May-thurner Syndrome: a Case Report

May-Thurner Syndrome (MTS) or iliac vein compression syndrome is caused by compression of the left common iliac vein by the right common iliac artery. This obstruction may cause leg swelling, vari-cosities, deep venous thrombosis, chronic venous stasis ulcers, or more serious complications, such as pulmonary embolism. Iliac vein compression can be assessed with computed tomography (CT) and iliac venography. The goals of treatment are to reduce symptoms and to reduce the risk of complications. Stent placement is an alternative method to a direct surgical approach. We present a case of MTS, treated with stent placement. Anahtar Kelimeler: İliak ven kompresyonu, May-Thurner sendromu


Introduction
May-Thurner syndrome, also known as iliac vein compression syndrome, Cockett syndrome, or iliocaval compression syndrome is caused when the left iliac vein is compressed by the right iliac artery, which increases the risk of deep vein thrombosis (DVT) in the left leg [1][2][3].A history of persistent left lower extremity swelling with or without deep venous thrombosis in a woman between the 2 nd and 4th decades of life, without an obvious cause, is highly suggestive of May-Thurner syndrome.The clinical suspicion can be confirmed with CT and iliac venography [4].We present a case of MTS with persistent painless swelling of the left thigh.

Case Report
A 28-year-old female presented with left thigh swelling for approximately three years.Bilateral lower extremity venous Doppler ultrasonography (US) revealed normal findings.Abdominopelvic contrast-enhanced wide area detector CT angiography [5,6] was performed to assess the patient.CT scan demonstrated normal arterial anatomy and compression of the left iliac vein by the right common iliac artery (Figure 1).Stenting of the iliac vein was applied as treatment (Figures 2-4).

Discussion
May-Thurner syndrome is caused by compression of the left common iliac vein by the right common iliac artery.It is not an infrequent source of venous abnormalities in the left lower extremity [7].The overlying artery appears to induce a partial obstruction of the vein in two ways: by its anatomic orientation with subsequent physical entrapment of the left common iliac vein, and by extensive intimal hypertrophy of the vein resulting from the chronic pulsatile force of the right common iliac artery [7].This condition has been estimated to occur in 2-5% of patients who undergo evaluation for lower extremity venous disorders [3].
Reported findings show that lower extremity deep venous thrombosis occurs three to eight times more frequently in the left side than on the right [2,8].İliac vein compression should be diagnosed prior to the onset of iliofemoral venous thrombosis and venous insufficiency syndrome.An iliac venogram obtained via femoral artery is the diagnostic test of choice because it can demonstrate the compression itself and because the pressure gradient measurement can be performed to confirm the hemodynamic significance.Contrast material-enhanced CT scans at the level of the distal abdominal aorta can also demonstrate the extrinsic compression caused by the right common iliac artery.
May-Thurner syndrome is a progressive disease with longterm disabling complications [4].This type of obstruction may cause leg swelling, varicosities, deep venous thrombosis, chronic venous stasis ulcers, or more serious complications, such as pulmonary embolism or phlegmasia cerulea dolens [3,7].Multiple surgical treatment options have been advocated.These include vein-patch angioplasty with excision of the intraluminal bands, division of the right common iliac artery and relocation behind the left common iliac vein or inferior vena cava, and contralateral saphenous vein graft bypass to the ipsilateral common femoral vein with creation of a temporary arteriovenous fistula (Palma crossover) [8,9].The reported long-term success, which is defined primarily as patency of the left common iliac vein or venous bypass, is 40%-88% [8].In recent years, treatment with endovascular  techniques has been described [8,10,11].Excellent shortterm results with stent placement have been reported in case reports and small series [8,11,12].
In conclusion, May-Thurner syndrome should be taken into consideration if there is persistent edema of the left leg, especially in young Women.CT and iliac venography demonstrates the iliac vein compression.The mechanical compression should be recognized prior to the onset of deep venous thrombosis and venous insufficiency.Endovascular treatment with stent placement is an alternative to direct surgical repair that yields excellent short-term results.

Figure 1 .
Figure 1.Contrast-enhanced CT scan revealed absence of the left common iliac vein due to compression.

Figure 2 .
Figure 2. Contrast-enhanced CT scan revealed stent placement in the left common iliac vein compressed by the right common iliac artery.

Figure 3 .
Figure 3. Three-dimensional volume rendering contrast-enhanced CT scan revealed stent placed left common and external iliac vein (arrow).

Figure 4 .
Figure 4. Contrast-enhanced coronal CT scan revealed the stent placement in the left common and external iliac veins.