MEDizzy - A 43-year-old woman presents for the evaluation of bleeding

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hematology

A 43-year-old woman presents for the evaluation of bleeding gums. The patient reports that for the past 2 months, her gums have bled more easily when she brushes her teeth. Physical examination reveals palatal petechiae and scattered petechiae over the lower extremities bilaterally. Which of the following laboratory tests is most likely to identify the abnormality responsible for this patient's bleeding disorder?

ExplanationBleeding occurs as a consequence of thrombocytopenia, deficiencies of coagulation factors, or both. Thrombocytopenia usually presents as petechial bleeding that is first observed in the lower extremities. Deficiencies in coagulation factor more often cause bleeding into the gastrointestinal tract or joints. Intracranial bleeding, however, can occur with a deficiency of platelets or coagulation factors and can be catastrophic. CBCs are routinely performed in most laboratories through the use of an electronic particle counter, which determines the total white blood cell and platelet counts and calculates the hematocrit and hemoglobin from the erythrocyte count and the dimensions of the red cells. For this patient, a CBC would likely disclose a decreased platelet count (thrombocytopenia). Impaired hepatic synthetic function and vitamin K deficiency would result in prolongation of the PT and INR. Coagulation factor deficiencies and coagulation factor inhibitors would result in prolongation of the PTT. A mixing study is obtained to differentiate between a coagulation factor deficiency and a coagulation factor inhibitor by mixing patient plasma with normal plasma in the laboratory.