Diagnosis of recurrent venous thromboembolism.

The diagnostic management of suspected recurrent venous thromboembolism (VTE) is challenging for four main reasons. First, clinical decision rules are less useful to identity patients with a low pre-test probability. Second, the diagnostic performance of D-dimer tests is decreased. Together, these two point lead to a clearly lower proportion of patients in whom recurrent VTE can be ruled out without performing imaging tests. Third, recurrent thrombi may be difficult to differentiate from residual thrombi, which may be often identified in patients with a history of VTE. Fourth and lastly, the prevalence of VTE in patients with suspected recurrent disease is higher than in patients with suspected first VTE. As a consequence, the failure rates of the algorithms in patients with suspected recurrent VTE are higher as well, underling the relevance of accurate diagnostic management of this specific patient population. There is a lack of large well designed diagnostic studies that focus mainly on patients with prior VTE. Even so, available evidence suggests that diagnostic algorithms validated for first VTE are also largely applicable to suspected recurrent VTE. Emerging imaging techniques such as magnetic resonance direct thrombus imaging (MRDTI) are likely to improve the accuracy of the algorithms in the near future.