Cervical collagen is reduced in non-pregnant women with a history of cervical insufficiency and a short cervix

Cervical length of preoperative cervical cerclage prognostic impacted the effect of cervical insufficiency

BACKGROUND

This study aimed to analyze the impact of preoperative cervical length before cervical cerclage on the extension of gestational days in patients with various diagnostic types of cervical insufficiency, including obstetric history-based diagnosis, ultrasound-based diagnosis, and physical examination-based diagnosis.

METHODS

168 patients were segregated into four categories based on cervical length: 0-0.4 cm, 0.5-1.4 cm, 1.5-2.4 cm, and ≥ 2.5 cm. Kaplan-Meier, linear regression curve and Cox regression analyses were used, with a focus on clinical variables, particularly cervical length and the duration of extension after cervical cerclage.

RESULTS

The length of the cervix prior to cervical cerclage correlated with the prognosis of 168 postoperative patients by linear regression analysis. When delivery beyond 28 or 34 weeks was set as the primary prognostic indicator, univariate Cox analysis showed that postoperative C-reactive protein (CRP) level was identified as a risk factor for gestational age extension in cervical cerclage patients. Longer cervical length was identified as a protective factor for overall gestational age extension in cervical cerclage patients. In addition, the obstetrical-history diagnosis group had a better prognosis compared to the emergency cerclage group, which had a worse prognosis compared to the ultrasound-based diagnosis group. Kaplan-Meier curve analysis of all patients revealed a statistically significant impact of different cervical lengths on the gestational age of delivery (P < 0.001). However, in the physical examination-based diagnosis group, Kaplan-Meier curve analysis demonstrated a statistically significant impact of different cervical lengths on gestational age at delivery (P = 0.006).

CONCLUSION

Longer preoperative cervical length was associated with better outcomes in terms of gestational prolongation and newborn survival after cervical cerclage.

Trajectory of Postpartum Cervical Remodeling in Women Delivering Full-Term and Spontaneous Preterm: Sensitivity to Quantitative Ultrasound Biomarkers

OBJECTIVE

Women with a history of spontaneous preterm birth (sPTB) face an increased risk of recurrence. Yet, the factors contributing to the increased risk are unknown, hampering the development of targeted interventions. Noninvasive quantitative ultrasound (QUS) has been validated in the characterization of cervical tissue and has the potential to provide information about postpartum cervical remodeling. The objective of this study was to determine the postpartum cervical remodeling trajectories of women over 12 mo post-delivery and to determine whether there were differences between women who delivered full-term and spontaneous preterm that were sensitive to QUS biomarkers.

METHODS

Data were collected prospectively from 55 women: 41 who delivered full-term and 14 who delivered spontaneously preterm at 6 wk, 3, 6, 9 and 12 mo (±2 wk) postpartum. Data from QUS biomarkers: Attenuation Coefficient; Backscatter Coefficient; Shear Wave Speed; and Lizzi-Feleppa Slope, Intercept and Midband were analyzed from the acquired radiofrequency data using a Siemens S2000 ultrasound system with a transvaginal MC 9-4 MHz probe. The biomarkers were analyzed using descriptive statistics and linear mixed-effects models.

RESULTS

QUS biomarkers, Backscatter Coefficient and Lizzi-Feleppa Intercept showed significant differences during the year after delivery between women who had a full-term birth and sPTB (p < 0.05), suggesting that there are differences in the cervical remodeling trajectories between the two groups. All QUS biomarkers demonstrated significant variations between the full-term birth and sPTB groups over time (p < 0.05), indicating ongoing cervical remodeling for both groups during the 12-mo postpartum period.

CONCLUSION

QUS biomarkers identified cervical microstructure differences and trajectories in the year after delivery between women who delivered full-term and spontaneous preterm.

Genetic Polymorphisms of COL1A1 Promoter Region (rs1800012) and TGFB1 Signal Peptide (rs1800471): Role in Cervical Insufficiency Susceptibility?

