Femoral artery pseudoaneurysm following percutaneous intervention

INTRODUCTION — Iatrogenic pseudoaneurysm (IPA) is a false aneurysm that occurs after localized arterial wall injury related to an incomplete hemostatic plug at the injury site. Localized extravasation of blood outside the arterial wall is confined and controlled by the pseudocapsule that develops.

Any arterial site used for arterial puncture can develop a pseudoaneurysm, but IPA secondary to femoral arterial access for percutaneous-based diagnostic and interventional procedures is by far the most common etiology and site. Most uncomplicated IPAs can be managed without open surgery, either with observational management or by using ultrasound-guided or, occasionally, endovascular techniques to effect closure. For complicated IPAs and those failing nonsurgical management, surgical repair of the artery with or without patch closure will be needed.

The evaluation and management of femoral artery pseudoaneurysm as a result of percutaneous intervention will be reviewed here. The evaluation and management of acquired arteriovenous fistula, which is another common complication of percutaneous access, is reviewed separately. (See "Acquired arteriovenous fistula of the lower extremity".)

Other complications of percutaneous intervention (femoral, other site) are reviewed separately. (See "Access-related complications of percutaneous access for diagnostic or interventional procedures" and "Periprocedural complications of percutaneous coronary intervention".)

Traumatic pseudoaneurysm and pseudoaneurysms affecting other sites (eg, aortoiliac, visceral, radial arteries) are discussed in separate topic reviews. Pseudoaneurysm associated with a prior open vascular procedure usually occurs in the context of an infected surgical field and requires an aggressive surgical approach. (See "Severe lower extremity injury in the adult patient" and "Abdominal vascular injury" and "Overview of visceral artery aneurysm and pseudoaneurysm" and "Overview of infected (mycotic) arterial aneurysm".)

INCIDENCE — Iatrogenic femoral pseudoaneurysm (IPA) is overall uncommon, occurring in <1 percent of all interventional procedures (eg, diagnostic peripheral or cardiac catheterization or peripheral or cardiac intervention); however, the reported incidence of IPA ranges widely, which is attributed to variability in the frequency and the methods of assessment [1-6]. According to standards put forth by the Society of Cardiovascular and Interventional Radiology, an acceptable rate of IPA and/or arteriovenous fistula following percutaneous access should be ≤0.2 percent [7]. While this guideline is nearly two decades old, most experts still agree that the acceptable incidence of IPA is <1 percent.

ETIOLOGY AND RISK FACTORS — The femoral artery is the most frequently used access vessel for vascular intervention (cardiac and noncardiac) and thus the most common site for iatrogenic pseudoaneurysm (IPA).

Technical factors contribute to the incidence of IPA, and proper technique is an important strategy for IPA prevention. As an example, a double wall entry during arterial catheterization (ie, anterior and posterior wall puncture) can lead to persistent arterial bleeding from the posterior wall puncture site even after hemostasis has been achieved from the anterior puncture site. Likewise, an inaccurate arterial entry, such as puncturing the superficial femoral, deep femoral, or other arteries (external iliac, inferior epigastric) rather than the common femoral artery, can lead to pseudoaneurysm. The use of real-time ultrasound to guide arterial access can help to decrease access errors and subsequent complications [8]. (See "Percutaneous arterial access techniques for diagnostic or interventional procedures" and "Periprocedural complications of percutaneous coronary intervention", section on 'Vascular complications' and "Access-related complications of percutaneous access for diagnostic or interventional procedures".)

Pseudoaneurysm formation arises following a disruption of all layers of the arterial wall when the arterial defect fails to be covered by a hemostatic plug of clotting factors. Arterial bleeding into the soft tissue results in hematoma formation, which will expand unless the hematoma can be confined. The development of a pseudocapsule is a result of pressure on the tissues from arterial bleeding and the developing soft tissue hematoma, which promotes atrophy and inflammation of the surrounding soft tissue, resulting in the development of thickened fibrous tissue or pseudocapsule formation. The pseudocapsule does not include any true layer of the arterial wall. The pseudocapsule limits additional extravasation of blood into the soft tissue and prevents life-threatening hemorrhage from the arterial defect that might otherwise be seen with a simple unencapsulated hematoma. When the hematoma maintains a soft liquid central region, blood can freely circulate outside the injured vessel into the soft tissue as a controlled extravasation. The pseudocapsule with such contained, circulating arterial flow defines the presence of pseudoaneurysm.

