Use of D Dimers in Patients with Previous PE

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Do you get d dimers in patients with CP/SOB and history of PE? Or just send straight to scan?

Where I trained, it seemed more common to send to scan - but a friend of mine went to the ED (hx of PE in pregnancy) with SOB and was "ruled out" by d dimer. It seems like, all other things being negative by Wells criteria, hx of PE still makes a person "low risk" - and therefore d dimer can still apply.

What is your practice?

 

[deleted109597]

As few scans as possible. So if that means a dimer, then I'll do it.

 

[coachB]

I'm all for minimizing scans, but I think it's pretty tough to consider a person with a history of thromboembolic disease "low risk."

 

[goodoldalky]

It all depends on the etiology of the PE. Most PE's are provoked so I don't really consider those people to be at high risk when they come back 2 years after their hip replacement PE for a chest pain workup. Factor V and some other things may make me more likely to do a scan.

 

[edgesofsanity]

Which will be easier to understand for the jury - the defense with Well's criteria and math; or the prosecution's story of "So they had a previous history of pulmonary embolism; you didn't think that they could have another one?"

So personally I scan them, but you can make the medical argument either way.

 

[deleted109597]

Which will be easier to understand for the jury - the defense with Well's criteria and math; or the prosecution's story of "So they had a previous history of pulmonary embolism; you didn't think that they could have another one?"

So personally I scan them, but you can make the medical argument either way.

And this is why people rarely have 1 chest CT, and rather have about 20.

 

[edgesofsanity]

And this is why people rarely have 1 chest CT, and rather have about 20.

I'm not advocating this as a "one size fits all" philosophy. If a patient comes in with previous history of PE and a good clinical story, I lean towards scanning. If they come in with a previous history of PE 10 years ago and 20 negative CT scans in the interim, I lean towards not. You just have to use your clinical experience and judgement, as always.

 

[thorg12]

Wells 4 or less I order d-dimer;
Jama 2006 Effectiveness of Managing Suspected Pulmonary
Embolism using an Algorithm combining Clinical
Probability, D-dimer Testing and Computed
Tomography

Also I Perc as many as possible and am considering stopping if pt "low risk" wells, and not even doing d-dimer; David Newman talks about this on smart EM
I think we are doing a real disservice by thinking were are helping the patent by scanning their chest

 

[Birdstrike]

Of course, the answer to this question depends entirely on the sensitivity and negative predictive value of your labs d-dimer. Prediction rules can be helpful, but many patients don't fall into the filtered and pasteurized patient groups used in the studies to form the rules. Even a highly sensitive test is still not going to be 100%, which brings you back to the dreaded "clinical judgement." The downside of missing a PE is obviously pretty high. After formulating your level of suspicion for PE, and prior to ordering your d-dimer, ask yourself, "If this d-dimer is negative, will I be completely satisfied ending the work up there?"

If yes, order your d-dimer.

If no, cancel d-dimer and order your CT.

There's no easy answers these questions, unfortunately. PEs aren't that hard to miss, and can present in varied and non-specific ways.

 

[Arcan57]

Has anyone on this board diagnosed a PE of any significance in the face of a negative d-dimer?

 

[Snelgrave]

Use your gestalt.

Comparison of the Unstructured Clinician Gestalt, the Wells Score, and the Revised Geneva Score to Estimate Pretest Probability for Suspected Pulmonary Embolism
Andrea Penaloza, Franck Verschuren, Guy Meyer, Sybille Quentin-Georget, Caroline Soulie, Frédéric Thys, Pierre-Marie Roy

Annals of emergency medicine 1 August 2013 (volume 62 issue 2 Pages 117-124.e2 DOI: 10.1016/j.annemergmed.2012.11.002)

 

[Bostonredsox]

I would think its tough to avoid the scan unless the pt is essentially normal vitals, non recent surgery and cancer free. If they come in mildly tachycardic, which most chest pains and dyspneic pts do, and they have had a previous PE, that's a wells of 3 by itself. Any remotely significant dvt symptoms which are often quite ambiguous, and your at 4. I don't think anyone, certainly no one on the hospitalist front would fault you for proceding straight to the ct and skipping the dimer. A lot of my attendings would stop you at, "mildly tachy pt with history of PE and current chest pain/hypoxia...did you scan them? Like others have mentioned, it may lead to unnecessary CTs, but few pts with prior PE would qualify as low risk, which is in fact what the indication for a dimer is, rule out PE In low risk for PE pt.