A structural or functional cervix problem prevents a woman from carrying a full-term pregnancy, which leads to the disease known as cervical insufficiency. Cervical insufficiency is partially inherited, and in certain situations, variations in genes related to connective tissue metabolism may be involved. The main objective of this investigation was to describe the collagen type I alpha 1 chain (COL1A1) gene rs1800012 polymorphism and the transforming growth factor beta 1 (TGFB1) gene rs1800471 polymorphism in a cohort of patients suffering from cervical insufficiency. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays have been used to analyze the DNAs of 93 patients with cervical insufficiency and 103 healthy controls. The chi-square test was used for statistical analysis. There were significant differences in the genotype frequencies of the COL1A1 gene rs1800012 (G > T) and TGFB1 gene rs1800471 (G > C) polymorphisms between the patient and the control groups (p = 0.049 and p = 0.049, respectively). Also, the C allele of the TGFB1 rs1800471 polymorphism was significantly higher in the patient group than the control group (p = 0.016). Following clinical assessment, the COL1A1 rs1800012 polymorphism was found to be connected to the history of cerclage (p = 0.010). Additionally, the frequency of the TT/GG composite genotype of COL1A1 rs1800012/TGFB1 rs1800471 polymorphisms was significantly lower in the patient group than the control group (p = 0.049). The TT genotype of COL1A1 rs1800012 polymorphism was found to be protective against cervical insufficiency, while the C allele of TGFB1 rs1800471 polymorphism was found to predispose to the disease. It appears that the TT/GG composite genotype of COL1A1 rs1800012/TGFB1 rs1800471 polymorphisms protects against cervical insufficiency.

Systems biology approach: identification of hub genes, signaling pathways, and molecular docking of COL1A1 gene in cervical insufficiency

The collagen type I alpha 1 (COL1A1, OMIM #120,150) gene, encoding the alpha-1 chain of type I collagen (UniProt #P02452), plays a key role in life-homeostasis due to its remarkable involvement in collagen synthesis. It is a promising candidate gene implicated in the pathogenesis of cervical insufficiency (CI). This study aimed to identify genetic variations within the COL1A1 gene that contribute to the development of CI. Polymerase chain reaction (PCR) and amplicon sequencing were implemented for single nucleotide polymorphisms (SNPs) detection (+ 1245G/T, SP1 rs1800012), which revealed wild-type sequence for targeted SNPs in enrolled proband indicated negative results regarding COL1A1 gene involvement for current form of CI. It allows further investigation of other closely connected genes probed in this study. Computational approaches viz. Protein-protein interaction (PPI), gene ontology (GO), and pathway participation were used to identify the crucial hub genes and signaling pathways for COL1A1 and CI. Using the Yet Another Scientific Artificial Reality Application (YASARA) software, molecular docking, and molecular dynamic (MD) simulation with the oxytocin (CID 439,302), estradiol (CID 129,728,744), progesterone (CID 5994) and hydroxyprogesterone (CID 150,788) were done. Interactive bioinformatics analysis demonstrated that the COL1A1 and more than 10 collagen sister genes had a strong connection with CI. In sum, the findings of this study provide insights into a modus operandi that can be utilized to illuminate the path toward studying sister genes and smooth diagnosis of CI. These findings have implications for understanding the foundational process of the condition and potentially developing screening, diagnostic, and therapeutic interventions.

Graphical Abstract

Effect of different surgical routes on pregnancy outcome of history-indicated cervical cerclage

OBJECTIVE

To study the guiding significance of medical history on laparoscopic and vaginal cervical cerclage in the treatment of cervical incompetence and its influence on pregnancy outcome.

METHODS

A total of 53 cases by laparoscopic abdominal cervical cerclage (LAC group) before pregnancy and 73 cases by transvaginal cervix cerclage (TVC group) at 12-14 weeks of pregnancy were collected. Multivariate logistic regression analysis was performed on the influencing factors of delivery gestational weeks. Furthermore, the gestational weeks after cervical cerclage were compared between the two groups with high- and low-risk grades.

