot, says WebMD.