An embolism is a medical condition in which a substance travels through the bloodstream and becomes lodged in a blood vessel, blocking the normal flow of blood. The blockage can deprive tissues and organs of oxygen and nutrients, leading to damage that can range from mild and temporary to severe and life threatening. What defines an embolism is movement. The obstructing material forms elsewhere in the body and is carried by the circulation until it becomes stuck.
The material that causes an embolism is called an embolus. The most common type is a blood clot, but emboli can also be composed of fat droplets, air or gas bubbles, cholesterol crystals, amniotic fluid, or even foreign material introduced during medical procedures. Once an embolus becomes trapped in a vessel too small for it to pass through, blood flow beyond that point is reduced or completely stopped.
One of the most well known forms is pulmonary embolism. In this case, a blood clot usually forms in the deep veins of the legs or pelvis and then travels to the lungs. When it blocks a pulmonary artery, oxygen exchange is impaired, which can cause sudden shortness of breath, chest pain, rapid heart rate, and in severe cases, collapse or death. Pulmonary embolism is a medical emergency because the lungs are essential for oxygenating the blood.
Another major type is cerebral embolism, which occurs when an embolus travels to the brain. This can cause an ischemic stroke by cutting off blood supply to a portion of brain tissue. The effects depend on which area of the brain is affected but may include weakness on one side of the body, difficulty speaking, vision problems, or loss of consciousness. Brain tissue is especially sensitive to oxygen deprivation, so rapid treatment is critical.
Embolisms can also affect other organs. A coronary embolism can block blood flow to the heart muscle and cause a heart attack. An embolus lodging in the kidneys can impair filtration and lead to kidney injury. In the limbs, embolic blockage can cause sudden pain, pallor, coldness, and loss of function, sometimes progressing to tissue death if circulation is not restored.
The underlying causes of embolism vary depending on the type of embolus. Blood clot emboli are often associated with conditions that promote abnormal clot formation, such as prolonged immobility, surgery, trauma, cancer, pregnancy, smoking, and certain genetic clotting disorders. Fat embolism may occur after fractures of long bones, where fat from bone marrow enters the bloodstream. Air embolism can result from intravenous lines, surgical procedures, or rapid changes in pressure. Amniotic fluid embolism is a rare but severe complication of childbirth.
Diagnosis typically involves imaging studies tailored to the suspected location of the embolism. These may include ultrasound, CT scans, MRI, or specialized angiography. Blood tests and clinical assessment help guide the diagnosis but are rarely sufficient on their own.
Treatment depends on the type, size, and location of the embolism, as well as the patient’s overall condition. Blood clot embolisms are often treated with anticoagulant medications to prevent further clotting, and in severe cases with clot dissolving drugs or mechanical removal. Supportive care such as oxygen, fluids, or surgery may be required for other forms of embolism. Prevention is a major focus, especially in high risk individuals, and may include blood thinners, compression devices, early mobilization after surgery, and management of underlying risk factors.
In essence, an embolism is dangerous not because of what it is made of, but because of what it interrupts. By blocking the flow of blood, an embolism turns a moving circulatory system into a stalled one, and the consequences are determined by which tissues are suddenly cut off from life sustaining circulation.