RESULTS

The number of previous uterine cavity operations in LAC group was more than that TVC group, and the costs of operation were more than TVC group. At the same time, the hospitalization days and operation time were longer than those in TVC group, and the delivery rate of cesarean section was higher than TVC group, but the total hospitalization times were less than TVC group (P < 0.05). The rate of delivery before 34 weeks of pregnancy and the incidence of premature rupture of membranes or premature labor in LAC group were lower than those in TVC group (P < 0.05). In TVC group, the increased number of prior PTB or STL and the history of cervical cerclage failure would increase the risk of premature delivery before 34 weeks of pregnancy. There was no increased risk of preterm delivery before 34 weeks of pregnancy in LAC group (P > 0.05). According to the risk level, in the high-risk group, the delivery rate of LAC group at gestational weeks < 37 weeks, < 34 weeks and < 28 weeks was lower than that of TVC group.

CONCLUSION

Laparoscopic cervical cerclage might be more effective in preventing premature delivery before 34 weeks of gestation, and its influence on delivery gestational weeks was not affected by related medical history. For high-risk patients with the history of prior PTB or STL and failed cerclage, laparoscopic cervical cerclage might be more effective than vaginal cervical cerclage in preventing extremely preterm before 28 weeks, premature delivery before 34 weeks and premature delivery before 37 weeks. Therefore, our limited experience suggested that LAC can be a recommended option for patients with high-risk history.

Quantitative strain elastography of the uterine cervix assessed by the GE Voluson E10 system in combination with a force-measuring device

OBJECTIVE

During pregnancy, the stiffness of the cervical tissue decreases long before the cervical length decreases. Therefore, several approaches have been proposed in order to ensure a more objective assessment of cervical stiffness than that achieved by digital evaluation. Strain elastography has shown promising results. This technique is based on an ultrasound assessment of the tissue deformation that occurs when the examiner applies pressure on the tissue with the ultrasound probe. However, the results are only semi-quantitative as they depend on the unmeasured force used by the examiner. We, therefore, hypothesized that a force-measuring device applied to the handle of the ultrasound probe may render the technique quantitative. With this approach, the stiffness is the force (measured by the device) divided by the compression (measured by the elastography platform). One perspective is the early identification of women at risk of preterm birth in whom cervical stiffness may decrease long before cervical shortening. Another perspective is cervical evaluation when planning labor induction. In this feasibility study, we aimed to evaluate how quantitative strain elastography performs when a commercially available strain elastography platform (by which the algorithm is unavailable) is combined with a custom-made, force-measuring device. We studied how the assessments were associated with the gestational age in women with uncomplicated pregnancies and how they were associated with cervical dilatation time from 4 to 10 cm in women undergoing labor induction.

METHODS

In the analysis, we included quantitative strain elastography assessments from 47 women with uncomplicated singleton pregnancies, with gestational age between 12⁺⁰ and 40⁺⁰, and from 27 singleton term-pregnant women undergoing labor induction. The force-measuring device was mounted on the handle of a transvaginal probe. The strain values (i.e. the compression of the cervical tissue) were obtained by the elastography software of the ultrasound scanner (GE Voluson E10). The region of interest was placed within the central part of the anterior cervical lip. Based on the force data and strain values, we calculated the outcomes cervical elastography index_GE (CEI_GE) and the cervical strength index_GE (CEI_GE x cervical length: CSI_GE).

RESULTS

The average CEI_GE was 0.24 N at week 12 and 0.15 N at week 30-34. For CSI_GE these figures were 8.2 and 4.7 N mm, respectively (p = 0.002). Among women undergoing labor induction, the CEI_GE was associated with a cervical dilatation time (4-10 cm) beyond 7 h. For nulliparous women, this area under the ROC curve was 0.94.

CONCLUSION

Quantitative strain elastography may constitute a tool for the evaluation of a uterine cervix with normal length in women at risk of preterm birth and in women undergoing labor induction. The performance of this tool deserves evaluation in larger clinical trials.

Nomogram based on the final antepartum ultrasound features before delivery for predicting failed spontaneous vaginal delivery in nulliparous women

Background

Accurate identification of nulliparous women with failed spontaneous vaginal delivery (SVD) is crucial to minimize the hazards associated with obstetrical intervention (OI). While abnormal labor progression can be identified with intrapartum ultrasonography, labor-related complications may be unavoidable due to the limited time window left to the obstetrician. Antepartum ultrasound enables sufficient obstetric planning. However, there is typically a longer gap between ultrasound assessment and delivery that often lowers the prediction accuracy compared to intrapartum ultrasonography.

