Evaluation of D-dimer during pregnancy.

Aim: The purpose of the present study was to elucidate the change of D-dimer and the possibility of deep vein thrombosis screening by D-dimer during pregnancy.
Methods: One thousand, one hundred and thirty-one pregnant women were enrolled in the study from April 2006 to March 2007. D-dimer was measured by latex immunoassay at 6 to 14 and 30 to 36 weeks of gestation, respectively, and the veins of the lower extremities were examined by ultrasound at 30 to 36 weeks of gestation.
Results: The mean and standard error of D-dimer was 1.1 +/- 1.0 microg/mL in the first trimester and 2.2 +/- 1.1 microg/mL in the third trimester, and both values were significantly higher than adult values. In addition, D-dimer significantly increased during pregnancy. D-dimer was not significantly different between singleton and twin pregnancies in the first trimester, but in the third trimester, the values of twin pregnancies were higher than singleton pregnancies (2.2 +/- 1.6 vs 3.7 +/- 2.5 microg/mL). The mean value of D-dimer of ultrasonographically positive women was 2.6 +/- 2.0 microg/mL, which was significantly higher than the value for negative woman during the third trimester (2.2 +/- 1.6 microg/mL). The positive predictive value was 7.4% and negative predictive value was 95.5% for ultrasonographically positive women when D-dimer was set at 3.2 microg/mL.
Conclusion: We clearly found a change of D-dimer during pregnancy. When D-dimer was higher than 3.2 microg/mL, the percentage of ultrasonographically positive women was high. We propose that women with D-dimer higher than 3.2 microg/mL are closely monitored for prevention of pulmonary thromboembolism.