56 year-old male with history of hypertension presented with left knee pain. Symptoms were initially mild until he then went on vacation from Ohio to South Carolina, driving 11 hours there and back. Pain was then noted in his groin with associated left upper leg swelling. An ultrasound was done which suggested left leg deep vein thrombus. He was started on warfarin with enoxaparin bridging therapy for presumed provoked DVT from the prolonged car ride. He was referred to a hematologist who was concerned with the extensive DVT found on venous doppler exam, and an MRI venogram of the pelvis was ordered. There was flattening of the left common iliac vein as it courses posterior to the right common iliac artery, suggestive of May-Thurner Syndrome. He was admitted to the hospital and underwent serial venographies by Interventional Radiology along with multiple stent placements and catheter-directed thrombolysis with ultrasound assistance (EKOS drug delivery system). Thrombus completely resolved and he was discharged on warfarin therapy.
May-Thurner syndrome, also known as iliac compression syndrome, is a relatively common congenital structural abnormality initially described in 1956 by May and Thurner with the left common iliac vein being compressed by the right iliac artery against the lumbar vertebrae. It is suggested to occur in about 20% of the population, however only causes about 2-5% of DVT cases. Most often occurring in young women ages 20-40, especially on oral contraceptives or during peripartum periods, DVT complications are at least 3 times less likely to occur in males. Review of case reports rarely include males or patients outside of this age group.
Standard DVT testing with venous Doppler ultrasounds are inadequate for iliac vein visualization and one must order special imaging studies of the pelvis to rule our extrinsic compression involved in this area. Various imaging modalities include CT venography, MR venography and contrast venography. These cases of DVT are usually diagnosed when anticoagulation therapy alone does not fully treat the DVT, or when recurrence occurs.
Treatment of this condition requires more than systemic anticoagulation, therefore the condition should be suspected with failure of initial therapy or DVT recurrence. It has been documented that thrombolytic therapy alone is not sufficient and standard treatment includes stent placement.
Deep vein thrombus is a common condition treated by an inpatient physician and determining the cause is crucial in management. Although a thorough history is often sufficient, physicians must keep in mind less common causes such as structural abnormalities. Even though May-Thurner Syndrome is a rare cause of DVT, we must not overlook it as a cause in males or patients older than 40, as the underlying condition is relatively common in the population.