Femoral artery aneurysm

INTRODUCTION — Although they are the second most common type of true peripheral aneurysm after those involving the popliteal artery, femoral artery aneurysms (FAAs) are uncommon, and their natural history is not well characterized.

Most FAAs are asymptomatic at presentation, but patients can develop a variety of symptoms related to expansion or thrombosis. FAAs can also present with limb-threatening complications due to occlusion, distal embolization, or rupture, although the incidence of acute limb ischemia is lower for femoral compared with popliteal artery aneurysms. The decision to repair an FAA primarily depends on the clinical presentation, the aneurysm diameter, and how fit the patient is for open surgery, the predominant method of repair.

The clinical features, diagnosis, and management of true FAAs will be reviewed. Other peripheral artery aneurysms that may be associated with FAAs are reviewed separately. (See "Popliteal artery aneurysm" and "Iliac artery aneurysm" and "Overview of abdominal aortic aneurysm".)

ANATOMIC ISSUES

Femoral anatomy — The common femoral artery is the continuation of the external iliac artery, the name changing as it crosses the inguinal ligament (figure 1 and figure 2). Approximately 2 to 6 cm below the inguinal ligament, the femoral artery bifurcates into the superficial and deep femoral (ie, profunda femoris) arteries.

Because of their less superficial location, aneurysms involving the deep femoral and superficial femoral arteries are less likely be detected until they are relatively large. (See 'Clinical presentation' below.)

Definition of femoral aneurysm — True aneurysms involve all three layers of the vessel wall, in contrast to pseudoaneurysms that may contain elements of the arterial wall but do not consist of all three layers.

The Society of Vascular Surgery defines a true aneurysm as a focal, isolated arterial dilation that includes all three layers of the vessel wall and measures at least 1.5 times the diameter of the disease-free proximal, adjacent segment [1,2]. For reference, the normal diameter of a common femoral artery is approximately 1.0 cm in men and 0.8 cm in women [3].

Classification and distribution — FAAs have been classified based on anatomic site and relationship to the femoral bifurcation (type I, type II) [4]. Another classification system includes isolated deep femoral and superficial femoral aneurysms as well, which are classified as type III and type IV, respectively (figure 3) [5]. While frequently used in research, classification of FAAs may be less useful compared with a simple clinical description of the size, location, and extent of the vessels involved.

Some argue that aneurysms of the distal superficial femoral artery that extend into Hunter's canal should be considered distinct from proximal femoral aneurysms since they behave more like popliteal aneurysms [6].

Among femoral aneurysms, those involving the common femoral artery are the most common, either in isolation or in conjunction with the superficial or deep femoral arteries. The distribution of common, superficial, and deep femoral involvement is approximately 80, 15, and 5 percent, respectively [7,8].

Aneurysms of the superficial and deep femoral arteries can exist in the absence of common femoral artery involvement, but these are rare [6,9-11]. In the literature, only 100 cases of isolated superficial femoral [12] and 46 cases of isolated deep femoral aneurysms have been reported [9].

PATHOGENESIS — Although peripheral aneurysms can be focal, they frequently occur concurrently with other aneurysms, suggesting a role for systemic or genetic factors in their pathogenesis. As with aortic and other peripheral aneurysms, weakening of the arterial wall observed with FAAs is associated with degenerative processes involving inflammation, proteolytic pathways, and changes in matrix composition with loss of medial elastic laminae [13-15].

Histologic evaluation of wall specimens from true femoral aneurysms reveals atherosclerotic plaque in the majority of cases [16]. Although approximately 60 percent of patients with FAAs have associated lower extremity occlusive disease, the role of atherosclerosis and whether it is causative or merely associated with aneurysm formation is still debated. Distinct risk factors exist for aneurysmal versus atherosclerotic disease [17]. In addition, aneurysmal disease is surprisingly rare in specific locations known to be particularly prone to atherosclerosis, such as the external iliac and superficial femoral arteries [13].

Infection, arteriomegaly, and other syndromes represent other minor etiologies of FAAs. (See "Epidemiology, risk factors, pathogenesis, and natural history of abdominal aortic aneurysm" and "Popliteal artery aneurysm", section on 'Pathogenesis' and "Overview of infected (mycotic) arterial aneurysm".)

EPIDEMIOLOGY AND RISK FACTORS — True degenerative FAAs are uncommon, occurring in approximately 5 per 100,000 patients [18]. There is a strong male predilection, with men comprising 90 to 100 percent of the study population in most published case series [7,16,19].

