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Preterm birth, defined as delivery at less than 37 weeks of gestation, is the leading cause of newborns mortality. The survivors may have life-long problems including neurological, hearing, respiratory and vision disorders. Preterm birth is often linked to the premature remodeling of the extracellular matrix of cervical collagen resulting from structural defects, infection or often unknown causes. The process of cervical remodeling, namely, the transformation of uterine cervix from a closed rigid structure to a compliant one for safe passage of the fetus, is a crucial stage of normal parturition, but this process can be drastically accelerated in preterm birth.
We explore the potential of Mueller polarimetry to detect these alterations of the extracellular matrix of cervical collagen early enough in order to provide the quantitative assessment of the preterm birth risk by polarimetric scoring of collagen. Unstained thin sections of the whole uterine cervices from both non-pregnant and pregnant mice were studied with the custom-built transmission Mueller matrix microscope. The results of statistical analysis and multi-Gaussian fit of the distributions of depolarization and linear retardance parameters of cervical tissue sections demonstrated that imaging Mueller polarimetry in the visible wavelength range is very sensitive to the changes of extracellular matrix of cervical collagen with pregnancy.
The circular arrangement of cervical collagen fibers around cervical os (that was observed for all non-pregnant mice) is lost through the whole length of mouse cervix one day before delivery. It suggests that the remodeling of cervical collagen may be evaluated in the direct observations with polarized light during the colposcopy test in late pregnancy. Thus, imaging Mueller polarimetry may serve as a fast and non-contact optical modality for the collagen scoring in pregnancy and the quantitative assessment of the preterm birth risk.
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