Acute left iliofemoral vein thrombosis: Comparison between simple and bony May-Thurner syndrome in CT venography

Abstract

Objectives

To explore the etiology of May-Thurner syndrome (MTS) with acute iliofemoral deep vein thrombosis (DVT) regarding imaging findings and clinical features.

Methods

We retrospectively analyzed 57 patients with acute left iliofemoral DVT from 2015 to 2020. The diameter of left common iliac vein (LCIV) at the maximal compression site and its percent compression regarding the average diameter of the uncompressed iliac vein were recorded in central and distal portions of the LCIV according to the location in the quadrant of lumbar vertebral body. Compression was categorized into simple and bony MTS; Simple MTS as LCIV compressed by the right common iliac artery (RCIA) versus Bony MTS as LCIV by lower lumbar degenerative changes regardless of RCIA compression. Initial computed tomographic venography (CTV) regarding chronic change of LCIV such as fibrotic atrophy or cordlike obliteration, extent of thrombus, and lumbar degenerative changes were evaluated. Therapeutic effect after initial therapy was assessed in follow-up CTVs after 3–6 months.

Results

All patients showed LCIV compression with 19 simple MTS (mean age, 42.8 ± 14.1 years [23–67 years]; 12 females; symptom for 4.4 ± 5.5 days) and 38 bony MTS (mean age, 73.0 ± 10.2 years [49–85 years]; 26 females; symptom for 5.5 ± 4.8 days). There was significant difference in age (p < .001) and no significant difference in sex or symptom duration between two groups (p = .691 and 0.415, respectively). All simple MTS showed compression only in the central LCIV and half of bony MTS showed compression in both central and distal LCIV (p < .001). Among the lumbar degenerative changes, symmetric anterolateral osteophyte (p < .001) and asymmetric osteophyte (p < .001) were significantly associated with bony MTS, but not scoliosis (p = .799), compared to simple MTS. Although there was no significant difference in chronic change of LCIV, thrombosis extent, and therapeutic effect between two groups (p > .05), chronic change of LCIV showed significant difference between single and dual compression (23.7% vs. 57.9%, p = .024) and residual thrombus after initial therapy was occurred in 21.1% of single compression and 47.4% in dual compression with non-significant trend (p = .082).

Conclusion

Bony MTS related to lumbar degenerative changes with acute iliofemoral DVT occurs in older patients, presenting more than one stenosis at LCIV, inducing more chronic change with possibly weaker therapeutic effect than simple MTS.

Keywords

Computed tomographic venography deep vein thrombosis acute iliofemoral vein thrombosis May-Thurner syndrome spine

Introduction

May-Thurner syndrome (MTS) is traditionally known as iliac vein compression syndrome, causing clinical symptoms such as unilateral lower extremity edema, pain, varicose veins, venous ulcers, and deep vein thrombosis (DVT) by compression of the left common iliac vein (LCIV) between the right common iliac artery (RCIA) and the lumbar vertebrae.^1,2 Although LCIV compression by RCIA crossing is the main cause, extrinsic compression of the iliac veins or inferior vena cava can occur due to a variety of causes, including large uterus, ectopic kidney, right iliac artery stent, and orthopedic hardware.^3–9 However, bony structures affecting venous compression have not been fully investigated and are thought to occur more frequently in elderly patients with degenerative spondylosis.^10,11

In general, if there is left-sided clinical symptom such as swelling and pain, it is highly suspected of iliac vein compression, and several studies may be accompanied with physical examination.^13,14 Catheter venography is considered a reference standard and intravascular ultrasound is accurate diagnostic modalities, but these studies are invasive and cannot provide extravascular cause of compression.¹⁴ Duplex ultrasound of lower extremity vein is accurate in identifying the presence of DVT, but it may be technically challenging especially in obese patients.^13–15 Since iliac vein compression is commonly caused by various anatomical variant, cross-sectional imaging studies such as CT venography (CTV) or MR venography (MRV) are helpful.^13–15 MRV has the disadvantages of higher cost and less availability.¹⁴ CTV has recently been used diagnostically for lower limb problems, and it has the potential to demonstrate various extraluminal causes of venous stenosis, especially in acute iliofemoral DVT.^12,14,16 If MTS is developed by non-vascular compression, it should be addressed in CTV interpretation because the management strategies may change.¹⁷

Therefore, this study explored the etiology of MTS with acute iliofemoral DVT using CTV and evaluated underrecognized bony MTS compared with the classic MTS regarding imaging findings and clinical features.