The risk factors for FAA are similar to those of other large vessel aneurysms (abdominal aorta, iliac, popliteal) and include older age, male sex, smoking, hypertension, hyperlipidemia, coronary heart disease, and peripheral artery disease [7,16,19,20]. Other risk factors include arteriomegaly, vasculitis, and connective tissue disease (eg, Marfan syndrome, vasculo-Behçet syndrome) [16,20-23]. (See "Epidemiology, risk factors, pathogenesis, and natural history of abdominal aortic aneurysm", section on 'Pathophysiology of AAA' and "Clinical features and diagnosis of abdominal aortic aneurysm", section on 'Risk factors'.)

Infection from bloodborne sources (eg, valve disease, dental procedure, skin infection) may cause aneurysms, but at the femoral site it is more likely to cause a pseudoaneurysm. (See "Overview of infected (mycotic) arterial aneurysm".)

Congenital idiopathic aneurysm has been reported in the superficial femoral artery [24]. Parkes Weber syndrome and its variants (capillary malformation, multiple arteriovenous fistulas) have also been associated with superficial FAA [25].

CLINICAL PRESENTATION — The clinical presentation of FAA varies, from the finding of an asymptomatic mass on routine physical examination to acute limb-threatening ischemia. The incidence of acute limb ischemia is lower for FAAs compared with popliteal aneurysms. (See "Popliteal artery aneurysm", section on 'Acute ischemia'.)

Up to three fourths of patients with FAAs in contemporary series are asymptomatic at presentation [7,16]. Many FAAs are first identified as incidental findings on computed tomography (CT) or magnetic resonance (MR) imaging performed for other reasons, including during evaluation of aortic or popliteal aneurysms [8]. (See "Popliteal artery aneurysm", section on 'Screening for other aneurysm'.)

Patients may notice a new pulsatile mass in the groin region or symptoms such as pain over the mass from compression of surrounding structures (eg, femoral nerve) or pain with walking (ie, claudication) that may be due to chronic thrombosis of the aneurysm. Deep vein thrombosis due to compression of the adjacent femoral vein has also been observed [4]. FAAs may also be bilateral in up to 25 percent of patients [7,16,26]. (See 'Screening for other aneurysm' below.)

FAAs can also present with limb-threatening complications such as acute aneurysm thrombosis, embolism from the aneurysm, and aneurysm rupture. The reported proportion of patients presenting with such life- or limb-threatening complications has been highly variable, ranging from 3 to 65 percent [4,7,19,27]. The deeper location of the deep and superficial femoral arteries may allow FAAs at these sites to become larger, compared with the common femoral artery, and thus more likely to present with symptoms of rupture that include acute severe pain, hypotension, extremity ecchymosis, and expanding hematoma [6,9,16,28,29]. However, a large series review of 236 FAAs in 182 patients from eight institutions did not report a significant association between location and natural history of the aneurysm [7]. (See "Clinical features and diagnosis of acute lower extremity ischemia".)

DIAGNOSIS — Asymptomatic FAAs can often be identified on physical exam, but this may depend on the patient's body habitus. When FAA is suspected based upon history, localized symptoms, or physical findings, duplex ultrasound is the initial imaging modality of choice for most patients. The demonstration of an abnormally dilated femoral artery (ie, ≥1.5 times the normal diameter or approximately 1.5 cm) confirms the diagnosis.

Vascular imaging — While duplex ultrasound is the most rapid and least invasive method, vascular imaging can also be accomplished with computed tomographic (CT) angiography or magnetic resonance (MR) angiography. CT and MR angiography provide greater anatomic definition and can aid in preoperative planning. The choice of modality depends upon institutional resources and the initial clinical presentation. These imaging modalities effectively exclude other etiologies that can cause lower extremity pain or ischemia. (See 'Differential diagnosis' below.)

Although uncommon as a primary etiology (infected anastomotic pseudoaneurysm being more common), infected FAA should be suspected when fluid, inflammation, pseudoaneurysm without prior instrumentation or trauma, or an irregular artery wall is identified on imaging or at the time of surgery. (See "Overview of infected (mycotic) arterial aneurysm".)

Screening for other aneurysm — It is well established that patients with FAAs frequently have synchronous aortic or other peripheral artery aneurysms (including other FAAs) in the ipsilateral or contralateral limbs. The published incidence rates vary widely, ranging from 29 to 92 percent for synchronous femoral and aortic aneurysms [30,31], 27 to 65 percent for synchronous femoral and other peripheral aneurysms [26,31], and 26 to 72 percent for synchronous contralateral FAAs [7,19]. Such large variations may be a result of differential screening by different authors.

