D-Dimer and aortic dissection

Introduction

D-Dimer is usually elevated in acute cases of aortic dissection with 91-97% sensitivity but is poorly specific, and not sufficiently sensitive that a negative D-Dimer will exclude dissection in those with high risk features, but a negative D-Dimer may be sufficient to exclude dissection in those with low risk features
a positive D-Dimer is not specific enough to indicate dissection and cannot differentiate from pulmonary embolism (PE), and there are many more common conditions which will result in a positive test than dissection, so a positive test alone should NOT indicate imaging, but decision to image needs to rely upon gestalt or clinical decision tools.

D-Dimer will be negative in 3-9% of cases of acute dissection due to either ¹⁾:
- time from onset of dissection > 48hrs (including chronic dissection)
- short length of dissection (ie. minimal thrombosis)
- young age
- presence of thrombosed false lumen or a localized intramural hematoma without an intimal flap

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