Methods

Patient population

This retrospective study was approved by the Institutional Review Board (approval number: VC21RASI0260) and informed consent was waived. Retrospective medial review and CTV analysis were conducted.

We included the patients who underwent CTV of lower extremity with clinical symptoms from January 2015 to December 2020. Inclusion criteria were patients who performed both initial and follow-up CTV of the lower extremity, patients without risk factor of DVT regarding lower extremity fracture or operation, and finally patients who presented DVT in lower extremity CTV. To include only patients with acute left iliofemoral DVT related to MTS, other DVT conditions were excluded as follows: (1) right-sided DVT only, (2) below popliteal vein DVT only, (3) segmental thrombus in femoral vein only, (4) chronic DVT, (5) superficial thrombophlebitis, and/or (6) extrinsic compression of the iliac vein by intraabdominal mass (pelvic cavity lesion, retroperitoneal lesion, lymphadenopathy). Finally, 57 patients with acute left iliofemoral DVT were enrolled in this study including 38 females and 19 males (mean age, 63 years; range 23–85 years). All patients had acute left lower extremity swelling and pain within 4 weeks of symptom onset. The flowchart of patient selection is summarized in Figure 1. Medical records were reviewed for onset age, sex, symptom duration, and treatment. In accordance with the widely-used anticoagulant protocols, intravenous heparin loading and continuous infusion were performed for initial anticoagulation therapy (mean, 5 ± 2 months; range, 2–12 months). It was also investigated whether endovascular intervention was performed.

Figure 1.

Flowchart of patient selection.

Image acquisition

All patients were examined using a dual-source CT scanner (Somatom Definition Flash, Siemens Healthineers, Forchheim, Germany) in standard single-energy CT mode. Nonionic iodinated contrast material (120 mL of iopamidol [Iomeron, Bracco Imaging SpA, Milan, Italy]) was injected at a rate of 4 mL/s through an 18-gauge catheter in the antecubital vein. The main scanning parameters were as follows: tube voltage, 120 kVp; tube current, 100–250 mAs (Care dose4D, Siemens Healthineers, Forchheim, Germany); collimation, 128 × 0.6 mm; pitch, 0.8; reconstruction slice thickness, 3 mm; reconstruction interval, 3 mm; and reconstruction B30f soft tissue algorithm. All images were transferred to a workstation with PC-based 3D reconstruction software (Syngo Via; Siemens Healthineers; Forchheim; Germany). Two experienced radiologists performed 3D reconstruction, which included volume rendering and multiplanar reformation along or across the venous segment of interest.

CTV analysis

Patient classification and image analysis were performed based on initial CTV in a blind fashion by two radiologists (S.K.L. and E.H.K. with 12 years of experience). The initial CTV was analyzed as presence or absence of LCIV compression, and percent compression was measured and classified as compression at 25% or more.^18,19 The method of measuring percent compression included the diameter of the maximal LCIV compression site and the diameter of the uncompressed area proximal and distal to the site of maximal LCIV compression.¹⁹ The percent compression was calculated in two steps: (1) average diameter of the uncompressed iliac vein was calculated by the mean of the uncompressed proximal and distal iliac vein, and (2) the percent compression of the LCIV was calculated by subtracting the maximal LCIV compression from the mean uncompressed iliac vein and dividing it by the mean uncompressed iliac vein¹⁹ (Figure 2). The diameter and percent compression of the LCIV stenotic segment were recorded in the central and distal portions of the LCIV, respectively. If the stenosis is located in the first quadrant of the lumbar vertebral body, we named it “central” stenosis in this study. If the stenosis is located in the second quadrant of lumbar vertebral body, we named it “distal” stenosis in this study (Figure 3). Based on measurement of stenotic areas along the central and distal LCIV, patients with LCIV compression were further divided into two groups: (1) Simple MTS: LCIV is simply compressed by the RCIA and (2) Bony MTS: LCIV is compressed by lower lumbar degenerative changes such as a disc, osteophyte, or anterior longitudinal ligament ossification at any site of the LCIV regardless of RCIA compression²⁰ (Figure 4).

Figure 2.

Measurement of percent compression in the left common iliac vein (LCIV). The method of measuring percentage compression includes the diameter of the maximal LCIV compression site (A) and diameter of the uncompressed area proximal (C) and distal (D) to the site of maximal LCIV compression. Percent compression was calculated by two steps: (1) the average diameter of the uncompressed iliac vein (B) = (C+D)/2, and then (2) percent compression of LCIV = (B–A)/B x 100.

