---

Disseminated Intravascular Coagulation (DIC): Complete Emergency Medicine Guide

---

1. DEFINITION

• Systemic thrombin generation
• Fibrin deposition in the microcirculation
• Consumption of clotting factors and platelets
• Secondary fibrinolysis

• Pre-DIC - laboratory abnormalities without clinical symptoms
• Early-phase / Subclinical DIC - compensated; lab changes precede symptoms (detected by Sepsis-Induced Coagulopathy [SIC] score)
• Overt DIC - advanced; frank coagulopathy + organ failure

---

2. PATHOPHYSIOLOGY

Molecular Cascade

• Bacterial endotoxins/exotoxins stimulate monocytes to express TF
• IL-1 and TNF from activated monocytes stimulate TF on endothelial cells AND simultaneously downregulate thrombomodulin (reducing protein C activation)
• Cancer cells (especially APL, adenocarcinoma) release TF and proteolytic enzymes directly

• Sepsis, burns, heat stroke, immune complex deposition, meningococcemia, rickettsiae
• Exposes subendothelial collagen + vWF, releases TF, downregulates thrombomodulin

1. Uncontrolled thrombin generation (thrombo-inflammation via neutrophil extracellular traps, polyphosphates)
2. Fibrin deposited in small and midsize vessels → organ ischemia (lung, kidney, liver, CNS)
3. Consumption of platelets + factors V, VIII, XIII, fibrinogen
4. Consumption of natural anticoagulants: antithrombin III, protein C, TFPI
5. Secondary fibrinolysis by plasmin → FDPs released → inhibit fibrin polymerization and platelet function → worsens bleeding

• Harrison's 22E, p. 977; Robbins Basic Pathology p. 426-427; Rosen's p. 2476

---

3. CAUSES / PRECIPITATING CONDITIONS

• Tintinalli Table 233-6; Harrison's Table 121-2

---

4. CLINICAL FEATURES

Hemorrhagic Manifestations

• Oozing from IV/venipuncture sites (classic early sign)
• Petechiae, purpura, ecchymoses
• Mucosal bleeding (gingival, nasal)
• GI hemorrhage, hematuria
• Intracranial hemorrhage (severe)
• Surgical wound oozing

Thrombotic Manifestations (often under-recognized)

• Skin: acral cyanosis, digital ischemia, purpura fulminans
• Renal failure (glomerular fibrin deposition)
• Hepatic dysfunction
• ARDS (pulmonary microvascular thrombosis)
• Altered mental status, focal neurologic deficits (CNS microvascular thrombosis)

Purpura Fulminans

Key ED Pearls

• Septic patients more often present with thrombosis than bleeding
• APL and obstetric DIC present with dominant bleeding
• Cancer-associated DIC is often chronic and compensated
• Hemodynamic instability and shock are common in acute DIC (mortality 30-80%)
• Harrison's 22E, p. 977; Tintinalli p. 1513; Rosen's p. 2476

---

5. DIAGNOSIS

ED Rule: DIC is a Clinical + Laboratory Diagnosis

Laboratory Abnormalities

• Tintinalli Table 233-7; Rosen's Table 111.8; Henry's p. 954

---

ISTH Overt DIC Scoring System (Score ≥5 = Overt DIC)

• Harrison's Table 121-3; Tintinalli Table 233-8; Henry's p. 954

Sepsis-Induced Coagulopathy (SIC) Score

• Platelet count: >150=0, 100-150=1, <100=2
• INR: <1.2=0, 1.2-1.4=1, >1.4=2
• SOFA score: 0=0, 1=1, ≥2=2
• SIC score ≥4 = positive (ISTH 2025 now formally endorses SIC as an early DIC detection tool)

Differential Diagnosis

---

6. EMERGENCY MANAGEMENT

Step 1: Treat the Underlying Cause (MOST IMPORTANT)

• Sepsis: Broad-spectrum antibiotics + source control + fluids/vasopressors (Surviving Sepsis)
• Obstetric: Delivery, uterotonic agents (amniotic fluid embolism, abruption)
• Trauma: Damage control resuscitation, hemorrhage control
• APL: Urgent all-trans retinoic acid (ATRA) + arsenic trioxide (dramatic DIC reversal)
• Heat stroke: Active external cooling

---

Step 2: Blood Product Replacement (For ACTIVE BLEEDING Only)

Platelets

• Actively bleeding: transfuse when platelets <50,000/mm³
• Prophylactic/high-risk (e.g., chemotherapy-associated DIC): transfuse when <20,000-30,000/mm³
• Target during active bleeding: >50,000/mm³

Fresh Frozen Plasma (FFP)

• Indications: active bleeding + PT/aPTT >1.5-2× normal OR fibrinogen <100 mg/dL
• Dose: 15 mL/kg (consider 30 mL/kg if volume overload not a concern)
• Replaces all clotting factors including natural anticoagulants (protein C, antithrombin)

Cryoprecipitate / Fibrinogen Concentrate

• Use when hypofibrinogenemia persists despite FFP
• Cryoprecipitate: each unit raises fibrinogen ~5-10 mg/dL; pool of 10 units typical
• Fibrinogen concentrate: when cryoprecipitate insufficient or volume is a concern
• Target fibrinogen: >150 mg/dL (Harrison's) or >100 mg/dL (Tintinalli)

Vitamin K

• Give parenterally when PT is prolonged (repletes vitamin K-dependent factors II, VII, IX, X)

