d-dimer in pregnancy

[tyson]

i feel as though we don't use d-dimer very much in pregnant women. conversations always go, "well, she's pregnant and she's short of breath, so she must be high risk." inevitably, we end up w/ a V/Q or CTA scan. 

I've seen a few articles on d dimer in pregnancy and that it can be quite reliable in regards to specificity as long as you correlate the d-dimer to the current semester the patient is in (Recent literature indicates that D-dimer levels in each of the three trimesters are

approximately 39% higher: 700, 1000, and 1400 ng/dL for each trimester (normal

cutoff 500 ng/dL). So, figure out what trimester your patient is in and use the

corresponding D-Dimer level for that trimester.) 

 Also, one of the ACEP articles mentioned that if you are concerned about a PE, start with a lower extremity U/S and if it comes back positive, then a CTA or VQ scan is uneccessary as the patient is going to be tx with lovenox anyway. 

are you guys pretty good about using D-dimer in low risk pregnancy?

do you get the lower extremity U/S before CTA, V/Q scan if you think the patient likely has a PE?  It makes sense from radiation standpoint, but i think there is something to be said for knowing size, location, quantity of PE potentially. Though I don't know if it would change management. 

Thoughts? 


Tyson






www.rhqn.org/news/HospitalPeerReview_2012_01.pdf

webapps.acep.org/CriticalDecisionsTesting/PDFpubs/15-cdem-february.pdf

[slevittMD]

There was an EMRAP about this topic a while back with regards to the d-dimer levels per trimester. However, I'm not sure if those are well accepted enough to actually use to rule out PE? I have ordered a d-dimer in pregnancy with the assumption that if it did happen to come back low, we could rule out. But, have never used the trimester based cutoffs.

I also haven't tried starting with the lower extremity Doppler. If I suspected DVT, I would have. But I thought it would be negative and just taken up more time than getting the CTA. I agree that if you're gonna treat the DVT the same as the PE, then no need to scan once you have a confirmed DVT.

I'm interested in Bruss' thoughts on this.

On a related note, I believe TTH uses a lower cutoff than 500, which I think is probably not appropriate. Another EMRAP mentioned that the appropriate cutoff is 500, regardless of where the test is done (not like lactate where the cutoffs vary based on the assay).

[tyson]

i'd like to hear what bruss thinks as well.

but you do make some good points regarding accepted cutoff for D-dimer. I guess we'd have to go institution based.

is it worth it to get the lower extremity U/S? I don't know the numbers. I would think that if there is a high rate of concomitant PE and DVT, then it makes sense to get U/S first. However, if say only 10% of those people that have PE's have a DVT as well, then really it's wasting a lot of resources on negative studies.

I'll see if i can find some numbers between PE and concominant DVT

[kemple]

Right, I don't think that there are set standards for D-Dimer in pregnancy to use. Thus you don't really have a valid cut off to say it's negative or positive. Something you could do as a research project maybe.

[tyson]

Right. Agree with what you said Kemple. Definitely not set standards in pregnancy which we can use. Does appear that there is at least a decent amount of literature out there regarding levels by trimester. But the problem lies therein. Should we be using the same d-dimer cutoff for someone at 8 weeks vs 13 weeks? At this point, I think institutions are reluctant to institute trimester based d-dimers until ACOG or some other governing body comes out with definitive standards. Right now there are just general guidelines. So until then, it appears that under 500 ng/dl will be the standard.

[kemple]

Yeah play the game, sometimes you win, sometimes you lose.

[pbruss]

good points by all. from my practice and what i have read, i do use a d dimer to try and rule out DVT/PE in pregnant chicks. if that is positive i usually go right to the CTA after a well documented conversation with the family. i used to offer lower ext Doppler but i have read that pregnancy increases the incidence of colts in other places like upper exts and in the pelvis. bottom line is a this point i sometimes role the dice and hope for a negative d-dimer. i also do not think we are anywhere near having a reliable "new" value or cutoff for what a negative d-dimer in pregnancy is. attached some papers for your review

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HospitalPeerReview_2012_01.pdf (84.69 KB)

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