Case Report/Case Presentation
A 32 -year old female with past medical history of hypothyroidism, gout,
cutaneous polyarteritis nodosa and recurrent miscarriages presented to
the emergency department (ED) with 1 week of progressive left lower
extremity swelling The swelling was associated with purplish
discoloration of her toes, along with a tingling sensation, especially
around the calf. She denied any shortness of breath, chest pain or
palpitations. Five weeks prior to her presentation, she had a
complicated delivery due to placenta accreta where she underwent a
Cesarean section. with a significant postpartum hemorrhage requiring 6
units of packed red blood cells and 2 units of fresh frozen plasma
transfusions. The bleeding continued, necessitating emergent
hysterectomy and bilateral salpingectomy. Due to surgical recovery and
post-operative pain, she had minimal ambulation for the month prior to
her presentation to the ED. Of note, given her recurrent miscarriages,
she had had a prior workup for antiphospholipid syndrome, which was
negative.
Assessment:
On exam, she was normotensive, afebrile, with a heart rate of 98. Lower
extremities showed left leg warmth, swelling and tenderness up to the
thigh with mild purplish discoloration over the toes along with livedo
reticularis. Bilateral dorsalis pedis pulses were intact and equal with
normal capillary refill. Ultrasound (US) revealed completely occlusive
deep vein thrombosis extending from the common formal vein through the
tibioperoneal trunk. Computed tomography venography (CTV) of lower
extremity showed demonstrated an extensive DVT, extending from
tibio-peroneal trunk through the common femoral vein and up to the
origin of inferior vena cava (IVC) shown in Figure 1.
Management
Anticoagulation was initiated with intravenous (IV) heparin drip.
Vascular surgery and
hematology was consulted, and she was deemed not fit for thrombolytics
due to her recent pelvic surgery and significant bleed. Her course was
complicated by sub-therapeutic activated partial thromboplastin time
(APTT) despite aggressive efforts, necessitating a switch to argatroban.
However, due to the unremitting left leg pain, she underwent mechanical
thrombectomy and thrombolysis in the left popliteal, femoral and common
femoral veins, with prophylactic intravenous vena cava filter placed
prior to the procedure.
Notably, her angiogram during the procedure showed high grade stenosis
in the distal left common iliac vein, indicative of May Thurner
Syndrome. Hence, during the procedure, she received left iliac vein
stenting to maintain patent venous outflow in the long term shown in
Figure 2 . Post procedure she remained on argatroban drip and Tissue
plasminogen activator (tPA) was initiated to maximize thrombolysis
efforts. Repeat angiogram in less than 48 hours showed the common
femoral vein, external iliac vein, common iliac vein to be widely
patent. tPA was stopped after 48 hours and the patient was switched to
subcutaneous fondaparinux 10mg daily. Three weeks later, she was
switched to the oral anticoagulant (OAC) rivaroxaban. Despite being on
rivaroxaban, a repeat US of her left leg 10 weeks later showed
thrombosis in the previously patent left common femoral vein, extending
into external and common left iliac veins with thrombosis of the left
iliac vein. Repeat angiogram showed the new complete occlusion of the
left common femoral vein as well as the common and external iliac veins.
The thrombosis appeared chronic and sclerotic and stent recanalization
was attempted but unsuccessful. She had intact pulses and did not have
increased lower extremity swelling or any other sign of DVT so remained
on anticoagulation with the plan for lifelong rivaroxaban therapy.
Repeat US 4 months later showed residual left iliac vein stent
thrombosis and nonocclusive thrombus in the left common femoral vein.
Another repeat US at 6 months revealed a patent left common iliac vein
suggestive of interval clot resolution but persistent left common
femoral vein thrombus. IVC filter has remained in place for these past
12 months due to the fluctuating clinical course to ensure
safety.