It is important to note that the composition of the pseudocapsule composition is in flux, consisting of hematoma predominately early in the process with formation of a fibrin shell as time progresses. For small pseudoaneurysms, hematoma resorption and shrinkage of the pseudocapsule can lead to spontaneous resolution, which is the basis of nonoperative management.

Risk factors — Well-described risk factors for IPA include female sex, increasing age, concomitant venous puncture, hypertension, severely calcified vessels, larger access sheath size (>6 French), and use of anticoagulation either at the time of arterial cannulation or in the immediate postprocedure period [9]. The incidence of femoral pseudoaneurysm has been reportedly increased when the left femoral artery is used for access compared with the right femoral artery, as well as in interventional procedures compared with diagnostic procedures [10,11]. Plausibly, other factors relating to the ease or difficulty of arterial access should affect the risk for developing IPA, such as the location of the arterial puncture, number of punctures, use of ultrasound to guide access, level of operator experience, and obesity, as well as the complexity of the intervention [12-16].

CLINICAL FEATURES AND DIAGNOSIS

History and physical — Pseudoaneurysms represent a spectrum of extravasation of blood from the artery with a wide range of findings depending upon the size of the pseudoaneurysm and its duration. Clinical suspicion for iatrogenic pseudoaneurysm (IPA) should be increased after any percutaneous femoral access that results in significant groin pain or swelling, particularly among those with risk factors. Typically, clinical findings suggestive of IPA are noted soon after the procedure, often within the first 24 hours after sheath removal. However, IPA can develop as patient activity increases, and delayed presentations have been reported 7 to 10 days after the initial procedure. A delayed diagnosis of IPA after an initially negative duplex ultrasound examination may be attributed to a false negative examination.

IPA is most commonly associated with pain at the access site combined with skin ecchymosis and a subcutaneous hematoma of varying size. The presence of a femoral bruit or thrill may indicate an IPA or, alternatively, an arteriovenous (AV) fistula, but the absence of a bruit does not exclude pseudoaneurysm. Embolization from thrombus that might develop within the pseudoaneurysm rarely occurs in the absence of IPA manipulation. (See 'Ultrasound-guided techniques' below.)

Complicated IPA, which is defined as the presence of any of the following clinical features, should prompt surgical evaluation and management. (See 'Management' below.)

●Hemodynamic instability

●Neurologic deficit (motor or sensory) or pulse deficit attributable to the IPA

●Expanding hematoma

●Extensive skin and subcutaneous damage

●Concern for soft tissue infection (eg, fever, cellulitis, purulent drainage)

Diagnosis — While clinical features may increase suspicion for iatrogenic femoral artery pseudoaneurysm, physical examination alone is notoriously inaccurate, and imaging is required to confirm IPA. Arterial duplex ultrasound evaluation, which has a near 100 percent accuracy for the diagnosis of IPA and other access-related pathology (eg, AV fistula), is recommended as the initial imaging modality [17]. (See 'Duplex ultrasound' below.)

Rarely, other imaging modalities may be needed to confirm the diagnosis of a pseudoaneurysm. Computed tomographic (CT) angiography or catheter-based angiography (ie, digital subtraction angiography) from a contralateral femoral access site can also be used to document IPA. These imaging modalities may provide additional value in cases where duplex ultrasound is equivocal or technically limited (eg, obesity), or if there are other anatomic issues (eg, high arterial puncture). Most often, other imaging is used for patients with a suspicion of ongoing bleeding to help determine if there is active extravasation from the puncture site, or to identify the presence of a retroperitoneal hematoma.

Duplex ultrasound — While B-mode imaging can identify hypoechoic fluid collections (ie, hematoma), color flow Doppler is needed to assess for arterial flow outside the boundaries of the femoral artery.

A 5 to 7 MHz probe is applied in both transverse and longitudinal orientations, and sampling of the femoral vessels is undertaken to record B-mode and color flow arterial images, assess waveform character, and provide velocity measurements of the common, proximal superficial, and deep femoral arteries. (See "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Duplex ultrasound'.)