Objective

In this study, antepartum ultrasound assessment was included to each fetal ultrasound examination after 36 weeks of gestation until the onset of labor. We aim to establish a nomogram to predict the likelihood of failed SVD in nulliparous women using the last antepartum ultrasound findings before labor beginning.

Methods

Of the 2,143 nulliparous women recruited, 1,373 were included in a training cohort and 770 in a validation cohort, based on their delivery date. Maternal and perinatal characteristics, as well as perinatal ultrasound parameters were collected. In the training cohort, the screened correlates of SVD failure were used to develop a nomogram for determining whether a nulliparous woman would experience SVD failure. This model was validated in both training and validation cohorts.

Results

SVD failure affected 217 nulliparous women (10.13%). In the training cohort, SVD failure was independently associated with BMI [odds ratio (OR) = 1.636], FHC (OR = 1.194), CL (OR = 1.398), and PCA (OR = 0.824) (all P < 0.05). They constituted a nomogram to estimate the individual risk of SVD failure. The model obtained clinical net benefits in both the training and validation cohorts and was validated to present strong discrimination and calibration.

Conclusion

The developed nomogram based on the last antepartum ultrasound findings may be helpful in avoiding OI and its related complications by assessing the likelihood of a failed SVD in nulliparous women.

The effect of cold-knife conization on pregnancy outcomes in patients with cervical lesions

OBJECTIVE

To analyze the pregnancy outcomes of patients with cervical lesions treated by cold-knife conization (CKC).

METHODS

Clinical data of healthy pregnant women and pregnant women who underwent CKC in Dalian Women and Children's Medical Group from March 2010 to December 2019 were retrospectively analyzed. These patients were divided into a CKC group and a control group according to inclusion and exclusion criteria. Statistical methods were used to compare pregnancy and delivery outcomes between the two groups.

RESULTS

There were 400 patients in CKC group and control group, with 200 patients in each. There was no significant difference in the mode of delivery, abortion, ectopic pregnancy, in-hospital perinatal management, and cervical cerclage between the CKC group and the control group (P>0.05). The rates of preterm delivery, premature rupture of membranes, cesarean section, and neonatal admission in the CKC group were higher than those in the control group (P<0.05). In the CKC group, the incidence of premature rupture of membranes within six months postoperatively was higher than that after six months (P<0.05). The incidences of preterm delivery and premature rupture of membranes were not completely consistent in different conization ranges (P<0.05).

CONCLUSION

CKC increases the incidence of preterm delivery, premature rupture of membranes, and neonatal adverse outcomes. Conization height can predict the occurrence of preterm delivery. Delaying pregnancy after surgery can reduce the incidence of adverse outcomes during the perinatal period.

A force-measuring device combined with ultrasound-based elastography for assessment of the uterine cervix

INTRODUCTION

In this feasibility study, we hypothesize that the evaluation of cervical biomechanical strength can be improved if cervical length measurement is supplemented with quantitative elastography, which is a technique based on conventional ultrasound elastography combined with a force-measuring device. Our aims were to: (a) develop a force-measuring device; (b) introduce a cervical elastography index (CEI) and a cervical strength index (CSI; defined as cervical length × CEI); (c) evaluate how these indexes assess the cervical softening that takes place during normal pregnancy; and (d) how these indexes predict the cervical dilatation time from 4 to 10 cm.

MATERIAL AND METHODS

An electronic force-measuring device was mounted on the handle of the transvaginal probe, allowing for force measurement when conducting elastography. The study group concerned with normal cervical softening included 44 unselected pregnant women. Outcomes were CEI and CSI at different gestational ages. The study group for labor induction included 26 singleton term pregnant women admitted for labor induction. Outcome was defined as cervical dilatation time from 4 to 10 cm. Elastography measured the changes in mean gray value (intensity) during manual compressions. Region of interest was set within the anterior cervical lip.

RESULTS

We found that the mean of all variables regarding cervical softening decreased from early to late pregnancy: ie cervical length from 34 to 29 mm, CEI from 0.17 to 0.11 N, and CSI from 5.9 to 3.1 N mm. Moreover, the cervical dilatation time during labor induction was associated with CEI, although not statistically significantly (area under the ROC curve of 0.67), but not with the Bishop score, the cervical length, or the CSI.

