A pseudoaneurysm, also termed a false aneurysm, is a leakage of arterial blood from an artery into the surrounding tissue with a persistent communication between the originating artery and the resultant adjacent cavity. This may occur after arterial puncture for a diagnostic cardiac catheterization or an arteriogram, but is more common after an arterial intervention. Catheter-directed interventions more commonly require larger arterial sheaths to be used, and the anticoagulation or antiplatelet agents that are administered can interfere with normal sealing of the puncture site.

Some pseudoaneurysms resolve themselves, though others require treatment to prevent hemorrhage, an uncontrolled leak or other complications.

An ultrasound study in the Vascular Laboratory may be requested to evaluate a puncture site if swelling, pain or extensive bruising suggests a pseudoaneurysm may have developed.

Surgery is sometimes required, but most pseudoaneurysms at arterial puncture sites can be treated with a brief, minimally-invasive procedure performed under local anesthesia. Preparation takes a few minutes. The procedure will be explained and informed consent obtained. Ultrasound imaging guides placement of a needle into the pseudoaneurysm and then thrombin is injected. Thrombin is an enzyme that promotes rapid clot formation, immediately obliterating the pseudoaneurysm cavity when injected. There are some risks of an adverse reaction or clot formation in a major artery or vein (which might require urgent surgery), but the procedure is usually uncomplicated.

No special preparation is required. A complete diagnostic study usually takes about 30 minutes. Treatment, if required, takes less than 30 minutes. A brief period of observation in the recovery area may follow.

A follow-up duplex scan is generally performed three to seven days after successful treatment. Further evaluation or treatment may be recommended if thrombin injection does not completely eliminate the pseudoaneurysm.