Assessment of the in vivo biomechanical properties of the human uterine cervix in pregnancy using the aspiration test A feasibility study

Department of Obstetrics and Gynecology, Medical University Graz, Graz, Austria.
European journal of obstetrics, gynecology, and reproductive biology (Impact Factor: 1.7). 04/2009; 144 Suppl 1:S77-81. DOI: 10.1016/j.ejogrb.2009.02.025
Source: PubMed

ABSTRACT To date no diagnostic tool is yet available to objectively assess the in vivo biomechanical properties of the uterine cervix during gestation.
We show the first clinical application of an aspiration device to assess the in vivo biomechanical properties of the cervix in pregnancy with the aim to describe the physiological biomechanical changes throughout gestation in order to eventually detect pregnant women at risk for cervical insufficiency (CI).
Out of 15 aspiration measurements, 12 produced valid results. The stiffness values were in the range between 0.013 and 0.068 bar/mm. The results showed a good reproducibility of the aspiration test. In our previous test series on non-pregnant cervices our repetitive measurements showed a standard deviation of >20% compared to <+/-10% to our data on pregnant cervices. Stiffness values are decreasing with gestational age which indicates a progressive softening of cervical tissue towards the end of pregnancy. Three pregnant women had two subsequent measurements within a time interval of four weeks. Decreasing stiffness values in the range of 20% were recorded.
This preliminary study on the clinical practicability of aspiration tests showed promising results in terms of reproducibility (reliability) and clinical use (feasibility). Ongoing studies will provide further insights on its usefulness in clinical practice and in the detection of substantial changes of the cervix in pregnancy indicative for threatened preterm birth or cervical insufficiency.

Download full-text


Available from: Mahmood Jabareen, Sep 18, 2014
1 Follower
32 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In normal pregnancy, the cervix maintains its shape during a period of substantial fetal and uterine growth. Hence, maintenance of biomechanical integrity is an important aspect of cervical function. It is known that cervical mechanical properties arise from extracellular matrix (ECM). The most important constituent of the cervical ECM is fibrillar collagen-it is collagen protein that the cervix derives its "strength" from. Other matrix molecules known to affect the collagen network include water, proteoglycans, hyaluronan, and elastin. The objective of this review is to discuss relationships between biochemical constituents and macroscopic mechanical properties. The individual constituents of the ECM will be discussed, especially in regard to collagen remodeling during pregnancy. In addition, the macroscopic mechanical properties of cervical tissue will be reviewed. An improved understanding of the biochemistry of cervical "strength" will shed light on how the cervix maintains its shape in normal pregnancy and shortens in preterm birth.
    Seminars in perinatology 10/2009; 33(5):300-7. DOI:10.1053/j.semperi.2009.06.002 · 2.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have characterized the viscoelastic properties of human cervical tissue through a range of precompressional loads and testing frequencies. Mechanical testing is necessary to develop robust elasticity-based techniques for the diagnosis of cervical abnormalities. The storage modulus (E') and material damping (tan 6) were measured in 13 patients, 40 to 76 years old. Our results showed that E' increased monotonically from approximately 4.7 to 6.3 kPa over the precompression range (1-6%) for a testing frequency of 1 Hz. Increases in precompressions of 4% or greater significantly increased E' obtained after dynamic compression testing when data were normalized to 1% precompression. Tan delta remained fairly constant (approximately 0.35) and was not significantly affected by changes in precompression. E' and tan delta increased significantly with frequency. E 'monotonically increased from 4.7 to 7.9 kPa for the 1-3% compression range (lowest precompression for 2% amplitude) and from 6.3 to 10.3 kPa for the 6-8% range (highest precompression for 2% amplitude) when increasing frequency from 1 to 30 Hz. Tan delta increased montonically from 0.35 to 0.45 for 2% amplitude compressions from 1 to 30 Hz regardless of initial precompression. Our results show that precompression and testing frequency must be taken into account in order to obtain consistent measurements in mechanical diagnostic tests developed for cervical abnormalities.
    Ultrasonic Imaging 10/2010; 32(4):214-28. DOI:10.1177/016173461003200402 · 0.91 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Attenuation estimation and imaging in the cervix has been utilized to evaluate the onset of cervical ripening during pregnancy. This feature has also been utilized for the acoustic characterization of leiomyomas and myometrial tissue. In this paper, we present direct narrowband substitution measurement values of the variation in the ultrasonic attenuation coefficient in ex vivo human uterine and cervical tissue, in the 5-10 MHz frequency range. At 5 MHz, the attenuation coefficient values are similar for the different orientations of uterine tissue with values of 4.1-4.2 dB/cm, 5.1 dB/cm for the leiomyoma, and 6.3 dB/cm for the cervix. As the frequency increases, the attenuation coefficient values increase and are also spread out, with a value of approximately 12.6 dB/cm for the uterus (both parallel and perpendicular), 16.0 for the leiomyoma, and 26.8 dB/cm for the cervix at 10 MHz. The attenuation coefficient measured increases monotonically over the frequency range measured following a power law.
    Ultrasonics 05/2011; 51(4):467-71. DOI:10.1016/j.ultras.2010.11.012 · 1.94 Impact Factor
Show more