General pathology · Hemodynamic disorders
Disseminated intravascular coagulation: how consumption causes both clots and bleeding !
- Mechanism
In DIC tiny clots form all over the body; by using up platelets and clotting factors, the patient also bleeds.
Updated 2026-11-01
What it is
Disseminated intravascular coagulation (DIC) is not a primary disease but a complication of another: sepsis, obstetric problems, cancer, severe trauma or venoms. A massive stimulus (tissue factor or widespread endothelial damage) generates thrombin throughout the vascular tree. Microthrombi form and damage organs, and at the same time platelets and factors are consumed and fibrinolysis is activated, which causes bleeding. It is a consumption coagulopathy with two faces.
Step by step
- A trigger releases tissue factor into the blood (placenta, tumour cells, damaged tissue) or injures the endothelium widely (sepsis).
- Thrombin is generated throughout the body, not just at one site of injury.
- Microthrombi of fibrin and platelets block small vessels in kidney, lung, brain, skin and adrenals.
- Red cells are cut as they pass the fibrin mesh: microangiopathic hemolytic anemia (schistocytes).
- Platelets, fibrinogen and factors V and VIII are used up faster than they are replaced.
- Plasmin is activated and makes D-dimer and other degradation products that hold back clotting further.
- Result: organ ischemia and, at the same time, bleeding from puncture sites, mucosa and wounds.
Triggers of DIC and how they act
| Trigger | Main mechanism |
|---|---|
| Sepsis (gram-negative bacteria, meningococcus) | Endotoxin and cytokines: endothelial damage and more tissue factor on monocytes |
| Obstetric complications (placental abruption, retained dead fetus, amniotic fluid embolism) | Placental or amniotic thromboplastin enters the maternal blood |
| Cancer (acute promyelocytic leukemia, mucin-producing adenocarcinomas) | Promyelocyte granules and mucins activate coagulation |
| Severe trauma, burns, heat stroke | Tissue factor from destroyed tissue and endothelial damage |
| Snakebite (Bothrops, the mapaná, in Colombia) | Venom enzymes activate factors and consume fibrinogen (consumption coagulopathy) |
Clinical notes
- Waterhouse-Friderichsen syndrome: DIC in meningococcemia with bleeding into both adrenals and acute adrenal failure.
- Acute DIC (sepsis, obstetrics) leans to bleeding; chronic DIC (cancer) leans to thrombosis.
- In Colombia, Bothrops snakebites are a frequent cause of consumption coagulopathy.
In the lab
- Peripheral blood smear: schistocytes (fragmented red cells).
- Serial platelet counts and fibrinogen, which track the pace of consumption.
Test yourself
Think of the answer, then tap the question to see it.
Why does a patient with DIC bleed if the problem is excess clotting?
Because widespread clotting consumes platelets and factors, and activated fibrinolysis makes products that inhibit hemostasis.
Which leukemia is classically linked to DIC?
Acute promyelocytic leukemia, because of the procoagulant granules of the promyelocytes.
Which laboratory findings are typical of DIC?
Low platelets, prolonged PT and aPTT, low fibrinogen, raised D-dimer and schistocytes.
What is Waterhouse-Friderichsen syndrome?
Bleeding into both adrenal glands during severe sepsis with DIC, classically from the meningococcus.
Related
- How septic shock develops
- Shock: types, stages and the organs it damages
- Fat, air and amniotic fluid embolism
- Hemorrhage: petechiae, purpura, ecchymosis, hematoma, and what blood loss does
Related conditions
- Disseminated intravascular coagulation
- Sepsis and septic shock
- Amniotic fluid embolism
- Placental abruption
- Meningococcal disease (meningococcemia)
- Acute leukaemia (AML and ALL)
- Snakebite envenomation (Bothrops, Lachesis, Crotalus)
- Major trauma (polytrauma): ATLS primary survey
- Burns (thermal, chemical, electrical; inhalation injury)
- Heat stroke and heat exhaustion
- Viral haemorrhagic fevers (Ebola and others)
Elsewhere in DurgiPedia
- The coagulation cascade
- Fibrinolysis and natural anticoagulants
- Coagulation tests: PT/INR, aPTT and platelets
- Thrombosis and bleeding: Virchow's triad and hemostatic defects
Microorganisms
In Pharmacology
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Disseminated intravascular coagulation (DIC): MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025); Septic shock: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.