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PT Affected by LMWH?

Sam Arcidiacono asks, One of our customers had a patient who stopped Coumadin for surgery and was given Lovenox (LMWH) I believe after the surgery.  PT was 20 seconds on admission, day after surgery PT was 205 seconds then 275 that evening. I didn’t think it was due to the Lovenox. No Lovenox was given that day of the 205 and 275 second PT. Any ideas?

Hi, Sam, and thank you for your question. No, LMWH does not prolong the PT. I suspect the patient is having trouble, perhaps moving into acute post-surgical DIC. Alternatively, is there any chance the patient was started on one of the oral anti-Xa anticoagulants, rivaroxaban, apixaban, or edoxaban? They prolong the PT, though the assay is generally not this sensitive to the anti-Xas. I’d first recommend a DIC workup, it may be an emergency situation. Geo.

Comments (1)
Bleeding Disorders
Mar 25, 2015 2:59am

Yes, something is certainly
Yes, something is certainly not right. LMWH does not affect the PT and most PT reagents are also insensitive to unfractionated heparin. If you can confirm that the sample was not taken through a blood gas syringe or heparin line (where the concentration of heparin may be very high) then you may have a serious problem. DIC is possible – hope this is not too late, but obviously test fibrinogen, APTT & d-dimer to start. What type of surgery? Also consider the possibility of a factor V inhibitor – do a mixing study and factor profile.

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