D-dimer: Covid considerations

[CoolDoc1729]

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Looking for thoughts on this ...

Is someone with no other risk factors who had covid 3 weeks “low risk” enough to rule out DVT with a ddimer ? What about 6,8 weeks out, etc?
What about 3 weeks out from the J&J vaccine? 6 weeks?
Asking as a full time midnight weekend shifter .. Doppler is never there when I am ☹️ and this is coming up more and more ...

 

[southerndoc]

I think there is a higher chance of the d-dimer being falsely elevated due to COVID than being falsely negative.

 

[Rekt]

Looking for thoughts on this ...

Is someone with no other risk factors who had covid 3 weeks “low risk” enough to rule out DVT with a ddimer ? What about 6,8 weeks out, etc?
What about 3 weeks out from the J&J vaccine? 6 weeks?
Asking as a full time midnight weekend shifter .. Doppler is never there when I am ☹️ and this is coming up more and more ...

Doppler them yourself. Often EM docs forget how long patients have been symptomatic. DVT isn't really an acute emergency. They can come back the next day for true scan if you think it's pertinent. Or if you're very scared, start them on NOAC/anticoagulant and get an ultrasound next day. It's not like they dissolve.

If they clinically have significant disease (phlegmasia/concern for May-Thurner, etc), you have your answer already.

 

[BoardingDoc]

Was going to write exactly what @southerndoc did above. I am not aware of any data suggesting that COVID causes falsely low dimers. If anything, I'd feel MORE confident in a negative dimer in that scenario than in others.

 

[thegenius]

Looking for thoughts on this ...

Is someone with no other risk factors who had covid 3 weeks “low risk” enough to rule out DVT with a ddimer ? What about 6,8 weeks out, etc?
What about 3 weeks out from the J&J vaccine? 6 weeks?
Asking as a full time midnight weekend shifter .. Doppler is never there when I am ☹️ and this is coming up more and more ...

That's a tough one. I don't know how long it takes for the DDimer to normalize after having COVID

 

[Cinclus]

Was going to write exactly what @southerndoc did above. I am not aware of any data suggesting that COVID causes falsely low dimers. If anything, I'd feel MORE confident in a negative dimer in that scenario than in others.

I do agree. But I did have a weird case back when COVID was really rampant in my area. Young, otherwise healthy guy who recently had COVID, improved, and then suddenly became really SOB with significant WOB (but great sats) came in. Triage ordered a dimer. I ordered a CTA before the dimer even resulted, because I had no other reason based on exam and initial results. The dimer resulted quite negatively. He had multiple pulmonary emboli. Medicine admitting doc was all 😵.

 

[southerndoc]

I do agree. But I did have a weird case back when COVID was really rampant in my area. Young, otherwise healthy guy who recently had COVID, improved, and then suddenly became really SOB with significant WOB (but great sats) came in. Triage ordered a dimer. I ordered a CTA before the dimer even resulted, because I had no other reason based on exam and initial results. The dimer resulted quite negatively. He had multiple pulmonary emboli. Medicine admitting doc was all 😵.

We've all had a case or two like this. I remember a saddle PE with a negative d-dimer (situation like yours -- ordered from triage). He had been dyspneic for 2-3 weeks. The admitting doc had a good theory. It likely had been going on for so long that the clot wasn't acute anymore. Sad for the patient because that means his PE is nothing but fibrin now.

 

[WilcoWorld]

I do agree. But I did have a weird case back when COVID was really rampant in my area. Young, otherwise healthy guy who recently had COVID, improved, and then suddenly became really SOB with significant WOB (but great sats) came in. Triage ordered a dimer. I ordered a CTA before the dimer even resulted, because I had no other reason based on exam and initial results. The dimer resulted quite negatively. He had multiple pulmonary emboli. Medicine admitting doc was all 😵.

As @southerndoc doc says, this will happen. I think it's notable that you had a high pre test suspicion based on the presentation alone. So this is a case where it's appropriate, just as you did, to not rely on the d-dimer (with or without COVID history).

Also, I thought the J&J vaccine was specifically being looked at for dural sinus thrombosis, not DVT. Am I wrong about that?

In summary, I'm still comfortable using d dimer to rule out PE in patients with a Wells <4.5, COVID or no.

 

[lymphocyte]

We've all had a case or two like this. I remember a saddle PE with a negative d-dimer (situation like yours -- ordered from triage). He had been dyspneic for 2-3 weeks. The admitting doc had a good theory. It likely had been going on for so long that the clot wasn't acute anymore. Sad for the patient because that means his PE is nothing but fibrin now.

My training is that after about a week, it's no longer a helpful test for that exact reason. There is good literature to support this.

