Disseminated Intravascular Coagulation (DIC): Comprehensive Overview
Presentation
DIC presents along a spectrum from asymptomatic laboratory abnormalities to life-threatening thrombosis or bleeding, with clinical manifestations determined by which pathophysiologic mechanism dominates. 1
Clinical Forms
DIC manifests in three distinct patterns that guide management:
Procoagulant DIC: Excess thrombin generation causes arterial ischemia, venous thromboembolism, or microvascular thrombosis; commonly seen in pancreatic cancer and adenocarcinomas 2
Hyperfibrinolytic DIC: Activation of the fibrinolytic system dominates, causing widespread bleeding from multiple sites; typical of acute promyelocytic leukemia and metastatic prostate cancer 2
Subclinical DIC: Laboratory markers show coagulation activation without obvious clinical manifestations of bleeding or thrombosis 1, 2
Key Clinical Pitfall
A 30% or greater drop in platelet count is diagnostic of subclinical DIC even when absolute platelet values remain in the normal range. 2, 3 This is frequently missed when clinicians focus only on absolute values rather than trends.
Diagnosis
Laboratory Approach
The ISTH recommends a two-step sequential screening approach: first screen for Sepsis-Induced Coagulopathy (SIC) using the ISTH SIC score (≥4 points indicates SIC), then apply the ISTH overt DIC score (≥5 points indicates overt DIC) for patients with more advanced coagulopathy. 2
Essential Laboratory Panel
The DIC diagnostic panel must include: 2, 3
- Complete blood count with platelet count
- Prothrombin time (PT)
- Partial thromboplastin time (PTT)
- Fibrinogen level
- D-dimer or fibrin degradation products (FDP)
Critical Diagnostic Caveat
Normal PT/PTT does not rule out DIC, as these may remain normal in subclinical or early cancer-associated DIC. 3 Clinicians must not be falsely reassured by normal coagulation times in the presence of other suggestive findings.
Monitoring Frequency
- Acute severe DIC: Daily monitoring 2
- Chronic stable DIC: Monthly monitoring 2
- ICU patients: Sequential screening on admission and 2 days later is associated with lower mortality 2
Causes
DIC is always secondary to an underlying disorder and never occurs as a primary disease. 1
Common triggers include:
- Sepsis: Most common cause overall, with pathological activation of intrinsic coagulation systems 4, 5
- Malignancy: Particularly acute promyelocytic leukemia, pancreatic cancer, adenocarcinomas, and metastatic prostate cancer 1, 2
- Trauma: Especially head trauma with activation of extrinsic coagulation pathway 6
- Obstetric complications: Including placental abruption and amniotic fluid embolism 4
Complications
Thrombotic Complications
- Arterial ischemia and infarction 2
- Venous thromboembolism 2
- Microvascular thrombosis leading to organ dysfunction 7
Hemorrhagic Complications
- Bleeding is the most common clinical manifestation in acute DIC 6
- Widespread bleeding from multiple sites in hyperfibrinolytic DIC 2
- Life-threatening hemorrhage requiring aggressive intervention 6
Organ Dysfunction
Treatment
Core Management Algorithm
Treating the underlying disease process is the absolute cornerstone of DIC therapy and must be addressed immediately. 2
Disease-Specific Treatment Priorities
- Cancer-associated DIC: Initiate appropriate cancer therapy immediately (chemotherapy, surgery, or radiation) 2
- Acute promyelocytic leukemia: Early initiation of all-trans retinoic acid achieves good resolution of DIC 2
- Sepsis-associated DIC: Source control and appropriate antibiotics are essential 2
Supportive Hemostatic Measures
Platelet Transfusion Thresholds:
- Active bleeding: Maintain platelets >50×10⁹/L 2, 3
- High bleeding risk without active hemorrhage: Transfuse if <30×10⁹/L in acute promyelocytic leukemia or <20×10⁹/L in other cancers/leukemias 2, 3
- Prophylactic threshold: <20×10⁹/L is a contraindication to anticoagulation 8
Important caveat: The half-life of transfused platelets may be extremely short in DIC with vigorous coagulation activation, requiring frequent reassessment 8
Fresh Frozen Plasma (FFP):
Fibrinogen Replacement:
- Replace with cryoprecipitate or fibrinogen concentrate if levels remain <1.5 g/L despite FFP 2, 3
- Typically give two units of cryoprecipitate 8
Anticoagulation Strategy
The ISTH recommends initiating prophylactic anticoagulation with heparin in all patients except those with hyperfibrinolytic DIC, unless contraindications exist (platelets <20×10⁹/L or active bleeding). 2, 8
Anticoagulation Algorithm
First-line choice: Low molecular weight heparin (LMWH) for most patients 2, 8
Alternative: Unfractionated heparin (UFH) in patients with high bleeding risk and renal failure due to its reversibility 8
Dose escalation: Escalate to therapeutic-dose anticoagulation if arterial or venous thrombosis develops 2
Special consideration for solid tumors with thromboembolism: LMWH at therapeutic dose for 6 months (first month at full dose, 5 months at 75% dose) is superior to warfarin 8
Critical Anticoagulation Caveat
Abnormalities in coagulation tests alone should not be considered an absolute contraindication to anticoagulation in the absence of active bleeding. 8 This is a common error where clinicians withhold necessary anticoagulation based solely on laboratory values.
Avoid heparin completely in hyperfibrinolytic DIC (such as acute promyelocytic leukemia presenting with bleeding), as it may worsen hemorrhage 8
Special Clinical Scenarios
IVC filter placement: Consider temporary IVC filter in patients who cannot be anticoagulated but have proximal lower limb thrombosis likely to embolize 2
Therapeutic heparin dosing: Use "therapeutic" doses adequate to overcome the coagulant forces that may have produced a relative heparin-resistant state 6
Chronic DIC: Long-term outpatient subcutaneous heparin therapy may be required if DIC persists because the underlying tumor does not regress; warfarin is ineffective 6
Treatment Sequence for Life-Threatening Hemorrhage
When severe or life-threatening hemorrhage occurs: 6
- Initiate heparin anticoagulation first
- Follow immediately with aggressive replacement: platelets, fresh plasma, and possibly cryoprecipitate
- Continue treating underlying disease