Ultrasound-guided thrombin injection (UGTI) is the preferred treatment of pseudoaneurysms (psA). The potential risk of complications increases with the number of UGTI treatments needed for complete psA obliteration. Identification of risk factors for recurrent psA is needed.

Material and methods:
In total, 508 patients with femoral artery psA underwent UGTI, followed by ultrasound examination repeated twice, at 1-week intervals, to assess UGTI effectiveness. In cases of psA recurrence, the procedure was repeated. Clinical and ultrasound data were prospectively collected.

The psA recurrence occurred in 76 (15%) patients. UGTI was repeated twice in 49 (64%), three times in 15 (20%) and more than three times in 12 (16%) patients. The median thrombin dose was 150 IU (80–250 IU), and was lower in initial procedures than repeated UGTI (p = 0.025). The median psA volume was 2.26 ml (0.86–5.47 ml). The median length of the communicating channel was 4 mm (0–12 mm). A time interval between vessel catheterization and UGTI greater than 7 days (p < 0.001), a late to early velocity index (LEVI) of < 0.2 identified during the outflow phase (p < 0.001), a psA volume > 5 ml (p = 0.032), and a short communicating channel between the psA and the artery (p = 0.037) predicted psA recurrence. Antiplatelet and anticoagulant agents did not increase the risk.

The LEVI and time interval between artery cannulation and UGTI treatment are strong parameters identifying patients at risk of psA recurrence. The psA volume and communicating channel length are less substantial risks, but still significant. Concomitant antiplatelet and anticoagulant therapy do not affect the success rate of UGTI.