Because of the high incidence of synchronous aneurysms, we recommend ultrasound or CT imaging to exclude abdominal aortic aneurysm or other peripheral artery aneurysms (ipsilateral or contralateral) in those identified with FAA [2]. (See 'Synchronous aneurysms' below.)

Differential diagnosis — The differential diagnosis of FAA includes vascular and nonvascular etiologies that may result in a mass in the groin region. These are usually easily distinguished from true femoral aneurysms with the vascular imaging studies discussed above. When ultrasound fails to demonstrate an FAA in the setting of a pulsatile mass in the groin, other imaging modalities such as CT scan or MR imaging may be used to further characterize the lesion as the pulse may be transmitted through other structures or masses. (See 'Diagnosis' above.)

●Femoral artery pseudoaneurysm – Pseudoaneurysms affecting the femoral artery are far more common than true aneurysms. The diagnosis may be suspected in a patient with a groin or thigh mass who has a history of iatrogenic injury from instrumentation or trauma, or a history of prior vascular surgery leading to the infection or disruption of previous vascular anastomoses. The treatment of femoral artery pseudoaneurysm differs from that of true arterial aneurysm. (See "Femoral artery pseudoaneurysm following percutaneous intervention".)

●Hematomas – Hematoma without arterial defects must also be considered, particularly in patients who are anticoagulated or among those who have undergone percutaneous intervention. (See "Periprocedural complications of percutaneous coronary intervention", section on 'Retroperitoneal bleeding' and "Access-related complications of percutaneous access for diagnostic or interventional procedures", section on 'Retroperitoneal hematoma'.)

●Tumors or enlarged lymph nodes – These can have a pulsatile quality when they reside directly over the femoral artery. (See "Evaluation of peripheral lymphadenopathy in adults", section on 'Inguinal'.)

●Femoral hernia – Femoral hernias present as a protrusion through the femoral ring, which is medial to the femoral vein and artery (figure 4). A large hernia may appear to be pulsatile. (See "Classification, clinical features, and diagnosis of inguinal and femoral hernias in adults".)

●Lipoma – Lipoma is typically a superficial, painless, mobile mass within the subcutaneous tissue. Large lipoma in the groin overlying the femoral artery may seem to be pulsatile on palpation. Lipoma in association with the femoral vein has been reported and could be confused for FAA on physical examination or may cause vein compression leading to lower extremity swelling [32]. Subfascial lipoma is much less common but may present as a mass that needs to be distinguished from superficial FAAs [33]. (See "Overview of benign lesions of the skin", section on 'Lipoma'.)

MANAGEMENT APPROACH — The decision to perform FAA repair is based largely upon the diameter of the aneurysm and any associated symptoms, with the location of the aneurysm influencing repair options (algorithm 1).

Symptomatic patients — Patients with FAA rupture or other symptoms attributable to the aneurysm (eg, pain, ischemia) require repair. Repair is indicated for intact symptomatic FAA to prevent future complications from rupture, thrombosis, or embolization. (See 'Femoral aneurysm repair' below.)

Asymptomatic patients — For patients who are asymptomatic, management is largely based on the diameter of the FAA, with the location of the aneurysm influencing repair options.

●Small FAA – Most asymptomatic, small (<3.0 cm) FAAs can be safely observed. The risk of rupture or other complications such as thrombosis or embolization is very low in these patients and is mainly associated with FAA diameter, albeit to a lesser extent than with abdominal aortic aneurysm. The risk of thrombosis may be higher for small FAAs and lower with larger FAAs. In a small retrospective review of 17 FAAs, the thrombosis rate for FAA <5.0 cm was 17 percent compared with 5 percent for those >5.0 cm, while the risk of rupture for FAA <5.0 cm was 1.6 percent compared with 16 percent for those >5.0 cm [31]. The risk of any aneurysm complication increased fivefold for FAA over 4 cm [7]. The two largest series of true degenerative FAAs in the literature also suggest that the natural course of FAA is more benign compared with popliteal aneurysms, with acute complications occurring only rarely in FAA <3.5 cm [7,19]. Thus, patients with small FAA can be followed annually with repeat clinical evaluation and vascular imaging, typically using duplex ultrasound.

Factors that may prompt clinicians to intervene on small, asymptomatic FAAs include rapid expansion (diameter increase >0.5 cm within one year), the development of intraluminal thrombus, or saccular aneurysm morphology (may indicate infected aneurysm) [7,34]. However, data to support these criteria are limited.

