Isolated aneurysms of the common iliac arteries (CIAs) are extremely rare, comprising only 0.4% to 1.9% of all aneurysmal diseases [1,2]. A pseudoaneurysm of the common iliac artery is an even rarer occurrence. In most cases, the development of iliac pseudoaneurysms is associated with arteriosclerosis, trauma, surgical interventions (particularly pelvic surgery), interventional procedures, infections, inflammatory conditions, connective tissue disorders, vasculitis, or local erosion caused by malignancy [2-4]. Spontaneous pseudoaneurysms of the iliac arteries are extremely rare [2].

Due to their deep pelvic location, most iliac pseudoaneurysms are asymptomatic and difficult to detect unless they grow large. When large, they can compress adjacent structures, causing complications such as hydronephrosis and recurrent urinary tract infections from ureteral compression, bowel obstruction from intestinal compression, deep vein thrombosis (DVT) and lower limb edema from iliac vein compression, or neurological symptoms from nerve root involvement. Rupture can result in life-threatening hemorrhage with high mortality rates [1-3].

We report a rare case of an infected right CIA pseudoaneurysm presenting with DVT, which was successfully managed with endovascular stent graft placement. This case underscores the clinical significance of prompt diagnosis and effective management in addressing this rare and potentially life-threatening condition. This report complies with the Surgical CAse REport (SCARE) criteria [5]. Institutional Review Board approval was waived due to the retrospective case report. Written informed consent was obtained from the patient for their anonymized information to be published in this article.

A 46-year-old previously healthy Sinhalese male from Sri Lanka developed dull right-sided lower back pain and right lower quadrant abdominal pain 6 months ago. The pain radiated down the back of his leg to the foot and worsened with movement. Over the past 2 months, he also developed painless swelling of the right lower limb. He denied colicky abdominal pain, urinary symptoms, weight loss, anorexia, or fever. The patient was an occasional smoker and denied intravenous drug use. Initially, he was treated at a primary care facility with oral antibiotics for a suspected soft tissue infection, followed by compression stockings for presumed lymphedema (Fig. 1).

Figure 1. Right lower limb swelled due to deep vein thrombosis.

As the swelling worsened, the patient developed tightening pain in the thigh and calf during exercise, relieved after 30 minutes of rest, suggestive of venous claudication. This prompted referral to a vascular surgeon at a tertiary hospital. On examination, the abdomen showed an ill-defined fullness in the right lower quadrant and mild tenderness in the right renal angle. The right thigh and lower limb were swollen, with calf tenderness. Pulses were normal, and there were no signs of varicose veins, venous gangrene, or inguinal lymphadenopathy. No clear thrombosis risk factors were identified, and the patient had no respiratory symptoms suggestive of pulmonary embolism. A provisional diagnosis of right lower limb DVT was made. Venous duplex ultrasound confirmed subacute DVT involving the common femoral, superficial femoral, popliteal, and posterior tibial veins.

Initial hematological investigations revealed neutrophil leukocytosis (white cell count 12×10³/µL), hemoglobin of 13 g/dL, elevated erythrocyte sedimentation rate (ESR) of 110 mm/1st hour, and elevated C-reactive protein (CRP) of 120 mg/L. Renal, liver, and coagulation profiles were normal. Peripheral blood smears showed neutrophil leukocytosis with toxic granules, indicative of bacterial infection, but multiple blood cultures were negative. The Mantoux test was also negative, and radiographs showed no evidence of pulmonary tuberculosis. Lumbosacral spine radiographs were also unremarkable (Fig. 2). Abdominal ultrasonography revealed mild hydronephrosis of the right kidney and a non-obstructive 5 mm calculus in the lower pole. The patient was commenced on therapeutic anticoagulation.

Figure 2. (A, B) Lumbosacral and (C) chest radiographs demonstrated normal findings.

Over the following 3 days, the patient’s abdominal pain worsened, and the hemoglobin level dropped from 13.6 to 10.0 g/dL. The worsening symptoms, elevated inflammatory markers, absence of provoking factors for DVT, and declining hemoglobin levels prompted a contrast-enhanced computed tomography (CECT) with CT angiography (CTA) (Fig. 3, 4). Imaging revealed a pseudoaneurysm of the right CIA, extending to its bifurcation, with an irregular wall and mural thrombosis. The right internal iliac artery (IIA) was not visualized beyond the aneurysm, likely due to thrombosis. The pseudoaneurysm was compressing the inferior vena cava (IVC) at its origin, with multiple filling defects observed in the right external iliac, common femoral, superficial femoral, and popliteal veins. These findings suggested that the DVT was secondary to venous stasis caused by the mass effect of the large CIA pseudoaneurysm. Mild right hydronephrosis and upper hydroureter were also noted, suggesting ureteric compression. The right ureter was retrogradely stented to alleviate this compression.

