The differential diagnosis of a long APTT with a normal prothrombin time can be due to either a clotting factor deficiency or the presence of an inhibitor, which can be distinguished by using a plasma-mixing study. The various clotting factor deficiency states are reviewed. Clinical bleeding following cardiac bypass surgery due to acquired factor V and thrombin antibodies is also reviewed.In this brief review, a few selected topics on evaluation of bleeding diathesis in either a preoperative or postoperative setting will be discussed.
Evaluation of a Prolonged APTT before SurgeryIt is fairly common that a hematologist is asked to see a patient, sometimes urgently, for evaluation of a long APTT discovered in a pre-operative setting. The anticipated surgery may vary from a relatively minor procedure to a major operation such as open-heart surgery or CNS surgery.The differential diagnosis of a long APTT with a normal prothrombin time is quite extensive, but can be divided into two groups, due to either a clotting factor deficiency or the presence of an inhibitor. The patient's history and physical examination are obviously important in considering the various possibilities. In eliciting a bleeding history, one should recognize its limitations. Mild bleeding symptoms are astonishingly common in the general population-epistaxis, easy bruising, and gum bleeding are reported in up to 25-45% of apparently healthy people, many of whom do not have any identifiable bleeding disorders.