Figure 3.

Measurement site for the diameter of stenotic segment along the left common iliac vein (LCIV). Axial image shows the right common iliac artery (thin arrow) compressing the LCIV at the opening site of the left iliac vein. If the stenosis is located in the first quadrant of the lumbar vertebral body, it is counted as “central” stenosis. Note the osteophyte (big arrow) compressing the LCIV at the second quadrant of the lumbar vertebral body; If the stenosis is located in the second quadrant of lumbar vertebral body, it is counted as “distal” stenosis. Diameter of the central stenotic segment was 3.63 mm and that of the distal stenotic segment was 1.39 mm.

Figure 4.

Classification of left common iliac vein (LCIV) compression. (A) Axial image shows where the right common iliac artery (thin arrow) compresses the LCIV (asterisk) at the central site of left iliac vein, anterior to the anterior margin of the vertebral body (big arrow)—classified as the simple May-Thurner syndrome (MTS) group. (B) Axial image shows where the right common iliac artery (thin arrow) compresses the LCIV (asterisk) at the central site. Note several osteophytes (big arrow+arrowheads) contribute to compression of distal LCIV (asterisks)—classified as the bony MTS group.

Observation indices related to LCIV compression were as follows: on initial CTV, (1) chronic change such as fibrotic atrophy or cordlike obliteration of the LCIV by overlying compression (Figure 5), (2) extent of thrombosis limited to iliofemoral vein or affected popliteal vein and below, and (3) lumbar degenerative changes such as symmetric anterolateral osteophyte, asymmetric osteophyte on axial images and scoliosis on scout image. On follow-up CTV at 3–6 months after initial therapy, the therapeutic effect was evaluated as partial/complete recanalization or residual/aggravated thrombus.

Figure 5.

Chronic change such as fibrotic atrophy or cordlike obliteration of the left common iliac vein (LCIV) by overlying compression. (A) Multiplanar reformatted axial image shows chronic change (thin arrows) such as fibrotic atrophy or cordlike obliteration of LCIV by overlying arterial (big arrow) and bony (arrowheads) compression. (B) Serial axial reformatted image shows thrombosis (arrow) of LCIV. (C) Sagittal reformatted image shows inferior vena cava with normal diameter (arrows). (D) Serial sagittal reformatted image shows atrophic LCIV (thin arrows) between the right common iliac artery (big arrow) and bony spur of the vertebral body (arrowhead).

Statistical analysis

Chi-square and Mann-Whitney U tests were used to compare findings between the two groups. Interobserver agreement for measurement was evaluated using intraclass correlation coefficient (ICC) with a two-way mixed model with absolute agreement. The degree of agreement was interpreted as follows: ICC: < 0.40, poor; 0.4–0.59, fair; 0.60–0.74, good; and 0.75–1.00, excellent. Statistical analysis was performed using MedCalc statistical software version 11.5.1.0 (MedCalc Software bvba). A p-value < .05 was considered statistically significant.

Results

Patient demographics and clinical findings between simple and bony MTS

Fifty-seven patients with acute left iliofemoral DVT were finally enrolled, and all patients showed LCIV compression. There were 19 patients with simple MTS (19/57, 33.3%) and the mean age was 42.8 years ± 14.1 (SD) (range: 23–67 years) with 12 females and seven males. A total of 38 patients (38/57, 66.7%), 26 females and 12 males, with a mean age of 73.0 years ± 10.2 (SD) (range: 49–85 years) was classified as bony MTS. Since bony MTS was defined when lumbar degenerative changes compressed LCIV regardless RCIA compression in methods, bony MTS could coexist with RCIA compression defining simple MTS, and occasionally both these two conditions contributed to DVT in left iliofemoral vein. There was no significant difference in sex distribution between the simple and bony MTS groups (p = .691). The mean age was significantly younger in simple than bony MTS (p < .001). There was no significant difference in symptom duration between simple and bony MTS (4.4 days ± 5.5 [SD] vs. 5.5 days ± 4.8 [SD], p = .415) (Table 1).

Table 1.

Patients demographics and clinical findings between simple and bony May-Thurner Syndrome (MTS).