Typical ultrasound characteristics of a pseudoaneurysm on duplex imaging include the classic swirling bidirectional color flow outside of the femoral artery (ie, yin-yang sign) (image 1), and to-and-fro waveforms within the tract leading to the sac. When a pseudoaneurysm is identified, the following anatomic features are documented: pseudoaneurysm sac size (cm²), dimensions of active flow outside the femoral artery (cm²), aneurysm sac morphology (single or multiple lobes), and pseudoaneurysm neck diameter and length.

The evaluation should also include views of the inflow external iliac artery. Identifying the common femoral vein is particularly important for excluding the presence of an associated arteriovenous fistula. Doppler waveform characteristics, including a low-resistance pattern with significant flow through the diastolic phase of the pulse cycle, raise suspicion of concomitant arteriovenous fistula. (See "Acquired arteriovenous fistula of the lower extremity".)

Differential diagnosis — The differential diagnosis of femoral IPA associated with a percutaneous arterial access includes simple hematoma (ie, no active arterial connection), seroma, or access site infection. Duplex imaging generally differentiates IPA from other causes of swelling in the groin (vascular, nonvascular) and from other access-related complications (eg, arteriovenous fistula). On occasion, advanced vascular imaging may be required to make the distinction. (See 'Diagnosis' above.)

External iliac artery or proximal common femoral artery defects may present with groin swelling but have a tendency to cause retroperitoneal hemorrhage, rather than focal pseudoaneurysm. Management is either surgical with direct repair or endovascular with covered stenting based on local expertise and clinical situation. (See "Periprocedural bleeding in patients undergoing percutaneous coronary intervention", section on 'Retroperitoneal space' and "Access-related complications of percutaneous access for diagnostic or interventional procedures".)

An infectious condition such as primary mycotic aneurysm or anastomotic pseudoaneurysm associated with an open surgical reconstruction is also in the differential diagnosis but generally can be excluded from the medical and surgical history. These require surgical drainage and debridement and removal of any infected material. (See "Overview of infected (mycotic) arterial aneurysm".)

MANAGEMENT — Our approach to managing femoral artery (common, deep, or superficial femoral) pseudoaneurysm (IPA) depends upon the size of the IPA and whether it is complicated or uncomplicated (algorithm 1).

Complicated pseudoaneurysm — Complicated femoral IPA is defined as the presence of any of the following clinical features:

●Hemodynamic instability

●Neurologic deficit (motor or sensory) or pulse deficit attributable to the IPA

●Expanding hematoma

●Extensive skin and subcutaneous damage

●Concern for soft tissue infection (eg, fever, cellulitis, purulent drainage)

Patients with complicated femoral IPA generally require open surgical repair. Endovascular repair (in the absence of infection) can be considered if the patient is deemed high surgical risk. (See 'Vascular and endovascular techniques' below.)

Uncomplicated pseudoaneurysm — Most patients with uncomplicated femoral IPA can be managed with ultrasound-guided treatment or observation.

●For patients with uncomplicated femoral IPA ≥3 cm (asymptomatic or symptomatic), we suggest intervention.

●We observe patients with uncomplicated femoral IPA <3 cm with interval duplex ultrasound. Most uncomplicated IPAs resolve with time; however, this assumes that the patient will be compliant with serial imaging and follow-up. Based upon the available limited data, patients taking conventional antiplatelet agents (aspirin, clopidogrel), including dual antiplatelet therapy, can be observed. With the use of newer-generation antiplatelet agents or direct oral anticoagulants, spontaneous resolution is less likely, and treatment rather than observation may be warranted.

●For patients under observation who develop acute symptoms (in the setting of an IPA ≥1 cm), IPA enlargement, or persistent IPA ≥1.0 cm by six weeks, we suggest intervention. (See 'Observation' below.)

●For uncomplicated femoral IPA that requires treatment, we suggest ultrasound-guided treatment, rather than surgical repair (open or endovascular). Based upon observational studies and one small randomized trial, we suggest ultrasound-guided thrombin injection (UGTI) as the first-line technique, rather than ultrasound-guided compression (UGC) [18-22]. Success rates are higher for UGTI compared with UGC, and recurrence rates after initially successful UGTI are low (<4 percent), even among those on antithrombotic therapy. If UGTI is not available, UGC can be considered prior to proceeding with surgical repair (open, endovascular). (See 'Ultrasound-guided techniques' below.)