Figure 3. Computed tomography angiography demonstrated 6.0×4.0 cm pseudoaneurysm of the right common iliac artery. (A) Three-dimensional reconstruction, (B) maximum intensity projection image highlighting the pseudoaneurysm.

Figure 4. Axial images of computed tomography angiography demonstrated (A) right hydronephrosis and hydroureter due to ureteric compression, (B) narrow proximal neck and partial inferior vena cava compression, (C) an eccentric pseudoaneurysm with mural thrombus, and (D) absent flow in the internal iliac artery.

Based on the radiological and biochemical investigations, a tentative diagnosis of an infected right CIA pseudoaneurysm was made, and anticoagulation therapy was discontinued. Despite negative cultures, the patient was started on intravenous meropenem (1 g every 8 hours). After 1 week of antibiotic therapy and normalization of CRP levels, the patient was scheduled for endovascular treatment.

An endovascular approach was choosen due to the higher morbidity associated with open surgery. Diagnostic angiography revealed contrast extravasation into a large 6.0×4.0 cm pseudoaneurysm arising from the right CIA, approximately 2.5 cm from the aortic bifurcation, with a discontinuous segment in the IIA. Distal run-off to the leg was intact. The affected segment was stented using an 8×58 mm LifeStream^TM Balloon Expandable Vascular Covered Stent (Becton Dickinson). Post-procedure imaging showed satisfactory stent expansion with in-line flow across the stent (Fig. 5).

Figure 5. (A) Angiogram demonstrated large iliac artery pseudoaneurysm extending from inferior to the aortic bifurcation to common iliac artery bifurcation with possibly thrombosed internal iliac artery, (B) the inserted endovascular stent, and (C) the post-procedure run.

Potential infection foci were reviewed, including spine imaging, transthoracic echocardiography, and abdominal CECT, but no definitive source was identified. Despite negative blood cultures, intravenous antibiotics were continued for 4 weeks based on microbiological guidance. Inflammatory markers (ESR and CRP) normalized, and the patient showed clinical improvement. Antibiotic therapy was subsequently de-escalated to oral clindamycin, with plans to reassess therapy duration after 6 weeks. Follow-up CTA, performed 2 weeks after endovascular stenting, demonstrated a reduced pseudoaneurysm size along with decreased pressure effects on the ureter and venous structures (Fig. 6). CT-guided aspiration for clot sampling was considered but deemed technically challenging and high risk for an asymptomatic patient. The patient remains asymptomatic.

Figure 6. Follow-up computed tomography scan demonstrated resolution of the (A) hydronephrosis (black arrow) and hydroureter after stent placement and (B) anterior displacement of the ureter (white arrow) with reduced pseudoaneurysm.

Isolated iliac aneurysms are rare and most commonly occur in the CIA (70%), followed by the IIA (20%), and rarely in the external iliac artery (EIA) [1]. Pseudoaneurysms of the iliac arteries are even less common and typically arise from trauma, iatrogenic procedures (e.g., endovascular or post-pelvic surgeries), vasculitis, connective tissue disorders, or malignancy-related erosion [2,6].

Microbial infections can also cause iliac pseudoaneurysms, either through primary vessel wall infections or secondary spread from nearby foci, such as appendicular or pelvic infections [7,8]. Common causative organisms include Streptococcus, Staphylococcus, and Salmonella species, with approximately 70% of patients yielding at least one positive culture. Less frequently, infections like tuberculosis or Aspergillus have been reported [9]. However, in 25%-40% of infected aneurysm cases, cultures may be negative, as observed in our case [10]. Prior antibiotic therapy, such as the oral antibiotics given for presumed soft tissue infection, may contribute to the negative culture results.