CONCLUSIONS

We propose that quantitative elastography based on changes in the intensity of the B-mode ultrasound recording, in combination with a force-measuring device on the handle of the vaginal probe, deserves further investigation as an approach for evaluation of cervical biomechanical strength.

Breaking Down the Barrier: The Role of Cervical Infection and Inflammation in Preterm Birth

Approximately 40% of cases of spontaneous preterm birth (sPTB) are associated with ascending intrauterine infections. The cervix serves as a physical and immunological gatekeeper, preventing the ascent of microorganisms from the vagina to the amniotic cavity. The cervix undergoes remodeling during pregnancy. It remains firm and closed from the start until the late third trimester of pregnancy and then dilates and effaces to accommodate the passage of the fetus during delivery. Remodeling proceeds appropriately and timely to maintain the pregnancy until term delivery. However, risk factors, such as acute and chronic infection and local inflammation in the cervix, may compromise cervical integrity and result in premature remodeling, predisposing to sPTB. Previous clinical studies have established bacterial (i.e., chlamydia, gonorrhea, mycoplasma, etc.) and viral infections (i.e., herpesviruses and human papillomaviruses) as risk factors of PTB. However, the exact mechanism leading to PTB is still unknown. This review focuses on: (1) the epidemiology of cervical infections in pregnant patients; (2) cellular mechanisms that may explain the association of cervical infections to premature cervical ripening and PTB; (3) endogenous defense mechanisms of the cervix that protect the uterine cavity from infection and inflammation; and (4) potential inflammatory biomarkers associated with cervical infection that can serve as prognostic markers for premature cervical ripening and PTB. This review will provide mechanistic insights on cervical functions to assist in managing cervical infections during pregnancy.

The Value of Posterior Cervical Angle as a Predictor of Vaginal Delivery: A Preliminary Study

Accurate prediction of failure to progress and rapid decision making regarding the mode of delivery can improve pregnancy outcomes. We examined the value of sonographic cervical markers in the prediction of successful vaginal delivery beyond 34 weeks of gestation. A retrospective chart review was carried out. Medical information of singleton gestations delivered at a single center from 1 July 2019 to 30 August 2020 was collected. Transvaginal sonographic records of cervical length, anterior and posterior cervical angles, and cervical dilatation were obtained and re-measured. The value of these markers and clinical characteristics of mother and baby on vaginal delivery were investigated and compared to women who underwent cesarean section. A total of 90 women met the inclusion criteria. The rate of vaginal delivery was 75.6%. There were no differences found in terms of maternal age, rate of abortion, induction of labor, premature rupture of membranes, preterm labor, hypertension, diabetes, cervical length, and neonatal sex and weight. The prediction of vaginal delivery was provided by parity, maternal body mass index, and posterior cervical angle. The area under the receiver operating characteristic curve for prediction of vaginal delivery was 0.667 (95% CI 0.581–0.864, p = 0.017) for the posterior cervical angle, with a cutoff of 96.5°. Regression analysis revealed a posterior cervical angle ≥96.5° in the prediction of vaginal delivery (adjusted odds ratio: 6.24; 95% confidence interval: 1.925–20.230, p = 0.002). Posterior cervical angle ≥96.5° is associated with successful vaginal delivery. It is simple and easy to measure and can be useful in determining the mode of delivery.

Cross talk: Trafficking and functional impact of maternal exosomes at the Feto-maternal Interface under normal and pathologic states

