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Morphology of Disseminated Intravascular Coagulation (DIC)

Q: What stages (phases) are distinguished in the classic pathogenesis of DIC?

Classic DIC pathogenesis comprises four sequential stages: Stage I — Hypercoagulation and thrombosis (intravascular clotting of proteins, platelet adhesion and aggregation).Stage II — Progressive consumption coagulopathy (depletion of procoagulants and platelets, transition to hypocoagulation).Stage III — Profound hypocoagulation and activation of fibrinolysis (pathological fibrinolysis, lysis of microthrombi).Stage IV — Restoration of the blood coagulation system (resolution of the polyuric period).

For medical students2 min readUpdated 2026-10-10

Disseminated intravascular coagulation (DIC) is a severe pathological process characterized by the formation of multiple microthrombi in the microvasculature. This leads to blood stasis, depletion of clotting factors, and combined necrotic and hemorrhagic tissue injuries, ultimately resulting in multiorgan dysfunction syndrome (MODS).

Acute formDevelops rapidly—from a few hours to 24 hours

SubstrateMultiple fibrin microthrombi in capillaries and venules

Lung-specificFibrin hyaline membranes within the alveolar spaces

Kidney damageSymmetrical cortical necrosis and tubulorrhexis

Classification and Clinical Courses

Based on the extent of the process, DIC is classified into generalized and localized forms. Depending on the duration, there are three main clinical forms:

Acute form (from a few hours to a day). It has the most severe clinical course, typically occurring against the background of shock of various etiologies. It predictably leads to generalized tissue damage with massive necrosis, hemorrhages, and the development of multiorgan failure.
Subacute form (from a few days to a week). Occurs in moderate intoxication, sepsis, burn disease, trauma, intravascular hemolysis, as well as late preeclampsia, leukemias, malignant tumors, immune complex disorders, and transplant rejection. It is characterized by patchy or localized damage. In the terminal phase or during exacerbation, it can transform into the acute form.
Chronic form (weeks and months). Accompanies malignancies, chronic leukemias, rheumatic and autoimmune diseases, prolonged intoxications, and sometimes chronic heart failure. It manifests as persistent, minimal, migrating changes (rarely generalized) and slowly progressive organ insufficiency.

A special variant is the Kasabach-Merritt phenomenon (synonyms: giant hemangioma with thrombocytopenia, hemangioma-thrombocytopenia syndrome, multiple fibrinopoietic angioectasia). It occurs in risk groups—neonates and young children. The cause is a large (greater than 5–6 cm) capillary or cavernous hemangioma. Blood clotting within the tumor triggers consumption coagulopathy, thrombocytopenia, and pronounced hemorrhagic diathesis.

General Morphological Findings

The primary target in DIC is the microvasculature. The main morphological substrate consists of multiple microthrombi. Most commonly, these are composed of fibrin; hyaline, white, or red thrombi are significantly less frequent.

Vascular changes present with pronounced blood stasis in capillaries and venules. Three types of pathological processes typically develop in the surrounding tissue: multiple hemorrhages, cellular dystrophy, and foci of necrosis.

Changes in the Lungs and Kidneys

These organs are among the first to suffer due to their specific blood supply and tissue composition.

Lungs: The organ is at high risk due to rich vascularization and an abundance of tissue thromboplastin. Microscopy reveals serous-hemorrhagic edema, erythrocyte sludging and agglutination, along with fibrin and hyaline thrombi. Multiple hemorrhages and small hemorrhagic infarcts develop, within which siderophages are identified. A specific sign is the formation of hyaline membranes, composed of fibrin that penetrates into the alveolar lumens.
Kidneys: Marked dystrophy of the proximal and distal convoluted tubular epithelium is observed. In severe cases, tubulorrhexis (epithelial cell necrosis) develops, alongside focal or total symmetrical cortical necrosis. The clinical equivalent of these changes is necrotizing nephrosis with acute kidney injury.