	Simple MTS (n = 19)	Bony MTS (n = 38)	p value
Gender
Female (n)	12 (63.2%)	26 (68.4%)	0.691
Male (n)	7 (36.8%)	12 (31.6%)	0.691
Age (years)	42.8 ± 14.1	73.0 ± 10.2	<0.001
Symptom duration (days)	4.4 ± 5.5	5.5 ± 4.8	0.415

On the 57 patients, 41 patients were treated only with anticoagulation with compression stockings, 13 patients were treated with mechanical thrombectomy, and only three patients were treated with stent placement.

LCIV compression degree and number between simple and bony MTS

By grading the percent compression of LCIV (<25%, 25–50%, >50%), no significant difference in the degree of central compression of the LCIV was found between the simple and bony MTS groups (p = .775). Simple MTS showed 10.5% of patients with compression degree between 25 and 50% and 89.5% with compression degree greater than 50%. Bony MTS showed 2.6% of patients with compression degree less than 25%, 10.5% with compression degree between 25 and 50%, and 86.8% with compression degree greater than 50%. Diameter of the LCIV central segment was 4.0 mm ± 1.6 (SD) in simple MTS and 4.3 mm ± 2.0 (SD) in bony MTS, without statistical significance (p = .638). However, compression degree of the LCIV distal segment was significantly different between the two groups (p < .001). Simple MTS showed 100.0% of patients with compression degree less than 25%. Bony MTS showed 47.4% of patients with compression less than 25%, 13.2% with compression between 25 and 50%, and 39.5% with compression degree greater than 50%. Diameter of the LCIV distal segment was 10.8 mm ± 1.6 (SD) in simple MTS and 8.4 mm ± 4.1 (SD) in bony MTS with a statistical difference (p = .004) (Table 2). The intraobserver ICC calculated based on the CTV measurements ranged from 0.8 to 0.9 and indicated favorable intra-observer reproducibility.

Table 2.

LCIV compression degree and number between simple and bony May-Thurner Syndrome (MTS).

	Simple MTS (n = 19)	Bony MTS (n = 38)	p value
Central compression grades
<25% (n)	0 (0.0%)	1 (2.6%)	0.775
25–50% (n)	2 (10.5%)	4 (10.5%)
>50% (n)	17 (89.5%)	33 (86.8%)
Central diameter (mm)	4.0 ± 1.6	4.3 ± 2.0	0.638
Distal compression grades
<25% (n)	19 (100.0%)	18 (47.4%)	<0.001
25–50% (n)	0 (0.0%)	5 (13.2%)
>50% (n)	0 (0.0%)	15 (39.5%)
Distal diameter (mm)	10.8 ± 1.6	8.4 ± 4.1	0.004
Number of compression sites
Only central (n)	19 (100.0%)	18 (47.3%)	<0.001
Only distal (n)	0 (0.0%)	1 (2.6%)
Both central and distal (n)	0 (0.0%)	19 (50.0%)

All simple MTS (19/19, 100.0%) showed compression only in the central segment of the LCIV, and half of bony MTS (19/38, 50.0%) showed compression in both central and distal segments of the LCIV (p < .001) (Figure 6, Table 2).

Figure 6.

66-year-old man with bony May-Thurner syndrome. (A) Multiplanar reformatted axial image shows that bony spurs compress left common iliac vein (LCIV) at both the central (arrow) and distal (arrowhead) segments. Note chronic change such as fibrotic atrophy (asterisk) presents along LCIV. (B) Serial axial reformatted image shows thrombosis (arrow) of LCIV. (C) Multiplanar reformatted axial image after initial therapy shows residual thrombus (arrow) of the LCIV.

Other CTV indices related to LCIV compression

On initial CTV, chronic change such as fibrotic atrophy or cordlike obliteration of LCIV by overlying compression showed no significant difference between simple and bony MTS (26.3% vs. 39.5%, p = .326). Extensive thrombosis that affected the popliteal vein and below also showed no significant difference between simple and bony MTS (84.2% vs. 78.9%, p = .635). Among the lumbar degenerative changes, symmetric anterolateral osteophyte (35/38 vs 0/19; p < .001) and asymmetric osteophyte (20/38 vs 0/19; p < .001) were significantly associated with bony MTS, but not scoliosis (2/38 vs 0/19; p = .799), compared to simple MTS. On follow-up CTV at 3–6 months (mean: 5.3 ± 2.2 months and range: 1.5–10.9 months) at after initial therapy, residual thrombus was noted in 21.1% of simple MTS and in 28.9% of bony MTS without statistical difference (p = .523) (Table 3).

