Disseminated intravascular coagulation

• Disseminated intravascular coagulation (DIC) is not one disease; it is a syndrome that any serious illness can switch on. The body's haemostatic system is activated throughout the circulation, forming thousands of tiny fibrin clots in small vessels.
• Those clots consume platelets and clotting factors, and at the same time the body's brakes fail because the natural anticoagulant pathways are overwhelmed. The result is the strange combination that defines DIC: microvascular thrombosis (organ damage) and, later, haemorrhage.
• It always has an underlying cause. The common triggers are severe infection (especially sepsis), major trauma, obstetric catastrophes, malignancy, snake envenomation, incompatible transfusion and acute pancreatitis.
• There is no single test for DIC. A first physician looks for the pattern of falling platelets, a lengthening prothrombin time (PT) and activated partial thromboplastin time (aPTT), a low fibrinogen and a markedly raised D-dimer, and scores it with the International Society on Thrombosis and Haemostasis (ISTH) algorithm.
• The single most important treatment is to treat the cause. Blood products are given only for bleeding or for high bleeding risk; heparin is reserved for patients whose picture is dominated by thrombosis.

By the end of this page you should be able to:

1. Define DIC and explain why the same process can produce both clots and bleeding.
2. List the conditions that most often trigger DIC and explain the mechanism that links each to coagulation activation.
3. Describe the laboratory abnormalities of DIC in terms of consumption, and score overt DIC with the ISTH algorithm.
4. Distinguish DIC from thrombotic thrombocytopenic purpura (TTP), haemolytic uraemic syndrome (HUS) and the coagulopathy of liver disease.
5. Outline rational blood product and anticoagulant support, including when heparin is, and is not, appropriate.
6. Recognise the low-resource strategies that keep patients safe when tests and components are scarce.

The ISTH's 2001 definition still underpins most of what follows: intravascular activation of coagulation arising from different causes, originating from and causing damage to the microvasculature, which, if severe enough, produces organ dysfunction. [1] In 2025 the ISTH subcommittee broadened the wording to emphasise that DIC is an acquired, life-threatening intravascular disorder characterised by systemic coagulation activation, dysregulated fibrinolysis and endothelial injury, resulting in microthrombosis, and that it progresses from a potentially asymptomatic early phase to an advanced phase with haemorrhage and/or organ dysfunction. [1] Both definitions share one message that the patient must understand: DIC is always secondary. It never appears on its own.

Two clinical faces are useful to keep in mind. "Consumption" DIC presents with bleeding from every puncture site, melaena, haematuria, and a platelet count that drops hour by hour. "Thrombotic" DIC presents with cool, ischaemic fingers and toes, purpura fulminans, renal failure or stroke, with comparatively little bleeding. Many patients have elements of both.

Incidence is quoted at roughly 20 to 30 cases per 100 000 people across settings, with a slow decline over recent decades. [1] Reported hospital prevalence varies widely because studies use different diagnostic criteria and different populations: a Japanese multicentre series using the Japanese Ministry of Health and Welfare criteria reported about 1.0 to 1.9% of all inpatients, and intensive care series report up to roughly a quarter of critically ill patients meeting ISTH DIC criteria. [1] Mortality remains high but is falling: two large cohort studies describe a decline from about 41.8% in 2010 to 34.7% in 2021 over ten years. [1] The commonest underlying triggers are, in order, severe infection or sepsis, then cardiac arrest, obstetric complications and trauma in Western series, and solid cancers, haematological malignancies, trauma and obstetric complications in Japanese series. [1] ^[1]

Poor outcome is predicted less by the label "DIC" than by how far the system has decompensated: a score that worsens over 24 to 48 hours is more dangerous than a high score that falls with treatment.

