The goal of this study is evaluate the clinical performance of the AQT90 FLEX D-dimer Test as an aid in the diagnosis of Venous Thromboembolism.

The objective is to evaluate the clinical performance of the AQT90 FLEX D-dimer Test as an aid in the diagnosis of VTE in patients presenting with low or moderate pretest probability (PTP), by determining the clinical sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), positive likelihood ratio (LR+) and negative likelihood ratio (LR-) of the assay.

Inclusion Criteria:

• Subject is 18 years of age and older
• Subject, who presents with signs and symptoms of VTE and had low or moderate pre-test probability of DVT or PE assessed by Well's score
• Subject must be able to understand information given, and be willing and able to voluntarily give their consent to participate in this study

Exclusion Criteria:

• Subject, who is pregnant
• Subject, who has received fibrinolytic therapy within the previous seven days
• Subject, who has received treatment with anticoagulants (unfractionated heparin, LMWH, VKA (vitamin K-antagonists), DOACs (direct oral anticoagulants) within the previous seven days
• Subject, who has had trauma or surgery within the previous four weeks
• Subject with malignancy
• Subject with disseminated intravascular coagulation (DIC)
• Subject, who has an invalid written informed consent or has withdrawn consent

The study population will consist of adult patients presenting with signs and symptoms of VTE and getting clinical evaluation of the pretest probability of VTE scored as low or moderate corresponding to a Well's score between 0-2 for DVT and between 0-6 for PE.