Comparisons of the fibrin networks during pregnancy, nonpregnancy and pregnancy during dysfibrinogenaemia using the scanning electron microscope.

In normal pregnancy there is an increase in procoagulant activity. Furthermore, the fibrinolytic activity is impaired and remains low during labor and delivery, but returns rapidly to normal, following delivery. Here, we show ultrastructural changes in fibrin networks found in pregnant individuals and nonpregnant individuals. Typically thick, major fibers, and irregularly placed thin, minor fibers are present in healthy, nonpregnant individuals. In this qualitative assessment, changes in fibrin networks and platelet morphology were studied with scanning electron microscopy in healthy individuals, a healthy individual at 30-week pregnancy and post partum. We also included results from an individual with dysfibrinogenaemia (30-week pregnant and postpartum). Results suggest that in the healthy pregnant and pregnant dysfibrinogenaemia individuals, the minor, thin fibers form a fine, dense net distributed evenly over the major fibers. This net was not present in the nonpregnant dysfibrinogenaemia or healthy nonpregnant individuals. No ultrastructural changes were found in platelet morphology. These morphological changes seen during pregnancy might contribute to increased thrombotic risk, because, due to the denser appearance of fibrin networks because of the fine minor network morphology during pregnancy, clots might take longer to be broken down by normal fibrinolytic activity.