Is a Positive D.Dimer Helpful in Diagnosing DVT P.E?

The question is asking, in which of the following patients would a positive de-dimer be helpful in prompting additional imaging to diagnose homoramblism or DVT? So the five patients are. Patient A is a 24-year-old woman who is 32 weeks pregnant and presents with calf pain following prolonged air travel. His room air oxygen saturation is 96%. Patient C is a 56- year-old woman undergoing chemotherapy for breast cancer. Patient D is a 62-year- old man who underwent hip replacement surgery four weeks ago. patient E is a 72-year-olds man who had an acute myocardial infarction two weeks ago.