Cleveland Clinic Journal of MedicineShould You Use Compression Duplex Ultrasonography to Detect Deep Vein Thrombosis to Evaluate Unexplained Fevers?

The most important risks of CDUS are stopping the diagnostic process prematurely if CDUS identifies an incidental thrombus, and the unlikely, but possible, risk of false-positive results leading to inappropriate anticoagulation therapy.

In the realm of clinical medicine, understanding the underlying causes of unexplained fevers in hospitalized patients remains a pivotal challenge. This article digs into the complex relationship between venous thromboembolism (VTE) and fever, unraveling the traditional beliefs and presenting new insights based on recent studies. It addresses the diagnostic considerations, risks, and implications of utilizing compression duplex ultrasonography (CDUS) in the evaluation of unexplained fevers, offering an evidence-based perspective for physicians.

Key Points:

1. Traditional Beliefs Challenged: Venous thrombosis of the extremities, traditionally thought to cause occult fevers, lacks strong evidence supporting its direct causation of fever.
2. Diagnostic Tools and Risks: Although CDUS is a risk-free procedure for detecting thrombosis, reliance on this test can lead to premature diagnostic closure and unnecessary anticoagulation therapy due to incidental or false-positive findings.
3. Association vs. Causation: Studies indicate that VTE and fevers often coexist, but this relationship is more associative than causal, with other underlying conditions potentially acting as confounders.
4. Limited Yield of CDUS in Fever Workup: Research shows a low diagnostic yield of CDUS in identifying fevers caused by VTE, questioning its routine use in initial fever investigations.
5. Consideration of Alternative Etiologies: Before attributing fevers to VTE, it’s crucial to thoroughly evaluate and exclude more common fever causes in hospitalized patients.
6. Specific Case Implications: In cases like the 84-year-old patient with pyelonephritis, findings of a small venous thrombus via CDUS should be cautiously interpreted, especially when alternative fever causes exist.
7. Upper-Extremity Doppler Ultrasonography: This should be considered only in patients with high pretest probability for upper-extremity thrombosis, like those with central venous catheters or active cancer.

According to a study published in The Lancet, the global incidence of deep vein thrombosis (DVT) is estimated to be 1-2 per 1,000 individuals annually, highlighting its prevalence in the general population.

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