Teaching Case

An 18-year-old man came to our department complaining with severe acute pain and swelling in the left thigh after a sport direct blunt trauma. He underwent US and MRI examinations. Some days later, because of a progressive anaemia and increased swelling, the patient underwent duplex ultrasound, angio-CT and angiographic examinations.

MRI examination showed an evident muscular lesion in the anterior upper-middle third of the thigh, mainly involving vastus intermedius of quadriceps femoris muscle with muscular edema and an inhomogeneous oval-shape formation measuring 17x7x4.5 cm as for subacute-phase muscular haematoma; a fluid collection in the subcutaneous tissue in the ipsilateral gluteal region was also evident (Fig. 1, 2). CT-angiography performed four days later demonstrated a round area of acute contrast extravasation measuring 11 mm in the anterior aspect of the middle-superior third of the left thigh consistent with pseudoaneurysm (Fig. 3, 4). The patient underwent immediate digital subtraction angiography that confirmed a post-traumatic pseudoaneurysm arising from a peripherical branch of deep femoral artery. The lesion was treated by transcatheter proximal and distal embolization of donor artery with coils and liquid embolic agent (Onyx®34). The post-procedural acquisitions showed no flow into the pseudoaneurysm and occlusion of the vessel distally (Fig. 5, 6).

Pseudoaneurysms (PA) are vascular abnormalities caused by a disruption in the arterial wall allowing blood to stream in tissues surrounding the damaged artery. This leads to the formation of a fibrous sac which communicates with the arterial lumen by a “neck”, progressively enlarging due to the arterial pressure [1, 2]. Infections, inflammatory conditions, trauma and percutaneous endovascular procedures are recognized causes of pseudoaneurysms [1]. Superficial femoral artery is the most common site of aberrant punctures causing iatrogenic pseudoaneurysms [3]. Clinical presentation of PA can be very different, ranging from asymptomatic forms, to anaemia and compartment syndrome [4] up to life-threatening conditions with severe haemorrhagia. In some cases, expecially if hematoma is large, it is difficult to detect PA by physical examination alone and diagnostic imaging is fundamental in diagnosis [3]. Duplex ultrasonography is a first level technique, useful to detect the size of PA and presence of thrombus formation [4] and can be a guide for manual compression in superficial PA [3]. CT and MRI-angiography are valuable noninvasive diagnostic tools in peripheric arterial lesions [3, 5] because they allow a better assessment of location and morphologic features of PA, enables to detect possible associated lesions and rule out diagnosis of arteriovenous fistula [5]. Digital subtraction angiography (DSA) is the gold standard for diagnosis and, in many cases, treatment of PA [1, 2, 4]. DSA allows detecting shape, size and position of PA and its neck; moreover DSA allows assessing proximal and distal end of parent artery and the expendability of donor artery, which is essential to select adequate treatment strategies [1]. A PA arising from an expendable donor artery can be treated with transcatheter embolization of the afferent artery. When embolising arteries with collateral vessels it is important to embolise both proximal and distal to the PA in order to obtain complete cessation of blood flow into and from the lesion [2]. Surgery is preferable in cases of PA with important local mass effect complications or if concomitant diseases are present. DSA is a mandatory imaging technique in patients with suspicion of PA, especially if a falling haemoglobin trend coexists, in order to assess the expendability of the donor artery. Endovascular techniques have a lower complication rate in treatment compared to surgical management. Transcatheter embolization of afferent artery is the preferable technique when the donor artery is expendable. Always think about the possibility of PA when important muscular trauma occurs.