NIV Congres

Introduction: About 300 patients a year are referred to our outpatient clinic at Orbis Medical Centre for suspected DVT. Referring general practitioners (GP’s) use a primary decision rule combined with D-dimer testing to stratify patients who should undergo a duplex ultrasound to safely exclude a deep vein thrombosis (DVT). In all patients with a negative duplex ultrasound but elevated D-dimer test and/or high clinical suspicion, guidelines advice to perform a second duplex ultrasound. In this study, we investigate prevalence of DVT after GP referral and the effectiveness of repeat ultrasound in case of elevated D-dimer test in these patients.

Methods: We performed a single centre, prospective analysis of GP referred patients suspected of DVT. Inclusion was started at July 17th 2012 and still ongoing, a preliminary analysis was performed after inclusion of 150 patients. All patients underwent clinical investigations to determine Wells-score, D-dimer testing and a duplex ultrasound. In case of elevated D-dimer test and/or a persisting clinical suspicion for DVT repeat duplex ultrasound after 5-7 days was performed in all patients.

Results: During a period of 5.5 months, 153 GP referred patients were seen to rule out a DVT. Of these 153 patients effectively 28.8% had a DVT and in 7.8% of cases a thrombophlebitis was diagnosed. Negative duplex ultrasound.

Results for thrombosis were seen in 97 patients. In these patients 56 had a repeat duplex ultrasound 5-7 days later. The repeat ultrasound was positive for DVT in 3.6% (n = 2) of cases. All patients with a primary Wells score > 4 had a positive duplex ultrasound, in two cases only the second duplex ultrasound. 41 patients had no repeat ultrasound performed; 29.3% had a normal D-dimer test, 43.9% had an alternative diagnosis and 19.5% had low Wells scores in combination with a D-dimer test < 750. Two patients refused additional ultrasound.

Conclusion: At our outpatient clinic 28.8% of GP referred patients had a comfirmed deep vein thrombosis by duplex ultrasound. Deep venous thrombosis was diagnosed in only 3.6% of patients after repeat duplex ultrasound. All patients with a Wells score above 4 had a positive duplex ultrasound, including the patients with a positive second duplex ultrasound. In conclusion a repeat duplex ultrasound seems effective in GP referred patients with high Wells scores (> 4) and a primary negative duplex ultrasound. Efficacy and effectiveness of repeat ultrasound will be further analysed in our prospective cohort study.