Femoral central venous catheter use is complicated by a high risk of deep venous thrombosis despite antithrombotic prophylaxis. Although some have recommended screening for femoral catheter-associated thrombosis to prevent pulmonary embolism, this strategy's economic implications are unclear. Therefore, we used a decision model to evaluate the potential cost-effectiveness of a doppler ultrasound-based screening strategy versus no ultrasound in averting thromboembolic complications associated with femoral catheters. The base-case analysis included a hypothetical cohort of 60-year old medical patients treated for acute respiratory failure. The perspective was that of the health care payor and the primary outcomes were quality-adjusted life expectancy, pulmonary embolism, and pulmonary embolism-associated deaths. The ultrasound strategy cost $8,688/quality-adjusted life-year (QALY) gained, $5,305/pulmonary embolism averted, and $99,286/pulmonary embolism death averted. The best and worst case scenarios, calculated in multi-way sensitivity analyses by varying in-hospital mortality, deep venous thrombosis prevalence, and ultrasound accuracy, ranged from $1,170/QALY to $35,342/QALY, respectively. Probablistic analyses, in which variables with uncertain values were varied randomly within their ranges, demonstrated median costs of $12,793/QALY (interquartile range $8,176/QALY, $20,648/QALY). In summary, ultrasound screening may improve outcomes among the critically ill with femoral venous catheters at acceptable costs and could complement venous thrombosis primary prevention programs.