●Large FAA – For patients with asymptomatic large FAAs (≥3.0 cm), we suggest repair if the patient is otherwise a good candidate for surgery. For poor-risk surgical candidates with favorable anatomy, an endovascular approach may be reasonable; otherwise, these patients are observed and repaired only if the FAA becomes symptomatic. (See 'Femoral aneurysm repair' below.)

Traditionally, repair was recommended for FAAs once they reached a diameter ≥2.5 cm. These guidelines were largely extrapolated from data on popliteal aneurysms [3]. However, given the more benign natural history of FAAs [7,19], we agree with consensus guidelines that advocate a more conservative approach, pointing to an extremely low rate of acute ischemic complications in aneurysms <3.5 cm [1,2].

Isolated aneurysms of the superficial and deep femoral arteries are uncommon with few natural history studies to guide management. It has been suggested that all deep FAAs be repaired due to the high incidence complications [28].

Synchronous aneurysms — For patients with synchronous peripheral artery aneurysms, repair of any symptomatic aneurysm should be performed first. For patients with asymptomatic femoral artery and abdominal aortic aneurysms that meet criteria for repair, the abdominal aneurysm should be repaired first, or both may be repaired concurrently. The exact location, size, and expected method of repair, whether open or endovascular, will need to be considered in each circumstance [20,35]. (See "Management of asymptomatic abdominal aortic aneurysm", section on 'Coexistent aneurysm or peripheral artery disease'.)

FEMORAL ANEURYSM REPAIR — The approach, role of endovascular repair, and outcomes for FAA repair are described below. Specific technical issues regarding lower extremity revascularization are discussed separately. (See "Lower extremity surgical bypass techniques".)

Approach — FAA repair is typically undertaken using an open surgical approach, in a manner that is similar to open repair of an abdominal aortic aneurysm (ie, endoaneurysmorrhaphy), but lower extremity bypass procedures may be needed for more extensive FAA.

●Common FAA – For aneurysms involving the common femoral artery only, repair is usually performed with an end-to-end interposition graft of polytetrafluoroethylene (PTFE) or Dacron. For more complicated FAAs of the common femoral artery, the uninvolved branch is implanted into the interposition graft with an end-to-side anastomosis [4]. For aneurysms that involve the origins of both the superficial femoral and profunda femoris arteries, the use of a Dacron bifurcated graft, traditionally used for axillobifemoral bypasses, has been described [36].

For more extensive aneurysms, vascular bypass with aneurysm exclusion (ligation of the artery above and below the aneurysm) can be undertaken from the external iliac artery to the common femoral artery, superficial femoral artery, or deep femoral artery. On occasion, a separate retroperitoneal incision or division of the inguinal ligament may be necessary to access and control the external iliac artery [3]. Alternatively, balloon occlusion may be used.

●Superficial femoral artery (SFA) aneurysm/deep FAA – True aneurysms of the SFA and deep femoral arteries are rare. Because of their deep position in the thigh, these are more likely to present at a larger diameter. True aneurysms of the SFA can be treated using endovascular stent-graft techniques or by proximal and distal ligation followed by femoral-popliteal bypass [12]. For patients with distal superficial femoral/popliteal aneurysm or associated femoropopliteal occlusive disease, bypass to the popliteal or tibial arteries may be needed [20]. Aneurysms of the deep femoral artery may be treated by ligation when the SFA is patent. When needed to prevent limb ischemia, revascularization of the deep femoral artery can be performed using great saphenous vein bypass [37]. Endograft repair using short, covered grafts has also been reported [38].

●Occluded FAA – Ligation of the aneurysm without repair or bypass is an option for occluded FAA if there is no evidence of distal ischemia, particularly for isolated deep femoral aneurysms with a patent femoropopliteal segment. Ligation is an acceptable approach for femoral aneurysms associated with chronic occlusion of the superficial femoral artery in asymptomatic or minimally symptomatic patients. In general, occluded FAAs should be repaired if there are suitable runoff vessels and it is thought that the patient would obtain symptomatic benefit from revascularization [4,9,39].

●Infected FAA – Infected FAA should be resected completely and sent for culture along with any surrounding fluid. Arterial reconstruction in the setting of infection is usually performed using autogenous conduit, typically saphenous vein. For severe infection and particularly in the case of intravenous drug abuse, ligation may be reasonable with extra-anatomic revascularization reserved for those who develop severe limb ischemia, typically from the obturator canal or axillary artery.

