Prothrombin Time
Alternate Names : PT
The prothrombin time test, also called PT, helps measure how well
your blood is able to clot. It is much like the partial thromboplastin
time test, which is also called PTT . These two tests are often ordered together.
At least 12 different proteins are involved in clotting. The
PT and PTT tests each measure the function of some of these proteins.
Who is a candidate for the test?
This test may be done:
when a person has a bleeding problem
to monitor a person who is taking blood-thinning medicine
before surgery to make sure a person will not bleed too much
during the operation
How is the test performed?
A blood sample is usually taken from a vein on the forearm
or hand. The skin over the vein is first cleaned with an antiseptic.
Next, a strong rubber tube called a tourniquet is wrapped around the
upper arm. This restricts blood flow through the veins in the lower arm
and causes them to enlarge.
A small needle is inserted into a vein and the tourniquet
is removed. Blood flows from the vein through the needle. It is collected
in a syringe or vial. After the needle is withdrawn, the puncture site is
covered to prevent bleeding. The blood sample is sent to a lab for testing.
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