Tissue factor-dependent blood coagulation is enhanced following delivery irrespective of the mode of delivery.
BACKGROUND
The risk of thrombosis is clearly increased in the postpartum period. Mice with a targeted deletion of the transmembrane domain of tissue factor (TF) develop serious activation of blood coagulation and widespread thrombosis after delivery.


OBJECTIVE
We hypothesized that TF, abundantly present in placental tissue, is released during delivery, resulting in the activation of blood coagulation. We measured sensitive markers for TF-dependent activation of coagulation before and after induction of labor in two groups: a vaginal delivery (VAG) group and a cesarean section (CS) group.


RESULTS
One hour after delivery, soluble TF (sTF) significantly increased in both groups [VAG group (mean +/- SD) 226 +/- 42 to 380 +/- 42 pg mL(-1) and CS group 193 +/- 17 to 355 +/- 44 pg mL(-1)]. The day after delivery, sTF was somewhat less increased. Both groups also showed an increase in factor VIIa, indicating activation of the TF pathway of coagulation. Indeed, after delivery, TF-dependent coagulation, as measured by the TF clotting time assay, was significantly enhanced. Increased plasma levels of prothrombin fragment 1 + 2 and thrombin-antithrombin complexes demonstrated thrombin generation following delivery. TF pathway-dependent activation of coagulation upon delivery was not blocked by TF pathway inhibitor and was not dependent on the mode of delivery.


CONCLUSIONS
The postdelivery increase in TF-dependent activation of coagulation is likely to be a natural mechanism to prevent excessive blood loss during and after delivery, and may also indicate a novel mechanism by which puerperal women have an increased risk of venous thromboembolism.
Boer
K
K
Department of Obstetrics, Academic Medical Center, Meibergdreef 9, Amsterdam, The Netherlands.
den Hollander
I A
IA
Meijers
J C M
JC
Levi
M
M
D000990:Antithrombin III; D001777:Blood Coagulation; D002585:Cesarean Section; D015942:Factor VIIa / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D006801:Humans; D007751:Labor, Induced; D007743:Labor, Obstetric / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood; D010447:Peptide Hydrolases / Q000097:blood; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000097:blood / Q000209:etiology*; D011250:Pregnancy Complications, Hematologic / Q000097:blood*; D011516:Prothrombin; D012307:Risk Factors; D013917:Thrombin / Q000378:metabolism; D013925:Thromboplastin / Q000378:metabolism*; D013997:Time Factors; D015854:Up-Regulation; D054556:Venous Thromboembolism / Q000097:blood / Q000209:etiology*
D010446:Peptide Fragments; C046193:antithrombin III-protease complex; C045879:prothrombin fragment 1.2; D000990:Antithrombin III; D011516:Prothrombin; D013925:Thromboplastin; D010447:Peptide Hydrolases; D015942:Factor VIIa; D013917:Thrombin