Discussion/Conclusion
May-Thurner syndrome is a condition where patients develop compression
of the iliocaval venous system by the arterial system on a bony
structure causing disruption of venous blood flow. Many variants exist;
the most commonly seen is compression of the left common iliac vein by
the right common iliac artery against the lumbar vertebrae. This
develops through intimal hypertrophy of the iliac vein wall secondary to
mechanical compression and arterial pulsation. It creates potential
stasis and subsequent thrombosis. As early as 1851, Virchow noted that
left leg DVT is more common than right by 5 times2. Afterwards, in 1908,
the anatomical variation was described and was linked to Virchow’s
finding3. However, MTS was not recognized until 1957 when May and
Thurner described the compression of left iliac vein by the right iliac
artery against lumbar spine causing thrombosis4. The exact incidence and
prevalence of MTS remains largely unknown. Multiple reports suggested
prevalence by 20-30%1,2,5. In general, it is a less reported cause of
DVT. MTS can be challenging to recognize and requires a high index of
suspicion, identifiable risk factors, and more invasive
testing to diagnose6. Interestingly, the mere presence of this
anatomical finding might not predispose patients to DVT, unless combined
with either the presence of hypercoagulability, endothelial injury and
more stasis in conjunction (Virchow’s triad) which would lead to
thrombus formation2. Patient have various clinical presentations,
ranging from asymptomatic to venous claudication and skin damage7.
Current observational studies suggest MTS is more commonly seen in young
females (60%) 8. Patients who develop DVT in this gender and age group
are mostly on oral contraceptives or may have had recent pregnancy, or
less commonly, prolonged immobilization1. These factors predispose the
asymptomatic MTS patient to become symptomatic. Other risk factors
include: scoliosis, which may predispose to MTS through compression from
the lower lumbar vertebra; dehydration; and radiation exposure9,10,11.
As such, signs of left sided DVT in high risk patients i.e., young and
female, particularly with risk factors, should prompt extensive
evaluation including a doppler US of the affected extremity. A
retrospective analysis of 50 abdominal computed tomography (CT) scans of
patients with abdominal pain but without lower extremity symptoms showed
that 25% of the individuals had hemodynamically significant lesions
causing at least 50% stenosis in the left common iliac vein while
two-thirds had at least 25% compression2. Thus, this finding may
represent a normal anatomic variant rather than a pathological
condition2. Treatment of May-Thurner syndrome involves thrombolysis of
the formed clot, stent placement to alleviate the anatomical compression
stenosis, and long-term anticoagulation to prevent further thrombosis.
In certain cases, thrombectomy could be also considered, especially in
cases that thrombolysis is at great risk. Vena cava filters are almost
always deployed to prevent pulmonary embolism from showering emboli
during the procedure 2,12. The question that arises is the choice of
anticoagulation (AC) and their duration. Recently a systematic review
and meta-analysis concluded stent thrombosis or occlusion occurred in
10%-20% of post-stent placement patients at median of 12 months
regardless of choice of antithrombotic management13. Thus, it was not
able to suggest a standard type, dose or duration due to inconsistencies
in the included studies and no availability of any prospective study
comparing treatments/therapeutic approaches. Endo., et al suggest
that after illiocaval venous stenting, stent patency is best predicted
by combined antiplatelet and anticoagulation rather than antiplatelets
alone14. There is a lack of data on postinterventional
medical therapy in endovascular therapy15. Although antiplatelet therapy
is
frequently used, the duration is variable given the absence of practice
guidelines15. The optimal approach with anticoagulation with or without
antiplatelets still remains unknown and warrants further randomized
control trials. Most DVTs that are associated with MTS can resolve with
or without stent placement while the patient is on anticoagulation.
Nevertheless, some patients develop extreme complications such as
post-thrombotic syndrome, venous claudication, varicose vein formation,
venous stasis ulceration and recurrent DVT16. For example, 36.8% of the
female patients that were involved in one study developed post-phlebitis
syndrome17. In these cases, like ours, complications occur even after
stent placement and in such cases venous bypass surgery remains as the
last resort.
CONCLUSION:
May-Thurner Syndrome is an underdiagnosed but well-known risk factor for
thromboembolic
events. Unidentified MTS carries a potential risk of recurrent DVT,
pulmonary embolism and
chronic venous insufficiency. Early recognition for the high-risk group
with typical features is
crucial. Endovascular intervention remains the mainstay of treatment.
However, evidence on the best anticoagulation regimen to be used is
still lacking. More randomized control trials on the guidance of
anticoagulation versus antiplatelets are warranted.