Acute on Chronic Venous Thromboembolism on Therapeutic Anticoagulation

A case of proximal venous thromboembolism in a patient who presented to the ED with lower extremity pain is presented. Making this diagnosis is very important as fifty percent of patients with symptomatic proximal DVTs will go on to develop PE without treatment. This report underscores the utility of bedside ultrasonography in the emergency department. 1. Introduction Venous thromboembolic disease is fairly common, with an approximate yearly incidence exceeding one in every 1000 adults [1], and two-thirds of these will present as isolated deep vein thrombosis (DVT) [2]. While more of these patients will have distal rather than proximal DVT, the mortality rate of proximal DVT is almost double that of distal DVT due to its propensity to migrate to the lungs and cause acute pulmonary embolus (PE) [3]. Multiple characteristics have been looked at in an attempt to differentiate acute from chronic DVT, as these are treated very differently. It can be difficult to differentiate acute from chronic DVT with ultrasound alone [4]. However, lumen echogenicity and vessel elasticity are two characteristics that have shown promise in aiding with this difficult diagnosis [5, 6], as chronic thrombi are more echogenic and less elastic than acute thrombi [7, 8]. 2. Case A 40-year-old male presented to the emergency department with the complaint of left lower extremity pain and swelling for three weeks which had acutely worsened. His past medical history was significant for PE and DVT, most recently five months prior to presentation. He was on daily Coumadin but had difficulty consistently maintaining a therapeutic INR. His most recent INR was 3.9 three days prior to admission. He had been instructed by his primary care physician to hold Coumadin for two days and then restart, which he did the day prior to presentation. Physical exam revealed a warm, erythematous left lower extremity. He was tender to palpation of the calf and had 2+ pitting edema distally from his knee. Distal pulses of his left leg were intact, and he had full strength and range of motion of the knee and ankle. A high frequency 7.5–10？MHz linear array transducer was used to perform the lower extremity ultrasound. Standard, water-soluble ultrasound gel was applied to the patient’s groin. The femoral region was scanned in the transverse plane, proximally from the level of the common femoral vein (CFV) just proximal to the junction of the long saphenous vein, distally through the division of the superficial and deep femoral veins. The vein was compressed every 2-3？cm in the usual fashion. The ultrasound