Case

A 29-year-old man presented to the emergency department with a chief complaint of right leg pain. The pain and swelling began suddenly in the posterior calf one week earlier. The pain is sharp, throbbing, and not relieved by warm soaks or ice. The patient denied recent trauma, surgery, prolonged immobilization, history of cancer or thrombosis, chest pain, shortness of breath, or weakness to his extremities. The patient did recall falling off of a balcony and landing on his right leg two months prior without fractures or dislocations. His symptoms from the fall had resolved long prior to his current presentation to the ED.

The patient’s vital signs were T 97.9 F°, P 65, BP 139/93, RR 17, O2 Saturation of 99% on room air. The physical examination was remarkable for subtle swelling and warmth of the right calf as compared to the left. The right calf measured 38 cm and the left calf measured 37 cm circumferentially. The right calf was tender to palpation with a positive Homan’s sign. Arterial pulses were present and equal bilaterally. The rest of the physical examination was unremarkable.

Limited ED bedside ultrasound examination was performed as part of the physical exam to evaluate for acute deep venous thrombosis (DVT) of the right lower extremity. The examination was performed using a high-resolution linear vascular transducer with a frequency of up to 12 MHz. The patient was placed in a supine position on the stretcher with the head of the bed elevated at fifteen degrees. The patient’s right hip was externally rotated and his right leg was slightly flexed at the knee (Set Up).

The transducer was placed in the transverse plane over the region of the right common femoral vein just distal to inguinal ligament. The transducer was moved caudad and medially along the course of the vessel in 1-2 cm increments to the distal one-third of the thigh. Next the probe was placed in the popliteal fossa (Popliteal Fossa Positioning).

In our patient transducer pressure applied over the right common femoral vein did not result in complete compression (DVT Femoral Vein with Compression).

In the popliteal fossa, the popliteal artery and vein were identified in the transverse view. Again compression failed to collapse the vein and intraluminal hyperechogenicity suspicious for thrombus was identified (DVT Popliteal Vein with Compression).

Discussion

Although the exact incidence of DVT in the United States is not known, approximately 600,000 patients are hospitalized annually for DVT (1). While DVT encompasses a disease spectrum, the lethal consequence of DVT is largely due to the development of pulmonary embolus (PE). The combined incidence of DVT and PE has been estimated to be about 5-7 per 10,000 person years in the general population (2). Approximately 10% of emergency department patients with PE die within 30 days despite prompt diagnosis and treatment. Therefore it is imperative for the emergency physician to accurately diagnose and treat DVT.

The variable clinical presentation of DVT is partly dependent on the timing of patient presentation and renders the history and physical exam an unreliable diagnostic tool. Complaints range from nonspecific mild cramping sensation or fullness in the calf to unilateral swelling. Physical exam findings may include edema, erythema, warmth, tenderness along the deep venous system, dilation of superficial collateral veins, and a palpable venous “cord.” The classic teaching of Homan’s sign as the presenting sign of acute DVT is neither sensitive nor specific.

The diagnostic approach to DVT begins with the clinical assessment of the pretest probability of DVT. The pretest probability can be derived via the application of clinical decision tools such as the Wells Criteria. A negative D-Dimer assay can exclude DVT in patients with a low pretest probability. In patients with intermediate and high pretest probability for DVT, the D-Dimer assay is unreliable and imaging studies are necessary. Duplex ultrasonography has replaced venography as the initial diagnostic imaging modality. Although duplex ultrasonography is readily accessible in most emergency departments during business hours, testing may be significantly delayed overnight. During off hours patients often empirically receive low molecular weight heparin prior to duplex ultrasonography with the risk of significant bleeding complications.

Efforts have been made over the past decade to determine if limited ED ultrasound accurately diagnoses acute DVT. In a study published by Pezzullo et al in 1996, 99% of symptomatic DVT involved either the common femoral or the popliteal vein (3). Thus, rather than assessing the entire length of the venous system as in a radiology duplex ultrasound study, limited ED ultrasound performed by the emergency physician involves compression at these two points. The examination begins with the identification of the common femoral and popliteal veins followed by compression of the venous structures to determine the presence of thrombus (4). The lack of compressibility signifies the presence of thrombus. Subsequent studies have shown that the compressibility of the venous structures at these two sites can adequately confirm the presence or absence of a DVT (5). Recently, Jacoby again demonstrated a sensitivity of 89% in the detection of acute DVT by limited, two-site ultrasonography performed by emergency medicine residents after a 90min training session (6). The sensitivity rises to 100% with a specificity of 91.8% in the detection of acute DVT by emergency medicine residents who perform compression ultrasound from the proximal femoral vein to the distal thigh and the entire popliteal fossae in 1-2 cm increments (7).

The greatest utility of the limited ED ultrasound for DVT is rapid and accurate clinical decision making at all hours. Compression ultrasonography is particularly helpful when patients present to the ED when radiology studies are not available and the follow-up is not reliable. In the unstable shock patient, evidence of acute right heart strain on limited ED echocardiogram and DVT on limited ED compression ultrasound may prompt life saving thrombolytic therapy. Moreover, ultrasonography performed by emergency physicians decreases time to disposition which is essential in a high-volume ED such as Cook County Hospital (8).

Conclusion

The patient was diagnosed with acute DVT and admitted to the hospital for continued anticoagulation therapy. Laboratory results two hours later were significant for an elevated D-Dimer. Ultrasound performed by the radiology department the next morning confirmed acute DVT from the mid right femoral vein through the popliteal vein.

References

1. Kline J. Pulmonary Embolism and Deep Venous Thrombosis. In: Marx J, editor. Rosen's Emergency Medicine. Mosby, 2007.
2. Heit JA, Melton LJ, III, Lohse CM, Petterson TM, Silverstein MD, Mohr DN et al. Incidence of venous thromboembolism in hospitalized patients vs community residents. Mayo Clin Proc 2001; 76(11):1102-1110.
3. Pezzullo JA, Perkins AB, Cronan JJ. Symptomatic deep vein thrombosis: diagnosis with limited compression US. Radiology 1996; 198(1):67-70.
4. Fox J. Lower Extremity Venous Studies. In: Cosby K, editor. Practical Guide to Emergency Ultrasound. Lippincott, 2006: 255-266.
5. Blaivas M, Lambert MJ, Harwood RA, Wood JP, Konicki J. Lower-extremity Doppler for deep venous thrombosis--can emergency physicians be accurate and fast? Acad Emerg Med 2000; 7(2):120-126.
6. Jacoby J, Cesta M, Axelband J, Melanson S, Heller M, Reed J. Can emergency medicine residents detect acute deep venous thrombosis with a limited, two-site ultrasound examination? J Emerg Med 2007; 32(2):197-200.
7. Jang T, Docherty M, Aubin C, Polites G. Resident-performed compression ultrasonography for the detection of proximal deep vein thrombosis: fast and accurate. Acad Emerg Med 2004; 11(3):319-322.
8. Theodoro D, Blaivas M, Duggal S, Snyder G, Lucas M. Real-time B-mode ultrasound in the ED saves time in the diagnosis of deep vein thrombosis (DVT). Am J Emerg Med 2004; 22(3):197-200.