Table 3.

Other CTV indices related to LCIV compression between simple and bony May-Thurner Syndrome (MTS).

	Simple MTS (n = 19)	Bony MTS (n = 38)	p value
Chronic change of LCIV
Absent (n)	14 (73.7%)	23 (60.5%)	0.326
Present (n)	5 (26.3%)	15 (39.5%)	0.326
Involved segment
Above knee (n)	3 (15.8%)	8 (21.1%)	0.635
Below knee (n)	16 (84.2%)	30 (78.9%)	0.635
Treatment response
Complete or partial (n)	15 (78.9%)	27 (64.3%)	0.523
Little or aggravated (n)	4 (21.1%)	11 (28.9%)	0.523

Although there was no significant difference regarding CTV indices between simple and bony MTS, we compared these CTV indices according to number of compressions. In bony MTS, half of the cases presented compression at both the central and distal portions of the LCIV. In simple MTS, all cases presented compression only at the central portion of the LCIV. On initial CTV, chronic change such as fibrotic atrophy or cordlike obliteration of the LCIV by overlying compression showed significant difference between single and dual compression (23.7% vs. 57.9%, p = .024) (Figure 6). Extensive thrombosis affecting the popliteal vein and below showed no significant difference between one and two sites of compression (78.9% vs. 84.2%, p = .906). On follow-up CTV after initial therapy, residual thrombus was noted in 21.1% of patients with one compression site along the LCIV and in 47.4% of patients with two compression sites along the LCIV with non-significant trend (p = .082) (Figure 6, Table 4).

Table 4.

Other CTV indices related to left common iliac vein (LCIV) compression according to number of compression sites along LCIV.

	One compression of LCIV (n = 38)	Two compressions of LCIV (n = 19)	p value
Chronic change of LCIV
Absent (n)	29 (76.3%)	8 (42.1%)	0.024
Present (n)	9 (23.7%)	11 (57.9%)	0.024
Involved segment
Above knee (n)	8 (21.1%)	3 (15.8%)	0.906
Below knee (n)	30 (78.9%)	16 (84.2%)	0.906
Treatment response
Complete or partial (n)	30 (78.9%)	10 (52.6%)	0.082
Little or aggravated (n)	8 (21.1%)	9 (47.4%)	0.082

Outcomes of initial therapy

On the 57 patients, 41 patients were treated only with anticoagulation with compression stockings. Since various departments performed DVT treatment in our institution, the treatment policy was somewhat heterogeneous and most of patients were treated with anticoagulation therapy alone, except for urgent symptoms. Among 41 patients, 13 patients were simple MTS presenting treatment response in 11 patients, and 28 patients were bony MTS presenting treatment response in 21 patients. Thirteen patients were treated with mechanical thrombectomy. Urgent endovascular intervention was performed when the patients with vascular compromise (phlegmasia cerulea dolens), severe swelling, severe pain, or with a contraindication to anticoagulation.²¹ Among 13 patients, five patients were simple MTS presenting treatment response in three patients, and eight patients were bony MTS presenting treatment response in five patients.

Only three patients were treated with mechanical thrombectomy and stent placement. In our institution, only small part of patients requiring urgent endovascular intervention were referred to interventional radiologist. These patients were performed for mechanical thrombectomy with stent placement. Among three patients, one patient was simple MTS showing treatment response, and two patients were bony MTS presenting treatment response in one patient and little treatment response in another patient (Figure 7).

Figure 7.

57-year-old man with bony May-Thurner syndrome treated with mechanical thrombectomy and stent placement. (A) Initial multiplanar reformatted axial image shows that bony spur compresses left common iliac vein (LCIV) at the central portion (big arrow). Note acute left iliofemoral thrombosis (thin arrow). (B) The first follow-up multiplanar reformatted axial image at 1 month after mechanical thrombectomy with stent placement shows residual thrombosis (arrow) of LCIV. (C) The second follow-up multiplanar reformatted axial image at 6 months after treatment shows residual thrombosis (thin arrow) of LCIV. Note collapsed stent between right common iliac artery and vertebra (big arrow).

Discussion

In this study, we revealed the etiologies, anatomical characteristics, and clinical outcomes of MTS with acute iliofemoral DVT. All patients with acute iliofemoral DVT had underlying anatomical abnormalities with simple MTS of 33.3% and bony MTS of 66.7%. Results showed that bony MTS occurred in older patients, presenting with more than one stenosis along the LCIV, and inducing more chronic fibrotic change of the LCIV with possibly weaker therapeutic effect after initial therapy compared to simple MTS.

