Dynamics of Cervical Remodeling during Pregnancy and Parturition: Mechanisms and Current Concepts

Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9032, USA.
Seminars in Reproductive Medicine (Impact Factor: 2.35). 02/2007; 25(1):69-79. DOI: 10.1055/s-2006-956777
Source: PubMed


The cervix serves as a protective barrier from invading microorganisms and as a structural barrier to delivery of the fetus. Among all biological processes, the phenomenal connective tissue remodeling that occurs in the cervix during and after parturition is unparalleled in scope and magnitude. The process of connective tissue remodeling in the cervix during pregnancy occurs in four stages: softening, ripening, dilation, and repair. Although overlapping in time, each stage is uniquely regulated. Results from studies using serial measurements of cervical length indicate that cervical ripening precedes myometrial contractions of labor by several weeks, suggesting that parturition in women is a process of long duration and that uterine contractions of labor are late events in the parturition process. A clear understanding of the biologic mechanisms that regulate cervical remodeling during pregnancy is needed to influence the preterm birth rate and to develop strategies to prevent preterm dilation of the cervix.

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    • "The process of cervical remodeling during pregnancy makes attenuation estimates particularly attractive as a non-invasive method to detect tissue changes that reflect early preparation and readiness for labor and birth. The cervix microstructure of collagen content and organization and tissue composition of water and proteoglycan content markedly change during pregnancy (Leppert 1995; Leppert and Yu 1991; Leppert et al. 2000; Word et al. 2007). As the cervix changes from a firm to a supple soft structure, ultrasonic attenuation estimates can provide clinicians with early tissue-based information, rather than waiting for symptoms of preterm birth. "
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    ABSTRACT: The purpose of this study was to determine whether cervical ultrasonic attenuation could identify women at risk of spontaneous preterm birth. During pregnancy, women (n = 67) underwent from one to five transvaginal ultrasonic examinations to estimate cervical ultrasonic attenuation and cervical length. Ultrasonic data were obtained with a Zonare ultrasound system with a 5- to 9-MHz endovaginal transducer and processed offline. Cervical ultrasonic attenuation was lower at 17-21 wk of gestation in the SPTB group (1.02 dB/cm-MHz) than in the full-term birth groups (1.34 dB/cm-MHz) (p = 0.04). Cervical length was shorter (3.16 cm) at 22-26 wk in the SPTB group than in the women delivering full term (3.68 cm) (p = 0.004); cervical attenuation was not significantly different at this time point. These findings suggest that low attenuation may be an additional early cervical marker to identify women at risk for SPTB. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
    Ultrasound in medicine & biology 08/2015; 41(11). DOI:10.1016/j.ultrasmedbio.2015.06.014 · 2.21 Impact Factor
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    • "Collagen breakdown would facilitate a higher degree of movement and stretch in the tissue, which is required for softening. Similarly, an increase in the GAG content of the tissues stimulated by prostaglandin would result in a decrease in collagen fibril agglutination and ultimately would reduce the stretch resistance of the remaining collagen [20]. Elevation of the GAG hyaluronan is a well known change that facilitates the degradation of collagen fibers and can cause further viscoelasticity of the cervix. "
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    ABSTRACT: Objective: To describe the use of cervical inversion for postpartum hemorrhage (PPH) management during cesarean delivery for placenta previa accreta/increta. Methods: In a retrospective, descriptive study, data were reviewed for cases in which cervical inversion was used to manage PPH during cesarean delivery at a center in Zahedan, Iran, between July 2, 2011, and September 25, 2014. Cervical inversion was applied when placental bleeding was persistent and the sites could not be clearly located. The cervix is inverted using ring forceps or straight Allis forceps, after which the placental bed is sutured to control bleeding. After bleeding is controlled, the cervix is returned to its original position. Results: Cervical inversion was successfully applied to 10 cases. Mean time to completion of cervical inversion was 4.1 +/- 0.7 minutes. In all 10 cases, the bleeding was stopped within 3-5 minutes from the beginning of the cervical inversion procedure. No apparent complications were reported, and blood transfusions or obstetric hysterectomies were not necessary. Conclusion: Cervical inversion is a simple, cost-effective, and time-saving procedure for PPH management in placenta previa accreta/increta. It could become a routine procedure for preserving the uterus and fertility of affected women.
    International Journal of Gynecology & Obstetrics 10/2014; 128(2). DOI:10.1016/j.ijgo.2014.08.020 · 1.54 Impact Factor
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    • "Failure of the cervix to relax impedes uterine clearance which leads to inflammation, increased fluid accumulation and adverse effects on fertility. Initiation of cervical relaxation requires synergistic and coordinated actions of inflammatory mediators including interleukin-8 (IL-8), prostaglandin E (PGE), inducible nitric oxide synthase (iNOS) and extracellular matrix metalloproteases (MMPs) (Word et al. 2007; Kelly 2002; Denison et al. 1999). Prostaglandin E, in particular, semi-selectively targets the cervix through vasoactive actions (Kelly 2002). "
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    ABSTRACT: ContentsMares who have not delivered a foal early in life may experience limitations in cervical relaxation, primarily during oestrus. A closed cervix prevents intrauterine deposition of semen during natural breeding, may delay uterine clearance after insemination leading to intrauterine fluid accumulation in, and subsequent infertility. Therefore, a reliable pharmacological method of dilating the equine cervix would have practical application in veterinary medicine. The goal of this study was to investigate the effectiveness of topically applied, synthetic prostaglandin E1 analogue (PGE1) for stimulating dilation of the equine cervix. Ten mares in dioestrus were randomly assigned to one of two treatments in a single-blind crossover study: (treatment) PGE1 gel (1000 mcg compounded misoprostol cream) applied topically to the external cervical os (n = 5), and (control) a vehicle cream applied topically to the external cervical os (n = 5). Transrectal palpation and ultrasonographic measurements of the cervix were performed prior to, six and 24 h post-treatment. Digital measurements were taken, per vagina, at six and 24 h post-treatment. Mares were monitored through the subsequent oestrous cycle for ovulation. Mares were assigned to the opposite treatment group such that each mare served as her own control (crossover). Data were analysed using parametric (split-plot anova), as well as nonparametric (Kruskal–Wallis anova, Wilcoxon's rank-sum test) methods. At six and 24 h there were no significant differences for tone, length, height, degree of relaxation or echotexture between control and PGE1 treated groups at the measured time points (p > 0.05). Topical cervical application of PGE1 did not induce a measurable degree of cervical relaxation under the conditions of this experiment.
    Reproduction in Domestic Animals 10/2014; 49(6). DOI:10.1111/rda.12435 · 1.52 Impact Factor
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