Partial thromboplastin time

The time required for clot formation in blood plasma after activation and addition of platelet particles such as phospholipids. The test called PTT or aptt is used to assess the coagulation pathways or clotting pathways in your blood. A prolonged aptt can indicate a deficiency of a component of the clotting pathways, such as factors xii, xi, ix, viii, x, v, and ii, and fibrinogen.