Every cause converges on the same final set of steps: tissue factor exposure or expression, thrombin generation that outruns the body's regulators, endothelial injury and impaired fibrinolysis. The ISTH lists conditions with a high level of evidence, split into those likely certain (microthrombi seen pathologically) and those probable (DIC confirmed by diagnostic criteria). [1]

Table 1: Clinical conditions that can precipitate DIC, grouped by ISTH category (certain or probable evidence) [1]

The items the question most often tests are these:

• Sepsis. The commonest trigger. Monocyte and endothelial tissue factor expression is driven by bacterial products and cytokines. Sepsis-induced coagulopathy (SIC) precedes overt DIC in every case and is worth detecting early. [1] [4]
• Major trauma. Severe injury releases tissue factor from damaged tissue and from brain when the head is injured. Early trauma DIC is fibrinolytic; later trauma DIC is thrombotic and is driven by inflammation. [1]
• Obstetric catastrophes. Placental abruption, amniotic fluid embolism, prolonged fetal death, HELLP syndrome and eclampsia all introduce large amounts of tissue factor or thromboplastin into the maternal circulation. [1]
• Malignancy. Solid tumours (especially pancreatic, gastric, prostatic and mucin-secreting tumours) express tissue factor and a direct activator of coagulation factor X on their cells. Haematological malignancy, particularly acute promyelocytic leukaemia (APL), produces a fibrinolytic DIC. [1]
• Snake bite. Envenomation can activate prothrombin, degrade fibrinogen or impair the clotting factors directly. [1]
• Incompatible transfusion. Massive intravascular haemolysis activates the complement and coagulation cascades. [1]
• Acute pancreatitis. Release of activated enzymes and cytokines from inflamed peripancreatic tissue. [1]

Risk factors are the underlying serious illness itself; there is no independent "DIC gene." Older age, severe organ dysfunction and shock worsen outcome because the microvascular thrombosis becomes harder to reverse.

Everything the patient experiences follows from a small set of mechanisms. It helps to walk through them in order.

1. Tissue factor gains the upper hand. In health, coagulation is kept at the site of injury by the endothelium and by the natural anticoagulant systems (protein C and protein S, antithrombin, tissue factor pathway inhibitor). In DIC the trigger exposes phospholipid surfaces and tissue factor, which binds activated factor VII, and thrombin generation becomes systemic rather than local. [1] Inflammation and coagulation are coupled: cytokines induce tissue factor, and thrombin itself feeds back to amplify inflammation. [1]

2. Thrombin generation runs ahead of the brakes. Antithrombin is consumed; its levels fall. The endothelium converts from an anticoagulant surface to a procoagulant one. Platelets are activated and consumed. [1]

3. Fibrin deposits where the vessels are narrow. Fibrin forms in the microcirculation of kidneys, lungs, liver, brain and limbs. This is the thrombotic half of DIC and it is the lethal half, even though bleeding is what the eye sees first. [1]

4. Consumption depletes the stores. As clotting proceeds, platelets and the coagulation factors (especially fibrinogen, prothrombin, factor V and factor VIII) are used up. Thrombocytopenia and prolongation of the PT and aPTT appear. [1]

5. The fibrinolytic system is usually suppressed. Plasminogen activator inhibitor 1 (PAI-1) rises early, so the tiny clots are not broken down. This "fibrinolysis-resistant" picture is typical of sepsis-related DIC. [1]

6. In a minority, fibrinolysis is excessive. In early trauma, in placental abruption and postpartum haemorrhage, and in acute promyelocytic leukaemia, tissue-type plasminogen activator is released in large amounts and the picture becomes dominated by bleeding from hyperfibrinolysis. [1] This matters because these patients, and only these, may benefit from antifibrinolytic drugs such as tranexamic acid. [1] [2]

Histones and neutrophil extracellular traps (NETs) are increasingly recognised as accelerants: histones released from damaged cells promote further thrombin generation and contribute to organ injury. [1] The practical consequence is that DIC is not merely "the laboratory numbers": the tiny clots and the inflammatory cascade together injure organs, and treatment must both fix the numbers and support the organs.

