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December 2011 Vascular Newsletter >>
Evaluation for Swollen Leg: A Clinical Workup
Patients who present in the primary care setting with acute lower extremity swelling—with or without pain—should undergo a timely workup for venous thromboembolism (VTE). The workup includes clinical risk assessment using the D-dimer blood test and/or the Wells score, and if indicated, duplex ultrasound imaging.
Prevalence, Risk Factors, and Complications
The Centers for Disease Control and Prevention (CDC) estimates that each year, approximately 300,000-600,000 patients in the US are affected by venous thromboembolism (VTE).
Lower-extremity deep venous thrombosis (DVT) is the most common type of VTE, with the majority of cases occurring in either the proximal lower extremity (36%) or the calf and proximal lower extremity (37%) (1).
Key risk factors for DVT include age over 40; immobility; obesity; malignancy; recent abdominal, pelvic, or joint replacement surgery; trauma; and/or a history of prior VTE.
Nearly one-third of patients with a DVT suffer from postthrombotic syndrome (PTS), a potentially disabling long-term complication marked by chronic leg edema, pain, claudication, hyperpigmentation, and ulcers.
Lower-extremity DVT is also a major underlying cause of acute pulmonary embolism (PE). One-quarter of patients with an acute PE die suddenly, before any other symptoms are noticed.
Clinical Assessment and Risk Scoring
Clearly, early recognition and treatment of VTE saves lives, but the disease can be challenging to diagnose, especially in the primary care setting. Pain and edema are classic symptoms, but because they may nonspecific or even absent, a thorough workup is critical to obtain a conclusive diagnosis.
For patients who are suspected to have a thrombosis, clinically validated prediction rules should first be used to estimate the probability of a DVT.
The quantitative D-dimer blood test is a fast, convenient way to rule out a potential DVT in low- to-intermediate risk patients. The Wells Score is another diagnostic algorithm used to assess clinical risk.
Patients who, based on the above criteria, are considered intermediate to high risk for DVT should undergo further diagnostic tests, starting with duplex ultrasound.
Duplex ultrasound is the first-line imaging method for diagnosing DVT, especially in patients with unilateral lower extremity swelling. Duplex ultrasound is noninvasive, cost-effective, and for femoropopliteal and tibial DVTs, has a 95% sensitivity and specificity.
Duplex ultrasound should always be performed by an experienced sonographer at an ICAVL-accredited laboratory.
During the scan, the patient is placed in a supine position. Then, starting at the common femoral vein, the technologist compresses every 2 to 3 cm, imaging the popliteal vein behind the knee. (The UW Health Peripheral Vascular Laboratory also examines the popliteal vein below the knee, the calf veins, and the calf muscle veins).
Veins should be easily compressible and collapse completely. The normal blood flow pattern should be spontaneous, phasic, cease with the Valsalva maneuver, and show augmentation with distal compression. Absence of this usually indicates the presence of a substantial obstruction.
For patients with a DVT, prompt and appropriate treatment reduces mortality.
Treatment can occur on an inpatient or outpatient basis, and may include anticoagulation therapy (low-molecular-weight heparin [LMWH], IV heparin, or warfarin), inferior vena cava (IVC) filters, or thrombolysis. Compression therapy also reduces the risk of PTS.
Consultation and More Information
We encourage and provide same-day consultations for patients with acute lower-extremity swelling (symptoms occurring within the last four weeks). For more information, or to contact us, click here.
1. Goldhaber, Samuel Z. A Prospective Registry of 5,451 Patients With Ultrasound-Confirmed Deep Vein Thrombosis, Am. J. Cardiol, 2004