The Case Files

Abstract

A 49-year-old woman presented to the emergency department with a complaint of color change to her left leg while walking. She was watching a parade when she developed paresthesias to her left thigh and leg, and noticed her entire left thigh and leg were discolored and blue. She denies prior occurrence or any injury or trauma to the leg. She had no headache, weakness, change in vision, chest pain, shortness of breath, palpitations, abdominal pain, nausea, vomiting, diarrhea, or urinary symptoms. She had no history of prior thromboembolism or arterial pathology. She is not a smoker, and has not seen a physician for years. She also denied recent travel, oral contraceptives, recent surgery, any medical conditions, or surgical history. She stated that her leg appears slightly better than before, and the paresthesias have resolved. She is morbidly obese, and appears slightly anxious, with an elevated heart rate of 115 bpm. Her vital signs are otherwise within normal limits. Her entire leg from her inguinal ligament to her foot is mottled and slightly cyanotic with marked swelling. She has normal range of motion. Her leg is warm and not tender. Sensation is intact, and distal pulses are palpable. The rest of her physical exam is unremarkable. Her EKG is sinus tachycardia without ST/T wave changes. A heparin drip is empirically ordered before the negative Doppler of the left lower extremity study for DVT. Vascular surgery is consulted, and a CT angiogram of the aorta with runoff is obtained. (Fig. 1–3.)Figure 1: Transverse view of right iliac artery compressing left iliac vein against lumbar spine just distal to venous bifurcationFigure 2: Transverse view of venous congestion in left lower extremity contributing to markedly swollen leg found on examImageThe patient was admitted when the CT suggested a pelvic DVT. Later review of the CTA lead to the diagnosis of a left iliac vein DVT due to May-Thurner syndrome. May-Thurner syndrome is also known as iliac compression syndrome, and is a rare congenital anatomic variant that causes narrowing of the left common iliac vein by compression from the chronic pulsation of the right common iliac artery against the lumbar spine. This compression leads to swelling, pain, varicosities, and venous ulcers, and predisposes the patient to thrombus formation. Establishing the diagnosis is critical because severe complications such as phlegmasia cerulea dolens or pulmonary embolus leading to sudden death can occur. This syndrome was first described by James Playfair McMurrich in 1908, but was named after May and Thurner in 1957 who described it after examining 430 cadavers. (Angiology 1957;8[5]:419.) They documented occurrence where the right iliac artery crossed over the left iliac vein, and hypothesized that this chronic compression impeded flow and thrombosis because of the intimal hyperplasia that ensued. It has been suggested from cadaver examinations and retrospective CT reviews that approximately 22–24 percent of the population has this variant and is asymptomatic. (J Vasc Surg 2004;39[5]:937.) May-Thurner most commonly affects women 20–40 years old. Thrombosis occurs more commonly on the left side, and should be considered a risk factor for patients presenting with a left-sided iliofemoral DVT. (Diagn Interv Radiol 2007;13[3]:152.) Risk factors are similar to those with a lower extremity DVT such as oral contraception, obesity, pregnancy, immobilization, cancer, recent surgery, and genetic hypercoagulable states. Venography is the study of choice. Ultrasound Doppler of the extremity is usually negative. Similar to other DVTs, patients are anticoagulated to prevent clot progression. Unfortunately, anticoagulation alone is not sufficient in these patients because reoccurrence most likely occurs from anatomical chronic compression. Localized thrombolytic therapy or catheter-directed administration of an antifibrinolytic is effective in eliminating the clot. Angioplasty with an endovascular stent can be placed after successful thrombectomy. Failure of stent placement increases the risk for rethrombosis or venous insufficiency. (J Vasc Surg 2004;39[5]:937; Diagn Interv Radiol 2007;13[3]:152.) Complications with stent placement include in-stent thrombosis, stent migration, and retroperitoneal hemorrhage. (J Vasc Surg 2007;46[4]:743.) Retrospective and prospective studies suggest that endovascular stent placement is the front-line treatment. (J Vasc Surg 2007;46[4]:743; J Cardiovasc Surg 2001;42[1]:83; AJR Am J Roentgenol 2004;183[5]:1523.)