The patient has no prior bleeding complications to date. He is in good health, but a recently performed aPTT test is prolonged. He is not receiving heparin or other anticoagulant therapy, and the patient's physician orders a mixing study. The results of the mixing study are as follows:
| Initial aPTT | Immediate aPTT Mixing Study | Incubated aPTT Mixing Study | Reference Range |
| 63 sec. | 26 sec. | 65 sec. | 21–34 sec. |
