Fibrinolytic Response to Venous Occlusion and Fibrin Fragment D-Dimer Levels in Normal and Complicated Pregnancy

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Abstract
Summary: The fibrinolytic response to venous occlusion was assessed in 29 women with normal or complicated pregnancy, by measurements of total t-PA and free t-PA with specific ELISAs. The release of t-PA from the vessel wall was 11±9 ng/ml in nonpregnant women (mean ± SD, n = 6) but was markedly reduced throughout pregnancy. Following venous occlusion, free t-PA increased by 12 ± 11 ng/ml in non-pregnant women but remained below the detection limit of 2 ng/ml towards the end of pregnancy. A markedly reduced t-PA release with absence of free t-PA was also observed during late pregnancy in patients with insulin-dependent diabetes mellitus, intra-uterine growth ietaida-tion and pre-eclampsia.Plasma levels of fragment D-dimer of cross-linked fibrin were measured with a specific FITS A in 79 pregnant women. D-dimer levels were 129 ± 36 ng/ml (mean ± SD, n = 8) in non-pregnant women and increased to 400 ± 170 ng/ml (n = 25) and 440 ± 220 ng/ml (n – 22) during the second and third trimester of pregnancy respectively. Significantly higher levels than observed in uncomplicated third trimester pregnancies were found in 3 out of 6 diabetic and in 2 out of 7 pre-eclamptic women.It is concluded that the t-PA release after venous occlusion is significantly reduced during pregnancy. In addition, released t-PA is rapidly inhibited. The levels of fragment D-dimer increase during pregnancy, suggesting that, notwithstanding the marked impairment of the fibrinolytic response to venous occlusion, the fibrinolytic system remains functionally active.