Disseminated intravascular coagulation (DIC): causes, signs and treatment

Blood clotting normally works in balance with a system that breaks clots down. Patient's clinical reference quotes the International Society on Thrombosis and Haemostasis definition: DIC is a syndrome in which blood coagulation is activated throughout the body, creating fibrin in the blood vessels, leading to thrombosis of small and medium vessels and eventually organ dysfunction.

As the clotting factors and platelets are used up, bleeding can follow. This combination of clotting and bleeding is why DIC is so dangerous and why it can look different in different people.

DIC is not a disease in its own right but a complication of another condition. Its presence usually signals that the underlying illness is severe, and it increases mortality from that illness.

Patient's reference lists numerous conditions that may be complicated by DIC. Infection, especially sepsis, is the most common cause, and the rash of meningococcal sepsis is described as classical.

• Severe infection and sepsis, including infections such as E. coli O157, typhoid fever and some parasites.

• Malignancy, especially leukaemias.

• Major trauma including crush syndrome and, occasionally, burns.

• Pregnancy complications including placental abruption, amniotic fluid embolism, fulminating pre-eclampsia and HELLP syndrome.

• Incompatible blood transfusion and transplant rejection.

• Severe liver disease, pancreatitis, heat stroke and dissecting aortic aneurysm.

• Complications after surgery, some snake bites, recreational drugs and some connective tissue disorders including antiphospholipid syndrome.

Patient says the immediately obvious features are usually those of the underlying condition, especially in acute cases. In addition there may be large bruises or spontaneous bleeding at venepuncture sites, on the soft palate, legs and sites of trauma.

In the acute situation, bleeding from at least three unrelated sites is described as typical, such as the ears, nose and throat, gastrointestinal tract, respiratory tract and drip or needle sites, alongside confusion, fever and skin signs such as petechiae, purpura and skin necrosis.

In subacute or chronic DIC the features may instead be thrombotic, with signs of venous thrombosis. Because DIC occurs in people who are already seriously ill, it is usually detected by blood tests rather than recognised by the person.

DIC is a hospital diagnosis and is not something to manage at home. Anyone who is seriously unwell, with signs of severe infection or sepsis, heavy bleeding or bleeding from several places, new widespread bruising or a spreading purple rash, confusion or collapse, needs emergency care.

Call 999 or go to A&E in these circumstances. For pregnancy, heavy bleeding or severe illness in late pregnancy or after birth also needs 999. If you are unsure, NHS 111 can advise.

Patient says diagnosis should include both clinical and laboratory information, with tests repeated to monitor change. Typical findings include a low and falling platelet count, raised fibrin degradation products including D-dimer, prolonged prothrombin time and activated partial thromboplastin time, and a low fibrinogen level, though fibrinogen can be normal in over half of cases.

The reference describes a scoring system from the International Society on Thrombosis and Haemostasis that gives an objective measurement and is only used when there is an underlying disorder known to be associated with DIC. Gloucestershire Hospitals NHS Foundation Trust's pathology guidance says a DIC screen should always be considered when there is an unexpected fall in platelet count, particularly with systemic infection.

It cautions that a prolonged clotting screen, reduced fibrinogen and raised D-dimer are indicative of DIC but may also be found after surgery and in advanced liver disease, and that raised D-dimer is also found in DVT. Interpretation is therefore made by haematology specialists in context.

Patient says the cornerstone of management is supportive, with blood components and treatment of the underlying condition: infection needs antibiotics, and obstetric complications may need intervention. DIC in many cases resolves spontaneously once the underlying disorder is treated.

Patient says DIC can rapidly lead to organ failure and is often fatal, especially when not identified and treated early. Mortality is hard to establish because of the severity and variety of underlying conditions, but it is estimated that mortality rates for sepsis and severe trauma double if DIC develops.

Organs can be damaged by infarction, and limb ischaemia can lead to loss of digits or more. However, the reference says that with appropriate care patients with DIC can have a favourable outcome, and that prognosis depends mostly on the underlying condition, as well as the severity of DIC and other illnesses.

DIC is managed in hospital, usually in a high dependency or intensive care unit, by the team treating the underlying illness together with haematology specialists. Blood tests and transfusion services are central to that care.

This is not a condition that people choose between NHS and private routes for in a planned way. Emergency care is delivered by whichever hospital the person reaches, and follow-up for the underlying condition is arranged afterwards.

This page is built on clinician-facing UK references because no patient-facing NHS page specifically on DIC was found. The clinical detail should therefore be read as background and not as guidance for individual care.