Iatrogenic intramuscular pseudoaneurysm with an arteriovenous fistula

An adult male suffered intraoperative complications during major abdominal surgery and was admitted to an intensive care unit, where central lines were inserted into the femoral veins bilaterally. Following the procedure, persistent swelling and tenderness developed in the patient’s right groin.

An ultrasound of the groin showed a 4.2 cm x 3.6 cm x 3.5 cm hypoechoic region adjacent to the common femoral artery (Figure 1). This showed a characteristic “yin-yang” pattern on the Colour Doppler imaging (Figure 2) [1]. A subsequent CT lower limb angiogram showed a contrast-filled collection in the right sartorius with a tract from the right superficial femoral artery (Figures 3 and 4). Additionally, there was early contrast filling into the right common femoral vein (Figures 5 and 6).

A pseudoaneurysm is an arterial injury that causes a haematoma contained locally within the pressure of the surrounding tissues [2]. The most common cause is iatrogenic. Less common causes include trauma, infection or pancreatitis with a pseudocyst/pancreatic fistula [3]. Pseudoaneurysms are common but can be a dangerous complication of vascular procedures, owing to the risk of arterial rupture and catastrophic haemorrhage [4]. Most pseudoaneurysms in the groin are contained by the adjacent subcutaneous tissues. This unusual case demonstrates an arterial puncture that caused a localised haematoma in the sartorius muscle, with continuity to the site of leak in the common femoral artery.

Appropriate confirmation of the anatomy before inserting a central venous catheter is vital, due to proximity of the important anatomical structures and potential complications. In this patient’s case, the catheter has most likely been inserted into the superficial femoral vein, with the needle going through the sartorius muscle and the superficial femoral artery before being inserted into the vein. This has likely caused the leak into the sartorius from the superficial femoral artery, but also the arteriovenous fistula, due to the very close proximity of those structures, as demonstrated on the CT angiogram lower limb (Figure 5).

Pseudoaneurysm repair is of paramount importance, due to potential further complications that could arise, including compression of the surrounding femoral nerve or the femoral vein, which could potentially cause a deep venous thrombosis. Small pseudoaneurysms, generally of less than 2 cm in diameter, can be treated with watchful waiting and compression, with larger ones requiring a more invasive approach, typically with thrombin injection into the haematoma. There is also a developing technique with closure using angioseal in common femoral artery pseudoaneurysms. However, these options are not able to treat the arteriovenous fistulas. Potential treatments for this include temporary balloon angioplasty, stent graft placement from the contralateral side if involving the external iliac or superficial femoral arteries, and open surgical repair [4,5]. This patient underwent a successful open surgical repair, due to the wide neck of the aneurysm, precluding thrombin injection, and the presence of an arteriovenous fistula.

This case demonstrates the unusual intramuscular involvement and the importance of good ultrasound technique and staff training, to try and reduce the rate of complications of central venous catheter insertion. Appropriate orientation within the area of interest and identification of anatomical landmarks is vital before performing the procedure. If this is achieved, then a rate of complications can be significantly reduced.

Written informed patient consent for publication has been obtained.