The ISTH divides DIC by whether the endothelial regulation can be restored. In controlled DIC the anticoagulant networks (protein C and thrombomodulin, antithrombin, tissue factor pathway inhibitor) are transiently overridden but recover once the cause is removed; placental abruption in its early phase and early trauma are examples, and prompt haemostasis and shock prevention allow re-equilibration. [1] In uncontrolled DIC these systems are overwhelmed and the endothelium itself switches to a procoagulant and antifibrinolytic state; sepsis and late trauma are examples, and this is where active treatment of the coagulopathy is required. [1]

Apart from the timing (non-overt versus overt, below), DIC is currently classified into three fibrinolytic phenotypes: [1]

• Fibrinolysis-suppressed (prothrombotic), the most common, typical of sepsis. Clots dominate; bleeding is late.
• Fibrinolytic (hyperfibrinolytic), seen in early trauma, postpartum critical bleeding, APL and isolated severe head injury, where t-PA release outstrips PAI-1. Bleeding dominates.
• Balanced, typical of solid tumours, where thrombotic and fibrinolytic forces are more evenly matched and the picture is subtler.

There is no symptom that is, by itself, specific. The history is of the underlying illness plus one or more of:

• Bleeding. Oozing from venepuncture sites and wounds; mucosal bleeding, gingival bleeding, epistaxis; haematuria; melaena or rectal bleeding; haemoptysis; menorrhagia; petechiae and purpura.
• Thrombosis. Cold, cyanotic or gangrenous digits; purpura fulminans; renal failure; stroke; digital or visceral ischaemia; painful, swollen limbs.
• Organ dysfunction. Sepsis-like decline, acute kidney injury, respiratory failure, encephalopathy, hepatic impairment, shock.
• Constitutional symptoms from the trigger (fever, abdominal pain in pancreatitis, obstetric bleeding, a known cancer).

On examination the patient is usually critically ill. Look for bleeding from every puncture site and from surgical wounds, skin and digital ischaemia, and signs of the underlying cause. Laboratory evidence (below) should be sought in any patient with a serious illness who develops an unexpected bleeding or thrombotic tendency, or in whom the platelet count falls while the PT lengthens.

The three conditions most often confused with DIC, because they too cause thrombocytopenia with microangiopathic change, are thrombotic thrombocytopenic purpura (TTP), haemolytic uraemic syndrome (HUS), and the coagulopathy of chronic liver disease. They differ in mechanism and the laboratory pattern separates them if each component is read carefully. [1] [3] [4]

Table 2: DIC compared with TTP and chronic liver disease coagulopathy

A useful memory aid: DIC consumes the factory and the stock; liver disease fails at the factory but the stock may be normal; TTP is not a factory problem at all but uncontrolled platelet stickiness.

No single test diagnoses DIC, and none is specific, because any activated coagulation will produce some of these abnormalities. What matters is the combination and, above all, the trend over hours.

Table 3: typical laboratory pattern of DIC

Early DIC (non-overt) may have a normal fibrinogen and a normal platelet count with only a rising D-dimer and a lengthening PT; hence the value of serial testing and of the non-overt ISTH score.

The score is calculated only in a patient with an underlying disorder known to be associated with DIC. It combines platelet count, PT prolongation, a fibrin-related marker (D-dimer or fibrin degradation products) and fibrinogen. A score of 5 or more is compatible with overt DIC; if the score is under 5, repeat it in 1 to 2 days, because non-overt DIC may be present. [3] Prospective studies quote a sensitivity of 93% and specificity of 98%. [3] ^[3]

Table 4: ISTH overt DIC scoring algorithm (classic version) [3]

A score of 5 or more is compatible with DIC. Where INR is used instead of PT prolongation, an INR over 1.3 gives 1 point and over 1.5 gives 2 points, provided the thromboplastin reagent's International Sensitivity Index is close to 1. [3] ^[3]

The 2025 ISTH communication (an update of the overt DIC score rather than a new test) changes the fibrin-related marker points to use D-dimer cut-offs specifically: more than 3 times and more than 7 times the upper limit of normal. [4] ^[3][4]

Table 5: ISTH 2025 update of the fibrin marker points [4]

Because D-dimer assays are not standardised between manufacturers, applying a single numerical multiple of the upper limit of normal is an approximation; laboratory-specific reference ranges and clinical judgement remain essential. [4]

