Are too many compression ultrasounds being performed for acute lower limb deep venous thrombosis in tertiary inpatients?

BACKGROUND Venous thromboembolism (VTE) is a complex and serious condition, with high morbidity and mortality, especially in hospitalised patients. Yet its diagnosis remains challenging because of its unspecific clinical presentation. The objective of this study was to apply an algorithmic combination approach to diagnosing VTE by the addition of a D-dimer assay and Wells' criteria for our hospital's internal referral forms requesting compression ultrasound (CUS), to determine the effect on the number of referrals for CUS and the incidence of deep vein thrombosis (DVT) diagnoses. METHOD Inpatients who had been referred to the hospital's vascular laboratory and who had undergone a CUS to exclude an acute lower limb DVT were retrospectively analysed between January 2009 and December 2013, and compared to prospectively collected data for the full year (2014) after the introduction of the new referral form. Comparisons included the mean annual number of referrals for CUS and the incidence of DVT diagnoses. RESULTS The hospital incidence of diagnosed DVTs for 2009-2013 was 0.17%, compared to 0.16% for 2014 (ρ = 0.930). In contrast, the total number of referrals for CUS as a percentage of all hospital admissions dropped from 0.84% in 2009-2013 to 0.63% in 2014 (ρ = 0.009, odds ratio 0.76, 95% confidence interval: 0.62-0.93). CONCLUSION The implementation of Wells' criteria and D-dimer to the new request form for CUS significantly decreased referrals to the hospital's vascular laboratory without impacting on the number of DVT cases diagnosed. This is a positive change which simplifies care and reduces the expense of ultrasonography investigations.