May‐Thurner syndrome: History of understanding and need for defining population prevalence

Abstract

Patients with May‐Thurner syndrome (MTS) are at elevated risk of developing an extensive left iliofemoral deep vein thrombosis (DVT; localized blood clot) due to an anatomical variant where the right common iliac artery compresses the left common iliac vein against the lumbar spine. While MTS was initially presumed to be rare when it was first anatomically defined in 1957, case reports of this syndrome have recently become more frequent, perhaps due to improved imaging techniques allowing for enhanced visualization of the iliac veins. Still, the population burden of this condition is unknown, and there is speculation it may be higher than generally perceived. In the present review, we (a) review history of how MTS became recognized, (b) describe practical challenges of studying MTS in population‐based settings due to the specialized imaging required for diagnosis, (c) discuss why the contribution of MTS to DVT may be underestimated, (d) describe uncertainty regarding the degree of venous compression which leads to DVT, and (e) outline future research needs. Our goal is to raise awareness of MTS and spark additional research into the epidemiology of this condition, which may be an underappreciated causative venous thromboembolism risk factor.

Endovascular Deep Vein Stenting of Symptomatic Post-Thrombotic and Non-Thrombotic Iliac Vein Stenotic Lesions: A Multicentre Cohort Experience from Singapore

“…It is estimated to be present in 2% to 5% of patients with lower limb venous disease. [27][28][29] May and Thurner found spur-like projections in the left common iliac vein in 22% of 430 cadavers examined. 2 MTS is underdiagnosed, possibly due to its diagnostic difficulty and permissive role in chronic venous disease.…”

“…2 MTS is underdiagnosed, possibly due to its diagnostic difficulty and permissive role in chronic venous disease. 28 MTS is often asymptomatic, until an additional insult or pathology is superimposed, such as cellulitis or osteoarthritis of the knee resulting in loss of the venous calf pump mechanism. 25,30 A small prospective study on 20 asymptomatic volunteers who underwent angiography of the iliac veins found that 80% had at least 2 signs indicative of MTS.…”

Deep Venous Aberration

“…The true prevalence is still unknown. It ranges from 2-5% as per a few studies [5,6] Autopsy studies suggest a prevalence between 14-32% [5], radiology studies looking at the left lower extremity DVT alone suggest a prevalence from 22% to 76% [5]. A recent case series and extensive discussion by Katalin Mako et al [7] shows how it is often underestimated and needs a high index of suspicion for diagnosis.…”

Laterality of lower extremity deep vein thrombosis after colectomy: A retrospective study using the national inpatient sample

“…6 The casecontrol study by Narayan et al found that female sex had odds ratio 6.41 for compression of the left iliac vein, providing an underlying cause for the observed laterality associated with female sex. 7 It has been proposed that the accentuated lordosis of the lower spine in females pushes the left iliac vein forward against the right iliac artery (briefly reviewed by Harbin et al) 24 We did not perform adjustment for multiple comparisons because all analyses were driven by specific hypotheses. 25 Future studies may address whether the left-side predominance is restricted to female sex and what is the extent of its clinical significance.…”