●For pseudoaneurysms that fail UGTI, repeat UGTI, UGC, or endovascular treatment can be considered, but if these are unsuccessful, we proceed to open surgical repair. (See 'Vascular and endovascular techniques' below.)

OBSERVATION — For small-diameter (<3.0 cm) femoral artery iatrogenic pseudoaneurysm (IPA), we suggest initial observational management, rather than any form of intervention. Observational management includes limiting patient activity, serial examination, and serial ultrasound. Most clinicians obtain surveillance ultrasound every two weeks for a six-week period. Activity can be increased as the patient tolerates with demonstration of stability/regression of the IPA. Failure to resolve the IPA ≥1 cm by six weeks indicates the need for treatment. Almost all smaller IPAs thrombose within three months; if persistent, minimally invasive treatment is warranted.

The majority of femoral IPAs will thrombose spontaneously, requiring no further treatment. However, observational management of femoral IPAs is not without risk, and follow-up imaging is mandatory. Inadequate compliance with these examinations increases the risk for delayed problems.

Early reviews of observation alone for femoral artery IPAs reported a 50 to 100 percent spontaneous closure rate with thrombosis of the false aneurysm [9,23]. The largest prospective experience included over 80 patients managed with observation alone [24]. In this study, patients who were not anticoagulated had a spontaneous thrombosis rate of 89 percent when the maximum IPA size was <3.0 cm in diameter. The mean time for spontaneous closure was approximately three weeks, with approximately 2.5 duplex exams per patient performed.

A series evaluating the effect of advanced antiplatelet agents that were not available in earlier studies reported significantly higher rates of failed observation for those patients on dual compared with single antiplatelet therapy (44 versus 9 percent) [25].

ULTRASOUND-GUIDED TECHNIQUES — For most uncomplicated femoral iatrogenic pseudoaneurysms (IPAs) that require treatment (see 'Uncomplicated pseudoaneurysm' above), we suggest ultrasound-guided thrombin injection (UGTI) as the first-line technique, rather than ultrasound-guided compression (UGC) [14]. It is important to note that these techniques should not be combined (ie, thrombin injection and compression), as doing so can lead to peripheral embolization.

Observational studies and one small randomized trial comparing UGTI with UGC have generally found higher early success rates (>95 percent) and a shorter hospital stay for UGTI compared with UGC [13,18-22,26-31]. Recurrence rates are low (<4 percent) after UGTI, even among those on antithrombotic therapy [32].

In the randomized trial, 32 patients were randomly assigned to UGC or UGTI with bovine thrombin. At 24 hours, the rate of thrombosis was significantly higher in the UGTI compared with UGC group (100 versus 13 percent) [18]. Within 48 hours, 40 percent of UGC-assigned patients were thrombosed after one or two compression sessions. The length of stay was also significantly lower for the UGTI group. There were no complications in either group.

Thrombin injection — UGTI involves the administration of topical thrombin into the soft tissues comprising the pseudoaneurysm sac [33]. The originally described procedure from the late 1980s used bovine thrombin, but recombinant DNA products are commercially available for use.

Complications following thrombin injection are infrequent. The most serious complications are arterial thrombosis or distal embolization, which are rare (<1 percent). Distal embolization may be related to injection of a small-diameter pseudoaneurysm sac (<1 cm). Other limited evidence has suggested that distal embolization may also be associated with short or wide pseudoaneurysm neck, prompting some clinicians to avoid UGTI in necks >1 cm wide and <0.5 cm long. However, later clinical series have not implicated any particular anatomic criteria as contraindications to UGTI provided the neck of the sac can be clearly identified.

When embolization does occur, spontaneous improvement in arterial perfusion within 48 hours has been noted, but treatment of acute ischemia should be based on the nature and severity of the event. (See "Embolism to the lower extremities".)

Other complications, described in limited case reports, include varying degrees of allergic reactions related to bovine thrombin, infection after thrombin injection, and pseudoaneurysm rupture (one case in an extensive literature review).

