A 36-year-old woman comes to the emergency department due to right lower leg pain and ankle edema. Her symptoms began 2 days ago after a 14-hour flight from India. The patient has had no leg trauma, fever, chest pain, or shortness of breath. She has a history of asthma and takes inhaled albuterol as needed. The patient has no family history of blood clots.
Temperature is 36.8 C (98.2 F) , blood pressure is 142/72 mm Hg, pulse is 98/min, and respirations are 16/min. BMI is 26 kg/m². Cardiopulmonary examination shows no abnormalities. There is 2+ right lower extremity pitting edema extending to the mid-calf, and right foot dorsiflexion results in right calf pain. Left lower extremity examination is normal. Stool guaiac is negative. Laboratory results are as follows:
Compression ultrasonography of the right lower extremity shows no evidence of deep venous thrombosis. D-dimer is 65 µg/mL (normal: <0.5) .
Which of the following is the most appropriate next step in management of this patient?

Question

A 36-year-old woman comes to the emergency department due to right lower leg pain and ankle edema. Her symptoms began 2 days ago after a 14-hour flight from India. The patient has had no leg trauma, fever, chest pain, or shortness of breath. She has a history of asthma and takes inhaled albuterol as needed. The patient has no family history of blood clots.
Temperature is 36.8 C (98.2 F) , blood pressure is 142/72 mm Hg, pulse is 98/min, and respirations are 16/min. BMI is 26 kg/m². Cardiopulmonary examination shows no abnormalities. There is 2+ right lower extremity pitting edema extending to the mid-calf, and right foot dorsiflexion results in right calf pain. Left lower extremity examination is normal. Stool guaiac is negative. Laboratory results are as follows:

Compression ultrasonography of the right lower extremity shows no evidence of deep venous thrombosis. D-dimer is 65 µg/mL (normal: <0.5) .
Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec193a_961a_827b_853d_ad5f2d37c69d_MD0002_00 Although not enough clinical information is provided to assess this patient's modified Wells score, her recent long air flight, new-onset unilateral leg edema/pain, and positive Homan sign (pain in the calf on dorsiflexion of the foot) suggest a high pretest probability for deep venous thrombosis (DVT). Patients with suspected DVT are evaluated based on pretest probability as follows: Low probability - Obtain moderate- or high-sensitivity d-dimer level. A normal d-dimer rules out DVT (d-dimer has a sensitivity of up to 96% but specificity is low); an elevated d-dimer necessitates further evaluation with compression ultrasonography (CUS).High probability - Proceed directly to CUS, which has a diagnostic sensitivity of >97% for DVT. As false negatives can occasionally (<3%) occur, patients with a high pretest probability of DVT who have negative CUS testing, continue to be symptomatic, have no clear alternate diagnosis, and have an elevated d-dimer should have repeat CUS within days. Low probability - Obtain moderate- or high-sensitivity d-dimer level. A normal d-dimer rules out DVT (d-dimer has a sensitivity of up to 96% but specificity is low); an elevated d-dimer necessitates further evaluation with compression ultrasonography (CUS). Low probability - Obtain moderate- or high-sensitivity d-dimer level. A normal d-dimer rules out DVT (d-dimer has a sensitivity of up to 96% but specificity is low); an elevated d-dimer necessitates further evaluation with compression ultrasonography (CUS). High probability - Proceed directly to CUS, which has a diagnostic sensitivity of >97% for DVT. As false negatives can occasionally (<3%) occur, patients with a high pretest probability of DVT who have negative CUS testing, continue to be symptomatic, have no clear alternate diagnosis, and have an elevated d-dimer should have repeat CUS within days. High probability - Proceed directly to CUS, which has a diagnostic sensitivity of >97% for DVT. As false negatives can occasionally (<3%) occur, patients with a high pretest probability of DVT who have negative CUS testing, continue to be symptomatic, have no clear alternate diagnosis, and have an elevated d-dimer should have repeat CUS within days. Patients with moderate pretest probability can be initially evaluated with either high sensitivity d-dimer (normal rules out; elevated requires CUS) or CUS. (Choice A) Patients with low or moderate probability DVT who have negative CUS can be treated with symptomatic care. This patient has a clinical presentation highly concerning for DVT and an elevated d-dimer; repeat CUS should be performed to ensure that the original test was not falsely negative. (Choice B) Although CT angiography has a marginally better sensitivity than ultrasound, it is invasive, expensive, difficult to perform and interpret, and associated with a risk of complications (eg, renal failure, allergic reaction). As such, this test is rarely performed; CUS should be repeated instead. (Choice C) Screening for hypercoagulable disorders is not generally undertaken in the setting of acute thrombus as the level/activity of many of the anticoagulant factors is altered, which confounds the interpretation of results. Testing is generally undertaken approximately 2 weeks after the cessation of anticoagulation. (Choice D) Although rivaroxaban can be used for anticoagulation in acute DVT, anticoagulation should not be initiated prior to radiographic diagnosis due to risk of bleeding. This is in contrast to suspected pulmonary embolism, in which anticoagulation is initiated while awaiting diagnostic confirmation due to the immediately life-threatening nature of the condition. Educational objective: Patients with a high pretest probability of deep venous thrombosis (DVT) should undergo compressive ultrasonography for diagnosis. False negatives occur in 3% of high probability cases; patients who have negative initial testing, continue to be symptomatic, have no clear alternate diagnosis, and have an elevated d-dimer should be retested with whole leg compressive ultrasound within 24 hours. __________ References: Diagnosis of DVT: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/22315267)

A 36-Year-Old Woman Comes to the Emergency Department Due to Right