DIC simplify
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"disseminated intravascular coagulation"
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disseminated intravascular coagulation DIC overview causes signs treatment Merck Manual
DIC = Disseminated Intravascular Coagulation
It is a dangerous condition where the body’s clotting system becomes activated everywhere.
Simple idea
- Too many tiny blood clots form throughout small blood vessels.
- This uses up platelets and clotting factors.
- Then the patient can develop severe bleeding because there are no clotting materials left.
So DIC can cause both clotting and bleeding at the same time.
Common causes
- Severe infection, especially sepsis
- Major trauma, burns, shock
- Pregnancy complications: placental abruption, retained dead fetus, amniotic fluid embolism
- Some cancers, especially acute promyelocytic leukemia
- Severe pancreatitis or liver failure
Features
- Bleeding from IV sites, gums, wounds, or urine
- Bruising and tiny skin spots (petechiae)
- Low blood pressure, organ damage
- Clots can cause kidney, lung, brain, or limb problems
Typical laboratory findings
- Low platelets
- Prolonged PT/INR and aPTT
- Low fibrinogen
- High D-dimer
- Schistocytes may appear on blood smear
Treatment
The main treatment is to treat the cause immediately, for example antibiotics for sepsis or delivery/obstetric management for a pregnancy complication. If there is significant bleeding or an invasive procedure is needed, clinicians may give platelets, fresh frozen plasma, or cryoprecipitate. Heparin is used only in selected cases where clotting predominates. Merck Manual overview
Memory line:
DIC = “clotting everywhere, then bleeding everywhere.”
DIC = “clotting everywhere, then bleeding everywhere.”
Recent reviews and guidelines continue to emphasize that DIC is secondary to an underlying disorder and management must focus on controlling that trigger, for example ISTH systematic review, PMID 40383152.
Compare DIC with TTP and HUS
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"thrombotic microangiopathy" AND diagnosis
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DIC versus TTP HUS laboratory comparison ADAMTS13 coagulation tests
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https://www.ncbi.nlm.nih.gov/books/NBK430721
DIC vs TTP vs HUS
All three may cause low platelets and microangiopathic hemolytic anemia (MAHA) with schistocytes. The key distinction is:
- DIC: widespread activation and consumption of clotting factors
- TTP/HUS: platelet-rich microthrombi in small vessels, usually with normal clotting tests
| Feature | DIC | TTP | HUS |
|---|---|---|---|
| Main mechanism | Systemic coagulation activation causes clot formation and consumption of platelets/factors | Severe ADAMTS13 deficiency causes unusually large vWF multimers and platelet microthrombi | Endothelial injury, usually Shiga toxin; atypical HUS is complement-mediated |
| Typical trigger | Sepsis, trauma, obstetric emergency, malignancy | Usually acquired autoimmune ADAMTS13 inhibitor; sometimes inherited | Typical: diarrhea from Shiga toxin-producing E. coli; atypical: complement dysregulation |
| Platelets | Low | Low, often very low | Low |
| Hemolysis / schistocytes | Can occur | Prominent MAHA | Prominent MAHA |
| PT / aPTT | Prolonged | Usually normal | Usually normal |
| Fibrinogen | Low | Usually normal | Usually normal |
| D-dimer | Very high | May be mildly raised | May be mildly raised |
| Main organ effect | Bleeding plus thrombosis, possible multiorgan failure | Neurologic features more prominent: headache, confusion, seizure, stroke | Renal failure more prominent |
| Diarrheal prodrome | Not typical | Not typical | Common in typical HUS, often bloody diarrhea |
| ADAMTS13 activity | Not severely deficient | <10% strongly supports TTP | Usually >10% |
| Bleeding | Common, such as oozing from lines/gums and bruising | Usually less prominent | Usually less prominent |
| First principle of treatment | Urgently treat the trigger; give blood products if clinically indicated | Immediate plasma exchange plus corticosteroids; caplacizumab and rituximab are often used for immune TTP | Supportive care for Shiga-toxin HUS; complement inhibition, such as eculizumab/ravulizumab, for complement-mediated HUS |
Fast exam approach
Thrombocytopenia + schistocytes:
-
PT/aPTT prolonged, fibrinogen low, D-dimer very high
→ DIC -
PT/aPTT normal + major neurologic symptoms + ADAMTS13 <10%
→ TTP -
PT/aPTT normal + severe acute kidney injury, especially after bloody diarrhea
→ HUS
Memory aid
- DIC = Diffuse clotting-factor Inactivation/consumption, so bleeding is prominent.
- TTP = Thinking trouble, meaning neurologic symptoms predominate.
- HUS = Hurts the kidneys, meaning renal injury predominates.
TTP is a hematologic emergency. If it is suspected, treatment should begin urgently while ADAMTS13 testing is pending because waiting can be dangerous. The textbook material identifies severe ADAMTS13 deficiency as the defining feature of TTP, and recent clinical resources likewise stress that abnormal coagulation studies favor DIC rather than TTP/HUS. TTP evaluation summary
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