A research study published in Scientific Reports proposes the examination of cervix microstructure via polarized light based on a wide-field depolarization imaging method. Using wide-field depolarization imaging, a nonsurgical approach for rapidly analyzing cervical tissue in vivo, experts could better identify preterm delivery by keeping tabs on the continuous growth of the pregnancy.
The cervix plays a critical role in conception, childbirth, and delivery. As the uterus undergoes microstructural remodeling in preparation for birth, a pregnant woman’s cervix changes substantially in terms of mechanical characteristics. This process can be accelerated by external factors, leading to prematurity. This is the leading cause of infant mortality worldwide owing to the inadequacy of current diagnostic procedures.
As the pregnancy progresses, a significant shift occurs in the cervix's polarimetric capabilities. Pregnancy age has a significant linear connection with an integration of various depolarization characteristics due to a reduction in collagen thickness and a rise in cervical connective tissue permeability.
The Threat of Preterm Birth (TPB)
Premature birth is the leading cause of perinatal death globally. Prematurity occurs when a woman gives birth before 37 weeks of amenorrhea. In France and Europe, the prematurity rate is estimated at 6%, while in the United States, the rate is twice as high.
A tocolytic medication is given to women with the threat of preterm birth to reduce contractions and prevent preterm labor. In current medical practice, determining the severity of the threat of preterm birth to predict preterm delivery is challenging.
Limitations of Current TPB diagnosis Techniques
Transvaginal ultrasonography is the preferred method for measuring cervical length. Transvaginal ultrasonography can be augmented by biomarkers detection. Premature birth is more likely in women with amenorrhea for less than 37 weeks and a cervical length of less than 20 mm. However, there is no clear guideline for a threshold of cervical length that would consistently indicate preterm because of the difficulty of associating measured length with time to birth.
Premature delivery occurs in less than 50% of the women diagnosed with the threat of preterm birth, depending on the pregnancy age at the time of their initial admission. Many women are hospitalized unnecessarily which is expensive and may cause complications. Premature birth rates can be reduced, adverse occurrences can be avoided, and novel treatments can be developed if a better approach to diagnosing prematurity can be devised.
Role of Cervix in Maintenance of Pregnancy and Childbirth
The cervix plays a key role in the maintenance of childbirth and pregnancy. The mechanical capabilities of the cervix substantially alter as gestation continues. This process proceeds slowly up to roughly 37 weeks of amenorrhea in a full-term pregnancy, leading to progressive weakening of the cervix without any noticeable change in its anatomy.
After 37 weeks of amenorrhea, the cervix starts to contract and expand in preparation for labor and delivery which occur at around 41 weeks of amenorrhea.
The change in mechanical characteristics of the cervix during pregnancy is related to the cervix microstructure remodeling. This process predominantly affects the soft tissue or stroma, resulting in more than 95% of the cervix’s size.
Characterizing cervix microstructure remodeling throughout full-term gestation is critical for understanding how this process occurs in high-risk pregnancies.
Investigation of Cervix Microstructure Remodeling
This cervix microstructure remodeling process can be investigated using X-ray diffraction, second harmonic generation (SHG) microscopy, and optical coherence tomography (OCT).
X-rays can harm both mother and child. High magnetic fields have uncertain impacts on pregnancy. OCT and SHG microscopy can examine cervical tissues with high resolution but with less depth of measurement. Scanning broad regions render these approaches difficult and inappropriate for in vivo application.
A safe, novel technology is required to swiftly examine a pregnant woman's cervix in vivo and provide insights on cervix microstructure remodeling.
Rehbinder et al. reported the feasibility analysis of depolarization imaging for determining cervix microstructural remodeling during pregnancy. The researchers examined full-term pregnant women of varying gestational ages to discover the essential polarimetric parameters for monitoring pregnancy progress.
Wide-field depolarization imaging can characterize scattering or anisotropic surfaces that give specific polarimetric signals. This approach has shown potential for biological diagnostics. Depolarization imaging explores optically complicated biological tissues, where scattering and anisotropy effects coexist. Depolarization imaging emits photons to detect microstructural changes in diseased tissues and can be used to examine the collagen-rich cervix's microstructure remodeling.
Potential of Depolarization Imaging for Cervix Microstructure Remodeling
Rehbinder et al. with his team employed wide-field depolarization imaging to characterize the cervical tissue polarimetrically during pregnancy. The results showed that depolarization imaging is a viable technique for studying cervical microstructure during pregnancy.
Pregnant women of various gestational ages were examined using a Mueller polarimeter attached to a normal colposcope. It was discovered that the total depolarization, calculated from the Mueller matrix measured by symmetric decomposition, was the best indicator of cervical microstructure remodeling during pregnancy.
Many depolarization characteristics, especially those seen in the red and near-infrared regions of the visible spectrum, can be used to characterize microstructural changes in the cervix throughout pregnancy.
A more accurate preterm diagnosis could be obtained by identifying irregularities in the development of cervical depolarization characteristics throughout a full-term pregnancy.
Rehbinder, J., Vizet, J., Park, J., Ossikovski, R., Vanel, J.-C., Nazac, A., & Pierangelo, A. (2022). Depolarization imaging for fast and non-invasive monitoring of cervical microstructure remodeling in vivo during pregnancy. Scientific Reports, 12(1), 12321. https://www.nature.com/articles/s41598-022-15852-w