Postpartum Bleeding with Prolonged Clotting Times and Low Fibrinogen
A 31-year-old woman is admitted after a placental abruption at 34 weeks. She delivers by cesarean hysterectomy for uterine atony and receives 6 units of packed red cells, 4 units of fresh frozen plasma, and 1 apheresis platelet unit. Eight hours later she is oozing from venipuncture sites and the surgical incision. Vital signs: BP 88/52 mmHg, HR 128/min, temperature 37.9°C. Laboratory: platelets 78×10^9/L, PT 19.5 s (reference 11–13.5), INR 1.7, aPTT 58 s (reference 25–35), fibrinogen 0.9 g/L (reference 2–4), D-dimer 8.2 mg/L FEU (reference <0.5), and hemoglobin 7.4 g/dL. The obstetrician asks whether she has dilutional coagulopathy or disseminated intravascular coagulation (DIC), and whether more plasma or platelets are needed.
1. Calculate the ISTH DIC score for this patient and interpret it. State any assumptions about the PT reference range.
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Using the ISTH overt-DIC score: platelets 78×10^9/L is below 100 but above 50, giving 1 point. PT prolongation is measured against the reference range; using a mid-reference of about 12 s, 19.5 − 12 = 7.5 s, which is greater than 6 s and gives 2 points. If the upper reference of 13.5 s is used, the prolongation is 6 s, giving 1 point. Fibrinogen 0.9 g/L is below 1 g/L, giving 1 point. D-dimer 8.2 mg/L FEU is a strong increase, giving 3 points. The total is 7 points with the mid-reference assumption, or 6 points with the upper reference; either is at least 5, consistent with overt DIC. The score should be interpreted with the clinical picture of postpartum hemorrhage, shock, and oozing.
2. How should the laboratory distinguish dilutional coagulopathy from DIC in this setting, and what component therapy is indicated?
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Dilutional coagulopathy can coexist with DIC, but the combination of thrombocytopenia, prolonged PT and aPTT, low fibrinogen, and markedly elevated D-dimer in a bleeding postpartum patient supports DIC. Dilution alone usually produces a proportional fall in clotting factors and platelets without such a disproportionate fibrinogen decrease or D-dimer elevation. Treatment must address the cause: uterine atony, hypoperfusion, and source control. Platelets alone will not correct the coagulopathy. Give fibrinogen replacement, such as cryoprecipitate or fibrinogen concentrate, to maintain fibrinogen above 1.5 g/L during active bleeding. Give plasma for prolonged PT or aPTT with bleeding, and platelets if the count is below 50×10^9/L with bleeding. Use a massive transfusion protocol, keep the patient warm, and correct ionized calcium and acidosis.
3. What laboratory parameters should be monitored, and why is D-dimer alone not sufficient to guide therapy?
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Monitor CBC, PT/INR, aPTT, fibrinogen, D-dimer, ionized calcium, lactate, arterial pH, temperature, and urine output. Fibrinogen is one of the most sensitive markers of consumptive coagulopathy and should be followed closely because it falls early in obstetric DIC. D-dimer is elevated in DIC but also in surgery, trauma, and pregnancy, and it does not quantify the severity of bleeding or direct component replacement. Trends in platelets, fibrinogen, and clotting times, together with the clinical bleeding site and hemodynamic response, are more useful for guiding therapy than a single D-dimer value.