negative venous duplex in PE work-up

[doctorFred]

had a 40ish year old guy the other day with left lower extremity pain and swelling, as well as tachycardia to the 120s. he didn't have any risk factors for PE, and had no chest pain or dyspnea, so i decided i would get a d dimer, and based on that, rule him out.

my attending adds on a venous duplex, which is obviously appropriate. however, it's read as no signs of DVT. meanwhile, his dimer comes back >1000. attending tells me to d/c the patient without the scan, because a negative venous study "rules out PE."

i didn't fight back, but i feel like i should have. in the face of tachycardia and an elevated dimer in a patient with a painful, swollen leg, do you really send them out without spinning their chest? regardless of what the venous study shows?

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[Apollyon]

Negative for lower extremity DVT does not rule out PE. Your attending either didn't know, or that was bravado (misplaced in this case). What if the whole clot cut loose and the guy now has a saddle?

On the other hand, was it a cellulitis? That will bump your D-dimer, too.

Do a follow up - look up his info, and check on him. I do hope that you gave him explicit instructions to return.

 

[Hawkeye Kid]

Negative for lower extremity DVT does not rule out PE. Your attending either didn't know, or that was bravado (misplaced in this case). What if the whole clot cut loose and the guy now has a saddle?

On the other hand, was it a cellulitis? That will bump your D-dimer, too.

Do a follow up - look up his info, and check on him. I do hope that you gave him explicit instructions to return.

Cellulitis was my first thought as well. Could also cause tachycardia in addition to elevating the dimer. It's also possible that he had a very proximal DVT causing his US to be normal. It would be unusual (though not impossible) to have a massive PE in a relatively young person with no cardiopulmonary symptoms. Probably the thing that would have given me the most trepidation is that the guy had an unexplained, abnormal vital sign. Agree with Apol that it would be a great learning case for follow-up.

 

[EctopicFetus]

Uh... IIRC 2/3s of people with PE have no identifiable source of clot.

+ D-dimer in this setting MANDATES a V/q or CTA IMO.

 

[WilcoWorld]

Neg doppler does not rule out PE, but in this case you were evaluating leg pain without any chest pain or dyspnea. In my opinion, if the vitals had normalized it was safe to d/c this patient without a PE work up. The + dimer mandates a follow-up repeat doppler, not a chest CT.

 

[Khaos]

From personal experience had a guy with a d-dimer of 1300, no chest pain, no dyspnea but right leg swelling and tachycardia. Duplex was negative, CT showed clot at the prox right common iliac with small scattered PE's. Duplex does not rule out pe, it does not rule out clot everytime. I think I would've gotten a CT in your situation. Also, why are you doing the d-dimer if you're already doing the US and not going to use the result of the d-dimer anyway?

 

[WilcoWorld]

From personal experience had a guy with a d-dimer of 1300, no chest pain, no dyspnea but right leg swelling and tachycardia. Duplex was negative, CT showed clot at the prox right common iliac with small scattered PE's. Duplex does not rule out pe, it does not rule out clot everytime. I think I would've gotten a CT in your situation. Also, why are you doing the d-dimer if you're already doing the US and not going to use the result of the d-dimer anyway?

I use the dimer in evaluation of DVT to determine whether there is a need for f/u doppler after a negative study:

neg dimer + neg US = you're done
pos dimer + pos US = need f/u US

Reading this thread would suggest that my approach is an uncommon one.

 

[Groove]

Only you and your attending were looking at the pt, but if you had a low clinical suspicion of PE, negative doppler and VS stabilized, don't get the d-dimer, otherwise you're kind of obligated to get the CTA at that point, IMO. If he throw's (or has thrown) one, you miss it, and if he dies outside your door, the lawyers will fight like piranhas over who gets to prosecute you (or your attending, I guess) on that one... and they'll win. Bad for the pt too...

I would imagine he was probably a bit peeved that you got the d-dimer if you didn't run it past him and he had a low clinical suspicion. Just my 2 cents, but I would have gotten the CTA from what you described. I think most of the attendings at my institution would have done the same.

 

[xaelia]

http://emcrit.org/misc/imaging-in-pe-diagram/

Smart people - the debate from which this flow-chart was derived is worth watching. The key element is - do you really think they have a PE? - since that gives you +3 from Wells' criteria.

A negative u/s in the setting of positive d-Dimer doesn't help you rule out venous thromboembolism in isolation - sure, if it looks like cellulitis, then it's cellulitis and not a DVT. And, if you haven't ruled out DVT, and you think the patient has a PE, then they need imaging. If you don't think they have a PE, then maybe they don't need it - and you have to judge whether the d-Dimer is of any clinical utility based on causes of systemic inflammation.

The recent ACEP guidelines basically barely offer anything stronger than a slight breeze in their recommendations.

Would be an interesting case to follow-up - but I always caution about changing practice based on individual patient outcomes without considering them in the context of the existing evidence.

 

[Pinner Doc]

I use the dimer in evaluation of DVT to determine whether there is a need for f/u doppler after a negative study:

neg dimer + neg US = you're done
pos dimer + pos US = need f/u US

Reading this thread would suggest that my approach is an uncommon one.

I do this as well.

 

[doctorFred]

i'd like to stress that this was my attending's care plan, not mine. usually, i do something like this:

don't think they have a PE => PERC rule => negative = done, can't use it => dimer => negative = done, positive = CT
think they have a PE => CT

as far as i'm concerned, a doppler is usually not involved.. which is why i was so put off. i was ready to call his leg cellulitic as well.

 

[Apollyon]

Tachycardia and positive D-dimer? I'd have CT'd him. Sure, by probability, it would be negative, but, if it's positive, you're on target. I am of the mind that the younger/healthier crowds often will tolerate PEs better, and, even if manifesting tachycardia, might not have chest pain or SOB.

 

[EctopicFetus]

I use the dimer in evaluation of DVT to determine whether there is a need for f/u doppler after a negative study:

neg dimer + neg US = you're done
pos dimer + pos US = need f/u US

Reading this thread would suggest that my approach is an uncommon one.

I do this as well.

Me too.. gold standard practice IMO.

 

[Arcan57]

i'd like to stress that this was my attending's care plan, not mine. usually, i do something like this:

don't think they have a PE => PERC rule => negative = done, can't use it => dimer => negative = done, positive = CT
think they have a PE => CT

as far as i'm concerned, a doppler is usually not involved.. which is why i was so put off. i was ready to call his leg cellulitic as well.

I'd amend as follows:
don't think they have a PE => don't work-up
low suspicion for PE => PERC or dimer
mod. to high suspician => CT or V/Q

For r/o DVT without suspician of PE, I tend to doppler rather than dimer for the sake of efficiency. Unless there is clear source for infection, anterior tibial cellulitis without edema, or an obvious abscess, I tend to doppler all my red,warm legs.