In normal pregnancy, the cervix functions as a protective mechanical barrier that must remain tight and closed. Premature remodeling and consecutive shortening occur in many cases of spontaneous preterm birth. Although the complex underlying physiology of normal and abnormal cervical remodeling is not fully understood, it is clear that cervical softening occurs prior to delivery, and inappropriate timing seems to be associated with preterm delivery. Also, degree of cervical softness is a component of the Bishop score currently used clinically to predict successful induction of labor. Therefore, the assessment of changes in cervical stiffness with ultrasound elastography techniques might be useful in the prediction of preterm delivery or successful induction of labor. Two different approaches for cervical elastography for quantitative determination of the physical properties of the pregnant cervix have been developed: strain elastography and shear wave elastography. Recently, several feasibility studies showed the reliability of these cervical elastography techniques for the prediction of preterm delivery and successful labor induction. In this review, we contrast strain elastography, which determines only relative values of tissue stiffness because the applied transducer pressure is unknown, with shear wave elastography, which provides, in principle at least, a more objective description of tissue softness. While more promising preliminary results involving these approaches to assessing cervical softness have been recently published, current limitations in technical implementation need to be addressed before elastography techniques will become clinically useful. We discuss these limitations and present challenges for future studies and equipment development.
Late first and second trimester cervical elastography was shown to be feasible and to have a high interobserver reliability. Its clinical value needs to be assessed in further studies on selected obstetric populations.
Preeclampsia is a pregnancy-specific hypertensive syndrome and a major cause of maternal and fetal morbidity and mortality. At the present time, no reliable screening tests to identify women at risk are available. We have compared the amniotic fluids (AF) proteomic maps of five preeclamptic patients with those of five controls. The analysis was carried out by two-dimensional electrophoresis followed by peptide mapping and tandem mass spectrometric analysis. Besides the implementation of the previously published AF proteomic maps, our results show that transthyretin (TTR), the protein responsible for transporting both the thyroid hormone tyroxine and the retinol binding protein, is present in the AF of both preeclamptic and control women as a mixture of dimeric and post-translationally modified monomeric forms. Although the nature of these forms is similar in both groups, the preeclamptic women showed a significant increase in the amount of monomeric proteins with respect to the control group. Since the TTR monomeric forms are the results of different oxidizing reactions, we hypothesize that the higher oxidative stress in preeclampsia is the major destabilizing factor of the TTR functional dimeric form in the preeclamptic women.
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