D-Dimer negative means?

D-Dimer negative means?

• A. D-Dimer negative requires CTA to rule in PE
• B. PE is ruled out
• C. CTA will definitively diagnose PE
• D. PERC rule is not applicable

Answer: (B)

A negative D-dimer is most informative when the patient’s pretest probability for pulmonary embolism is low. In that context, a negative result makes the post-test probability of PE so small that the condition can essentially be ruled out without further imaging. D-dimer is highly sensitive but not specific, so a negative result helps exclude PE rather than confirm it, provided the clinical assessment supports a low likelihood. If the pretest probability is high or if clinical suspicion remains after a negative D-dimer, imaging (such as CT angiography) may still be warranted because a negative D-dimer does not completely exclude PE in those scenarios. CTA can confirm PE when indicated but is not required to “rule in” PE after a negative D-dimer. The PERC rule is a separate decision tool used to avoid testing in very low-risk patients and is not determined by a negative D-dimer alone.

A negative D-dimer is most informative when the patient’s pretest probability for pulmonary embolism is low. In that context, a negative result makes the post-test probability of PE so small that the condition can essentially be ruled out without further imaging. D-dimer is highly sensitive but not specific, so a negative result helps exclude PE rather than confirm it, provided the clinical assessment supports a low likelihood.

If the pretest probability is high or if clinical suspicion remains after a negative D-dimer, imaging (such as CT angiography) may still be warranted because a negative D-dimer does not completely exclude PE in those scenarios. CTA can confirm PE when indicated but is not required to “rule in” PE after a negative D-dimer. The PERC rule is a separate decision tool used to avoid testing in very low-risk patients and is not determined by a negative D-dimer alone.