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 µg/mL in the first trimester and 2.2 ± 1.1 µg/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 µg/mL). The mean value of D‐dimer of ultrasonographically positive women was 2.6 ± 2.0 µg/mL, which was significantly higher than the value for negative woman during the third trimester (2.2 ± 1.6 µg/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 µg/mL. Conclusion:  We clearly found a change of D‐dimer during pregnancy. When D‐dimer was higher than 3.2 µg/mL, the percentage of ultrasonographically positive women was high. We propose that women with D‐dimer higher than 3.2 µg/mL are closely monitored for prevention of pulmonary thromboembolism.