| Lab | Finding | Why |
|---|---|---|
| Platelets | โโ | Consumed in microthrombi ISTH DIC Score, Taylor 2001 |
| Fibrinogen | โ (< 100 = severe) | Consumed. Most specific for DIC severity. |
| PT/INR, aPTT | โ | Clotting factors consumed |
| D-dimer | โโโ | Massive fibrinolysis |
| Smear | Schistocytes | RBCs sheared through fibrin strands |
| Component | Replacement | Target |
|---|---|---|
| Fibrinogen | Cryoprecipitate 10 units | > 100โ150 mg/dL. Most critical to replace. ISTH DIC Guidelines, Levi 2009 |
| Platelets | Platelet transfusion | > 50K if bleeding; > 10K if not |
| Factors | FFP 15 mL/kg | INR < 1.5 if bleeding |
| RBCs | pRBCs | Hgb > 7 (or > 8 if active bleed) |
| Product | Indication | Dose | Target |
|---|---|---|---|
| Platelets | Plt <10K (any) or <50K with active bleeding | 1 apheresis unit or 6-pack | Plt >50K if bleeding, >10K if stable |
| Cryoprecipitate | Fibrinogen <100-150 mg/dL | 10 units (pools) | Fibrinogen >150 mg/dL. Each pool raises fibrinogen ~50 mg/dL. |
| FFP | PT/aPTT >1.5× normal WITH active bleeding | 15 mL/kg (typically 4 units) | INR <1.5. Replaces all clotting factors. |
| pRBCs | Hgb <7 (or <8 if active hemorrhage) | Per transfusion protocol | Hemodynamic stability, adequate oxygen delivery. |
| Heparin SELECT CASES | Chronic/compensated DIC with thrombosis predominance | Low-dose UFH or prophylactic LMWH | Only when thrombosis outweighs bleeding risk (e.g., Trousseau syndrome, purpura fulminans). Contraindicated in acute DIC with active hemorrhage. |
| Tranexamic acid | Hyperfibrinolysis-predominant DIC | 1g IV load then 1g over 8h | Consider in APL-associated DIC or trauma. Use with caution -can worsen microvascular thrombosis. |
Patient: 65M with septic shock from E. coli urosepsis. Developing diffuse oozing from IV sites, petechiae, and hematuria.
Key findings: Plt 28K, INR 3.2, fibrinogen 62, D-dimer > 20,000. Peripheral smear: schistocytes. ISTH DIC score 7 (overt DIC). Factor VIII LOW (confirming DIC, not liver disease).
Management:
Teaching point: Fibrinogen is the most specific and actionable lab in DIC. Factor VIII is LOW in DIC but ELEVATED in liver disease, this is the single best lab to differentiate them when the clinical picture is unclear.
Patient: 32F presenting with pancytopenia and gum bleeding. Peripheral smear: blasts with Auer rods. Diagnosed with acute promyelocytic leukemia (APL). Labs: plt 18K, INR 1.8, fibrinogen 85, D-dimer 12,000.
Key findings: APL-associated DIC, unique because it has both bleeding AND thrombotic features. APL blasts release tissue factor and annexin II causing consumptive coagulopathy.
Management:
Teaching point: APL is a hematologic emergency because of severe DIC. ATRA corrects the DIC by inducing differentiation of the leukemic promyelocytes. In APL, maintain higher fibrinogen (> 150) and platelet (> 50K) thresholds than typical DIC.
Patient: 44F with thrombocytopenia (plt 22K), schistocytes on smear, and elevated LDH. Presenting with confusion and fever. Is this DIC or TTP?
Key findings: PT/INR NORMAL. Fibrinogen 310 (NORMAL). D-dimer mildly elevated. Cr 2.1. This is NOT DIC, normal coags with thrombocytopenia + MAHA = TTP until proven otherwise.
Management:
Teaching point: The key differentiator: DIC = prolonged PT/INR + low fibrinogen + very high D-dimer. TTP = NORMAL PT/INR + NORMAL fibrinogen. Both have MAHA + thrombocytopenia. If coags are normal, think TTP. Platelet transfusion is treatment in DIC but contraindicated in TTP.
| Parameter | Frequency | Target / Action |
|---|---|---|
| CBC (platelets, Hgb) | q6-8h in acute DIC | Platelet trend (rising = improving). Hgb drop = ongoing hemorrhage or hemolysis. Check smear for schistocytes. |
| Fibrinogen | q6-8h in acute DIC | Target >150 mg/dL. Most specific lab for DIC severity. Replete with cryoprecipitate if <100-150. |
| PT/INR, aPTT | q6-8h in acute DIC | Trend toward normalization. Prolonged + bleeding → FFP. Improving PT/fibrinogen = resolving DIC. |
| D-dimer | q6-12h | Massively elevated in DIC. Trending down = resolving. Not specific -use in context of ISTH score. |
| ISTH DIC score | Daily recalculation | ≥5 = overt DIC. Track serial scores -declining score confirms resolution. Components: platelets, D-dimer, PT, fibrinogen. |
| Clinical bleeding assessment | q2-4h | IV sites, surgical sites, mucosal bleeding, petechiae, hematuria, GI bleeding. Simultaneous bleeding AND thrombosis is pathognomonic. |
| Thrombotic complications | Each assessment | Skin necrosis (purpura fulminans), acral ischemia, organ dysfunction (renal, hepatic). DVT/PE screening if clinical concern. |