A clinical probability assessment and D-dimer measurement should be the initial step in the investigation of suspected venous thromboembolism.

@article{Kelly2003ACP,
  title={A clinical probability assessment and D-dimer measurement should be the initial step in the investigation of suspected venous thromboembolism.},
  author={James S Kelly and Beverley J Hunt},
  journal={Chest},
  year={2003},
  volume={124 3},
  pages={1116-9}
}