Disseminated Intravascular Coagulation (DIC)

Disseminated intravascular coagulation (DIC), also known as disseminated intravascular coagulopathy, consumptive coagulopathy, or defibrination syndrome, is a severe medical condition where blood clots form throughout the body, blocking small blood vessels. This condition is primarily managed within the specialty of haematology.

Signs and Symptoms

DIC can manifest with a variety of symptoms, which often depend on the underlying cause. Common symptoms include chest pain, shortness of breath, leg pain, problems speaking, and difficulties moving parts of the body. As clotting factors and platelets are consumed, bleeding becomes a significant issue, presenting as blood in the urine, blood in the stool, or bleeding into the skin. Complications can include organ failure, which significantly worsens the prognosis.

Causes

DIC can be triggered by several conditions:

• Infections: particularly sepsis from Gram-negative or Gram-positive bacteria.
• Cancer: especially acute promyelocytic leukaemia and other solid tumours.
• Pregnancy complications: such as abruptio placentae, pre-eclampsia, amniotic fluid embolism, and postpartum haemorrhage.
• Massive tissue injury: from trauma, severe burns, hyperthermia, and surgery.
• Others: Snake bites, ABO incompatibility transfusion reactions, and hemangioma (Kasabach–Merritt syndrome).

Pathophysiology

Under normal conditions, the body maintains a balance between coagulation and fibrinolysis. In DIC, this balance is disrupted, leading to widespread clotting and subsequent bleeding. A key mediator of DIC is tissue factor (TF), which is released into the circulation following vascular damage and exposure to cytokines, tumour necrosis factor, and endotoxins.

TF binds with activated factor VIIa, initiating the extrinsic tenase complex, which further activates factors IX and X, ultimately leading to thrombin and fibrin formation. Excess thrombin converts fibrinogen to fibrin, forming multiple fibrin clots and consuming platelets and coagulation factors, leading to thrombosis and subsequent bleeding.

Diagnosis

Diagnosing DIC involves a combination of clinical history and laboratory findings. Laboratory markers indicative of DIC include:

• Prolongation of prothrombin time (PT) and activated partial thromboplastin time (aPTT).
• Elevated fibrin degradation products, including D-dimer.
• Low platelet count and fibrinogen levels.
• Presence of schistocytes (fragmented red blood cells) on a peripheral blood smear.

A scoring system proposed by the International Society of Thrombosis and Haemostasis helps in diagnosing DIC, with a score of 5 or higher indicating compatibility with DIC.

Treatment

The primary focus of DIC treatment is addressing the underlying condition. Supportive treatments may include transfusions of platelets or fresh frozen plasma in cases of significant bleeding, with target goals depending on the clinical situation. Cryoprecipitate can be used for low fibrinogen levels. Anticoagulants like heparin are rarely used due to the high risk of bleeding.

Prognosis

The prognosis of DIC varies based on the underlying cause and the extent of thrombosis. Generally, the condition carries a high mortality rate, with 20% to 50% of patients dying from the condition. The prognosis is worse in cases of DIC associated with sepsis compared to those related to trauma.

Epidemiology

DIC is observed in approximately 1% of hospital admissions, with higher rates in those with bacterial sepsis (83%), severe trauma (31%), and cancer (6.8%).

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Self-assessment MCQs (single best answer)

What is the primary specialty involved in managing Disseminated Intravascular Coagulation (DIC)?

Which of the following conditions is NOT a trigger for DIC?

What is a common symptom that patients with DIC might experience?

Which laboratory finding is indicative of DIC?

What is the role of tissue factor (TF) in the pathophysiology of DIC?

Which of the following treatments is rarely used in DIC due to high bleeding risk?

What is a significant complication associated with DIC?

What percentage of patients with bacterial sepsis develop DIC?

Which of the following is NOT a common diagnostic marker for DIC?

What is the mortality rate range for patients with DIC?