Determining a solid management plan for deep vein thrombosis.
A 78-year-old woman currently being treated for pancreatic cancer presents with a swollen, painful left calf, progressive over three days. She denies trauma, fevers, chest pain, new shortness of breath, or change in her exercise tolerance. She denies hormone medications, recent long trips, travel, surgeries, or hospitalizations.
Her vital signs are within normal limits and her exam reveals tenderness to palpation posteriorly on her left calf with mild edema. A formal ultrasound including the calf veins is negative for a deep vein thrombosis. What is the best next step in the management?
- Discharge with primary care follow-up as needed
- Initiate apixaban and repeat the ultrasound in one week
- Initiate low molecular weight heparin and repeat the ultrasound in one week
- Perform a CT venogram of the left leg
- Repeat ultrasound in one week
Correct answer: E. Repeat ultrasound in one week
Typically, ultrasounds for deep vein thrombosis (DVT) only assess from the femoral vein to the popliteal vein. As such, approximately 5% of patients with a negative DVT study will have ultrasound confirmed DVTs one week later.
In this patient with a high clinical suspicion and a significant risk factor (active cancer), she should have a repeat DVT study done in one week. Another option would be to do a D-Dimer (even in patients with cancer) and an ultrasound together on this visit. Two large studies have confirmed a very low rate of missed DVT in patients with a negative ultrasound and a negative D-Dimer. Additionally, patients with a positive D-Dimer had a much higher rate of DVT one week later. Negative ultrasound + positive D-Dimer–> repeat ultrasound in one week.
Incorrect answer choices:
Discharge for general follow-up (Choice A) is not appropriate since she needs repeat imaging in seven days. At this point, an oral anticoagulant (Choice B) or low molecular weight heparin (Choice C) are not indicated since her initial study is negative. In general, patients with negative ultrasounds on their initial visit are very low risk for death or acute pulmonary embolism in the next seven days. It is worth noting that heparin–whether unfractionated or LMWH — is the preferred agent for cancer-related VTE, over coumadin and NOACs. She does not have a confirmed DVT, but if she did, LMWH would be the correct medication. Lastly, the patient has no chest pain, shortness of breath, tachycardia, hypoxemia, or change in exercise tolerance.
Although she may have a calf DVT in the setting of a false negative study, additional imaging (Choice D) for the DVT, unless there is concern for a pelvic DVT, is not indicated. It is reasonable to accept the results of the formal US and follow up in a week.
References
- Kearon C et al The role of venous ultrasonography in the diagnosis of suspected deep venous thrombosis and pulmonary embolism. Thromb Res. 2013 Jun;131(6):487-92. doi: 10.1016/j.thromres.2013.04.022. Epub 2013 May 9.
- Kline J. Ch. 56. Venous Thromboembolism. In Tintinalli JE, Stapczynski J, Ma O, Yealy DM, Meckler GD, Cline DM. eds.Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e New York, NY: McGraw-Hill; 2016.
- Kearon C, Ginsberg JS, Douketis J, et al. A randomized trial of diagnostic strategies after normal proximal vein ultrasonography for suspected deep venous thrombosis: D-dimer testing compared with repeated ultrasonography. Ann Int Med. 2005;142(7):490-496.
- Zierler BK. Ultrasonography and diagnosis of venous thromboembolism. Circulation. 2004;109[suppl I]:I-9-I-14.