Technical tips — UGTI can be performed at the bedside or in the vascular laboratory setting.

●Prior to the procedure, a lower extremity duplex arterial examination should be performed and documented, including the distal tibial arterial waveforms and pedal Doppler signals.

●The groin is prepared with standard antiseptic agent. A sterile ultrasound probe cover is recommended.

●Some clinicians use local anesthetic; however, with experience, and the use of a micropuncture or spinal needle (20 to 22 gauge) to make a single puncture of the pseudoaneurysm sac, local anesthesia may not be necessary.

●Using B-mode imaging, the needle tip is identified and directed into the pseudoaneurysm sac. The clinician should take care to keep the needle tip just inside the capsule as far away from the pseudoaneurysm neck as technically possible. This minimizes the possibility of thrombin administration into the pseudoaneurysm neck and, possibly, into the arterial circulation.

●Recombinant or bovine thrombin (100 to 1000 units/mL) is administered using a 1 mL syringe. Under duplex guidance, the sac is injected with 0.1 mL increments of thrombin until flow is successfully obliterated. Color duplex examination is performed to further confirm pseudoaneurysm closure.

●After successful thrombosis, the distal arterial circulation is assessed, including the distal pedal pulses, and compared with preprocedural findings.

●Following successful thrombosis, bed rest is typically recommended for a period of four to six hours.

●For those in whom thrombin is not initially successful, repeat UGTI can be attempted.

Pseudoaneurysm compression — UGC is another minimally invasive technique for uncomplicated femoral IPA to effect pseudoaneurysm thrombosis (see 'Uncomplicated pseudoaneurysm' above). When it was first described the 1990s, UGC was the first-line treatment for uncomplicated IPA; however, in most centers, UGC has been replaced by percutaneous UGTI, which has less pain and is associated with higher success rates and shorter hospital stays. (See 'Thrombin injection' above.)

UGC success rates range from 60 to 90 percent in experienced hands [27,34-37]. However, compression times greater than one hour can be required, and multiple compression sessions are needed to treat at least 10 percent of femoral artery pseudoaneurysms [38]. The procedure is often painful, which is one of the main reasons UGC fell out of favor. Pain management typically requires some anxiolytic and analgesic administration to permit adequate compression. This requires ongoing physician supervision during the procedure, which may pose logistical issues.

UGC involves static compression of the pseudoaneurysm neck to stop the flow of blood out of the artery. Real-time, duplex, and color Doppler are performed first to identify the neck of the pseudoaneurysm using a linear or curvilinear ultrasound probe (5 or 7 MHz). Manual compression is subsequently applied to the neck of the pseudoaneurysm with the transducer, allowing flow through the native artery but preventing flow into the aneurysm sac. Flow is continuously studied during compression. Duplex-guided compression is maintained for 5 to 10 minute intervals, at the end of which time compression is slowly released to assess for any flow into the pseudoaneurysm. The procedure is repeated until either IPA thrombosis has occurred, the ultrasound operator becomes fatigued, or patient discomfort limits the ability to continue.

Factors associated with failed compression have been evaluated in several reviews [36,39]. Systemic anticoagulation significantly reduces the likelihood of successful UGC with failure rates ranging from 33 to 75 percent in anticoagulated patients. A short neck (<5 mm) length also has unfavorable compression outcomes [40]. In most series, successful UGC is also negatively influenced by increasing size of the pseudoaneurysm [41]. Generally, femoral artery pseudoaneurysms smaller than 2 cm respond best to UGC.

Complications following UGC can include arterial or venous thrombosis and the potential for ongoing groin hemorrhage from compression, as well as reports of aneurysm rupture following UGC.

VASCULAR AND ENDOVASCULAR TECHNIQUES — Open surgical repair remains the best treatment strategy for complicated femoral iatrogenic pseudoaneurysm (IPA), defined as hemodynamic instability, extensive skin and subcutaneous damage, or soft tissue infection. In addition, surgical repair is the final option for those IPAs that have failed other treatment. (See 'Complicated pseudoaneurysm' above and 'Uncomplicated pseudoaneurysm' above.)