In contrast to simple MTS, which occur more widely in the younger population,²² bony MTS is more frequent among symptomatic MTS with iliofemoral DVT and occurs in older patients. As aging processes, vessel changes, atherosclerosis, and spine degenerative changes induce bony MTS with iliofemoral DVT.²³ The anatomical characteristics of bony MTS and the effects ofdegenerative change of the lumbar spine on the LCIV have only been reported in a few studies.^12,20,24 According to CT findings, Ou-Yang et al. classified MTS as simple MTS, degenerative MTS, and other-cause MTS.²⁰ Among them, degenerative MTS was caused by forward bulging discs, anterior vertebral spurs, and lumbar spondylolisthesis pressing into the iliac vein.²⁰ Narrowing of the LCIV opening could have existed congenitally, but it seems that lumbar degenerative changes induce or aggravate MTS.²⁰

We found that bony changes related to lumbar spine degeneration compress not only the opening of the LCIV but also the distal portion of the LCIV in half of bony MTS cases. Farina et al. reported that dual compression of the LCIV was found due to osteophytes.²⁵ Similarly, in our study, compression of the distal LCIV was due to narrowing between lumbar degenerative change and the LCIA, and it accounted for half of bony MTS cases. Degenerative lumbar change is more likely to occur broadly rather than focally, and a larger range of the LCIV is more likely to be compressed in bony MTS. Accurate evaluation of the LCIV compression range might assist and optimize clinical decision-making including endovascular treatment using stents.¹⁹

More than one stenosis along the LCIV was only noted in bony MTS. This subgroup with both central and distal LCIV compression appeared more frequently with chronic changes of the LCIV such as fibrotic atrophy or cordlike obliteration. Jeon et al. divided morphologic features of the LCIV into three types as focal extrinsic compression, diffuse atrophy, and cordlike obliteration and observed that MTS could induce diffuse atrophy or cordlike obliteration of the LCIV, due to diminished flow or organized mural thrombus with flow stagnation.²⁶ We thought that bony MTS occurred in older patients and compressed LCIV occurred along a larger range from the central to distal portion with longer duration, and these clinical and anatomical features induced chronic changes of the LCIV more frequently. Chronic change of the LCIV could affect treatment planning or clinical outcomes and it may be evidence that bony MTS with dual compression might not respond well to stent placement.^26,27

Anticoagulation therapy remains the mainstay of treatment in symptomatic MTS with acute DVT.^13,28 In our study, bony MTS with dual compression showed possibly weaker therapeutic effect after initial therapy compared to simple MTS. As such, it seems difficult to resolve the thrombotic MTS with anticoagulation alone.^14,16 Additional invasive treatment with catheter-directed thrombolysis combined with percutaneous mechanical thrombectomy, is indicated for immediate symptom relief and reduces post-thrombotic syndrome incidence.^29,30 Angioplasty with an endovascular stent is recommended as a definite treatment after treating acute DVT.^30–32 Although the stent placement at the stenotic area is main treatment for MST, bony MTS creates a solider occupancy effect from the degenerated lumbar structures and sharper compression with fulcrum effect compared to the simple MTS.^10,33 For these reasons, a stent with higher radial force may be suited for bony MTS to achieve durable patency, and if the osteophytes are accessible, surgical excision of osteophyte also can be considered.^10,34 It will be important to determine appropriate treatment by identifying anatomical features of MTS by CTV.

This study has several limitations. First, this was a single-center retrospective study with a relatively small sample size. Second, there is a lack of variable treatment options in this study, which only small population of patients underwent endovascular intervention. Since various departments including vascular surgery, cardiothoracic surgery, and internal medicine performed DVT treatment in our institution, treatment is being performed on various guidelines without unity and conduct more traditional treatment rather than endovascular intervention by intervention radiologist. Another limitation includes the exclusion of orthopedic patients. Orthopedic patients are hospitalized for fractures or surgeries, and their risk factors for venous thromboembolism are higher. We plan to continue this study with orthopedic patients that are likely to develop a hypercoagulable state to investigate asymptomatic and symptomatic MTS.

