A 70-year-old woman presents to the Emergency Department with a 2-day history of dysuria and...

This patient is in septic shock, likely from pyelonephritis, with hypotension, tachycardia, and fever. Her laboratory findings demonstrate thrombocytopenia (platelets 85 × 10⁹/L), elevated INR, very low fibrinogen ( < 1 g/L), and schistocytes on blood film, along with active bleeding from the central line site. These findings are classic for disseminated intravascular coagulation (DIC).

MCCQE objectives emphasize recognizing DIC as a complication of severe sepsis. In DIC, systemic activation of coagulation leads to widespread microthrombi formation and consumption of platelets and clotting factors (consumptive coagulopathy), resulting in both thrombosis and bleeding. Low fibrinogen and prolonged INR are key distinguishing features.

ITP causes isolated thrombocytopenia without coagulation abnormalities. TTP presents with thrombocytopenia and schistocytes but typically has normal coagulation studies. Heparin-induced thrombocytopenia requires prior heparin exposure and does not cause elevated INR or low fibrinogen. Vitamin K deficiency causes prolonged INR but does not produce thrombocytopenia or schistocytes.

Thus, DIC secondary to sepsis is the most likely cause of her bleeding.