About This Page
This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- DIC is caused by systemic coagulation activation with consumption of platelets, fibrinogen, and clotting factors
- Common triggers: sepsis, trauma, obstetric catastrophe, malignancy, acute promyelocytic leukemia, pancreatitis, and massive transfusion
- Labs: thrombocytopenia, prolonged PT/aPTT, elevated D-dimer, low fibrinogen, schistocytes
- Treat the underlying cause; blood products are guided by bleeding, procedures, and severity of factor depletion
- TTP has normal PT/aPTT; DIC has abnormal coagulation studies
Overview
DIC is an acquired syndrome in which widespread tissue factor exposure or endothelial activation triggers thrombin generation throughout the circulation. Microvascular fibrin deposition causes organ dysfunction and RBC fragmentation, while consumption of platelets and coagulation factors causes bleeding. DIC can be acute and hemorrhagic or chronic and thrombotic.
Epidemiology
DIC occurs secondary to severe systemic illness rather than as a primary disease. It is common in septic shock, major trauma, placental abruption, amniotic fluid embolism, retained dead fetus, severe pancreatitis, metastatic adenocarcinoma, and acute promyelocytic leukemia.
Clinical Features
Symptoms
Bleeding from IV sites, mucosa, wounds, or surgical drains
Purpura, ecchymoses, petechiae
Dyspnea, confusion, oliguria, or shock from organ dysfunction
Symptoms of trigger: fever/sepsis, trauma, obstetric emergency, leukemia symptoms
Signs
Diffuse oozing or uncontrolled bleeding
Hypotension and signs of shock
Digital ischemia, skin necrosis, or purpura fulminans
Jaundice or pallor if MAHA contributes
Investigations
First-line
CBC and smearThrombocytopenia; schistocytes may be present
Coagulation profilePT prolonged, aPTT prolonged, fibrinogen low, D-dimer markedly elevated
CMP, lactate, ABG when critically illAssess organ dysfunction and underlying sepsis/shock
Second-line
Serial fibrinogen and plateletsTrends guide replacement during active bleeding or procedures
Blood cultures and infection workupSepsis is a major trigger
Leukemia evaluation if suspectedAPL can present with catastrophic DIC and abnormal promyelocytes
Specialist
ISTH DIC scoreCombines platelet count, fibrin markers, PT prolongation, and fibrinogen
1
Treat the underlying cause
- Source control and antibiotics for sepsis
- Urgent obstetric management for abruption, amniotic fluid embolism, or retained products
- Immediate ATRA if acute promyelocytic leukemia is suspected; do not wait for genetic confirmation
- Resuscitate shock and correct hypothermia, acidosis, and hypocalcemia
2
Blood product support
- Platelets for active bleeding or procedures when platelets are low
- Cryoprecipitate or fibrinogen concentrate for low fibrinogen, especially with bleeding
- FFP for bleeding with prolonged PT/aPTT or before urgent procedures
- RBC transfusion for severe anemia or hemorrhagic shock
3
Thrombosis-predominant DIC
- Heparin may be considered in selected chronic or thrombotic DIC under specialist guidance
- Do not use heparin in uncontrolled bleeding unless there is a compelling indication and expert input
Complications
- Major hemorrhage: Intracranial, pulmonary, gastrointestinal, surgical, or obstetric bleeding
- Microvascular thrombosis: Renal failure, respiratory failure, hepatic injury, digital ischemia
- Shock and death: Often driven by the underlying trigger
- Purpura fulminans: Severe skin necrosis, often meningococcemia or severe sepsis
USMLE Step 2 CK Exam Tips
- 1DIC labs: low platelets, prolonged PT/aPTT, low fibrinogen, high D-dimer
- 2TTP labs: low platelets and schistocytes but normal PT/aPTT
- 3Septic patient bleeding from IV sites = DIC
- 4Obstetric catastrophe plus bleeding = DIC until proven otherwise
- 5APL with bleeding/DIC: start ATRA immediately
- 6Treat the underlying cause first; blood products support bleeding and procedures
practicetest your knowledge on disseminated intravascular coagulation (dic)Apply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — hematology & oncology and beyond.
open q-bank