In conclusion, the majority of patients with acute iliofemoral DVT has underlying anatomical abnormalities, consisting of simple MTS at 33.3% and bony MTS at 66.7%. Bony MTS occurred in older patients, presented with more than one stenosis along the LCIV, and had greater chronic fibrotic change of the LCIV with possibly weaker therapeutic effect after initial therapy. Therefore, bony MTS should be considered as the potential etiology of left-sided iliofemoral DVT in elderly patients, and reporting spine degeneration causing extrinsic venous compression on CTV may be helpful to guide the treatment strategies targeted to bony MTS from the anticoagulation therapy to the advanced endovascular management.

Footnotes

Abbreviation

CTV, computed tomographic venography

DVT, deep vein thrombosis

ICC, intraclass correlation coefficient

LCIA, left common iliac artery

LCIV, left common iliac vein

MRV, magnetic resonance venography

MTS, May-Thurner syndrome

RCIA, right common iliacartery

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Research ethics

IRB approval number: VC21RASI0260.

ORCID iD

Seul Ki Lee

References

Mathur

Cohen

Bashir

. May-Thurner syndrome. Circulation 2014; 129: 824–825. DOI: 10.1161/circulationaha.113.004739

May

Thurner

. The cause of the predominantly sinistral occurrence of thrombosis of the pelvic veins. Angiology 1957; 8: 419–427. DOI: 10.1177/000331975700800505

Wax

Pinette

Rausch

, et al. May-Thurner syndrome complicating pregnancy: a report of four cases. J Reprod Med 2014; 59: 333–336.

Cockett

Thomas

Negus

. Iliac vein compression.--Its relation to iliofemoral thrombosis and the post-thrombotic syndrome. Br Med J 1967; 2: 14–19. DOI: 10.1136/bmj.2.5543.14

Yoshida

Akiba

Tamakawa

, et al. Spiral CT venography of the lower extremities by injection via an arm vein in patients with leg swelling. Br J Radiol 2001; 74: 1013–1016. DOI: 10.1259/bjr.74.887.741013

Nwoke

Picel

. May-Thurner Syndrome and Horseshoe Kidney. J Vasc Intervent Radiol : JVIR 2016; 27: 369. DOI: 10.1016/j.jvir.2015.11.049

Young

Kwon

Arosemena

, et al. Symptomatic compression of right iliac vein after right iliac artery stent placement. J Vas Surg Venous Lymph Disor 2017; 5: 735–738. DOI: 10.1016/j.jvsv.2016.10.082

Woo

Ogilvie

Krueger

, et al. Iliac vein compression syndrome from anterior perforation of a pedicle screw. J Surgical Cas Rep 2016; 2016: 2016. DOI: 10.1093/jscr/rjw003

Foxx

Kwak

Latzman

, et al. A retrospective analysis of pedicle screws in contact with the great vessels. J Neurosurg Spine 2010; 13: 403–406. DOI: 10.3171/2010.3.Spine09657

10.

Shin

Mokkarala

Allison

, et al. Osteophytic Iliac Venous Compression: Technical Considerations for a Bony May-Thurner Syndrome Variant. J Clin Interv Radiol ISVIR 2018; 02: 095–100.

11.

Aydin

Engin

. Lower limb deep venous thrombosis due to vertebral osteophyte: a May-Thurner-like syndrome. Eur Res J 2020. DOI: 10.18621/eurj.601306

12.

Chung

Yoon

Jung

, et al. Acute iliofemoral deep vein thrombosis: evaluation of underlying anatomic abnormalities by spiral CT venography. J Vas Intervent Radio : JVIR 2004; 15: 249–256. DOI: 10.1097/01.rvi.0000109402.52762.8d

13.

Birn

Vedantham

. May-Thurner syndrome and other obstructive iliac vein lesions: meaning, myth, and mystery. Vasc Med 2015; 20: 74–83. DOI: 10.1177/1358863x14560429

14.

Tzeng

, et al. Comprehensive MDCT evaluation of patients with suspected May-Thurner syndrome. AJR Am J Roentgen 2012; 199: W638–W645. DOI: 10.2214/ajr.11.8040

15.

Butros

Liu

Oliveira

, et al. Venous compression syndromes: clinical features, imaging findings and management. Br J Radiol 2013; 86: 20130284. DOI: 10.1259/bjr.20130284

16.

Oguzkurt

Tercan

Pourbagher

, et al. Computed tomography findings in 10 cases of iliac vein compression (May-Thurner) syndrome. Eur J Radiol 2005; 55: 421–425. DOI: 10.1016/j.ejrad.2004.11.002

17.

