A Closer Look At Deep Vein Thrombosis
- Volume 17 - Issue 12 - December 2004
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Venous thromboembolism (VTE) or deep vein thrombosis (DVT) is a common medical condition associated with considerable morbidity and mortality. Undiagnosed and untreated VTE can put patients at an unacceptable risk for a pulmonary embolism, which can be fatal. Thromboemboli account for 600,000 new cases, 300,000 admissions and approximately 100,000 deaths a year. Given that VTE has a recurrence rate of approximately 30 percent, early diagnosis and treatment are imperative.
In order to understand the risk factors of deep vein thrombosis (DVT), one must first appreciate Virchow’s triad. He noted there is a triad of hypercoagulability, venous stasis and endothelial damage with DVT. Clinical risk factors for DVT include immobility from surgery, prolonged automobile rides or airplane flights, age, pregnancy (usually in the third trimester or immediately following delivery), oral contraceptives and obesity. Endothelial damage is caused by injuries or leg trauma, hypoxia and infection.
Additional risk factors for DVT include inherited clotting disorders (which include factor V and prothrombin gene mutations), previous DVTs, varicose veins, inflammatory diseases, cancer and smoking.
How To Differentiate Between DVT And Other Conditions
The differential diagnosis of DVT includes lymphedema, cellulitis/infection, compartment syndrome, popliteal cyst rupture, congestive heart failure, venous insufficiency and arterial occlusive disease.
Patients with cellulitis or infection can present with edema, erythema, pain and a low-grade fever, symptoms that are shared by those who may have DVT. One can differentiate between these conditions by obtaining a complete blood count (CBC) and differential, sed rate and blood cultures. Keep in mind that patients who have an infection will also have more cardinal signs such as chills, sweats, a high-grade fever, nausea or vomiting.
When it comes to compartment syndrome, patients who have this condition will have out of proportion pain, parasthesias, absent pulses and swelling. One can make this diagnosis by checking the compartment pressures of the foot and leg. Compartment pressures greater than 30 mm Hg are indicative of compartment syndrome.
A popliteal or Baker’s cyst lies in the head of the gastrocnemius muscle belly. When these cysts rupture, the leg swells and becomes painful, and clinicians will note a positive Homan’s sign. The clinical signs of DVT may include unilateral edema, pain, color and temperature changes, a positive Homan’s sign and a low-grade fever. One can confirm the presence of a popliteal or Baker’s cyst via radiographs, ultrasound or magnetic resonance imaging. Clinicians can differentiate between the cyst and DVT by obtaining a CBC and differential, blood cultures and/or sed rate.
Arterial vascular disease may be acute or chronic. Patients with acute arterial disease present with asymmetric symptoms such as absent pulses, severe pain, less movement of the extremity and a cold, pale limb, but little edema. Those who have chronic arterial disease can present with skin and hair atrophy, ulcers or intermittent claudication. Acute venous insufficiency has symptoms that are asymmetric with moderate edema, deep muscle pain and normal pulses. The symptoms get worse at the end of the day and improve with elevation.
Lymphedema can appear to have similar clinical symptoms to DVT, but usually starts out as soft and pitting edema. It is usually bilateral, unlike DVT, which is usually unilateral. Congestive heart failure can also cause pitting edema in the lower extremity.