Answer and Explanation 3

3.  Choice D is correct.  By definition of the Wells criteria the patient with cancer does not put the patient in a low risk population so a D-Dimer would not be helpful.  A VQ scan would not be the best test because the ventilation portion may be obscured by the pneumonia and lung cancer and will likely yield inconclusive results.  Selective pulmonary angiography could give you the diagnosis but is quite invasive and the procedure could have some complications.  Therefore the correct answer is D.