- 0I wonder if someone might help shed some light here. Post-op day 4, abdo abcess drainage patient who went from room air to tachypneic 30-40 and 100% FiO2 over a couple of hours. I did a D-dimer as I suspected a possible PE. Came back 6000. Doc said it would be elevated since the patient is 4 days post-op, and you need a result of 10 000 for it to indicate PE.
Then a few days later, 3 day post-op cystectomy, same symptoms as patient above, D-dimer 3120, but ultrasound showed PE.
I don't understand! Please help! Many thanks in advance.
- 9Mar 11, '13 by juan de la cruz GuideUsing D-dimer as an adjunct in differential diagnosis of a patient presenting with a possible PE is not a crazy thought in the absence of other conditions that could also cause an elevated result such as recent surgery, trauma, liver disease. The test is part of the algorithm for PE. In your patient's case, the D dimer will be elevated because of the recent surgery and will have limited utility.
The definitive test is a contrast CT of the chest but there are patients who have contraindications to IV dye or who are at risk for contrast nephropathy. Those patients tend to not get scanned so other findings such as elevated D-dimer, lower extremity VTE, and clinical suspicion of PE based on presentation justifies treatment with anticoagulation.
Pneumatic boots can prevent lower extremity VTE but not always. Adding Heparin SQ or Enoxaparin SQ can decrease the likelihood. Ultrasound does not diagnose a PE.
- 4Mar 11, '13 by juan de la cruz Guide...and there are case reports of patients who was found to have a PE yet never evidence of a lower extremity VTE. The thought is that the clot may have embolized from an upper extremity source or a "de novo" PE (meaning it originated in the lung itself).
- 1Mar 11, '13 by BostonFNPD-dimers still have some use, especially in ambulatory settings. I use serial elisa d-dimers in low-risk patients to rule out a DVT while keeping them away from the hospital. I will also use them in younger patients to avoid having to spiral CT them if I am not overtly concerned by their presentation.
- 2Mar 11, '13 by hodgieRNThat's bs what the doc said. You don't need a level of 10,000 or above. Pts can have a PE with half that. A negative d-dimer is the only thing that matters. It's either is negative or inconclusive. True, there are dozens of other things that can raise the d-dimer, but if they need a scan, then they need a scan. But, if you can get a d-dimer and it is negative, then the pt can be spared the radiation. We order too many test these days. VQ scans are great. Nurses just don't like sitting in Nuc Med and would rather do a quick CT so they can get back to the unit. Not the best advocating.
- 3Mar 11, '13 by edmiaQuote from maloneysYes!Hmm, thanks for all the wonderful feedback. So in these cases, both patients should have been scanned then!
With an elevated ddimer all you have is an inconclusive or low specificity result (50% Sp for ddimer). This means the test is good to rule out embolic disease but not to rule it in.
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