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Activated Partial Thromboplastin Time

What is it?

Activated partial thromboplastin (throm-bo-plas-ten) time (APTT) is a blood test that measures how long it takes your blood to clot. Clotting is necessary to stop bleeding.

Why do I need it?

APTT is a screening test for bleeding problems and is usually done before surgery. If you are getting an anticoagulant (an-ti ko-ag-u-lunt) called heparin, this test may be used to make sure you are getting the right amount. Anticoagulants keep blood from clotting and are sometimes called blood thinners. Partial thromboplastin time may be too long in conditions such as hemophilia (heem-uh fill-ee a), liver disease, lupus and vitamin deficiency. Caregivers will explain the test and why you need it.

How do I get ready for the test?

Your caregiver will tell you when to have your blood test. The blood test may be done before or after eating. You may need to stop taking some medicines before the test. Your caregiver will tell you if you should take your normal medicines before your blood is taken.

How is the specimen collected?

A caregiver will put a wide rubber strap around your arm and tighten it. Your skin will be cleaned with alcohol. A small needle attached to a special test tube will be put into a vein in your arm or hand. The tube has suction to pull the blood into it. When the tube is full, the rubber strap, needle and tube are removed. The caregiver will press a piece of cotton where the needle was removed. You may be asked to hold the cotton on the site for a few minutes to help stop the bleeding. Tape may then be put over the cotton on your arm.

What do I do after the test?

You may remove the tape and cotton in about 20 to 30 minutes. Call your caregiver to get the results of your test. Your caregiver will explain what your test results mean for you. Follow the instructions of your caregiver.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your lab tests. You can then discuss the results with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.