What is DIC?
Disseminated intravascular coagulation (DIC) is a serious, sometimes life-threatening condition in which the proteins in the blood involved in blood clotting become overactive. Blood clots form in small blood vessels throughout the body. This can disrupt normal blood flow to organs such as the kidneys and liver and can lead to organ failure. Because the clotting uses up coagulation proteins and platelets, excessive bleeding can occur. This abnormal activation of blood clotting mechanisms can develop as the result of a variety of diseases and conditions.
Typically, when a person has an injury to a blood vessel and bleeding occurs, the body stops the bleeding by initiating a process called haemostasis. First, platelets adhere to the injury site and clump together, forming a loose plug. Then coagulation factors are sequentially activated (see coagulation cascade) to produce a net of fibrin threads that weave through the platelet plug and form a stable clot. The clot stays in place until the injury is healed, then other factors break the clot down (fibrinolysis) and remove it. This clotting process is tightly regulated. Feedback mechanisms accelerate the clotting process, then slow it down, and control the volume of clot produced.
Normally, the body initiates haemostasis and forms a blood clot only when needed, i.e., when there is an injury and bleeding. The body detects a pro-coagulant, a substance such as tissue factor that is released from cells when they are damaged. Based on the extent of the injury, the body responds by stimulating sufficient clotting to stop the bleeding and confining it locally, that is, only at the site of injury.
With conditions that trigger DIC, the response is exaggerated, clotting is activated throughout the body, and control mechanisms are inhibited. The result is the formation of a multitude of tiny clots that can block small blood vessels and prevent blood and oxygen from getting to tissues and organs, leading to multi-organ failure. Widespread clotting can use up platelets and coagulation factors at a rapid rate. This can overwhelm the system to the point that the body begins to bleed excessively because platelets and clotting factors have been depleted. Simultaneous clotting and bleeding can occur. DIC can develop very quickly, becoming serious or even life-threatening in a short time.
DIC may occur with conditions such as:
- Infections, especially with severe or systemic infections (and sometimes resulting sepsis), primarily bacterial but also sometimes seen with fungal, viral, or parasitic infections
- Trauma, such as due to an accident, head injury or significant burns
- Major surgery, such as cardiopulmonary bypass surgery
- Pregnancy and childbirth, for example when a woman has an abruption (bleeding under the placenta), or a foetus that has died (stillbirth) or amniotic fluid escapes to the lungs
- Cancers, such as acute promyelocytic leukemia or tumours that develop within glands (adenocarcinoma); cancer cells may release a pro-coagulant.
- Organ failure, such as liver or pancreas
- Other less common causes, such as snake bite venom, toxic drug reaction, blood transfusion reaction, organ transplant, or frostbite
Most cases of DIC that are diagnosed develop rapidly and suddenly (acute), but there are cases in which it develops gradually, occurring over a longer period of time. This chronic form of DIC is difficult to recognise and is much less often diagnosed. Simultaneous clotting and bleeding can occur with chronic DIC, but in most cases this is a lower grade, persistent clotting activation process and the body has sufficient capacity to compensate. With chronic DIC, the predominant feature is typically increased clotting, not bleeding. Cancer is one of the most common causes of low-grade DIC.
Signs and symptoms of DIC depend upon the underlying condition, such as infection, trauma or malignancy, and on the severity and the extent of DIC. In addition to signs and symptoms of the underlying condition, those of DIC are associated with bleeding and/or inappropriate clotting.
Bleeding
Significant bleeding usually occurs from at least three different sites.
- Blood in the stool or urine from internal bleeding
- Headaches and other symptoms associated with bleeding in the brain
- Bruising and the formation of small red dots on the skin (petechiae)
- Bleeding at the site of wounds, surgical sites, intravenous (IV) needle or catheter sites
- Mucosal bleeding – from the nose, gums, mouth, etc.
Blood Clotting
Symptoms depend on the location of blood clots and may include:
- Symptoms associated with organ dysfunction caused by blood clots blocking blood flow and oxygen to organs such as the liver and kidney, leading to liver and kidney failure
- Blackening of the skin caused by blockage from blood clots and poor blood flow to the skin
- Chest pain, coughing up blood, and/or difficulty breathing caused by blood clots in the lungs
- Chest pain and/or a heart attack caused by clotting in the heart
- Headaches and other symptoms associated with a stroke, caused by clotting in the brain
The goals of testing are to identify DIC, evaluate its severity, and to monitor its effects over time. There is not a single test that can be used to definitely diagnose DIC. A healthcare professional will consider many factors when assessing a person who may have this condition, such as signs and symptoms, presence of an underlying condition, physical examination, and medical history.
The severity and extent of DIC can change over time so laboratory testing is often performed at several intervals to monitor a person's status. Some routine tests that may be performed include:
- FBC (full blood count) – includes a platelet count; in DIC, platelets are often low.
- Blood films from individuals with DIC often show decreased number of platelets and presence of large platelets and fragmented red cells (schistocytes).
- PT (prothrombin time) – often prolonged with DIC as coagulation factors are consumed
- APTT (activated partial thromboplastin time) – may be prolonged
- D-dimer – a test that detects a protein that results from clot break-down; it is often markedly elevated with DIC; if normal, then DIC is unlikely.
- Fibrinogen – one of the clotting factors; is low with DIC
A test scoring system developed by the International Society on Thrombosis and Haemostasis may be used to evaluate a group of test results to help determine if DIC is present. The score is based on the results of a platelet count, PT, D-dimer (or fibrin degradation products) and fibrinogen. The higher the score, the more likely it is that DIC is present.
As DIC can affect the health and function of several organs, more general testing, such as a biochemical profile, may be requested to evaluate, for example, the functional status of kidneys and liver. Additionally, several other tests may be ordered to help detect the underlying disease or condition that is causing a person to develop DIC.
Non-Laboratory Tests
An X-ray or other imaging scan is sometimes performed to help locate blood clots and evaluate organs.
The goals of treatment for DIC are to address the underlying condition that is causing the clotting activation and to stabilise the affected person. In most cases, DIC will resolve when the disease or condition is treated. Acute DIC is typically treated in a hospital setting.
Supportive measures may need to be taken to address bleeding and clotting. People primarily presenting with severe bleeding may be given platelets or fresh frozen plasma or cryoprecipitate that contains clotting factors, especially when surgical procedures are required to address the underlying condition.
See the Related Content section of this article for links to web resources on treatment.