Role of endovascular repair — Experience with endovascular treatment of FAAs is limited. Endovascular repair has primarily been performed in urgent situations involving aneurysm rupture, or for patients who are hemodynamically unstable, critically ill, or not likely to tolerate traditional open repair [40].

Stent placement in the common femoral artery is generally avoided, given the risk of future stent fracture or migration due to repeated hip flexion [41]. In addition, the short length of the common femoral artery makes it difficult to obtain an adequate seal while preserving flow into both the superficial and deep femoral arteries [8].

Covered stents have been used successfully for FAAs of the mid- to distal superficial femoral artery, a location for which there is generally an adequate zone for sealing, and protection from bending stresses [42]. However, few cases of such repair are reported in the literature, and long-term data are unavailable [43]. Hybrid procedures involving open surgical techniques and endovascular stent grafting have also been described [44]. In addition, endovascular techniques may be used as an adjunct to open surgery to obtain vascular control.

While not commonly necessary, thrombolysis can be used to help manage virtually any peripheral arterial occlusion, including acutely thrombosed FAA, and may salvage runoff vessels. Endovascular thrombolysis in the setting of acute FAA has not been adequately assessed. (See "Embolism to the lower extremities", section on 'Approach to limb management'.)

Outcomes — Perioperative mortality following FAA repair has been reported to be between 1 and 5 percent [4,7,19]. Long-term patency and limb salvage rates are overall excellent, with no graft thrombosis or late limb loss reported in two separate series [7,26]. For patients undergoing repair, in one of these series, the risk of graft-related complications was low (approximately 1 percent), while the overall risk of surgery was 20 percent when including seroma, hematoma, systemic illness, and infection [7].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic and other peripheral aneurysms".)

SUMMARY AND RECOMMENDATIONS

●Femoral artery aneurysm – Femoral artery aneurysms (FAAs) are the second most common true peripheral aneurysms after those affecting the popliteal artery, but they remain uncommon. A femoral artery is considered aneurysmal if its diameter is 1.5 times the diameter of a normal proximal adjacent arterial segment, or approximately 1.5 cm. FAAs are seen almost exclusively in older male smokers with hypertension. (See 'Introduction' above and 'Anatomic issues' above and 'Epidemiology and risk factors' above.)

●Clinical presentations – Up to three fourths of FAAs are asymptomatic at presentation. Symptoms and findings may include localized pain, pain with ambulation (ie, claudication), and a palpable pulsatile groin or thigh mass. Acute limb-threatening ischemia from aneurysm rupture, thrombosis, or distal embolization can also occur. (See 'Clinical presentation' above.)

●Diagnosis – The diagnosis of FAA is based upon confirmatory imaging. Duplex ultrasound is the initial study of choice. Computed tomography (CT) angiography and magnetic resonance (MR) angiography may be helpful for preoperative planning. Screening for synchronous abdominal aortic aneurysms or other peripheral aneurysms is mandatory. (See 'Diagnosis' above and 'Synchronous aneurysms' above.)

●Management – The decision to repair FAA is based largely upon the diameter of the aneurysm and any associated symptoms, with the location of the aneurysm influencing repair options (algorithm 1). (See 'Management approach' above.)

•The presence of FAA rupture or other symptoms attributable to the aneurysm (eg, pain, ischemia) indicates the need for repair.

•Most small (<3.0 cm), asymptomatic FAAs can be safely observed with annual clinical evaluation and vascular imaging.

•For large (≥3.0), asymptomatic FAA, we suggest repair (typically open surgical) for good-risk surgical candidates (Grade 2C). An endovascular approach may be reasonable for poor-risk surgical candidates with favorable anatomy; otherwise, these patients are observed and repaired only if the FAA becomes symptomatic. Factors that may prompt clinicians to intervene on smaller FAA include rapid expansion (>0.5 cm in one year), saccular morphology (possibly infected), and the presence of significant intraluminal thrombus (increased risk for thrombosis, embolization).

•Few data are available to guide management of isolated aneurysm of the superficial and deep femoral arteries. All deep FAAs may benefit from repair due to the high incidence complications [28].

●Femoral aneurysm repair – Repair of FAA is typically undertaken using an open surgical approach. Symptomatic, occluded femoral aneurysms should be managed with vascular reconstruction rather than simple ligation, if feasible. Endovascular repair has generally been limited to urgent cases involving aneurysm rupture or for patients who cannot tolerate traditional open repair, provided it is anatomically feasible. (See 'Femoral aneurysm repair' above.)