Fetal cell-derived exosomes promote inflammation in uterine and cervical cells to promote labor and delivery. However, the effect of maternal exosomes on fetal cells is still not known. We tested the hypothesis that cervical cells exposed to infectious and oxidative stress (OS) signals produce exosomes that can induce inflammation at the feto-maternal interface (FMi). Exosomes isolated from medium samples from human ectocervical epithelial cells (Ecto), endocervical epithelial cells (Endo), and cervical stromal cells (Stroma) in normal cell culture (control) or exposed to infection or OS conditions were characterized based on morphology, size, quantity, expression of tetraspanin markers, and cargo proteins. Human decidual, chorion trophoblast (CTC), chorion mesenchymal (CMC), amnion mesenchymal (AMC), and amnion epithelial cells (AEC) were treated with control, LPS-, or OS-treated cervical exosomes. ELISA for pro-inflammatory cytokines and progesterone was done to determine the recipient cells' inflammatory status. Ecto, endo, and stroma released ∼110 nm, cup-shaped exosomes. LPS and OS treatments did not affect exosome size; however, OS significantly increased the number of exosomes released by all cervical cells. Cervical exosomes were detected by fluorescence microscopy in each target cell after treatment. Exosomes from LPS- and CSE-treated cervical cells increased the inflammatory cytokine levels in the decidual cells, CMC, AMC, and AEC. LPS-treated stromal cell exosomes increased IL-6, IL-8, and progesterone in CTC. In conclusion, infection and OS can produce inflammatory cargo-enriched cervical exosomes that can destabilize FMi cells. However, the refractoriness of CTC to exosome treatments suggests a barrier function of the chorion at the FMi.

Extracellular Matrix Rigidity Modulates Human Cervical Smooth Muscle Contractility-New Insights into Premature Cervical Failure and Spontaneous Preterm Birth

Spontaneous preterm birth (sPTB), a major cause of infant morbidity and mortality, must involve premature cervical softening/dilation for a preterm vaginal delivery to occur. Yet, the mechanism behind premature cervical softening/dilation in humans remains unclear. We previously reported the non-pregnant human cervix contains considerably more cervical smooth muscle cells (CSMC) than historically appreciated and the CSMC organization resembles a sphincter. We hypothesize that premature cervical dilation leading to sPTB may be due to (1) an inherent CSMC contractility defect resulting in sphincter failure and/or (2) altered cervical extracellular matrix (ECM) rigidity which influences CSMC contractility. To test these hypotheses, we utilized immunohistochemistry to confirm this CSMC phenotype persists in the human pregnant cervix and then assessed in vitro arrays of contractility (F:G actin ratios, PDMS pillar arrays) using primary CSMC from pregnant women with and without premature cervical failure (PCF). We show that CSMC from pregnant women with PCF do not have an inherent CSMC contractility defect but that CSMC exhibit decreased contractility when exposed to soft ECM. Given this finding, we used UPLC-ESI-MS/MS to evaluate collagen cross-link profiles in the cervical tissue from non-pregnant women with and without PCF and found that women with PCF have decreased collagen cross-link maturity ratios, which correlates to softer cervical tissue. These findings suggest having soft cervical ECM may lead to decreased CSMC contractile tone and a predisposition to sphincter laxity that contributes to sPTB. Further studies are needed to explore the interaction between cervical ECM properties and CSMC cellular behavior when investigating the pathophysiology of sPTB.

The association between operative hysteroscopy prior to assisted reproductive technology and cervical insufficiency in second trimester

PURPOSE

To assess the association between operative hysteroscopy prior to assisted reproductive technology (ART) cycle and cervical insufficiency (CI) in the second trimester of pregnancy.

METHODS

A retrospective cohort study was conducted. The charts of all women who got pregnant following an ART cycle between January 2015 and June 2018 were reviewed. The study group consisted of pregnant women who underwent operative hysteroscopy within 6 months before conception. The control group consisted of pregnant women who did not undergo hysteroscopy or any type of cervical surgical procedure before conception. The primary outcome measure was CI during the second trimester (13-27 weeks of gestation).

RESULTS

A total of 363 pregnancies achieved by ART cycles were assessed. After the exclusion of multiple pregnancies (n = 19), previous surgical procedures (n = 4) and first-trimester pregnancy losses (n = 80), there were 29 women in the study group and 231 women in the control group. The mean ages of the study and control groups were 31.2 ± 4.06 and 29.82 ± 4.71 years, respectively (P = 0.13). The indications for operative hysteroscopy were uterine septum (n = 19), T-shaped uterus (n = 4), endometrial polyp (n = 4), and submucosal fibroids (n = 2). The rates of CI in the study and control groups were 13.7% (4/29) and 3.4% (8/231), respectively (P = 0.012). The term delivery rates in the study and control groups were 79.3 and 91.8%, respectively (P = 0.044).

CONCLUSIONS

Operative hysteroscopy prior to ART cycles is significantly associated with CI between 13 and 27 weeks of gestation. Further investigation with larger cohorts is urgently needed to clarify this issue.

