Deep Venous Thrombosis

CLINICAL FEATURES The clinical examination is unreliable for the detection or exclusion of DVT. Assessment of risk factors ( Table 55-1 and Table55:2i) may be a stronger predictor whenever the diagnosis is entertained. One study showed that a single risk factor is associated with DVT in 24 percent of patients, while those with four or more risk factors are virtually certain to have the diagnosis established. 3 The constellation of pain, redness, swelling, warmth, and tenderness is present in less than half of patients with confirmed DVT. Swelling and tenderness in the involved extremity are the most common findings, occurring in 80 and 75 percent, respectively, of patients with DVT. Though some patients with DVT may have a low-grade fever, one should be careful to exclude an infectious process such as cellulitis. Differences in calf measurements made 10 cm below the tibial tuberosity of greater than 2 cm have been historically suggested as a screening tool for a DVT, but there is no published scientific evidence to validate this practice. Suspicion of DVT by symptoms alone is sufficient to initiate objective investigations even with a negative physical exam. Pain in the calf with forced dorsiflexion of the ankle and the leg straight (Homans' sign) is not reliable for DVT. The physical findings with DVT depend on its location and the degree of venous obstruction, inflammation, and collateral blood flow. For example, significant iliofemoral vein occlusion can present with minimal to absent clinical findings but can result in a catastrophic PE.

Symptomatic DVT will be in the popliteal or more proximal veins in more than 80 percent of cases. An isolated calf DVT will extend proximally only 20 percent of the time, usually within a week of presentation.4 Unlike proximal DVT, nonextending calf DVT will rarely cause a PE.

Uncommon presentations of DVT include phlegmasia cerulea dolens (painful blue inflammation) and phlegmasia alba dolens ("milk leg"). In the former, the patient presents with an extensively swollen, cyanotic leg from venous engorgement due to massive iliofemoral thrombosis. This high-grade obstruction can compromise perfusion to the foot from high compartment pressures and lead to venous gangrene. Petechiae and bullae may be present on the skin. Phlegmasia alba dolens is also due to massive iliofemoral thrombosis, but the patient's leg is pale or white secondary to associated arterial spasm. Dorsalis pedis and posterior tibial pulses may be diminished or absent, which can lead to a false diagnosis of arterial occlusion. The arterial spasm with milk leg is transient and often followed by venous engorgement, suggesting the correct diagnosis.

The PPS is manifest by signs and symptoms that can be difficult to differentiate from acute DVT. Pain, swelling, and occasionally ulceration of the skin can occur months to years after the resolution of DVT. Long-term follow-up of patients reveals that the syndrome (PPS) can occur in up to 60 percent of patients who have had a previous proximal DVT and one-third of patients with calf DVT.2

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