Subscribe to RSS
DOI: 10.1055/s-0036-1592905
Cervical softening occurs early in pregnancy: characterization of cervical stiffness using the aspiration technique
Introduction: During pregnancy the cervix remains firm and closed. At term, the cervix must allow delivery, which requires it to soften, shorten and dilate. Critical problems occur when the timing and extent of the mechanical changes are altered. The objective of our research is to quantitatively describe the changes in cervical stiffness and the relation to cervical length in normal pregnancy, and thus contribute to a better understanding of cervical insufficiency.
Material and methods: A device has been developed at ETH Zurich to measure cervical stiffness using the aspiration method. The probe is vaginally positioned on the cervix. The device then applies a weak vacuum and measures the negative pressure necessary for a controlled displacement of the cervical tissue. This maximal negative pressure (pcl) is directly proportional to cervical stiffness. Cervical length was assessed according to the standard procedure.
Results: Aspiration and ultrasound measurements were carried out on pregnant women (n = 50) at each routine consultation and on non-pregnant subjects (n = 50). Stiffness in the first trimester is significantly lower than for the non-pregnant group, by a factor > 2 for the mean value. pcl continuously decreases during gestation, with significant differences between first and second trimester. In contrast, cervical length only decreased in the third trimester.
Conclusion: The aspiration method allows to measure cervical stiffness during pregnancy, indicating that the cervix softens before it shortens. A multi-center study is currently ongoing to evaluate the usefulness of the cervical stiffness parameter for prediction of the risk for preterm birth.