Septic embolism is an infection in a blood vessel. The infection starts in one area of the body and travels through the bloodstream to another location, potentially obstructing blood vessels.

Septic means an infection that affects the entire body, and an embolus is a particle that circulates through the bloodstream until it becomes trapped and unable to pass through a small vessel. A septic embolus is an infected blood clot that gets stuck in a small blood vessel and stops blood flow.

This article examines septic embolism and its symptoms and causes. It also discusses how doctors diagnose and treat septic embolism, whether people can prevent it, and the outlook.

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Septic embolism is the blockage of a blood vessel by a blood clot that contains bacteria, known as a septic embolus. The septic embolus develops from an infectious source elsewhere in the body, becomes dislodged, and travels through the bloodstream until it obstructs small blood vessels. Septic emboli can be bacterial as well as fungal.

Septic emboli attack the body in two ways:

  1. They wholly or partially block blood flow.
  2. They contain infectious agents that could lead to inflammation and possible abscess formation.

Outcomes from septic emboli range from mild to severe. Some people may experience minor skin changes while, for others, septic embolism could be fatal.

People with septic embolism tend to have nonspecific symptoms that make them feel generally unwell. They typically have signs and symptoms of infection, such as:

Specific symptoms of septic embolism depend on the location of the septic embolus. For example, if a clot causes a blockage in the lung vessels, a person may develop a lung infection or abscesses, but if a clot affects the vessels under the skin, it may cause painful skin lesions.


Septic pulmonary embolism may cause:


Septic cerebral emboli could cause infection of the vessel wall — mycotic aneurysm — in the cerebral arteries, leading to stroke. They could also result in brain abscesses, which cause various neurological-related symptoms and bleeding within the brain tissue.


Septic splenic emboli can prevent blood from flowing to the spleen, resulting in decreased oxygen and nutrients to the tissues and eventual tissue death.

Septic embolism in the spleen can also cause hemorrhages and abscesses. Symptoms of a splenic abscess may include:


Septic emboli can cause several tiny abscesses in the liver that combine to form a large abscess. A person with septic embolism in the liver may have symptoms such as:

  • fever
  • nausea
  • right shoulder pain
  • pain behind the right ribs
  • shortness of breath
  • unexplained weight loss
  • dark urine


Renal septic emboli can obstruct the blood supply to a kidney, potentially resulting in necrosis and kidney failure. People may experience symptoms such as:

  • sudden abdominal or flank pain
  • loin tenderness
  • nausea
  • vomiting
  • blood in urine
  • decreased urine output


When septic emboli affect the skin, a person may experience skin manifestations such as:

  • areas of skin discoloration around the fingers or toes that are sometimes painful
  • tender discolored, slightly raised lumps, typically on the fingers or toes
  • patches of skin discoloration on the palms of the hands and soles of the feet that are generally not tender
  • discolored spots on the hands, feet, or other areas that do not fade under pressure

If a person has symptoms of infection that do not improve or an unusual skin rash, they should speak with a doctor.

Anyone experiencing difficulty breathing, chest pain, or fainting should seek urgent medical attention.

Various conditions and infections can cause septic embolism. Septic emboli arise from a site of infection where large numbers of bacteria are present. Inflammatory processes and changeable blood flow increase the risk of clot formation.

The infected clot, or small fragments, can dislodge and travel to another location, damaging tissue by blocking blood flow, preventing oxygen supply, and delivering infection.

Sources of septic emboli may include:

Certain factors also increase a person’s risk of septic embolism. For example, IV drug use increases the risk of an infection that contributes to endocarditis and septic embolism. Infective endocarditis damages the heart valves, which may cause congestive heart failure and recurring septic embolism.

Although rare, fungal septic emboli can also occur.

Infective endocarditis

Infective endocarditis is a common cause of septic embolism. It is an infection of the muscle lining the heart and the valves. Septic embolism tends to happen when the infection occurs from Staphylococcus aureus bacteria.

Causes of the condition include IV drug use, bacteria entering from a pre-existing infection such as from the mouth, and infected cardiac valves. Apart from septic emboli, infective endocarditis can also lead to heart failure, septic shock, and life threatening cardiac rhythm disturbances.

Septic embolism can be challenging for doctors to diagnose. A healthcare professional may initially take a blood culture to check for bacteria. A positive culture can help identify the type of bacteria and the antibiotic that will be most effective against it.

Although a positive blood culture can confirm the presence of bacteria, healthcare professionals need to perform other tests to locate the area of infection and its extent.

Healthcare professionals may use the following to test for septic embolism:

Doctors treat septic embolism by managing the source of the infection. The most suitable way to manage septic embolism depends on which pathogen causes it, the embolus’s location, and the size of the obstruction and inflammatory area.

Bacteria is the most common pathogen that causes septic embolus. When a septic embolus contains bacteria, doctors typically treat it with antibiotics.

Other treatment strategies depend on the septic embolus location but may include:

  • removing infected or dead tissue to improve the healing process
  • draining abscesses
  • surgery to repair a damaged heart valve
  • surgical procedure to partially or entirely remove the spleen

Outcomes for people with septic embolism can range from mild to severe. The long-term outlook depends on many factors, such as:

  • the organs involved
  • the severity of the infection
  • the general health of the person before the infection
  • complications, such as congestive heart failure or cerebral difficulties
  • failure to follow recommendations for treatment or surgery

People with mild infection and septic emboli that affect the skin typically respond well to treatment. However, if septic emboli cause extensive infection of the limbs, resulting in gangrene, doctors may have to amputate the affected areas.

Infection of some of the internal organs, such as the lungs or brain, could lead to sepsis and can be life threatening.

People cannot always prevent septic embolism. However, the following steps may help reduce the risk:

  • maintaining hygiene, such as regular handwashing
  • maintaining dental health
  • keeping cuts and wounds clean and covering them until they heal
  • keeping the area surrounding tattoos or body piercings clean
  • refraining from sharing needles, such as for injecting drugs or tattooing
  • getting immediate medical attention for infections

A septic embolism occurs when an infection starts in one area of the body and travels through the bloodstream to elsewhere via an infected blood clot or septic embolus. The septic embolus can obstruct a blood vessel, block blood flow, and deliver infectious agents to tissues that cause inflammation and abscesses.

People with septic embolism typically have symptoms of infection and other symptoms that depend on the location of the septic embolus. Doctors diagnose septic embolism by ordering bloodwork and performing imaging tests.

Treatment for septic embolism typically involves antimicrobial therapy, such as antibiotics, and other procedures depending on the source of the infection and location of the septic embolus.

Although people cannot prevent septic embolism, they can take steps to help lower their risk of infection. The outlook for people with septic embolism varies. People with a mild infection have a high chance of recovery, but for some people with severe infection and complications, septic embolism can be life threatening.