Red Leg in the Heartland of America: A Rural Physician’s Approach to the Patient with a Potential DVT

Author: Braeden D. Johnson, MD (Community EM, Salina Regional Health Center) // Reviewed by: Joshua Lowe, MD (EM Attending Physician, USAF); Marina Boushra, MD (Cleveland Clinic Foundation, EM-CCM); Brit Long, MD (@long_brit)

Case

A 40-year-old woman presents to a rural emergency department (ED) with left leg pain and swelling for the past 5 days. Her past medical history is significant for hypertension, for which she takes amlodipine. She denies any history of exogenous estrogen use or personal history of deep vein thrombosis (DVT).

Her vital signs are within normal limits. Her exam is notable for a mildly swollen, non-erythematous left lower leg without pitting edema.  The patient is concerned about a potential DVT.  The facility does not have ultrasound (US) availability at the time of the patient’s presentation, as the sonographer comes to the hospital only 2 days a week. What are the next steps in the diagnosis and management of this patient?

Background

Duplex ultrasonography is the gold standard in the diagnosis of DVTs, with a sensitivity of 98% and specificity of 95% for a proximal DVT [1]. However, duplex ultrasonography may not be readily available at all times in rural or critical access facilities.

Approach

For patients who are short of breath, have abnormal vital signs, or have other signs or symptoms concerning for pulmonary embolism (PE), urgent workup and transfer as needed to a higher level of care should be undertaken. In patients who do not meet these criteria, consider the differential diagnosis for a swollen leg, including dependent edema or lymphedema, stasis dermatitis, cellulitis, DVT, ruptured baker’s cyst, or mild CHF with pre-existing unilateral venous insufficiency. First, examine the patient and risk-stratify them for the diagnosis of DVT before deciding on the clinical utility of an ultrasound.

What findings make a DVT more likely? The Wells’ Criteria for DVT can help risk stratify [2,3]. Each finding is worth +1 point.

• Active cancer
• Immobile/bedridden >3 days or major surgery within 3 months
• History of DVT
• Paralysis, paresis, or recent plaster immobilization of the affected limb
• Exogenous estrogen use
• ENTIRE leg swollen
• Unilateral calf swelling >3mm
• Pitting edema in the affected limb
• Presence of collateral (non-varicose) superficial veins
• Localized tenderness along the deep venous system

What makes DVT less likely?

• Bilateral swelling and/or redness (-1 point)
• Fever (-1 point)
• An alternate diagnosis to DVT is as likely or more likely (-2 points)

Can DVT be ruled out without an US?

• If the patient’s Wells score is ≤ 0, DVT is nearly clinically excluded and no further immediate lab or ultrasound is necessary. Initial studies showed the prevalence of DVT as high as 5% with a Wells ≤ 0, but follow-up studies have shown negative predictive values as high as 98.8% [4,5]. Individual practice patterns, risk tolerance, and shared decision-making dictate whether this degree of risk is acceptable.
• In patients with a Wells’ score of 1-2 (moderate risk), DVT can be ruled out with a negative d-dimer rather than an US. A score of 1-2 has a 17% prevalence of DVT [6]. In conjunction with a negative D-dimer, the risk of DVT is reduced to less than 1%[6].
• In those with a high-risk Wells’ score (>2), a negative D-dimer has less clinical utility. If the patient does not have phlegmasia cerulea dolens/albicans, they can be treated the same as a moderate risk with positive D-dimer (see below). This is because the high probability Wells/ score with a negative D-dimer only reaches a sensitivity of 92%, which is inadequately high [4].
• Symptom onset should be within 7 days to rely on a D-dimer [7].

In patients with a Wells’ score of 1-2 with positive D-dimer or a high-risk Wells’ Score (>2) in whom US cannot be urgently obtained, consider starting short-term empiric anticoagulation.

• Start treating with a direct oral anticoagulant (DOAC) such as apixaban or rivaroxaban. Alternatively, in patients without renal dysfunction, consider a therapeutic 12 or 24-hour dose of enoxaparin pending definitive testing. Give the first dose of enoxaparin in the ED: 1 mg/kg subcutaneously for 12 hours or 1.5 mg/kg for 24 hours.
• Document a risk and benefit discussion with the patient regarding empiric anticoagulation, perhaps even including the HAS-BLED score in the documentation [10].
• Patients being empirically treated still need an US evaluation within the next 24-72 hours. If the system allows, physicians should schedule the ultrasound for the patient. If this is not possible in the hospital system, physicians should  communicate directly with someone who can facilitate the order.
• Practice groups should have a clear plan for who receives the US result when done, the next steps in management, and how to how to document that communication
  • Potential options include having the results called to the on-call physician (or county-call physician if the patient has no PCP), who is then responsible for continuing therapy if needed. This can also be arranged with the PCP (this is ideal, but not always possible). This may be more difficult in systems that do not allow outpatient imaging without prepayment or insurance.
  • The follow-up physician contacts the patient with negative results as well to discontinue anticoagulation and discuss further follow-up and treatment for non-DVT diagnosis.
• What diagnoses are left with a negative US?
  • • Venous stasis, cellulitis, etc.
    • It could still be a DVT! Follow-up US scheduled in roughly one week through their PCP should symptoms persist [8,9]

Starting the anticoagulant

Physicians should have a risk/benefit discussion before initiating empiric anticoagulation.  A study in 2020 led to 624 patients with delayed US strategy started on rivaroxaban had 0% major bleed rate and eventual diagnosis of 119 DVTs [11].

• Is one DOAC better than another? Apixaban is probably the best based on existing literature around atrial fibrillation. However, the best DOAC is the DOAC the patient can afford and will actually take.
  • An indirect study of various RCTs around the four major DOACs showed no meaningful differences in major bleeding rates when treating VTE [12].

