CPT® Code 85732

The CPT® Code 85732 refers to the laboratory test known as the partial thromboplastin time (PTT) with substitution, specifically utilizing plasma fractions. This test is commonly referred to as activated PTT or aPTT. The primary purpose of performing a PTT is to diagnose the underlying causes of bleeding disorders or to serve as a screening tool prior to surgical procedures, ensuring that any potential coagulation defects are identified and addressed. The test involves the mixing of a specific reagent, which contains silica and synthetic phospholipids, with the patient's plasma. The silica acts as a negatively charged surface that activates the contact pathway of the coagulation cascade. Following this activation, calcium chloride is added to the mixture to initiate clot formation. The time it takes for the clot to form is then measured using photo-optical methods. In cases where the PTT results are elevated and the patient is not on anticoagulant therapy, a follow-up test known as a PTT mixing study may be conducted. This involves mixing the patient's plasma with normal plasma in a 1:1 ratio, incubating the mixture, and measuring the clotting time again. The results of this mixing study can help determine whether the patient has an inhibitor, such as lupus anticoagulant, or a coagulation factor deficiency. The CPT® Code 85732 is specifically reported for each instance of the PTT mixing study performed, highlighting its importance in the diagnostic process for coagulation disorders.