The ddimer has a high sensitivity and low specificity. That means LOTS of false positive results. You need to identify patients based on age, illness, history, physical exam vitals etc to select the subgroup the test is useful in. If you shotgun the test you end up with a large number of false positives you have to then deal with. That usually means a CT angiogram of the chest which involves a very large radiation dose, and contrast which can shut down your kidneys.
Good ER docs are VERY selective in who they get d dimers on.
I am aware of that. It can catch near 99$ of all PEs and probably 100% of all massive PEs. I had a positive d-dimer and all that was done was a v/q scan. PEs are also very elusive and some say kill over 200,000 people ever year, it should be high on the list whenever anyone comes to the ER with chest pain and pain when breathing.