A Case of Isolated External Iliac Vein Compression Syndrome and the Role of Advanced Imaging

Introduction

Iliac vein compression syndrome can cause venous hypertension of the lower legs. Nonthrombotic iliac vein lesion (NIVL) is a variant of May-Thurner syndrome, which occurs in the absence of a deep venous thrombosis (DVT). ^1,2 Typically, NIVL involves the common iliac vein due to its anatomic relation to surrounding structures such as the iliac artery. Here, we report our experience with a rare case of symptomatic isolated external iliac vein compression without involvement of the common iliac vein, documented by venogram and intravascular ultrasound (IVUS), and its successful treatment with venous stenting. Diagnosis and management of isolated external iliac vein compression is not well reported.

Case Presentation

An 86-year-old male presented with a history of persistent left lower extremity swelling for several years associated with superficial skin blisters and ulcerations despite conservative measures and a trial of diuretics (Figure 1A). He underwent a comprehensive evaluation with blood tests and imaging. His blood test revealed normal creatinine, thyroid function, serum albumin, d-dimer, and age-adjusted brain natriuretic peptide. Transthoracic echocardiogram showed normal left and right ventricular function and no significant valvular disease. Duplex ultrasonography (DUS) did not reveal any DVT; however, it showed a blunted respirophasic flow pattern and 4.3 second axial reflux in the left common femoral vein (Figure 2A). He underwent invasive femoral digital subtraction venography that revealed left external iliac vein (LEIV) stenosis (Figure 3A) caused by pulsatile compression from the left external iliac artery (Supplemental Video 1). This was followed by IVUS imaging with an 8.5F Volcano Vision PV catheter (Volcano) that showed a patent left common iliac vein (Figure 4A) and a focal stenosis along with significant wall thickening in the LEIV with a lumen area of 64.8 mm² (65.4% stenosis to reference lumen) caused by ipsilateral external iliac artery compression (Figure 4B). The lesion was treated with a 16 mm × 60 mm Wallstent (Boston Scientific) implanted successfully in the affected vein that resulted in resolution of the stenosis with a final luminal area of 106 mm² (Figure 4C). One month later, his swelling significantly decreased and the blisters healed (Figure 1B). Repeat DUS showed a patent left external iliac stent and resumption of respirophasic flow in the left common femoral vein (Figure 2B). At 6-month follow-up, his swelling resolved with the flow in lower limb veins remains preserved.

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Figure 1.

A, Significant left lower extremity swelling associated with blisters. B, Resolution of swelling and blisters after treatment with a venous stent.

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Figure 2.

A, A 4.3 second axial reflux in the left common femoral vein (LCFV) as a result of upstream stenosis in the left external iliac vein (LEIV). B, After LEIV stenting, normal respirophasic flow in the LCFV was restored.

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Figure 3.

A, Focal stenosis of the left external iliac vein. B, Successful deployment of stent in the affected segment with resolution of stenosis.

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Figure 4.

A, Patent left common iliac vein (#) at the level of the right common iliac artery bifurcation (*). B, Left external iliac vein (#) with significantly thickened walls and stenosis of 65.4% with luminal area of 64.8 mm² as a result of compressive occlusion from the ipsilateral external iliac artery (*). C, Left external iliac vein (#) after the lesion was treated successfully with a venous stent, resulting in a complete resolution of stenosis and a luminal area of 106 mm². Patent left external iliac artery (*).

Discussion

The prevalence of silent venous compression stenosis is estimated to be up to 50% in the general population. ³ These lesions show a predilection for the left lower extremity and are more common in women than men. Typically, the left common iliac vein is compressed between the right common iliac artery and the spine. However, it is not uncommon to have bilateral or right-side involvement. ⁴ This is a unique case as our patient was a male, in the later stages of his life, and had significant isolated external iliac vein compression without involvement of the common iliac veins. This led to gross thickening of the vein walls and eventual stenosis (Figure 4B), resulting in venous hypertension. Over time, repetitive arterial pulsations on a thin-walled vein can cause mural fibrosis, thickening, or webs that obstruct antegrade blood flow. Our case highlights that veno-occlusive disease is neither exclusive to young females nor restricted to iliocaval region.

The use of multiple imaging modalities such as Doppler ultrasound, computed tomography venogram, and single-plane venography may assist in the diagnosis of veno-occlusive disease. The use of conventional single-plane venography limits diagnosis of veno-occlusive disease in up to a third of the cases. ⁵ A previous paper by Raju and Neglen reported superior sensitivity of diagnostic testing when IVUS was used in conjunction with single-plane venography. ⁶ Intravascular ultrasound can accurately localize the affected segment and, as in our case, aid in the diagnosis of a seemingly normal vein on prior testing. Intravascular ultrasound also plays a pivotal role in the determination of the vessel diameter and lesion length for appropriate equipment selection and meticulous deployment of the stent in the affected segment. ³

Pooled data from multiple series including almost 1500 patients with iliac vein stenosis showed common iliac vein stenting to be safe and effective. Primary patency of stents for nonthrombotic lesions ranged from 90% to 100% at 3 to 5 years of follow-up. The complication rates associated with the procedure are estimated to be <1%. Risk factors associated with poor long-term success rates include prior thrombosis, male sex, recent trauma involving the limb, age <40 years, and a chronic total occlusion. Ninety percent of patients report relief from pain in the long run. Improvement in swelling is seen in 65% to 89% and healing of ulcers in about 75% patients with or without resolution of accompanying venous reflux. ⁴

This case of isolated external iliac vein compression underscores the importance of comprehensive evaluation with detailed history, blood testing, and multimodality imaging in patients with leg swelling and ulcerations.

Conclusion

Isolated external iliac vein compression can cause painful leg swelling, stasis dermatitis, and ulceration in patients without prior history of deep vein thrombosis. Invasive and/or noninvasive vascular imaging studies can lead to prompt diagnosis and timely intervention to alleviate this chronic debilitating condition. We advise health care providers to have a high index of suspicion for these conditions that are not uncommon and emphasize the need to consider NIVLs in difficult-to-treat cases of painful leg swelling with stasis dermatitis and/or ulceration.