 

[SoCuteMD]

I don't think anyone, certainly no one on the hospitalist front would fault you for proceding straight to the ct and skipping the dimer.

I think I need to introduce you to some more hospitalists...

 

[Apollyon]

Has anyone on this board diagnosed a PE of any significance in the face of a negative d-dimer?

Yes - febrile guy, white count, diaphoretic. Dry, though, and questionable CXR. He looked like a pneumonia. I called the admitting doc - first thing he says is, "Could it be a PE?" He wants the d-dimer and the scan (at the same time).

Pt gets scan before d-dimer comes back, but dimer returns before scan is read. D-dimer? 479 (negative - 500 line for us). CT? Segmental PE on R side.

So, that wasn't in the right order, but, had I gone on the d-dimer, I would have argued to not scan, and would have missed a significant PE.

 

[DrMom]

I think I need to introduce you to some more hospitalists...

I have more of an issue with radiology than the hospitalists.

 

[dotcb]

I use D dimer for low and moderate probability.

I would CT them straight away if I actually thought they had a PE, or if I felt the CT would give other important information (such as also being concerned about aortic disease).

 

[WilcoWorld]

History of PE = 1.5 points on Wells. If all else is negative, that's "low risk". If you don't think it's a PE, but you can't quite rule it out - I say d-dimer away.

If you think it's as likely to be a PE as it is anything else, then give 'em another 3 points on Wells for a total of 4.5. This puts them in the "PE likely" group of the aforementioned dichotomized Wells, so you should probably skip to the scan.

Now, a Hx of PE during pregnancy? That's a provoked PE, and assuming she's had no recurrence for 6 months post-treatment, I'd consider her to be at the population-baseline risk. So I might not even test that person if I have a solid alternative diagnosis. Let's say she has a history of asthma and seasonal allergies, the local pollen counts are high, she is wheezing on exam, and both symptomatically and objectively improves with nebs? I wouldn't dimer or scan that patient. However, I will talk to the patient about the possibility of missed PE vs "radiation exposure", and my note will say something about the risks of a scan exceeding the likely benefit and instructions to return to the ED "for immediate reevaluation of new, worsening or otherwise concerning symptoms".

It might seem like a lot to do/chart, but it takes less time than it does to order the dimer (and the creatinine), see the result, order the scan and then follow up on the result. Add in the frequent difficulties with IV access, having to follow up on incidentalomas, having to explain to an upset family member why they've been here for "almost two hours, but nothing's been done"...and you're starting to save some real time.

 

[turkeyjerky]

I would think its tough to avoid the scan unless the pt is essentially normal vitals, non recent surgery and cancer free. If they come in mildly tachycardic, which most chest pains and dyspneic pts do, and they have had a previous PE, that's a wells of 3 by itself. Any remotely significant dvt symptoms which are often quite ambiguous, and your at 4. I don't think anyone, certainly no one on the hospitalist front would fault you for proceding straight to the ct and skipping the dimer. A lot of my attendings would stop you at, "mildly tachy pt with history of PE and current chest pain/hypoxia...did you scan them? Like others have mentioned, it may lead to unnecessary CTs, but few pts with prior PE would qualify as low risk, which is in fact what the indication for a dimer is, rule out PE In low risk for PE pt.

You're painting a completely different picture. Signs and symptoms of a dvt on wells' scoring doesn't mean "vague calf pain 3 weeks ago" they had a specific definition, along the lines of "deep calf tenderness and a difference in circumference of 3 cm". And most chest pain patients do not present tachycardic, or hypoxic. You're essentially saying that you should scan high risk patients. There's a big difference between a patient w/ a history of provoked dvt/pe who presents w/ isolated chest pain or dyspnea and someone who's got a history and presents tachy, hypoxic and with unilateral leg swelling.

Yes - febrile guy, white count, diaphoretic. Dry, though, and questionable CXR. He looked like a pneumonia. I called the admitting doc - first thing he says is, "Could it be a PE?" He wants the d-dimer and the scan (at the same time).

Pt gets scan before d-dimer comes back, but dimer returns before scan is read. D-dimer? 479 (negative - 500 line for us). CT? Segmental PE on R side.

So, that wasn't in the right order, but, had I gone on the d-dimer, I would have argued to not scan, and would have missed a significant PE.

How do you know it wasn't a chronic PE? Did they stop treatment for Pneumonia?