Surgery involves obtaining control of the artery proximal and distal to the arterial defect. The location of the puncture and size of the defect dictates the method of repair. A small defect can be repaired primarily. For a larger defect or if the tissue is friable, a vein patch is generally used. The use of prosthetic material in the setting of an urgent exploration or clinical features suggestive of infection is discouraged.

Excluding conditions associated with infection, endovascular techniques can also be considered in cases where ultrasound-guided thrombin injection (UGTI) is not possible due to inability to see the pseudoaneurysm neck or in cases where previous UGTI has not been successful. Small case series have been reported, but endovascular therapy should not be routinely considered as first-line treatment for asymptomatic or complicated iatrogenic femoral artery pseudoaneurysms, as UGTI offers excellent success rates with a low incidence of complications. Endovascular options include coil embolization of the pseudoaneurysm or the use of a covered stent to exclude the pseudoaneurysm from the circulation. For complicated IPA, open surgery is the mainstay of treatment [42].

SUMMARY AND RECOMMENDATIONS

●Iatrogenic pseudoaneurysm (IPA) related to access of the femoral artery for percutaneous-based diagnostic and interventional procedures is the most common site and etiology of pseudoaneurysm. IPA is overall uncommon, occurring in <1 percent of interventional procedures (eg, diagnostic peripheral or cardiac catheterization or peripheral or cardiac intervention). Risk factors for IPA are listed above. (See 'Incidence' above and 'Etiology and risk factors' above.)

●Femoral IPA typically presents shortly after removal of the access sheath but can present in a delayed fashion. Symptoms suggestive of femoral IPA are similar to other complications related to femoral artery puncture and may include ecchymosis, hematoma, swelling, bruit, and pulsatile mass. (See 'Clinical features and diagnosis' above.)

●Duplex ultrasound is recommended as the initial imaging modality to diagnose IPA in any patient with signs and symptoms suspicious for IPA. A mosaic color pattern with classic to-and-fro flow pattern outside the artery wall surrounded by hematoma confirms the diagnosis (image 1). On occasion, advanced arterial imaging may be needed to make a diagnosis or exclude other access-related complications. (See 'Diagnosis' above and 'Differential diagnosis' above.)

●Complicated femoral IPA is defined as the presence of any of the following clinical features:

•Hemodynamic instability

•Neurologic deficit (motor or sensory) or pulse deficit attributable to the IPA

•Expanding hematoma

•Extensive skin and subcutaneous damage

•Concern for soft tissue infection (eg, fever, cellulitis, purulent drainage)

●Our approach to managing femoral IPA depends on the size of the IPA and whether it is complicated or uncomplicated (see 'Management' above):

•Patients with complicated femoral IPA generally require open surgical repair. Endovascular repair (in the absence of infection) can be considered if the patient is deemed high surgical risk. (See 'Vascular and endovascular techniques' above.)

•Most patients with uncomplicated femoral IPA can be managed with ultrasound-guided treatment or observation. For patients with uncomplicated femoral IPA ≥3 cm (asymptomatic or symptomatic), we suggest intervention (Grade 2C). Patients with uncomplicated femoral IPA <3 cm can be managed with observation with interval duplex ultrasound. For patients under observation who develop acute symptoms (in the setting of an IPA ≥1 cm), IPA enlargement, or persistent IPA ≥1.0 cm by six weeks, we suggest intervention (Grade 2C). Almost all smaller IPAs thrombose within three months; if persistent, minimally invasive treatment is warranted. (See 'Uncomplicated pseudoaneurysm' above and 'Observation' above.)

•For uncomplicated femoral IPA that requires treatment, we suggest ultrasound-guided treatment, rather than surgical repair (open or endovascular) (Grade 2C). We suggest ultrasound-guided thrombin injection (UGTI) as the first-line technique, rather than ultrasound-guided compression (UGC) (Grade 2C). Success rates are higher and hospital stays are shorter for UGTI compared with UGC. Technical tips for successful UGTI are provided above. If UGTI is not available, UGC can be considered prior to proceeding with surgical repair (open, endovascular). (See 'Ultrasound-guided techniques' above.)

•For pseudoaneurysms that fail UGTI, repeat injection, UGC, or endovascular options can be considered, but if these are unsuccessful, we proceed with open surgical repair. (See 'Vascular and endovascular techniques' above.)