Case Presentation: A 17 year old female was diagnosed with a pulmonary embolus 3 months ago. A partially occlusive thrombus was also noted in her left common iliac vein. She was diagnosed with May-Thurner syndrome (MTS), and treatment was started with therapeutic doses of Lovenox. She missed only five doses of Lovenox during the ensuing 3 months.
She presented to the emergency room due to a two day history of pain and edema in her left lower extremity, which were interfering with her ability to ambulate. A left lower extremity venous Doppler was done, and this revealed occlusive deep vein thrombosis (DVT) extending from the popliteal vein to the iliac vein. Subsequently she was started on an intravenous heparin drip. Interventional Radiology recommended mechanical thrombectomy/thrombolysis and iliac vein stent placement for further management of her venous thromboembolism (VTE).
In the emergency room, the patient’s pregnancy test was positive. Her pregnancy was deemed to be high risk, and later during this admission she opted to have it terminated. She had mild uterine bleeding postoperatively. Since there is a relative contraindication to the use of tissue plasminogen activator (tPA) with active bleeding, it was decided that thrombolysis would be done at a later date. She was discharged to home on therapeutic doses of Lovenox, with a plan for her to undergo thrombolysis and iliac stent placement in two weeks.
Discussion: May-Thurner syndrome (MTS) is caused by venous outflow obstruction in the iliocaval venous territory. Most commonly, it is caused by compression of the left iliac vein between the fifth lumbar vererbra and the right common iliac artery; however, other variants exist. Risk factors for the development of MTS include female sex, dehydration, hypercoagulable disorders, and scoliosis. Some estimates attribute between 2 to 5 percent of symptomatic lower extremity venous disorders to MTS. However, since most people with MTS anatomy are asymptomatic, the precise prevalence of this condition is uncertain. It is probably underestimated.
After VTE has been diagnosed in a patient with MTS, anticoagulation should be promptly started. The next treatment step involves thrombolysis (pharmacomechanical or catheter-directed) in order to reduce the thombus volume. This is followed by angioplasty and stent placement in the affected iliocaval segment. Poorer outcomes are observed if only anticoagulation is used to manage MTS. Compression stockings should be utilized following angioplasty and stent placement. Anticoagulation should be continued for patients with DVT, according to standard VTE guidelines.
Conclusions: Most patients with May-Thurner syndrome (MTS) are asymptomatic; however, the typical clinical presentation is a young female with left lower extremity DVT. Optimal treatment outcomes are observed with full anticoagulation, plus thrombolysis, angioplasty, and stent placement.