In general, the utility of D-dimer for the evaluation of venous thromboembolism declines with gestational age. The typical cut-offs for the 95th percentile, depending on your assay, become less and less relevant as pregnancy progresses. Wouldn’t it be nice, perhaps, if we had reliable data?
So, well, here’s something:
One glaring hole in this data is the broad inclusion criteria of “healthy” women. No testing was specifically performed to exclude asymptomatic venous thromboembolism, so the possibility exists of inclusion of small, subsegmental pulmonary emboli, or of non-occlusive lower extremity deep venous thrombosis. The effect on this data would be to increase the 95% percentile, and to widen the 95th percentile confidence interval.
Jeff Kline has proposed gradually increasing cut-offs of 750, 1000, and 1250 ng/mL for the first, second, and third trimester, respectively (based on a standard cut-off of 500 ng/mL). This sample is much larger than the one cited by Kline in his “PE in pregnancy” algorithm, but his appear to be reasonable, sensitive cut-offs. By far, the most important aspect of evaluating pulmonary embolism in pregnancy is simply to communicate the uncertainty, and to inform and share decision-making with the patient along the way.
“Gestation-specific D-dimer reference ranges: a cross-sectional study”
http://www.ncbi.nlm.nih.gov/pubmed/24828148