The diagnostic yield of D-Dimer in relation to time from symptom onset in patients evaluated for venous thromboembolism in the emergency medicine department - PubMed

D-Dimer concentrations increase following the thrombotic event and decrease thereafter. Timing of D-Dimer evaluation in relation to the onset of the disease might have a diagnostic impact. We have presently performed a retrospective analysis of diagnostic procedures performed in individuals who...

pubmed.ncbi.nlm.nih.gov

 

[pkwraith]

I use d-dimer exactly the same for any other low risk PE rule out. covid-19 doesn't change things, except I don't order it when they have acute severe covid-19 when it is false elevated for diagnostic purposes.

 

[Groove]

Looking for thoughts on this ...

Is someone with no other risk factors who had covid 3 weeks “low risk” enough to rule out DVT with a ddimer ? What about 6,8 weeks out, etc?
What about 3 weeks out from the J&J vaccine? 6 weeks?
Asking as a full time midnight weekend shifter .. Doppler is never there when I am ☹️ and this is coming up more and more ...

As someone else said, just POCUS them yourself. It takes 5 minutes and is probably one of the easiest ultrasound exams to teach and perform. You can even do it with a butterfly. If I have a low pre-test probability patient, I often will just do this myself as it takes less time than sending off a dimer. It's totally within your training. I even got the APCA EM POCUS certification in case my qualifications were ever called into question though that's kind of an overkill and an incredibly easy examination.

To answer your question, I just don't think there is enough data right now to guide dimer interpretation in post COVID pt's. I haven't changed my practice in ordering them since COVID other than increased frequency as surrogate markers for COVID admissions. However, I'm not using the dimer to guide selection of candidates for CTA in that pt population.

If you're not comfortable doing the exam yourself and the dimer is + with no formal US available at night, then just give them a dose of lovenox and bring them back during banker hours for the exam after discussing risks/benefits of anticoagulation.

 

[Janders]

My opinion is DDIMEr is still useful to r/o DVT/PE in COVID similar to other conditions.

I do think COVID likely makes PERC troublesome...

 

[AlmostAnMD]

I haven't ordered a dimer on a covid patient since we got the antigen testing

I just assume it's gonna be elevated and only pursue PE stuff if suspicious

I also work in an area of fatties and it's a largely useless test because of that that I rarely order anyway, everyone is positive

 

[RustedFox]

I haven't ordered a dimer on a covid patient since we got the antigen testing

I just assume it's gonna be elevated and only pursue PE stuff if suspicious

I also work in an area of fatties and it's a largely useless test because of that that I rarely order anyway, everyone is positive

So, you work in the USA.

ADDENDUM: I'm not casting any shade at you. I just walked my dog and noticed that I was the only non-obese individual on my walk.
Seriously, America. You're making it hard to be proud.

 

[Tenk]

So, you work in the USA.

ADDENDUM: I'm not casting any shade at you. I just walked my dog and noticed that I was the only non-obese individual on my walk.
Seriously, America. You're making it hard to be proud.

He went to our residency soooo yeah....

 

[Tenk]

So they use dimers to actually stratify and follow severity of covid.

D-dimer as a biomarker for disease severity and mortality in COVID-19 patients: a case control study - Journal of Intensive Care

Background Over 5,488,000 cases of coronavirus disease-19 (COVID-19) have been reported since December 2019. We aim to explore risk factors associated with mortality in COVID-19 patients and assess the use of D-dimer as a biomarker for disease severity and clinical outcome. Methods We...

jintensivecare.biomedcentral.com

You should probably be ordering a dimer on all very ill covid patients and probably ctaing them as well. I have lost count on how many PEs I have found on covid patients.

 

[Groove]

I do agree. But I did have a weird case back when COVID was really rampant in my area. Young, otherwise healthy guy who recently had COVID, improved, and then suddenly became really SOB with significant WOB (but great sats) came in. Triage ordered a dimer. I ordered a CTA before the dimer even resulted, because I had no other reason based on exam and initial results. The dimer resulted quite negatively. He had multiple pulmonary emboli. Medicine admitting doc was all 😵.

I always have someone in my group that's had one of these and although I've been searching my entire career, I still can't find a PE with a negative dimer. Maybe some day I can join the club!

It seems to be a rare bird though...

Negative D-dimer Testing Excludes Pulmonary Embolism in Non-High Risk Patients in the Emergency Department - PMC

To assess the ability of d-dimer testing to obviate the need for cross-sectional imaging for patients at “non-high risk” for pulmonary embolism (PE). This is a retrospective study of emergency department patients at an academic medical center who ...

www.ncbi.nlm.nih.gov