The activated partial thromboplastin time (APTT) is a screening test that helps to assess the functionality of both the intrinsic and common pathways. The effectiveness and presence of all the coagulation factors are assayed by this diagnostic test with the exception of factors VII and XIII. In addition to being an integral part of the coagulation disorder assessment process, the APTT is used to determine therapeutic effectiveness of heparin administration.
The results of the activated partial thromboplastin time are used in conjunction with other diagnostic tests, as well as the clinical picture of the patient, to determine hemostatic abnormalities which may be present.
Activated partial thromboplastin time results are presented to the clinician in seconds- the actual time elapsed until a clot was detected using the laboratory's instrument/reagent system.