<p>The Comparative Study of Cervical Shear Wave Elastography Between Twin and Singleton Pregnancy</p>

Objective

To compare the cervical shear wave elastography (SWE) by using transvaginal ultrasound (TVS) between twin and singleton pregnant women.

Materials and Methods

This was a prospective cohort study involving the twin and singleton pregnant women who attended the antenatal care at Ramathibodi Hospital, Bangkok, Thailand. The participants who met the inclusion criteria were serially measured the shear wave speed (SWS) by using TVS at early, mid-, and third trimester. The changes in SWS with advancing gestational age between twin and singleton pregnancies were evaluated. The gestational age at delivery and spontaneous preterm delivery rate were also analyzed.

Results

A total of 36 twin pregnancies and 38 singleton pregnancies were analyzed. No significant difference in baseline characteristics, except the age of participants (twin pregnancies 33.1±4.6 years, singleton pregnancies 29.9±5.4 years, p-value = 0.006) was observed. The cervical SWS decreased with advancing gestational age in both twin and singleton pregnancy, but there was a statistically significant difference of cervical SWS at the lower point in mid-trimester (twin pregnancies 2.27±0.4, singleton pregnancies 2.71±0.6 m/s, p-value = 0.001). However, no significant difference in cervical SWS at the upper point and the lower point in the early and third trimester was demonstrated. Even though the gestational age at delivery between both groups revealed a significant difference (twin pregnancies 35.9±2.8, singleton pregnancies 37.6±2.9 wk., p-value = 0.008) but the spontaneous preterm delivery rate did not differ significantly (twin pregnancies 22.2%, singleton pregnancies 15.8%, p-value = 0.483).

Conclusion

The mid-trimester cervical SWS measurement at the lower point detects the difference in cervical softness between twin pregnancies and singleton pregnancies. The cervical SWS might be an additional option for monitoring the change in cervical softness in twin pregnancies.

Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.

Cervical Gene Delivery of the Antimicrobial Peptide, Human β-Defensin (HBD)-3, in a Mouse Model of Ascending Infection-Related Preterm Birth

Approximately 40% of preterm births are preceded by microbial invasion of the intrauterine space; ascent from the vagina being the most common pathway. Within the cervical canal, antimicrobial peptides and proteins (AMPs) are important components of the cervical barrier which help to prevent ascending vaginal infection. We investigated whether expression of the AMP, human β-defensin-3 (HBD3), in the cervical mucosa of pregnant mice could prevent bacterial ascent from the vagina into the uterine cavity. An adeno-associated virus vector containing both the HBD3 gene and GFP transgene (AAV8 HBD3.GFP) or control AAV8 GFP, was administered intravaginally into E13.5 pregnant mice. Ascending infection was induced at E16.5 using bioluminescent Escherichia coli (E. coli K1 A192PP-lux2). Bioluminescence imaging showed bacterial ascent into the uterine cavity, inflammatory events that led to premature delivery and a reduction in pups born alive, compared with uninfected controls. Interestingly, a significant reduction in uterine bioluminescence in the AAV8 HBD3.GFP-treated mice was observed 24 h post-E. coli infection, compared to AAV8 GFP treated mice, signifying reduced bacterial ascent in AAV8 HBD3.GFP-treated mice. Furthermore, there was a significant increase in the number of living pups in AAV HBD3.GFP-treated mice. We propose that HBD3 may be a potential candidate for augmenting cervical innate immunity to prevent ascending infection-related preterm birth and its associated neonatal consequences.

Assessment of Uterocervical Angle Width as a Predictive Factor of Preterm Birth: A Systematic Review of the Literature

Background

Uterocervical angle (UCA) has been recently proposed as a potential marker that could accurately predict preterm birth (PTB). The purpose of the present systematic review is to accumulate current evidence and provide directions for future research.

Materials and Methods

We used the Medline (1966–2018), Scopus (2004–2018), Clinicaltrials.gov (2008–2018), EMBASE (1980-2018), Cochrane Central Register of Controlled Trials CENTRAL (1999-2018), and Google Scholar (2004-2018) databases in our search.

