A blood clot will show up on blood work, any good ER doctor will order a d-dimer test to rule out a pulmonary embolism whenever chest symptoms are present.
That’s good to know!
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.