Mechanical behavior of the uterine cervix during pregnancy
The occurrence of cervical ripening before 34 weeks of gestation leading to preterm delivery represents a serious problem. Thus, the assessment of the mechanical properties of the cervix is an important diagnostic procedure in obstetrics. In daily practice digital palpation is used to determine consistence, effacement, dilatation and position of the cervix and is complemented by endovaginal ultrasound to describe the morphology of the organ. The predictive power of current methods however is low.
Recently, we applied our in vivo aspiration experiment to evaluate the biomechanical function of the cervix. In a preliminary study (Medical University Graz, [11p, 12p]) measurements were conducted on post-menopausal subjects before vaginal/abdominal hysterectomy. The currently ongoing clinical study (at the Department of Obstetrics, University Hospital of Zurich) aims at quantifying the mechanical response of normal cervical tissue at different gestational ages. A new version of the aspiration device was developed for this purpose.
Measurements were taken between 21 and 36 weeks of gestation. The response of the cervix observed so far in this study is considerably softer as compared to [12p]. Decreasing values of cervical stiffness with gestational age were observed, showing a progressive softening cervical tissue towards the end of pregnancy, [19p]. An important result of the current study is the confirmation of the absolute harmlessness of the proposed procedure. This, in fact, represents the pre-requisite for future clinical investigations in which the aspiration experiment will be performed on pregnant subjects with risk of pre-term delivery, so to eventually assess the clinical relevance of this technique for diagnosis.
Mahmood Jabareen, Technion Haifa, Israel
Michael Bajka, Laila Sultan, Roland Zimmermann, University Hospital Zurich
Margit Bauer, Medical University Graz
Gerhard Holzapfel, TU Graz