The Author’s Perspective

This is what we do in the sticks, but don’t be a cowboy. This is the approach we take in rural Kansas for a few reasons. There are times when we have no access to a formal US, unless the patient gets transferred to another ED 50+ miles away. When US is available, but the tech would be required to come in at night, we don’t want to burn them out when we can use an approach with a temporizing measure so the patient can get their study safely n a less emergent timeframe. It is paramount to make sure this approach is agreed upon in your ED or urgent care and that there is a clear pathway before implementing a similar strategy.

Caveats 

• This is not a clinical guideline, but rather a clinical approach to these patient encounters guided by data over the past 20 years [13,14,15].
• This is for patients with symptoms of less than one week. D-dimer in patients with symptoms greater than a week have decreased sensitivity, which likely unacceptably increases risk [7].
• Choosing the right patient to order a d-dimer on is an important consideration.
• This is NOT for the high-risk patients.
• This is NOT for patients in whom PE is suspected.
• Being on estrogen does not preclude patients from this pathway (but it does give them a point on the Well’s score, decreasing the margin for error).

Pearls and Pitfalls

• Examine and risk stratify the patient for the diagnosis of DVT AND PE.
• In patients at low risk for PE, consider getting outpatient US in the next day or two with temporary anticoagulation.
• Have a clear algorithm and workflow for the follow-up of outpatient studies ordered from the ED.

References

1. Kraaijpoel N, Carrier M, Le Gal G, et al. Diagnostic accuracy of three ultrasonography strategies for deep vein thrombosis of the lower extremity: A systematic review and meta-analysis. PLoS One. 2020;15(2):e0228788. Published 2020 Feb 11. doi:10.1371/journal.pone.0228788
2. Wells PS, Anderson DR, Rodger M, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227-1235. doi:10.1056/NEJMoa023153
3. Wolf SJ, McCubbin TR, Feldhaus KM, Faragher JP, Adcock DM. Prospective validation aof Wells Criteria in the evaluation of patients with suspected pulmonary embolism. Ann Emerg Med. 2004;44(5):503-510. doi:10.1016/j.annemergmed.2004.04.002
4. Wells PS, Owen C, Doucette S, Fergusson D, Tran H. Does this patient have deep vein thrombosis?. JAMA. 2006;295(2):199-207. doi:10.1001/jama.295.2.199
5. Dybowska, M., Tomkowski, W.Z., Kuca, P. et al. Analysis of the accuracy of the Wells scale in assessing the probability of lower limb deep vein thrombosis in primary care patients practice. Thrombosis J 13, 18 (2015). https://doi.org/10.1186/s12959-015-0050-4
6. Deep Venous Thrombosis (DVT). TheNNT. Accessed September 20, 2023. https://thennt.com/lr/deep-venous-thrombosis-dvt/#:~:text=When%20combined%20with%20a%20negative,DVT%20is%20less%20than%201%25.
7. Goldin Y, Pasvolsky O, Rogowski O, et al. The diagnostic yield of D-Dimer in relation to time from symptom onset in patients evaluated for venous thromboembolism in the emergency medicine department. J Thromb Thrombolysis. 2011;31(1):1-5. doi:10.1007/s11239-010-0480-6
8. Tung-Chen Y, Pizarro I, Rivera-Núñez A, et al. Reaffirmation of the importance of follow-up ultrasound studies in patients with high D-dimers and clinical suspicion of vein thrombosis. Ultrasound. 2020;28(1):23-29. doi:10.1177/1742271X19865000
9. Needleman L, Cronan JJ, Lilly MP, et al. Ultrasound for Lower Extremity Deep Venous Thrombosis. Circulation. 2018;137(14):1505-1515. doi:https://doi.org/10.1161/circulationaha.117.030687
10. Brown, J. D., Goodin, A. J., Lip, G. Y., & Adams, V. R. (2018). Risk stratification for bleeding complications in patients with venous thromboembolism: application of the HAS‐BLED bleeding score during the first 6 months of anticoagulant treatment. Journal of the American Heart Association, 7(6), e007901.
11. Fronas SG, Dahm AEA, Wik HS, et al. Safety and feasibility of rivaroxaban in deferred workup of patients with suspected deep vein thrombosis. Blood Adv. 2020;4(11):2468-2476. doi:10.1182/bloodadvances.2020001556
12. Li G, Zeng J, Zhang J, Thabane L. Comparative Effects Between Direct Oral Anticoagulants for Acute Venous Thromboembolism: Indirect Comparison From Randomized Controlled Trials. Front Med (Lausanne). 2020;7:280. Published 2020 Jun 19. doi:10.3389/fmed.2020.00280
13. Imberti D, Ageno W, Dentali F, Giorgi Pierfranceschi M, Croci E, Garcia D. Management of primary care patients with suspected deep vein thrombosis: use of a therapeutic dose of low-molecular-weight heparin to avoid urgent ultrasonographic evaluation. J Thromb Haemost. 2006;4(5):1037-1041. doi:10.1111/j.1538-7836.2006.01940.x
14. Siragusa S, Anastasio R, Porta C, et al. Deferment of objective assessment of deep vein thrombosis and pulmonary embolism without increased risk of thrombosis: a practical approach based on the pretest clinical model, D-dimer testing, and the use of low-molecular-weight heparins. Arch Intern Med. 2004;164(22):2477-2482. doi:10.1001/archinte.164.22.2477
15. Anderson DR, Wells PS, Stiell I, et al. Thrombosis in the emergency department: use of a clinical diagnosis model to safely avoid the need for urgent radiological investigation. Arch Intern Med. 1999;159(5):477-482. doi:10.1001/archinte.159.5.477