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.


METHODS
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 <2 cm. An association with the duration of labor was found for the neutrophil count and the concentrations of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinases-1. Multiple linear regression analysis showed that the degree of cervical dilatation is more closely related to the 4 laboratory parameters investigated than to the duration of labor.


CONCLUSIONS
The findings support the hypothesis that local changes (ie, collagenolysis) in the lower uterine segment unrelated to uterine activity play a crucial role in cervical dilatation at term.
Winkler
M
M
Department of Obstetrics and Gynecology and the Institute of Clinical Chemistry and Pathobiochemistry, Technical University (RWTH), Aachen, Germany.
Oberpichler
A
A
Tschesche
H
H
Ruck
P
P
Fischer
D C
DC
Rath
W
W
D002584:Cervix Uteri / Q000201:enzymology* / Q000502:physiology*; D003094:Collagen / Q000378:metabolism*; D017364:Collagenases / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D016014:Linear Models; D020784:Matrix Metalloproteinase 8; D020780:Matrix Metalloproteinase 9; D009504:Neutrophils / Q000378:metabolism; D011247:Pregnancy; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism
D019715:Tissue Inhibitor of Metalloproteinase-1; D003094:Collagen; D017364:Collagenases; D020784:Matrix Metalloproteinase 8; D020780:Matrix Metalloproteinase 9