Collagenolysis in the lower uterine segment during parturition at term: Correlations with stage of cervical dilatation and duration of labor

Objective: The objective of this study was to quantify the extent of neutrophil infiltration and the concentrations of enzymes involved in collagenolysis in the lower uterine segment in relation to the degree of cervical dilatation and the duration of labor. Study Design: Biopsy specimens of the lower uterine segment were obtained from 62 women undergoing cesarean section at term. The number of extravascular neutrophils was assessed with enzyme histochemical evaluation, and the concentrations of matrix metalloproteinase-8, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 by were assessed by enzyme-linked immunosorbent assay. Results: The neutrophil count and the concentrations of matrix metalloproteinase-8, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 increased with increasing cervical dilatation. At >6 cm the neutrophil count and the concentrations of matrix metalloproteinase-8, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 were significantly higher than at