Damage to Other Internal Organs

Multiple microthrombi and hemostatic disorders leave their mark on virtually all body systems:

Liver: Dystrophy and necrosis of hepatocytes (up to centrilobular necrosis). Fibrin thrombi are found in the central veins, and free fibrin strands and cords are seen in the sinusoids.
Adrenal glands: Characterized by lipid depletion (dystrophy), necrosis of the cortex and medulla, and microthrombosis. In severe infections (e.g., meningococcemia), extensive hemorrhages occur—a condition known as Waterhouse-Friderichsen syndrome.
Pancreas: Edema, hemorrhages, and microthrombi can progress to severe pancreatic necrosis.
Spleen: Hemorrhages beneath the capsule and into the parenchyma. Hyaline and fibrin thrombi are visible in small arteries and veins, with fibrin strands in the sinusoids.
Gastrointestinal tract and skin: Small hemorrhages, erosions, and acute ulcers appear on the GI mucosa. Petechial rashes and small foci of necrosis caused by capillary thrombosis are seen on the skin.
Brain and myocardium: Edema, cellular dystrophy, microthrombi, petechial hemorrhages, and micronecroses are documented.

Mnemonic

To remember the classic triad of tissue changes in DIC, use the mnemonic HDN: Hemorrhages, Dystrophy, Necrosis. These exact processes develop in organs following microthrombosis.

Frequently asked questions

What stages (phases) are distinguished in the classic pathogenesis of DIC?

Classic DIC pathogenesis comprises four sequential stages:

Stage I — Hypercoagulation and thrombosis (intravascular clotting of proteins, platelet adhesion and aggregation).
Stage II — Progressive consumption coagulopathy (depletion of procoagulants and platelets, transition to hypocoagulation).
Stage III — Profound hypocoagulation and activation of fibrinolysis (pathological fibrinolysis, lysis of microthrombi).
Stage IV — Restoration of the blood coagulation system (resolution of the polyuric period).

Which laboratory markers are used to confirm consumption coagulopathy in DIC?

A complex of laboratory markers reflecting the depletion of clotting factors is used to confirm consumption coagulopathy in DIC:

Platelets — critical thrombocytopenia.
Fibrinogen — significant hypofibrinogenemia with concentrations dropping to 1–2 g/L.
Antithrombin III — critical drop in blood levels.
FDPs and D-dimer — substantial elevation of fibrin degradation products and D-dimer.
Coagulation panel — prolonged thrombin time (up to 25–50 s) and clotting time, decreased prothrombin index (to 30–60%), and altered INR and aPTT.

What pathogenetic mechanisms, besides fibrin leakage, participate in the formation of hyaline membranes in the lungs?

In addition to fibrin, hyaline membranes contain tyrosine-α1-antitrypsin and the C3 complement component. Immaturity and deficiency of the surfactant system also contribute to hyaline membrane development; during meconium aspiration, surfactant inhibition leads to atelectasis and is frequently accompanied by hyaline membrane formation.

Which thrombi predominate in the microvasculature during DIC?

In the vast majority of cases, fibrin microthrombi are formed. Hyaline, white, and red thrombi occur significantly less frequently.

What is Waterhouse-Friderichsen syndrome?

It is a pathological condition characterized by massive bilateral adrenal hemorrhage and subsequent necrosis, typically associated with severe infectious pathologies, particularly meningococcemia.

What specific sign of DIC can be detected in the lungs?

A specific microscopic marker is the presence of hyaline membranes. They form from fibrin strands that have leaked from blood vessels into the lumens of the pulmonary alveoli.

Who is at risk for developing the Kasabach-Merritt phenomenon?

This specific variant of DIC develops predominantly in neonates and young children in association with large hemangiomas. It is extremely rare in adults.

Go deeper

Pathogenesis of consumption coagulopathy in the Kasabach-Merritt phenomenon
Mechanisms of hyaline membrane formation in pulmonary alveoli
Morphogenesis of symmetrical renal cortical necrosis
Differences between local and generalized forms of DIC
Role of tissue thromboplastin in the development of pulmonary complications