Which of the following abnormalities is consistent with the presence of lupus anticoagulant?

The presence of lupus anticoagulant is associated with an increased risk of thrombosis and typically manifests in laboratory findings as a prolonged activated partial thromboplastin time (APTT). This prolonged APTT is a characteristic feature because the lupus anticoagulant interferes with the normal clotting process in vitro, leading to these abnormal results on coagulation tests.

While the presence of lupus anticoagulant indicates a hypercoagulable state, it might not necessarily correlate with increased bleeding risk, despite the prolonged APTT seen in testing. Instead, patients with lupus anticoagulant often have an increased tendency for thrombosis, which is contrary to what might traditionally be expected from the prolonged APTT.

This is why the combination of prolonged APTT with thrombosis accurately reflects the clinical picture associated with lupus anticoagulant. In summary, the correct answer highlights the paradoxical nature of lupus anticoagulant, emphasizing its role in promoting clotting rather than causing bleeding complications, despite the prolonged APTT seen in laboratory tests.