Non-overt DIC is a stressed but compensated system that may recover if the cause is controlled. [1] The ISTH non-overt score adds a falling trend of (platelets, PT), together with sensitive molecular markers. [1] The sepsis-induced coagulopathy (SIC) score was designed to pick up the early phase in patients with sepsis before it meets overt DIC criteria: it combines platelet count, PT-INR and the Sequential Organ Failure Assessment (SOFA) score. [1] SIC precedes overt ISTH DIC in every reported case, so a two-step approach (screen with SIC, then apply the overt DIC score to those who are positive) is recommended for patients with sepsis. [1] [4] A SIC score of 4 or more, with the total of platelet and PT points exceeding 2, indicates sepsis-induced coagulopathy. [4] ^[4]

The order of therapeutic priorities never changes:

1. Treat the underlying cause. This is the only thing that actually stops DIC. Antibiotics and source control for sepsis, surgery and damage-control resuscitation for trauma, delivery and correction of coagulopathy for obstetric causes, chemotherapy or all-trans retinoic acid for acute promyelocytic leukaemia. Supportive organ care (ventilation, renal replacement) while the cause is controlled. [1] [2] [3]
2. Support the patient haemostatically with blood components, when bleeding or at high bleeding risk. [2] [3]
3. Consider anticoagulation when thrombosis dominates. [2] [3]
4. Avoid the therapies that cause harm: routine antifibrinolytics in non-hyperfibrinolytic DIC, and unjustified prophylactic component therapy. [2] [3]

• Sepsis: early, appropriate broad-spectrum antibiotics and prompt source control (drainage of an abscess, removal of an infected line, debridement). Delaying source control while transfusing blood is the common error. [1] [3]
• Trauma: stop haemorrhage surgically, correct hypothermia, acidosis and hypocalcaemia, and resuscitate with balanced component therapy rather than crystalloid alone. Massive transfusion protocols are preferred. [1]
• Obstetric DIC: deliver the fetus and placenta, control uterine atony and bleeding, and give uterotonics. Reversal is usually rapid once the products of conception are removed. [1]
• Malignancy: treat the tumour (ATRA for APL; chemotherapy; control of the cancer where possible). DIC from cancer often resolves in hours to days if the cancer is responsive. [1] [3]
• Snake bite: antivenom and supportive care. [1]
• Incompatible transfusion: stop the transfusion immediately, support the patient, and manage renal and haemostatic complications. [1]

Because DIC consumes so much, the laboratory numbers often look worse after antibiotics or surgery, before they get better; this is expected and is not a reason to escalate transfusion. [3]

Transfusion of platelets or plasma is not driven by the laboratory alone; it is reserved for bleeding patients, patients at high risk of bleeding, patients undergoing an invasive procedure, and those with overt haemorrhage. [2] [3] The evidence base is thin: no randomised trial has shown benefit for component transfusion in DIC. [3]

• Platelets. Transfuse when bleeding (or at a high risk of bleeding, for example postoperative or before an invasive procedure) and the count is below 50 x 10^9/L. In non-bleeding patients without a high bleeding risk, prophylactic transfusion is not given. [2] [3] ^[5]
• Fresh frozen plasma. Give 15 to 30 mL per kg to bleeding patients with prolonged PT and aPTT. FFP does not "feed" the DIC; there is no evidence that it overstimulates coagulation, but it is nonetheless used only for bleeding or invasive procedures. [2] [3] [5] ^[5]
• Fibrinogen. Treat severe hypofibrinogenaemia of under 1.0 g/L that persists despite FFP with fibrinogen concentrate or cryoprecipitate. [2] [3]
• Prothrombin complex concentrate. May be substituted when bleeding coexists with fluid overload that prevents FFP, with the caveat that it contains only selected factors and will only partially correct a global deficiency. Expect to repeat and monitor. [2] [3]
• Red cells. Transfuse for anaemia and haemodynamic compromise as usual; in active bleeding, use a massive transfusion or balanced component strategy. [3]

Targets for initial control, often quoted in major haemorrhage protocols, are PT and aPTT normalised to under 1.5 times the upper limit of normal, fibrinogen over 1.5 g/L and platelets over 50 x 10^9/L, titrated to bleeding rather than to the score. [3] ^[5]

