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 hemostasis. 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 hemostasis 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 or significant burns
- Major surgery, such as cardiopulmonary bypass surgery
- Pregnancy and childbirth, especially when a woman has retained placental material, or a fetus that has died (stillbirth)
- Cancers, such as acute promyelocytic leukemia or tumors that develop within glands (adenocarcinoma); cancer cells may release a pro-coagulant.
- Organ failure, such as liver, pancreas, or kidney failure
- 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 recognize 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.