Stephan Moll, MD writes…. Recurrent DVT can be challenging to diagnose, as it may be difficult on Doppler ultrasound to tell chronic changes from additional new clot. A guidance statement from the ISTH (International Society for Thrombosis and Haemostasis) published this week (May 18th, 2013) provides solid, clinically useful, evidence-based recommendations [ref 1]. When there is suspicion for a recurrent clot,
- it is suggested to use a pre-test probability assessment to determine which patient should get a D-dimer blood test as the first intervention, and who should go straight to getting a Doppler ultrasound. The Wells score can be used as such a tool [ref 2].
- It is suggested that patients with high pre-test probability should not get a D-dimer but go straight to getting a venous Doppler ultrasound.
- It is suggested that patients with low pre-test probability should get a D-dimer and, if it is negative, do not need to undergo venous Doppler ultrasound.
- When it is impossible to tell from the Doppler ultrasound whether changes seen are old or new clot, i.e. when findings are equivocal, it is suggested that further evaluation be done, to include D-dimer testing and possibly other imaging modalities (such as CT-venogram, MR-venogram)
Finally, to potentially help in the future should a patient with previous DVT present again with new leg symptoms, it is suggested to obtain a leg Doppler ultrasound when a patient stops anticoagulation at the end of the treatment period for a DVT, so that a baseline study is available with an assessment of chronic, residual changes.
- Ageno W et al. The diagnosis of symptomatic recurrent pulmonary embolism and deep vein thrombosis: guidance from the SSC of the ISTH. Accepted Article. J Thromb Haemost, May 18,2013, http://onlinelibrary.wiley.com/doi/10.1111/jth.12301/abstract .
- Wells PS et al. Does this patient have deep vein thrombosis? JAMA 2006;295:199-207.
Last updated: May 24th, 2013