Partial thromboplastin time (PTT)

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APTT; PTT; Activated partial thromboplastin time

This test is often done on people who may have bleeding problems. The risks of bleeding and hematoma in these patients are slightly greater than for people without bleeding problems.

In general, risks of any blood test may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

When you bleed, the body launches a series of activities that help the blood clot. This is called the coagulation cascade. There are three pathways to this event. The PTT test looks at special proteins, called factors, found in two of these pathways.

Review Date: 03/09/2007
Reviewed By: Mark Levin, MD, Hematologist and Oncologist, Newark, NJ. Review provided by VeriMed Healthcare Network.