Monitoring Response

• Slowing of bleeding
• Decrease in FDPs/D-dimer
• Rise in platelet count and fibrinogen
• Normalization of clotting times (this occurs later - less useful for initial monitoring)
• Reassess frequently; repeat labs q6-8h in critically ill
• Harrison's 22E p. 977; Tintinalli Table 233-9; Rosen's p. 2477

---

Step 3: Anticoagulation - Selective Use

Heparin - When to Use

• Low-grade DIC with solid tumors or APL when thrombosis dominates
• Purpura fulminans (heparin + protein C replacement)
• Recognized arterial/venous thromboembolism complicating DIC
• Acral ischemia or skin necrosis

Heparin - When NOT to Use

• Active hemorrhagic DIC (will aggravate bleeding)
• Meningococcemia, abruptio placentae, severe liver disease, trauma
• Heparin use in severe DIC improves coagulation parameters but has no proven survival benefit

DVT Prophylaxis

• LMWH recommended in DIC patients when bleeding is absent and platelets >30,000/mm³

Tranexamic Acid (TXA)

• Generally avoid in DIC (risk of pathological thrombosis by blocking fibrinolysis)
• Exception: trauma-associated DIC - TXA reduces mortality (give within 3 hours of injury)
• Harrison's 22E p. 977-978; Tintinalli p. 1515; Rosen's p. 2477

---

Step 4: Other Agents (Limited/Investigational)

---

7. SPECIAL SITUATIONS

Obstetric DIC (ED Perspective)

• Notify obstetrics team immediately
• Delivery/evacuation of uterus is often the definitive treatment
• Amniotic fluid embolism: sudden cardiovascular collapse + DIC + bronchospasm
• HELLP: may coexist with DIC; deliver if >34 weeks or hemodynamically unstable
• Dead fetus syndrome: chronic/prothrombotic DIC (NOT hemorrhagic)

Trauma-Associated DIC

• Early coagulopathy present in 25-35% of major trauma patients on arrival
• Damage control resuscitation: balanced blood product ratio (1:1:1 PRBC:FFP:Platelets)
• TXA: give within 3 hours of injury (CRASH-2 trial)
• Avoid dilutional coagulopathy (limit crystalloids)
• Hypothermia, acidosis, hypocalcemia worsen coagulopathy ("lethal triad")
• Correct calcium (ionized Ca²⁺) - often depleted with massive transfusion

Sepsis-Associated DIC

• Most common cause of DIC globally
• 42% pooled mortality (ISTH systematic review, PMID 40383152)
• Gram-negative > gram-positive, but both can cause DIC
• Use SIC score for early detection
• Source control + antibiotics are the cornerstone

Purpura Fulminans

• Extensive skin thrombosis - limb- and life-threatening
• Therapeutic UFH infusion (if possible)
• Protein C concentrate (Ceprotin) is the preferred specific treatment
• Kcentra (4-factor PCC) or FFP if protein C concentrate unavailable
• Consider early surgical/dermatology consultation
• Stress-dose steroids for adrenal insufficiency (in meningococcemia)

Cancer-Associated DIC

• Often chronic, compensated - monitor serial labs
• APL: urgent ATRA (ALL-TRANS retinoic acid) - dramatic DIC reversal; low-dose heparin + blood products while awaiting ATRA effect
• Prostate cancer: tends toward bleeding; adenocarcinomas tend toward thrombosis (Trousseau)

---

8. ED DISPOSITION

• All patients with confirmed DIC require admission (usually ICU)
• Hematology consult for complex or unclear cases
• Transfer if hematologic expertise not available
• Obstetric DIC: immediate OB involvement; delivery as needed
• Serial monitoring of labs q6-8h during acute phase

---

9. KEY TAKEAWAYS FOR ED PHYSICIANS

1. DIC is always secondary - find and treat the trigger aggressively
2. Transfuse for bleeding, not numbers (except in prophylactic settings with very low platelets)
3. Fibrinogen is the most specific consumptive marker but can be falsely normal early
4. D-dimer alone is insufficient - use the full ISTH score with all 4 parameters
5. Heparin for thrombotic DIC (APL, purpura fulminans); avoid in hemorrhagic DIC
6. TXA only in trauma DIC - contraindicated in other DIC
7. Septic patients get thrombosis more than bleeding - consider anticoagulation early
8. LMWH prophylaxis when platelets >30,000 and no active bleeding
9. Repeat labs q6-8h in critically ill - rapid worsening is characteristic
10. ISTH 2025 introduced phase-based classification and refined D-dimer scoring thresholds

---

10. RECENT EVIDENCE UPDATES (2023-2025)

• [ISTH 2025 New DIC Definition] (scholars.duke.edu): Updated definition now emphasizes dynamic, phase-based classification (Pre-DIC → Early-phase → Overt DIC) with thrombotic vs hemorrhagic phenotyping. D-dimer thresholds revised: >3× ULN = 2 pts, >7× ULN = 3 pts.
• [PMID 40383152] (ISTH SSC Meta-Analysis, 2025): Pooled mortality of DIC is very high and heterogeneous - 42% in sepsis, 36% in trauma, 32% in heat stroke, 28% in leukemia. Odds ratio for mortality: 3.15 in sepsis, 4.80 in trauma. No clear improvement trend over years.
• [PMID 39676120] (Japan DIC Guidelines 2024 - Sepsis): Recommends antithrombin (GRADE 1B) and recombinant thrombomodulin (GRADE 1B) for sepsis-associated DIC. Heparin and serine protease inhibitors lack sufficient evidence.
• [PMID 36695377] (ISTH SSC 2023 - Sepsis-Induced Coagulopathy): SIC is now formally endorsed as the preferred tool for early DIC detection in septic patients.

---