APTT is a screening test that helps to assess the functionality of both the intrinsic and common pathways. The presence and effectiveness of all the coagulation factors are assayed by this diagnostic test, with the exception of factors VII and XIII. In other words, factors XII, XI, X, IX, VIII, V, II, and I are all involved in this assay.
The results of the aPTT are used in conjunction with other diagnostic tests, as well as the clinical picture of the patient, to determine hemostatic abnormalities that may be present. In addition to being an integral part of the coagulation disorder assessment process, the aPTT is used to determine therapeutic effectiveness of heparin administration.
APTT results are reported in seconds, which represent the actual time elapsed until a clot was detected using the laboratory's instrument/reagent system.