Pseudoaneurysm and Mycotic Aneurysm

A pseudoaneurysm is a false aneurysm, a swelling or ballooning of a blood vessel that occurs as a result of damage to the blood vessel wall, typically caused by injury or surgery, that allows blood to leak into the surrounding tissues. Both aneurysm and pseudoaneurysm are conditions in which the wall of a blood vessel bulges out and weakens, but they differ in their cause and location.

An aneurysm is a permanent, balloon-like dilation of a blood vessel that occurs due to a structural weakness in the blood vessel wall. A pseudoaneurysm is a collection of blood that forms outside of a blood vessel but is contained within an outer layer of tissue. It typically occurs after an injury to the blood vessel, such as from a surgical procedure or a puncture wound.

A mycotic aneurysm is caused by a fungal or bacterial infection. It occurs when an infected blood vessel wall becomes weakened, leading to a swelling or ballooning of the vessel. Mycotic aneurysms can develop in any part of the body and can cause serious health problems if left untreated, including rupture and potentially life-threatening bleeding. The formation of a mycotic aneurysm is usually a complication of a systemic infection, and prompt medical attention is required for proper diagnosis and treatment.


The cause of a pseudoaneurysm can depend on its location in your body. Pseudoaneurysms can be divided into different categories based on their locations. Examples include femoral, visceral, and aortic pseudoaneurysms. The most common type of pseudoaneurysm is femoral (occurs in an artery in the groin). Some other common causes include:

  • An injury or blunt force trauma to a blood vessel
  • Surgical procedures: Certain surgical procedures, such as coronary artery bypass surgery, can cause damage to the blood vessel wall
  • Medical procedures: Some medical procedures, such as angiograms or cardiac catheterization, can cause trauma to the blood vessel wall
  • Infection: An infected blood vessel can weaken and develop a pseudoaneurysm

A mycotic aneurysm is caused by a fungal or bacterial infection. The infection weakens the blood vessel wall and leads to a swelling or ballooning of the vessel. Some common causes of mycotic aneurysms include:

  • Bacterial infections, such as streptococcal infections, staphylococcal infections, or endocarditis
  • Fungal infections, such as aspergillosis or candidiasis
  • Systemic infections, such as sepsis, can spread from other parts of the body to the blood vessels.
  • Atherosclerosis, or hardening of the arteries can reduce blood flow to the aneurysm and increase the risk of infection.
  • Previous surgery, particularly heart or blood vessel surgery, can increase the risk of developing a mycotic aneurysm.
  • Injection drug use can introduce bacteria into the bloodstream and increase the risk of a mycotic aneurysm.


Symptoms of a pseudoaneurysm may include:

  • Pain or swelling at the site
  • A pulsating mass that can be felt or seen near the site
  • Bruising or discoloration of the skin near the site
  • Weakness, numbness or a feeling of pressure in the area

It is important to seek prompt medical attention if you suspect you have a pseudoaneurysm as there is a risk of it rupturing, which can lead to serious complications.

Symptoms of a mycotic aneurysm may include:

  • Fever
  • Abdominal or back pain
  • Weakness or numbness in limbs
  • Rapid pulse or heart rate
  • Unexplained weight loss
  • Vomiting or nausea
  • Change in mental function or confusion

Some mycotic aneurysms may not produce any symptoms until they rupture, so it is important to seek medical attention if you have any concerns or underlying health conditions that may increase your risk.


Diagnosis of a pseudoaneurysm typically involves a combination of medical history, physical examination, and imaging tests. The specific tests used to diagnose a pseudoaneurysm may include:

  • Physical exam: Your doctor may feel for a pulsating mass near the site of the pseudoaneurysm and look for signs of swelling, discoloration, or bruising
  • Doppler ultrasound: This test uses high-frequency sound waves to produce images of blood flow through the blood vessels
  • CT scan: This test produces detailed images of the blood vessels using X-rays and computer technology.
  • MRI: This test uses a powerful magnetic field and radio waves to produce detailed images of the blood vessels and surrounding tissues
  • Angiogram: This test involves injecting a special dye into the blood vessels, which allows your doctor to see the blood vessels and the flow of blood on X-ray images

The following tools are used to diagnose a mycotic aneurysm:

  • Physical exam: Your doctor may be able to feel a pulsating mass or a tender area over the aneurysm.
  • Blood tests can help determine if there is an infection present
  • Imaging tests: Imaging tests such as CT scans, MRI scans, and angiograms are often used to visualize the affected blood vessel and confirm the presence of an aneurysm
  • Angiogram: An angiogram involves injecting a dye into the blood vessels and taking X-ray images to visualize the blood flow and the aneurysm

It is important to diagnose and treat both pseudoaneurysm and mycotic aneurysm promptly to prevent the risk of rupture, which can be life-threatening.

Treatment Options

Some pseudoaneurysms resolve themselves, while others require treatment to prevent hemorrhage, an uncontrolled leak or other complications. Treatment of a pseudoaneurysm typically involves surgical or interventional radiology methods to repair the damaged blood vessel. The choice of treatment depends on various factors including size and location of the pseudoaneurysm and your overall health and preferences.

Common options include:

  • Surgical repair: Open surgical repair involves making an incision to access the damaged blood vessel and repair it with sutures or a patch.
  • Endovascular repair: This is a minimally invasive procedure performed by a radiologist, using a catheter and imaging guidance. The damaged vessel is repaired by placing a stent or coil to seal the pseudoaneurysm.
  • Thrombin is a blood-clotting medication that is commonly used in the treatment of pseudoaneurysms. It can be delivered directly to the site through a minimally invasive endovascular procedure, such as injection through a catheter, to promote clotting and sealing of the damaged blood vessel. Injection of thrombin is typically performed under imaging guidance, such as ultrasound or angiography, to ensure precise placement and to monitor the effectiveness of the treatment.
  • Observation may be suitable depending on the location and size of the pseudoaneurysm.

Treatment of a mycotic aneurysm typically involves a combination of antibiotics and surgical intervention. The first step is to identify and treat the underlying infection. Antibiotics are prescribed to treat the infection and prevent its spread. In some cases, the aneurysm may be repaired or removed through surgical intervention. This is typically done in cases where the aneurysm is causing symptoms, is at risk of rupturing, or is large and growing rapidly.

The specific treatment plan will depend on the size, location, and severity of the aneurysm, as well as the overall health of the patient. The University of Michigan boasts a prominent infectious disease team that is readily available for consultation. Our approach is multidisciplinary and involves collaboration from various departments to effectively tackle infectious disease-related concerns.

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To schedule an appointment to discuss an aortic aneurysm or any other cardiovascular condition, call us at 888-287-1082 or visit our Make a Cardiovascular Appointment page, where you may view other information about scheduling a cardiovascular appointment.