What is Activated Partial Thromboplastin Time?
This blood test gives doctors an indication of blood clotting time. Blood is moved to the lab in vials that contain an anticoagulant (stops blood clotting). Once in the lab, a coagulant is added to the vial and the lab tech notes how long it takes for a clot to form. Activated Partial Thromboplastin Time is commonly used to measure the effects of heparin and other anticoagulant medications.
Normal Value Range
- Adult Negative Pregnancy: 26.3 to 39.4 Seconds
- Pregnancy Trimester One: 24.3 to 38.9 Seconds
- Pregnancy Trimester Two: 24.2 to 38.1 Seconds
- Pregnancy Trimester Three: 24.7 to 35.0 Seconds
A prolonged aPTT measurement may be associated with the use of certain blood thinning medications, including heparin, lupus anticoagulant, coumadin, coagulation factor deficiencies and other inhibitors of the coagulation factor. Other factors not listed here may cause prolonged aPTT measurement.