Can you tell me how accurate is a d dimer in ruling out a pulmonary embolisim?

Depends.....: If a d-diner is normal, then pulmonary embolism is unlikely. However, if the d-diner is elevated, it can be from many different causes, including but not limited to a pe, or pulmonary embolism. If the d-diner is elevated and the clinical scenerio fits, then pe must be ruled out with further testing, like a chest ct angiogram.

Not accurate: A negative d-dimer is helpful in excluding pulmonary embolism in pts at low risk for the disease. It does not replace a history and physical as well as use of wells criteria or other screening tool for pulm embolism.