A 22-year-old female presents in the ER with a spider bite. Lab results show schistocytes on a blood smear, platelets 50, PT 20, aPTT 60, and a positive d-dimer. The most likely diagnosis is:

A 22-year-old female presents in the ER with a spider bite. Lab results show schistocytes on a blood smear, platelets 50, PT 20, aPTT 60, and a positive d-dimer. The most likely diagnosis is:

• A. Disseminated intravascular coagulation
• B. Secondary fibrinolysis
• C. Hemophilia A
• D. Immune thrombocytopenia

Answer: (B)

The main concept here is that when coagulation is massively activated, the body often turns on fibrinolysis to break down the clots that form. This secondary fibrinolysis leaves a telltale pattern on labs: low platelets from consumption, prolongation of both PT and aPTT due to depletion of clotting factors, schistocytes from microvascular clots causing hemolysis, and a positive D-dimer from fibrin degradation. A spider bite can trigger a venom-induced coagulopathy that starts this cascade, so the labs point to fibrinolysis occurring as a downstream, secondary response to coagulation activation. Among the options, this pattern best fits secondary fibrinolysis because it emphasizes the fibrinolytic activity following coagulation, supported by the D-dimer rise and the evidence of consumptive changes. Hemophilia A would not typically raise D-dimer or cause widespread coagulation activation; immune thrombocytopenia would usually have normal coagulation times and a normal D-dimer; while disseminated intravascular coagulation involves a similar process, the presentation is most consistently explained by secondary fibrinolysis in this context.

The main concept here is that when coagulation is massively activated, the body often turns on fibrinolysis to break down the clots that form. This secondary fibrinolysis leaves a telltale pattern on labs: low platelets from consumption, prolongation of both PT and aPTT due to depletion of clotting factors, schistocytes from microvascular clots causing hemolysis, and a positive D-dimer from fibrin degradation. A spider bite can trigger a venom-induced coagulopathy that starts this cascade, so the labs point to fibrinolysis occurring as a downstream, secondary response to coagulation activation. Among the options, this pattern best fits secondary fibrinolysis because it emphasizes the fibrinolytic activity following coagulation, supported by the D-dimer rise and the evidence of consumptive changes. Hemophilia A would not typically raise D-dimer or cause widespread coagulation activation; immune thrombocytopenia would usually have normal coagulation times and a normal D-dimer; while disseminated intravascular coagulation involves a similar process, the presentation is most consistently explained by secondary fibrinolysis in this context.