A pseudoaneurysm occurs when a blood vessel wall is injured. Blood leaking from the vessel collects in surrounding tissue. It is sometimes called a false aneurysm. It may also be called pseudoaneurysm of the vessels.

In a true aneurysm, the vessel wall weakens and bulges. It sometimes forms a blood-filled sac. But the vessel wall is not injured.

A pseudoaneurysm may be a complication of cardiac catheterization. This procedure is commonly used to view blood flow through the heart. It can show blockages in the heart arteries. During the procedure, a long, thin flexible tube called a catheter is inserted in a blood vessel, usually in the groin or wrist. It's guided to the heart. If blood leaks and gathers outside the artery where the catheter is placed, a pseudoaneurysm can form.

Pseudoaneurysms also can occur in other arteries throughout the body as a result of:

• Infection
• Rupture of an aneurysm
• Surgery
• Trauma

A small pseudoaneurysm of a femoral artery due to cardiac catheterization may go undetected and not cause any complications. The femoral artery is a large blood vessel in the thigh. It sends blood to the lower part of the body. Some people have mild swelling in the thigh area. You may not notice it until days or weeks after the procedure.

If you have a small pseudoaneurysm, your health care provider may recommend regular medical checkups and an occasional ultrasound test to see if it goes away on its own.

You may need other treatments if the pseudoaneurysm is wider than 2 centimeters (about 3/4 inch) or if you take certain medicines, such as blood thinners. Treatment for pseudoaneurysm may include:

• Ultrasound-guided compression repair. Ultrasound uses sound waves to show blood flow in the body. Once the pseudoaneurysm is found, the provider presses the ultrasound wand onto the area. The pressure releases the built-up blood.
• Ultrasound-guided medicine delivery. The provider uses ultrasound imaging to locate the pseudoaneurysm. A medicine called thrombin is then injected into the pseudoaneurysm. It helps prevent the pseudoaneurysm from growing or bursting.
• Surgery. Sometimes, ultrasound-guided treatment isn't helpful or recommended. Surgery may be needed to correct the pseudoaneurysm.

If you've had any type of catheter procedure and notice tenderness or swelling in the area, contact your health care provider.