Results

Eleven studies were finally included in the present systematic review that evaluated data from 3,018 women. The significant heterogeneity in terms of outcome reporting and outcome reporting measures (use of optimal cut-off values) precluded meta-analysis. However, existing data support that second trimester UCA measurement might be used as a predictive factor of PTB <34 weeks, as at least two studies in unselected singleton pregnancies and two studies in pregnancies with an ultrasonographically shortened cervix seem to support this hypothesis. The most commonly reported cut-off values were 105° and 95°.

Conclusions

UCA measurement during the second trimester of pregnancy may be a useful method of determining women at risk of delivering preterm. However, more studies are needed to assess the reproducibility of these findings and reach conclusive evidence.

A soft cervix, categorized by shear-wave elastography, in women with short or with normal cervical length at 18-24 weeks is associated with a higher prevalence of spontaneous preterm delivery

OBJECTIVE

To determine whether a soft cervix identified by shear-wave elastography between 18 and 24 weeks of gestation is associated with increased frequency of spontaneous preterm delivery (sPTD).

MATERIALS AND METHODS

This prospective cohort study included 628 consecutive women with a singleton pregnancy. Cervical length (mm) and softness [shear-wave speed: (SWS) meters per second (m/s)] of the internal cervical os were measured at 18-24 weeks of gestation. Frequency of sPTD <37 (sPTD<37) and <34 (sPTD<34) weeks of gestation was compared among women with and without a short (≤25 mm) and/or a soft cervix (SWS <25th percentile).

RESULTS

There were 31/628 (4.9%) sPTD<37 and 12/628 (1.9%) sPTD<34 deliveries. The combination of a soft and a short cervix increased the risk of sPTD<37 by 18-fold [relative risk (RR) 18.0 (95% confidence interval [CI], 7.7-43.9); P<0.0001] and the risk of sPTD<34 by 120-fold [RR 120.0 (95% CI 12.3-1009.9); P<0.0001] compared to women with normal cervical length. A soft-only cervix increased the risk of sPTD<37 by 4.5-fold [RR 4.5 (95% CI 2.1-9.8); P=0.0002] and of sPTD<34 by 21-fold [RR 21.0 (95% CI 2.6-169.3); P=0.0003] compared to a non-soft cervix.

CONCLUSIONS

A soft cervix at 18-24 weeks of gestation increases the risk of sPTD <37 and <34 weeks of gestation independently of cervical length.

Cervical alterations in pregnancy

Spontaneous preterm birth (SPTB), defined as delivery before 37 weeks' gestation, remains a significant obstetric dilemma even after decades of research in this field. Although trends from 2007 to 2014 showed the rate of preterm birth slightly decreased, the CDC recently reported the rate of preterm birth has increased for two consecutive years since 2014. Currently, 1 in 10 pregnancies in the US still end prematurely. In this chapter, we focus on the "compartment" of the cervix. The goal is to outline the current knowledge of normal cervical structure and function in pregnancy and the current knowledge of how the cervix malfunctions lead to SPTB. We review the mechanisms by which our current interventions are hypothesized to work. Finally, we outline gaps in knowledge and future research directions that may lead to novel and effective interventions to prevent premature cervical failure and SPTB.

The pathophysiology of human premature cervical remodeling resulting in spontaneous preterm birth: Where are we now?

Approximately one in ten (approximately 500,000) pregnancies results in preterm birth (PTB) annually in the United States. Although we have seen a slight decrease in the U.S. PTB rate between 2007 and 2014, data from 2014 to 2015 shows the preterm birth rate has slightly increased. It is even more intriguing to note that the rate of PTB has not significantly decreased since the 1980s. In order to decrease the rate of spontaneous preterm birth (sPTB), it is imperative that we improve our understanding of normal and abnormal reproductive tissue structure and function and how these tissues interact with each other at a cellular and biochemical level. Since other chapters in this issue will be focusing on the myometrium and fetal membranes, the goal of this chapter is to focus on the compartment of the cervix. We will review the current literature on normal and abnormal human cervical tissue remodeling and identify gaps in knowledge. Our goal is also to introduce a revised paradigm of normal cervical tissue structure and function which will provide novel research opportunities that may ultimately lead to developing safe and effective interventions to significantly decrease the rate and complications of prematurity.