Most iliac pseudoaneurysms are asymptomatic and remain clinically undetected due to their deep pelvic location. Symptoms typically result from the mass effect on adjacent structures. Bowel compression may cause intestinal obstruction, while ureteric compression can lead to hydroureter, hydronephrosis, and an increased risk of urinary tract infections or pyelonephritis. Compression of the IVC and iliac vein can cause unilateral or bilateral lower limb venous edema, DVT, venous claudication, or, in severe cases, venous gangrene [1,2]. Neurological symptoms, such as radiculopathy, sciatica, or rarely, foot drop, are more commonly associated with IIA aneurysms, due to lumbar plexus compression [11,12]. In rare cases, CIA pseudoaneurysms can fistulate into the common iliac vein, causing further complications [13].

Since pseudoaneurysms are not covered by all three layers of the vessel wall, they have a high risk of rupture [10]. Emergency presentation following aneurysm rupture has a high mortality rate of 25%-57% [1]. To date, CIA pseudoaneurysms presenting with unilateral limb swelling secondary to DVT remain exceedingly rare, with only a few reported cases [14].

Ultrasonography is the preferred initial screening tool for aneurysms due to its low cost and availability; however, CT or magnetic resonance angiography offers superior diagnostic accuracy, particularly in assessing the site and size of the aneurysms, and is crucial for operative planning [1]. CTA is the first-line investigation for pelvic pseudoaneurysm, providing high sensitivity and specificity [2,10]. In retrospect, CTA should have been considered earlier in our patient, given the unprovoked thrombosis, dull abdominal pain, and radiculopathy. Despite resource limitations, cross-sectional imaging should be prioritized in such cases. Our case highlights the need for greater awareness of potential provoking factors in the evaluation of unprovoked iliofemoral DVT.

The choice between surgical and endovascular repair depends on patient fitness for surgery, arterial anatomy, and surrounding structures. Endovascular techniques are increasingly favored as they minimize complications from pelvic dissection, reduce blood loss, shorten hospital stays, and enable faster recovery [1,2]. Open surgery may be preferable in cases with severe pressure-related symptoms for quicker symptom relief [2]. In this case, surgical dissection through an inflamed field was deemed risky due to the potential for damaging nearby structures, such as the cecum, bladder, and ureter [1,15]. Notably, current guidelines also indicate that infection is not a contraindication for endovascular management of pseudoaneurysm [3].

A 1 cm proximal and distal landing zone of normal artery is required for successful landing and attachment of a stent graft. If the distal landing zone is inadequate, the stent can be extended to the EIA, often with IIA embolization to prevent retrograde perfusion and type 2 endoleak [1]. In this case, a balloon-expandable covered stent was placed retrogradely into the CIA and extended distally to the EIA. Since no flow was observed in the IIA, embolization was not performed. Post-procedure angiogram showed no evidence of endoleak. Balloon-expandable covered stents are preferred over self-expanding stents for iliac interventions due to their precision [16].

Despite negative blood cultures and the absence of tissue or fluid cultures from the hematoma, the patient was managed for an infected pseudoaneurysm based on clinical, radiological, and biochemical findings. CT-guided aspiration was considered 2 weeks after endovascular stenting but was not performed due to the patient’s complete clinical response and the potential morbidity of the procedure. The optimal duration of antibiotic for infected aneurysms is uncertain; however, most guidelines recommend approximately 8 weeks of parenteral antibiotics. In this case, complete resolution of biochemical markers was noted, suggesting sensitivity to intravenous carbapenems, and 18 months of oral antibiotics was prescribed after multidisciplinary review. The duration of oral antibiotic therapy remains controversial, particularly in the absence of confirmatory microbiological cultures and sensitivity patterns.

In summary, pseudoaneurysms of the CIA are rare but associated with high mortality. Lower limb DVT as a presentation of an infected iliac pseudoaneurysm is exceptionally uncommon. Early referral to vascular surgery and timely intervention are essential for favorable outcomes. Given the lack of clear guidance on the management of infected pseudoaneurysms, a multidisciplinary, patient-centered approach is crucial for optimizing treatment strategies, including intervention, microbiological sampling, and antibiotic therapy.

None.

The authors have nothing to disclose.

Concept and design: DMG, LE, TG. Analysis and interpretation: DMG, TG. Data collection: DMG. Writing the article: DMG, LE. Critical revision of the article: PA, TG. Final approval of the article: DMG, TG. Statistical analysis: none. Obtained funding: none. Overall responsibility: DMG.