Thrombin Generation by Fetoscopic Trauma to the Fetal Membranes: An in vivo and in vitro Study

Abstract

Objective: We first aimed to investigate in vivo thrombin generation induced by fetoscopy, and second we used term membrane explants for measurement of thrombin generation, thrombin receptor location and induction of selected matrix metalloproteinases (MMPs) in tissue culture. Materials and Methods: In vivo study (37 cases): samples of amniotic fluid were taken at the beginning and end of fetoscopy (mean gestational age 26.7 weeks) and analyzed by ELISA for thrombin-antithrombin complexes. In vitro study: fetal membranes were put in culture and punctured for measurement of thrombin generation by calibrated automated thrombography and ELISA. Induction of MMP-9 and MMP-2 was analyzed by zymography. PAR-1 was localized by immunohistochemistry. Results: No significant increase in thrombin-antithrombin was measured in amniotic fluid obtained during fetoscopy. In vitro, thrombin generation induced by needle trauma of membrane cultures is correlated to the amount of plasma. Activity of MMP-9 but not MMP-2 was elevated in cultured membranes but could not be inhibited by a thrombin inhibitor. On histology, the thrombin receptor PAR-1 was located in the chorion and decidua, but not in the amnion. Discussion: Despite the influence of thrombin on punctured fetal membranes in vitro, the role of thrombin in iatrogenic preterm premature rupture of membranes is questionable.