Heparin has a plausible mechanism (it slows thrombin generation) and is recommended in selected thrombotic cases, but no randomised trial has proved a patient outcome benefit in DIC. [2] [3] [4]

Use heparin when thrombosis dominates: arterial or venous thromboembolism, severe purpura fulminans with acral ischaemia, vascular skin infarction, or a clearly thrombotic laboratory and clinical picture (rising D-dimer with falling platelets and organ ischaemia but little bleeding). [2] [3]

Practical points from the guidelines: [2] [3]

• Continuous infusion of unfractionated heparin (UFH) has an advantage because of its short half-life and reversibility, which matters where bleeding risk coexists. A weight-adjusted rate of about 10 units per kg per hour may be used, without targeting an aPTT 1.5 to 2.5 times the control; monitoring the aPTT is difficult in this setting, and clinical observation for bleeding is more important than the number. [2] [3] ^[2]
• Low molecular weight heparin is commonly used in practice and is preferred for prophylaxis; for therapeutic anticoagulation in DIC with thrombosis neither UFH nor LMWH has a robust evidence base, and both need local haematology input. [1] [2] [3]
• In critically ill non-bleeding patients, prophylaxis against venous thromboembolism with prophylactic heparin or LMWH is recommended. [2] [3]
• Anticoagulant therapy in sepsis appears to help when DIC is established and disease is severe (high APACHE II or SOFA scores); it is not for all patients with sepsis. [1] [4]

Do not anticoagulate routinely: in a bleeding-dominant picture, in severe thrombocytopenia with a high bleeding risk, and where there is no thrombosis. Antithrombin concentrate is not recommended in general, because randomised evidence of benefit on a clinically relevant endpoint is lacking. [2] [3] Recombinant human activated protein C was formerly used in severe sepsis but was withdrawn from the market. [1] [2] Recombinant thrombomodulin is used in some countries, notably Japan, and is supported by the Japanese guidelines, but its evidence is also not definitive. [1]

Where bleeding and clotting coexist, the decision is often to treat the underlying cause, to give low-dose heparin or prophylactic LMWH first, and to escalate only on specialist advice.

In general, patients with DIC should not receive tranexamic acid or other lysine analogues, because the clots of suppressed-fibrinolysis DIC may be worsened. [2] [3] The exception is a patient with DIC characterised by a primary hyperfibrinolytic state who presents with severe bleeding, such as in early trauma or postpartum haemorrhage (for example tranexamic acid 1 g every 8 hours, given as part of a massive haemorrhage protocol). [1] [2] [3] Even here it should be combined with, not instead of, control of the cause. ^[2]

• Microvascular and macrovascular thrombosis: acute kidney injury, stroke, limb ischaemia, bowel infarction, myocardial infarction.
• Haemorrhage: gastrointestinal bleeding, intracranial bleeding, exsanguination from surgical or obstetric sites.
• Multiple organ dysfunction syndrome (MODS) from the combined insult.
• Thrombosis of catheters and extracorporeal circuits.
• Long-term, in survivors, organ scarring (for example chronic kidney disease after renal cortical necrosis).

Mortality is driven by the underlying disease and by how far the coagulopathy has gone at presentation, not by the diagnosis alone. [1] Failing to control the cause, or a DIC score that rises over 48 hours, are the best predictors of a poor outcome. With successful treatment of the trigger, the clotting abnormalities often normalise within 24 to 72 hours, and fresh frozen plasma and platelets usually are no longer needed soon afterwards. [3]

• Pregnancy and the puerperium. DIC is approached as an emergency with the obstetric team. Delivery of the placenta, control of haemorrhage, tranexamic acid and component replacement are all standard; women should be managed in a maternity high-dependency or intensive care setting. [1] [3]
• Children. Neonates can develop DIC from sepsis or necrotising enterocolitis. Dosing and transfusion thresholds are paediatric-specific and should follow local neonatal protocols, but the principles of treating the cause and replacing what is consumed are the same. [1]
• Cancer patients. DIC may be chronic (low-grade) and present with thrombosis (Trousseau syndrome) rather than bleeding; such patients may be anticoagulated long term and the underlying cancer treated. [1] [3]
• Patients with liver disease. See Table 2. Failure to correct a prolonged PT by vitamin K is an important clue that the problem is hepatic synthesis rather than consumption.

