Look for other cause of elevación of the D dimer, because it is nonspecific

If you have elevated d Dimer along with clinical features suggestive of pulmonary embolism and / or echo features of pulmonary hypertension but at the same time normal pulmonary CT, you should ask for pulmonary ventilation Perfusion scan (VQ scan). Because some of CTEPH are only detected by VQ scan.

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Cigarette smoking, infection, or sepsis may cause elevation of D-dimer in the absence of PE, DVT, or DIC.

As a general question - what is the accuracy of the CT. Locally we have a wide variety of what is reported as positive. (Technical factors of when they push the dye, how the images obtained). Some aspect of accuracy falls off – we clinically see about 30 percent of the patients with PE showing it on the CT scan. If the scan is done at the right time, right place, and all parts come together the test will show the PE – but I have found we miss them more and more often. Evidence is clinically patient with PE who have negative scans over time (years of interrupted symptoms that were suspected to be PE) only to finally have a diagnosis of PE/DVT and hypercoaguable state – thus “looking back” the other episodes in the patient were suspected to have been PE. Compounding the confusion is a PE on scan that will not be there in 18 hours at a repeat scan is confusing, but evaluated as the lack of attention to detail in the world of the imaging center used (would love to know another reason).

For this situation, I would do a V/Q scan also. The possibility of CTEPH has been mentioned - I agree that is a good suggestion - and even with acute PE, if it is small and peripheral that it may be difficult to detect in CTPA. I agree with many of the other points - it depends a lot on technical factors and you may need to assess for other causes of D-dimer being elevated.