Babies born before they reach full-term are at an increased risk of long-term complications. Currently, there are no accurate ways to predict when preterm birth (PTB) will occur. The cervix, which plays an essential role in maintaining a pregnancy to term, has to remain closed throughout gestation. However, for birth to occur, it has to shorten, soften and dilate. This crucial remodeling process appears to be linked to variations in the arrangement of collagen. Previous in vitro work using X-ray diffraction suggests that collagen fibers exhibit a preferential orientation in the non-gravid cervix: adjacent to the endocervical canal and in the outermost areas, fibers are mainly arranged in a longitudinal fashion whereas in the middle area they are circumferentially organized. We proposed using a potentially non-invasive imaging technique, polarization-sensitive optical coherence tomography (PS-OCT), to detect the changes in the collagen arrangement of human non-gravid cervix (n=10). Qualitatively, we found that PS-OCT is capable of discriminating between the three cervical regions. Quantitatively, the apparent birefringence of these areas is significantly different across all samples (p<0.05). As expected, apparent birefringence is much lower adjacent to the endocervical canal and in the outermost areas. PS-OCT also seems to be capable of estimating the thickness of the cervical epithelium. Our study, therefore, shows that PS-OCT can assess the microstructure of the human cervical collagen in vitro and holds the potential to help us better understand cervical remodeling prior to birth and develop more timely identification and prevention of PTB pending the development of an in vivo probe.
|