2.1.1 A pseudoaneurysm (also called a false aneurysm) is a collection of blood and blood clot that has formed outside a blood vessel, usually after an injury. The collection is connected by a channel to the blood vessel, so blood flows through it. A pseudoaneurysm may rupture and bleed. Pseudoaneurysms differ from true aneurysms in that blood within a true aneurysm is contained by the weakened wall of the blood vessel. The most common cause of a pseudoaneurysm is femoral artery puncture during cardiac catheterisation. A pseudoaneurysm may also occur after other procedures that involve puncture of an artery, including removal of an arterial blood pressure line or an intra-aortic balloon pump, or after accidental trauma.
2.1.2 Many pseudoaneurysms resolve spontaneously by thrombosis and need no treatment. If treatment is required, treatment options include compression under ultrasound control, embolisation of the pseudoaneurysm with a variety of materials, or surgical repair.
2.2.1 In this procedure, thrombin (a blood-clotting agent) is injected under ultrasound guidance into the pseudoaneurysm. This causes thrombosis of the pseudoaneurysm cavity, which seals the arterial puncture site. The resulting clot is gradually reabsorbed.
2.3.1 Three historically controlled studies and one retrospective cohort study were identified comparing thrombin injection with compression. All four studies reported greater success in treating pseudoaneurysms with thrombin injection. In these studies, success rates ranged between 93% (27/29 patients) and 100% (24/24 patients) using thrombin injection, and between 63% (25/40 patients) and 95% (102/107 patients) using compression. For more details, refer to the 'Sources of evidence' section.
2.3.2 The Specialist Advisors did not note any concerns regarding the efficacy of this procedure.
2.4.1 In the studies identified, the main complications reported were: intra-arterial thrombin injection necessitating thrombectomy for artery occlusion (2%, 3/131 patients); pseudoaneurysm rupture after thrombosis (1%, 1/131 patients); groin abscess (1%, 1/114 patients); leg ischaemia (1%, 1/114 patients); blue toe (1%, 1/114 patients); and buttock pain (1%, 1/114 patients). For more details, refer to the 'Sources of evidence' section.
2.4.2 The Specialist Advisors listed the main potential adverse events of this procedure as thrombosis of the damaged artery and treatment of a clinically infected pseudoaneurysm (because infection can cause late recanalisation and rupture).