Etiology: what triggers the process?
The syndrome is based on the inappropriate activation of the coagulation cascade. The trigger occurs via two main pathways:
- Extrinsic pathway starts with massive tissue damage. A huge amount of tissue thromboplastin is released into the bloodstream. This is characteristic of severe obstetric pathologies (placental abruption, amniotic fluid embolism), extensive trauma, burns, crush syndrome, and destructive inflammation (pancreatic necrosis, peritonitis).
- Intrinsic pathway is activated by endothelial cell alteration. It is observed in severe forms of shock, sepsis, systemic connective tissue diseases, and progressive atherosclerosis.
Additional powerful triggers are intravascular hemolysis (incompatible blood transfusion, action of hemolytic poisons) and oncological processes (solid tumors, hemoblastosis).
Stages of pathogenesis
The process develops rapidly, often has an "explosive" character, and goes through three consecutive phases:
- Stage of hypercoagulation and thrombosis. Lasts a relatively short time. Fibrin is massively formed inside the vessels, platelets stick together, forming loose and true microthrombi. The result is the blockade of microcirculation. Tissue ischemia leads to hypoxia and metabolic acidosis. This activates proteolysis, which, via positive feedback, once again accelerates coagulation. Clinically, skin pallor and tachypnea are noted; laboratory findings show hyperprothrombinemia and shortened clotting time.
- Stage of consumption coagulopathy. Due to total microthrombosis, the body critically expends its reserves of procoagulants and platelets. Hypofibrinogenemia and escalating thrombocytopenia develop.
- Stage of hypocoagulation and fibrinolysis. In response to excess fibrin, a powerful compensatory fibrinolysis is launched. The level of antithrombin III drops, and fibrin degradation products (FDPs) accumulate in the blood, which themselves have an anticoagulant effect. A severe hemorrhagic syndrome occurs: profuse bleeding from damaged vessels and spontaneous hemorrhages into intact tissues.
Complications and causes of mortality
The main threat in DIC syndrome is the development of multiple organ dysfunction syndrome against the background of ischemia and subsequent hemorrhages. The main causes of patient death:
- Acute renal failure (ARF).
- Respiratory failure (RF).
- Hemorrhages into vital organs (brain, adrenal glands).
- Hemorrhagic shock and coma due to acute blood loss.
Principles of treatment
Since DIC syndrome is secondary, absolute priority is given to etiotropic therapy: it is necessary to eliminate the cause (prescribe antibiotics for sepsis, resolve the obstetric situation, stop hemolysis).
Pathogenetic treatment aims to correct the hemostasis system and depends on the phase:
- In the hypercoagulation stage (strictly in the absence of active bleeding), anticoagulants are used.
- In the hemorrhagic phase with pronounced thrombocytopenia, platelet concentrate is transfused.
To maintain vital functions:
- Restoration of BCC with isotonic sodium chloride solution (avoiding cardiac overload to prevent pulmonary edema).
- Correction of gas composition and acid-base balance (oxygen inhalation, sodium bicarbonate administration for acidosis).
- Kidney support (sympathomimetics for hypotension, hemodialysis if acute kidney injury develops).
- Detoxification (plasmapheresis to remove FDPs, bacterial toxins, and immune complexes).
Briefly: answers to topical questions
What obstetric pathologies trigger the extrinsic pathway of DIC syndrome?
The extrinsic pathway of DIC syndrome in obstetric pathology is associated with massive tissue damage and the release of factors that stimulate the hemostasis system. The sources indicate the following obstetric pathologies:
- Premature placental abruption.
- Placenta previa and placental abruption.
- Amniotic fluid embolism.
- Atonic uterine bleeding.
- Antenatal fetal death.
- Destructive obstetric operations.
What are the stages in the pathogenesis of DIC syndrome?
The pathogenesis of DIC syndrome distinguishes several sequential stages reflecting the dynamics of disorders in the blood coagulation system:
- Stage I — Hypercoagulation and thrombosis — characterized by intravascular coagulation of proteins, platelet adhesion and aggregation, leading to the formation of microthrombi.
- Stage II — Escalating consumption coagulopathy — significant consumption of procoagulants and platelets occurs, leading to their depletion.
- Stage III — Profound hypocoagulation and activation of fibrinolysis — a decompensated phase with the development of pathological fibrinolysis and hemorrhagic syndrome.
Which laboratory markers indicate the hemorrhagic stage of DIC syndrome?
The development of the hemorrhagic stage (hypocoagulation stage) of DIC syndrome is indicated by markers of clotting factor depletion and fibrinolysis activation. The main ones are:
- Hypofibrinogenemia — a significant decrease in blood fibrinogen levels.
- Thrombocytopenia — a critical reduction in platelet count due to their excessive consumption.
- Antithrombin III deficiency — a critical drop in the level of natural anticoagulants.
- Elevated FDP levels — a substantial increase in fibrin and fibrinogen degradation products.
What drugs are used for the pathogenetic treatment of the hypercoagulation stage?
For the pathogenetic treatment of the hypercoagulation stage of DIC syndrome in the absence of active bleeding, anticoagulants are used.
The sources indicate for stage I:
- Low molecular weight heparins: enoxaparin sodium, nadroparin calcium.
- Heparin sodium — as part of agents for normalizing hemostasis in DIC syndrome.
What is transfused to patients in the hemorrhagic phase of DIC syndrome?
In the hemorrhagic phase of DIC syndrome, patients are transfused with blood components to restore coagulation potential and normalize hemostasis. The main transfusion media:
- Platelet concentrate — administered in hemorrhagic syndrome combined with critical thrombocytopenia.
- Fresh frozen plasma (FFP) — used intravenously as a bolus to replenish preserved plasma clotting factors.
- Native plasma — also used to normalize hemostasis and combat coagulopathy.
Remember the essence of the stages through the acronym PIC: Prolonged/increased clotting (hypercoagulation) → Issues/depletion of factors (consumption coagulopathy) → Clotting failure/bleeding (hypocoagulation and fibrinolysis).
Class and exam questions
Why do bleedings occur in DIC syndrome if blood initially clots actively?
Due to the mechanism of consumption coagulopathy. In the first phase, the body spends almost all platelets and plasma factors on forming microthrombi. When reserves are depleted, and clot destruction (fibrinolysis) is triggered in response, the blood completely loses its ability to clot.
Which laboratory markers indicate the hemorrhagic stage?
A sharp decrease in fibrinogen levels, a critical drop in antithrombin III, pronounced thrombocytopenia, and a significant increase in fibrin degradation products (FDPs).
Is it possible to cure DIC syndrome solely by transfusion of blood components?
No, since this is a complication of the underlying disease. Without etiotropic treatment (eliminating the root cause, e.g., sepsis, shock, or obstetric pathology), it is impossible to stop the pathological cascade.
What else to study on this topic
- Molecular mechanisms of activation of the extrinsic and intrinsic coagulation pathways.
- The role of fibrin degradation products (FDP) in maintaining hypocoagulation.
- Features of the course of DIC syndrome in obstetric pathology.
- Indications and contraindications for the use of anticoagulants at various stages.
- Methods of extracorporeal detoxification: plasmapheresis and hemodialysis.
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