Zucker

Ganguli

Ghoshhajra

, et al. Imaging of venous compression syndromes. Cardiovasc Diagnosis Therapy 2016; 6: 519–532. DOI: 10.21037/cdt.2016.11.19

18.

Kibbe

Ujiki

Goodwin

, et al. Iliac vein compression in an asymptomatic patient population. J Vascular Surgery 2004; 39: 937–943. DOI: 10.1016/j.jvs.2003.12.032

19.

Chen

, et al. Novel typing of iliac vein compression in asymptomatic individuals evaluated by contrast enhanced CT. Surg Radio Anat : SRA 2021; 43: 1149–1157. DOI: 10.1007/s00276-021-02678-w

20.

Ou-Yang

. Underlying Anatomy and Typing Diagnosis of May-Thurner Syndrome and Clinical Significance: An Observation Based on CT. Spine 2016; 41: E1284–e1291. DOI: 10.1097/brs.0000000000001765

21.

Liu

Peterson

Dooner

, et al. Diagnosis and management of iliofemoral deep vein thrombosis: clinical practice guideline. CMAJ 2015; 187: 1288–1296. DOI: 10.1503/cmaj.141614

22.

Kaltenmeier

Erben

Indes

, et al. Systematic review of May-Thurner syndrome with emphasis on gender differences. J Vas Surg Ven Lymph Disor 2018; 6: 399–407. DOI: 10.1016/j.jvsv.2017.11.006

23.

Park

Cho

, et al. Atypical iliac vein compression in patients with symptomatic May-Thurner syndrome. Diagn Intervent Radio 2021; 27: 372–377. DOI: 10.5152/dir.2021.20183

24.

Gonzalez-Urquijo

Torrealba

Vargas

, et al. Extrinsic venous compression secondary to spine osteophytes. Vascular 2022: 170853812210848. DOI: 10.1177/17085381221084815

25.

Farina

Foti

Iannace

, et al. May-Thurner Syndrome with Double Compression of the Iliac Vein: Lessons Based on a Case Report. Am J Cas Rep 2021; 22: e928957. DOI: 10.12659/ajcr.928957

26.

Jeon

Chung

Jae

, et al. May-Thurner syndrome complicated by acute iliofemoral vein thrombosis: helical CT venography for evaluation of long-term stent patency and changes in the iliac vein. AJR Am J Roentgenol 2010; 195: 751–757. DOI: 10.2214/ajr.09.2793

27.

O’Sullivan

Semba

Bittner

, et al. Endovascular management of iliac vein compression (May-Thurner) syndrome. J Vas Intervent Radio : JVIR 2000; 11: 823–836. DOI: 10.1016/s1051-0443(07)61796-5

28.

Singh

Alshareef

Meka

. Deep Vein Thrombosis Secondary to Extrinsic Compression: A Case Report. Cureus 2020; 12: e11160. DOI: 10.7759/cureus.11160

29.

Siddiqa

Haider

Fortuzi

, et al. May-Thurner Syndrome: A Rare Case of Unilateral Deep Vein Thrombosis in an Elderly Woman. Am J Cas Rep 2021; 22: e929897. DOI: 10.12659/ajcr.929897

30.

Thangjui

Trongtorsak

Zoltick

, et al. May-Thurner Syndrome in an Elderly Man. Cureus 2022; 14: e21611. DOI: 10.7759/cureus.21611

31.

Mako

Puskas

. May-Thurner syndrome - Are we aware enough? VASA Z Fur Gefasskrankheiten 2019; 48: 381–388. DOI: 10.1024/0301-1526/a000775

32.

Harbin

Lutsey

. May-Thurner syndrome: History of understanding and need for defining population prevalence. J Thromb Haem : JTH 2020; 18: 534–542. DOI: 10.1111/jth.14707

33.

Tian

Huang

, et al. A case report of May-Thurner syndrome induced by anterior lumbar disc herniation: Novel treatment with radiofrequency thermocoagulation. Medicine 2019; 98: e17706. DOI: 10.1097/md.0000000000017706

34.

Wasserburger

Haponyuk

Modhia

, et al. Lumbosacral exostosis as a rare cause of iliac vein compression and significant limb swelling. J Vas Surg Cas Innovat Tech 2019; 5: 529–531. DOI: 10.1016/j.jvscit.2019.05.006