Calculate the ISTH DIC score for diagnosing disseminated intravascular coagulation. Assess overt vs. non-overt DIC with treatment phenotype guidance.
The DIC (Disseminated Intravascular Coagulation) Scoring Calculator uses the International Society on Thrombosis and Haemostasis (ISTH) scoring system to diagnose overt disseminated intravascular coagulation — a life-threatening condition involving widespread activation of the coagulation cascade leading to simultaneous thrombosis and hemorrhage.
DIC is not a standalone disease but a complication of underlying conditions including sepsis, major trauma, malignancy (especially acute promyelocytic leukemia), obstetric emergencies, and severe organ injury. The pathophysiology involves uncontrolled thrombin generation that consumes platelets and clotting factors (consumptive coagulopathy) while simultaneously forming microthrombi that cause organ damage.
The ISTH scoring system evaluates four laboratory parameters: platelet count, D-dimer/fibrin degradation products, prothrombin time (PT) prolongation, and fibrinogen level. A score of ≥5 is compatible with overt DIC; scores of 3–4 suggest non-overt (early) DIC requiring repeat testing. This calculator also classifies the DIC phenotype (hemorrhagic vs. thrombotic) to guide treatment decisions — a critical distinction because hemorrhagic DIC requires replacement therapy while thrombotic DIC may benefit from anticoagulation.
DIC is a medical emergency with mortality rates of 40–80% depending on the underlying cause. Early recognition using the ISTH score — combined with identification of the DIC phenotype — guides critical treatment decisions. The scoring system is reproducible, objective, and endorsed by international guidelines for both diagnosis and monitoring treatment response.
ISTH Overt DIC Score (prerequisite: known underlying disorder): • Platelet count: ≥100k (0), 50–99k (1), <50k (2) • D-dimer/FDP: No increase (0), Moderate (2), Strong (3) • PT prolongation: <3 sec (0), 3–6 sec (1), >6 sec (2) • Fibrinogen: ≥100 mg/dL (0), <100 mg/dL (1) Score ≥5: Compatible with overt DIC Score <5: Suggestive, not affirmative — repeat in 12–24 hours
Result: ISTH DIC Score: 7/8 — Compatible with Overt DIC
Platelets <50k (2) + strongly elevated D-dimer (3) + PT prolonged 3–6 sec (1) + fibrinogen <100 (1) = 7 points. This exceeds the ≥5 threshold for overt DIC. With clinical bleeding present, this is a hemorrhagic phenotype — prioritize platelet transfusion, FFP, and cryoprecipitate while treating the underlying cause.
DIC begins with massive tissue factor exposure (from damaged endothelium, activated monocytes, or tumor cells) that triggers widespread thrombin generation. This causes: (1) diffuse fibrin deposition in small vessels → microthrombi → organ ischemia and failure, (2) consumption of platelets and clotting factors → hemorrhage, (3) secondary fibrinolysis → elevated D-dimer/FDP, and (4) microangiopathic hemolytic anemia (schistocytes on smear). The net result is a paradoxical state of simultaneous thrombosis and bleeding.
A single DIC score is a snapshot; serial scoring is essential for clinical management. An improving score (decreasing by 1–2 points over 24–48 hours) suggests treatment is working. A static or worsening score despite supportive care indicates the underlying cause is not controlled and requires escalation of therapy. Labs should be drawn every 8–12 hours in acute DIC.
Acute promyelocytic leukemia (APL) is unique: ATRA (all-trans retinoic acid) must be started emergently upon suspicion, as it directly addresses the DIC by inducing differentiation of malignant promyelocytes. Obstetric DIC typically resolves with delivery of the placenta. Trauma-DIC management follows damage control resuscitation principles with massive transfusion protocols. COVID-19-associated coagulopathy shares some features with DIC but is typically more thrombotic, requiring different management.
Disseminated Intravascular Coagulation (DIC) is a complex, life-threatening condition where the coagulation system is abnormally activated throughout the body, leading to widespread microthrombi formation (causing organ damage) and simultaneous consumption of platelets and clotting factors (causing hemorrhage). It is always secondary to an underlying condition like sepsis, trauma, or malignancy.
Overt DIC (ISTH score ≥5) represents fully decompensated coagulopathy with clinical bleeding and/or thrombosis and clear laboratory abnormalities. Non-overt DIC (score 3–4) represents a compensated or early stage where the body is still partially maintaining hemostasis. Non-overt DIC requires close monitoring as it commonly progresses to overt DIC.
The cornerstone of DIC treatment is addressing the underlying cause. Supportive care depends on the phenotype: hemorrhagic DIC → platelet transfusion (goal >50k), FFP (15–20 mL/kg), and cryoprecipitate (if fibrinogen <100). Thrombotic DIC → consider low-dose heparin. Universal measures include antithrombin replacement if AT <50% and avoiding intramuscular injections.
Common causes include: sepsis (most common, especially gram-negative), major trauma/burns, acute promyelocytic leukemia (APL), pancreatic/ovarian cancer, obstetric emergencies (placental abruption, amniotic fluid embolism, HELLP syndrome), transfusion reactions, snake envenomation, and vascular malformations. Use this as a practical reminder before finalizing the result.
Yes — many patients have a mixed phenotype with both microvascular thrombosis (causing organ failure) and hemorrhage (from consumption of clotting factors). The relative predominance depends on the underlying cause, disease stage, and the rate of coagulation activation. Treatment must balance replacement therapy against anticoagulation based on the predominant phenotype.
DIC mortality varies widely by underlying cause: sepsis-associated DIC has 40–80% mortality, trauma-associated DIC 20–50%, and obstetric DIC 5–20% (generally better prognosis because delivery addresses the cause). Higher ISTH DIC scores correlate with higher mortality. Early recognition and aggressive treatment of the underlying cause are the most important prognostic factors.