π©Έ ISTH DIC Score Calculator
Overt DIC criteria: 5 or more points from 4 lab domains.
Educational only. DIC diagnosis and management require the treating team; it is always secondary to an underlying cause.
Disseminated intravascular coagulation is clotting and bleeding at the same time: runaway thrombin generation consumes platelets and clotting factors, so microthrombi damage organs while the blood loses its ability to clot. The ISTH scoring system (Taylor et al., 2001) turns four lab domains into an 8-point score; 5 or more means overt DIC. Enter the labs above.
How to Use This Score
Enter platelets, fibrin marker level, PT prolongation, and fibrinogen. The score and interpretation appear.
Enter the four labs from the same draw: platelets, D-dimer/FDP category, PT prolongation in seconds, fibrinogen.
Read the total: 5+ is overt DIC, below 5 is not, but repeat scoring if suspicion persists.
Remember the principle: DIC is always secondary. The score diagnoses the complication; finding the cause (sepsis, trauma, malignancy, obstetric catastrophe) is the treatment.
The ISTH Criteria
Each domain reflects the consumption: platelets trapped in microthrombi, fibrin split products from clot breakdown, PT prolonged as factors are consumed, fibrinogen low as the substrate is eaten. The score requires an underlying condition known to cause DIC; it is not validated as a screening test in undifferentiated patients. Serial scoring tracks the trajectory: a score climbing from 3 to 6 tells the story of evolving DIC before any single value screams.
Non-overt (early) DIC has its own ISTH algorithm for scores below 5 with high suspicion, incorporating trends and additional markers like antithrombin. In practice, most clinicians use the overt score plus judgment: a septic patient with platelets falling from 200 to 80 and rising D-dimer is developing DIC whether the total is 4 or 5 today.
Worked Example
Septic patient: platelets 45 (2 points), strongly increased D-dimer (3), PT prolonged 4 seconds (1), fibrinogen 0.8 g/L (1). Total = 7: overt DIC. Contrast early sepsis: platelets 120 (0), moderate D-dimer (2), PT +2s (0), fibrinogen 2.5 (0): total 2, not overt, but the moderate D-dimer with falling platelets warrants repeat scoring in hours. The score's sensitivity to trends is its real clinical value; the 5-point line is the formal threshold, not the moment of truth.
Treatment: Cause First, Blood Products Second
DIC treatment is treatment of the cause: antibiotics and source control for sepsis, delivery for obstetric catastrophes, chemotherapy for promyelocytic leukemia (whose DIC is famously severe). Blood products support but do not fix: platelets for bleeding or pre-procedure thrombocytopenia, cryoprecipitate or fibrinogen concentrate for low fibrinogen with bleeding, fresh frozen plasma for prolonged clotting times with bleeding. Prophylactic correction of labs without bleeding is generally avoided; the numbers will just be consumed again.
Heparin is the nuanced exception: in chronic DIC with thrombosis (Trousseau's syndrome in malignancy, aortic aneurysm, retained dead fetus), low-dose heparin can help; in acute bleeding DIC it usually harms. Tranexamic acid is generally avoided in DIC except specific hyperfibrinolytic states like promyelocytic leukemia. These are ICU and hematology decisions, made with the score as one input among many.
Causes Worth Knowing
Sepsis is the commonest cause, especially gram-negative and meningococcemia. Trauma and burns release tissue factor massively. Malignancy, particularly mucinous adenocarcinomas and acute promyelocytic leukemia, drives chronic or explosive DIC. Obstetric catastrophes: placental abruption, amniotic fluid embolism, retained stillbirth, severe preeclampsia/HELLP. Transfusion reactions, heatstroke, and snake envenomation round out the list. When the score says DIC, the next question is always "from what," and the answer sets the entire plan.
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For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the ISTH DIC score?
A 0-8 score for overt disseminated intravascular coagulation: platelets (0-2), fibrin markers (0-3), PT prolongation (0-2), fibrinogen (0-1). A total of 5+ indicates overt DIC. Published by Taylor et al. for the ISTH in 2001.
What causes DIC?
Always something else: sepsis (commonest), trauma, malignancy (especially APL and mucinous adenocarcinomas), obstetric catastrophes (abruption, amniotic fluid embolism), transfusion reactions, and heatstroke. DIC is never a primary diagnosis.
How is DIC treated?
Treat the underlying cause first (antibiotics/source control for sepsis, delivery for obstetric causes). Support with blood products for bleeding: platelets, cryoprecipitate/fibrinogen, FFP. Heparin helps select chronic thrombotic DIC; it harms acute bleeding DIC.
What labs indicate DIC?
Falling platelets, rising D-dimer/FDP, prolonged PT/aPTT, and low fibrinogen, in a patient with a DIC-causing condition. The ISTH score formalizes these four domains; trends matter as much as single values.
Can DIC cause both clotting and bleeding?
Yes, simultaneously: microthrombi consume platelets and factors (causing organ damage), leaving the blood unable to clot (causing bleeding). This paradox is DIC's hallmark and its management challenge.
What is the mortality of DIC?
High, but it reflects the underlying cause more than the DIC itself: septic DIC mortality tracks sepsis severity. Early recognition and cause-directed treatment are what improve outcomes.
What is the difference between overt and non-overt DIC?
Overt DIC meets the 5+ ISTH score with manifest consumption. Non-overt (early) DIC has evolving abnormalities below the threshold; the ISTH has a separate algorithm using trends. Clinically, treat the trajectory, not just the threshold.
Should platelets be transfused in DIC?
For active bleeding or before invasive procedures with severe thrombocytopenia, yes. Prophylactic transfusion to correct numbers without bleeding is generally avoided: the products get consumed without fixing the cause.
Is heparin used in DIC?
Selectively: it can help chronic DIC with dominant thrombosis (e.g., Trousseau's syndrome, retained dead fetus syndrome). In acute bleeding DIC it usually worsens bleeding. Hematology guides these decisions.
What is purpura fulminans?
A severe DIC manifestation with rapidly progressive skin necrosis from microvascular thrombosis, seen in meningococcemia, severe sepsis, and protein C deficiency. It is a dermatologic emergency reflecting catastrophic DIC.