DIC is diagnosed as late as it is treated in many settings, because components and laboratory support are scarce. A few pragmatic rules keep patients safe.

• Treat the cause first and fastest. Antibiotics, delivery, haemorrhage control and snake antivenom save more lives than any laboratory test. [1] [3]
• A whole blood count, a peripheral blood film and a PT/aPTT/clotting screen, where available, are enough to recognise the pattern: falling platelets plus prolonged clotting times plus low fibrinogen (where measured) plus a raised D-dimer. [1] [3]
• If D-dimer is unavailable, fibrinogen is not measured and platelet counts are delayed, rely on clinical judgement: uncontrolled bleeding from multiple sites, a low platelet count (by clinical estimate or a simple cell counter), and a bedside clotting time from a fresh venous sample in a plain glass tube (often not clottable at all in severe DIC). [3]
• Components. Fresh whole blood or fresh frozen plasma, given in bleeding or before surgery, is better than none. Cryoprecipitate (often available from local blood banks) corrects fibrinogen. Where platelets are unavailable, controlling bleeding and the trigger is the priority. [3]
• Heparin. A continuous low-dose heparin infusion is cheap and the drug has a short half-life; it is the most realistic way to treat thrombotic DIC when monitoring is limited. [3]
• Escalate by telephone. A haematologist, even remotely available, can rationalise component use; phone advice is better than no advice. [3]
• Counsel families and staff. In the absence of components, the outcome depends on speed of source control, not on technology. [3]

• DIC is a syndrome triggered by another serious illness, not a disease of its own. Treating the underlying cause is the single most important step.
• It is characterised by systemic thrombin generation, microvascular thrombosis, consumption of platelets and factors, suppressed fibrinolysis, and a late haemorrhagic phase. [1]
• Common triggers include sepsis, major trauma, obstetric catastrophe, malignancy, snake bite, incompatible transfusion and acute pancreatitis. [1]
• The core laboratory pattern is a falling platelet count, prolonged PT and aPTT, a low (often very low) fibrinogen, a markedly raised D-dimer, and schistocytes on the blood film. [1] [3]
• No single test diagnoses DIC. Score it with the ISTH overt DIC algorithm (5 or more points) and repeat it serially. [3]
• For early sepsis, screen with the SIC score and apply the overt score to those who are positive. [1] [4]
• Blood products are for bleeding patients or those at high bleeding risk, not for abnormal numbers alone; platelets below 50 x 10^9/L, FFP 15 to 30 mL/kg, fibrinogen concentrate or cryoprecipitate for severe hypofibrinogen aemia under 1.0 g/L. [2] [3] ^[2]
• Prophylactic platelet transfusion is not given to a non-bleeding patient. [2] [3]
• Heparin is considered when thrombosis dominates: thromboembolism, purpura fulminans, acral ischaemia. Continuous UFH about 10 units/kg/hour, without chasing an aPTT. [2] [3]
• Anticoagulation in sepsis helps when DIC is established and disease is severe, not in every septic patient. [1] [4]
• Tranexamic acid is avoided unless the DIC is hyperfibrinolytic and bleeding is severe. [1] [2] [3]
• DIC and TTP/liver disease can be distinguished by whether the clotting cascade is truly consumed: low factors and inhibitors point to DIC. [3]
• Serial testing matters more than any single result. [3]
• Prophylaxis against venous thromboembolism should still be given to critically ill non-bleeding patients. [2] [3]
• With successful treatment of the trigger the coagulopathy usually resolves in 24 to 72 hours. [3]

Related reading within MedGrasp (titles are linked once those pages are published): the approach to the bleeding patient; acquired coagulopathies; sepsis recognition and management; obstetric haemorrhage; trauma assessment; haematological malignancies; and thrombotic microangiopathies. Thresholds and protocols vary by centre, so the numbers here should be checked against local haematology and transfusion guidance.