Disseminated intravascular coagulation (DIC) is a life-threatening condition characterised by systemic activation of the coagulation cascade, leading to microvascular thrombosis, consumption of clotting factors, and secondary bleeding. It is an essential topic for the UKMLA due to its association with critical illnesses.

Aetiology:

1. Infections:
   • Sepsis (especially Gram-negative bacteria).
2. Malignancy:
   • Acute promyelocytic leukaemia (APL).
   • Solid tumours (e.g., adenocarcinomas).
3. Obstetric Complications:
   • Placental abruption, amniotic fluid embolism, eclampsia.
4. Trauma:
   • Severe trauma, burns, fat embolism.
5. Other Causes:
   • Snake bites, heat stroke, severe liver disease, incompatible blood transfusions.

Pathophysiology:

1. Coagulation Cascade Activation:
   • Triggered by tissue factor or endotoxins, leading to widespread fibrin deposition and microthrombi formation.
2. Consumption of Clotting Factors:
   • Depletion of platelets, fibrinogen, and coagulation factors.
3. Secondary Fibrinolysis:
   • Excessive plasmin activation causes breakdown of clots, leading to bleeding.

Clinical Features:

1. Bleeding:
   • Oozing from venepuncture sites.
   • Mucosal bleeding (e.g., epistaxis, gum bleeding).
   • Gastrointestinal or intracranial haemorrhage in severe cases.
2. Thrombosis:
   • Microvascular thrombosis causing end-organ damage.
   • Signs include digital ischaemia, renal dysfunction, and respiratory distress.
3. Shock and Multiorgan Failure:
   • Associated with severe DIC, particularly in sepsis or trauma.

Investigations:

1. Coagulation Tests:
   • Prothrombin Time (PT): Prolonged.
   • Activated Partial Thromboplastin Time (aPTT): Prolonged.
   • Fibrinogen: Low (consumed).
   • D-Dimer: Elevated (reflects fibrinolysis and clot formation).
2. Full Blood Count (FBC):
   • Thrombocytopenia (low platelets).
3. Peripheral Blood Film:
   • Schistocytes (fragmented red cells) due to microangiopathy.
4. Organ Function Tests:
   • Raised creatinine (renal dysfunction).
   • Elevated liver enzymes (hepatic involvement).

Management:

General Principles:

1. Treat the Underlying Cause:
   • Antibiotics for sepsis.
   • Obstetric management for pregnancy-related DIC.
   • Chemotherapy for malignancy-associated DIC.
2. Supportive Care:
   • IV fluids and haemodynamic support.

Specific Interventions:

1. Replace Depleted Factors:
   • Fresh frozen plasma (FFP): For clotting factor replacement.
   • Cryoprecipitate: To replenish fibrinogen.
   • Platelet transfusion: If platelet count < 50 x 10⁹/L and bleeding risk is high.
2. Control Thrombosis:
   • Low-dose heparin in cases dominated by thrombosis (e.g., malignancy-associated DIC).
3. Monitor and Reassess:
   • Regular monitoring of coagulation parameters and organ function.

Complications:

1. Bleeding:
   • Intracranial haemorrhage, gastrointestinal bleeding.
2. Thrombosis:
   • Microvascular occlusion causing multiorgan failure.
3. Shock and Death:
   • High mortality rate without prompt treatment.

Prognosis:

• Prognosis depends on early recognition, severity of the underlying condition, and timely management.
• Mortality remains high in severe cases.

Key Exam Points for UKMLA:

1. Common Causes:
   • Sepsis, malignancy, obstetric complications, trauma.
2. Laboratory Findings:
   • Prolonged PT/aPTT, low fibrinogen, thrombocytopenia, elevated D-dimer.
3. Management Priorities:
   • Treat the underlying cause, replace clotting factors, and manage bleeding or thrombosis.
4. Complications:
   • Focus on multiorgan failure and critical bleeding.