D-Dimer levels at different stages of pregnancy in Australian women: A single centre study using two different immunoturbidimetric assays

Background To date there is minimal data available on D-Dimer levels at different stages of pregnancy. Patients and methods We prospectively measured D-Dimer levels in 632 consecutive pregnant women from March 2007 to January 2009. The median age of the participants was 31 years (range; 18–42) with a median weight of 78 kilograms (range; 46–137). All subjects were investigated during each trimester with two different immunoturbidimetric assays; D-Dimer PLUS and INNOVANCE D-Dimer. D-Dimer levels were determined using a Sysmex® CA 1500 analyser. Results Our data demonstrate that D-Dimer levels in pregnancy show different patterns of rise within the first trimester, depending on the assay used; D-Dimer PLUS = 0.88 (SD: mean ratio), INNOVANCE D-Dimer = 0.72 (SD: mean ratio). Furthermore, the rise in mean results was greater for the INNOVANCE D-Dimer assay compared to the D-Dimer PLUS assay as shown by the ratio of third to first trimester results of 3.68 and 1.96 respectively. Both D-Dimer assays demonstrated moderate levels of intra-subject variability, with overall mean CVs of 16.5% (D-Dimer PLUS) and 16.9% (INNOVANCE D-Dimer). Furthermore, we studied the association between D-Dimer levels and occurrence of diseases of pregnancy. For both assays, there was no consistently interpretable evidence of an association between raised mean D-Dimer levels or rising D-Dimer levels and any of the diseases or conditions associated with pregnancy. Conclusion Our data suggest that the INNOVANCE D-Dimer assay increases significantly with the advancement of pregnancy, and is more sensitive than D-Dimer PLUS assay in the pregnant population