Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.


Print this article
Share this page:
Also known as: Activated Partial Thromboplastin Time; aPTT; APTT
Formal name: Partial Thromboplastin Time

At a Glance

Why Get Tested?

As part of an investigation of a possible bleeding disorder or blood clot (thrombotic episode); to monitor unfractionated (standard) heparin anticoagulant therapy; as part of screening before surgery or other invasive procedure

When to Get Tested?

When you have unexplained bleeding, inappropriate blood cloting, or recurrent miscarriages; when you are on standard heparin anticoagulant therapy; sometimes as part of a pre-surgical screen

Sample Required?

A blood sample drawn by needle from a vein in your arm

Test Preparation Needed?