Changes in cervical elastography, cervical length and endocervical canal width after cerclage for cervical insufficiency: an observational ultrasound study.

BACKGROUND: We previously demonstrated that pregnant women with a history of cervical insufficiency had a softer anterior cervical lip, shorter cervical length and wider endocervical canal in the first trimester. The aim of this study was to investigate changes in cervical elastography, cervical length, and endocervical canal width in the second trimester after cerclage, and further discuss whether these ultrasound parameters are predictive of preterm delivery. METHODS: This was a secondary analysis of cervical changes in singleton pregnancies after cerclage from January 2016 to June 2018. Cervical elastography, cervical length, and endocervical canal width were measured during the second trimester in the cervical insufficiency group and control group without cervical insufficiency. Strain elastography under transvaginal ultrasound was used to assess cervical stiffness and presented as percentage (strain rate). RESULTS: Among the 339 pregnant women enrolled, 24 had a history of cervical insufficiency and underwent cerclage. Both anterior and posterior cervical lips were significantly softer in the cervical insufficiency group even though they received cerclage (anterior strain rate: 0.18 ± 0.06% vs. 0.13 ± 0.04%; P = 0.001; posterior strain rate: 0.11 ± 0.03% vs. 0.09 ± 0.04%; P = 0.017). Cervical length was also shorter in the cervical insufficiency group (36.3 ± 3.6 mm vs. 38.3 ± 4.6 mm; P = 0.047). However, there was no significant difference in endocervical canal width between the two groups (5.4 ± 0.7 mm vs. 5.6 ± 0.7 mm; P = 0.159). Multivariate logistic regression analysis also revealed significant differences in anterior cervical lip strain rate (adjusted odds ratio [OR], 7.32, 95% confidence interval [CI], 1.70-31.41; P = 0.007), posterior cervical lip strain rate (adjusted OR, 5.22, 95% CI, 1.42-19.18; P = 0.013), and cervical length (adjusted OR, 3.17, 95% CI,1.08-9.29; P = 0.035). Among the four ultrasound parameters, softer anterior cervical lip (P = 0.024) and shorter cervical length (P < 0.001) were significantly related to preterm delivery. CONCLUSIONS: Cervical cerclage can prevent widening of the endocervical canal, but not improve cervical elasticity or cervical length. Measuring anterior cervical elastography and cervical length may be valuable to predict preterm delivery.

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.

Use of cervical elastography at 18 to 22 weeks' gestation in the prediction of spontaneous preterm birth.

BACKGROUND: Accurate identification of the women who will have spontaneous preterm birth continues to be a great challenge. The use of cervical elastography for prediction of preterm birth is promising, but several limitations exist. Newer cervical elastography technology has been developed that may prove useful in evaluation of risk of preterm birth. OBJECTIVE: This study aimed to develop standard cervical elastography nomograms for singleton pregnancies at 18 to 22 weeks' gestation using the E-Cervix ultrasound application, assess intraobserver reliability of the E-Cervix elastography parameters, and determine whether these cervical elastography measurements can be used in the prediction of spontaneous preterm birth. STUDY DESIGN: This was a prospective cohort study of pregnant women undergoing cervical length screening assessment via transvaginal ultrasound examination at 18 to 22 weeks' gestation. A semiautomatic, cervical elastography application (E-Cervix) was used during the transvaginal examination to calculate 5 quantitative parameters (internal os stiffness, external os stiffness, internal -to -external os stiffness ratio, hardness ratio, and elasticity contrast index) and create a standard nomogram for each one of them. The intraobserver reliability was calculated using Shrout-Fleiss reliability. Cervical elastography parameters were compared between those who delivered preterm (<37 weeks) spontaneously and those who delivered full term. A multivariable logistic regression model was performed to determine the ability of the cervical elastography parameters to predict spontaneous preterm birth. RESULTS: A total of 742 women were included, of which 49 (6.6%) had a spontaneous preterm delivery. A standard nomogram was created for each of the cervical elastography parameters from those who had a full-term birth in the index pregnancy (n=693). Intraobserver reliability was good or excellent (intraclass correlation, 0.757-0.887) for each of the cervical elastography parameters except external os stiffness which was poor (intraclass correlation, 0.441). In univariate analysis, none of the cervical elastography parameters were associated with a statistically significant increased risk of spontaneous preterm birth. In a multivariable model adjusting for history of preterm birth, gravidity, ethnicity, cervical cerclage, and vaginal progesterone use, increasing elasticity contrast index was significantly associated with an increased risk of spontaneous preterm birth (odds ratio, 1.15; 95% confidence interval, 1.02-1.30; P=.02). CONCLUSION: Cervical elastography parameters are reliably measured and are stable across 18 to 22 weeks' gestation. Based on our findings, the elasticity contrast index was associated with an increased risk of spontaneous preterm birth and may be a useful parameter for future research.

Cervical elastography in predicting spontaneous preterm birth in singleton pregnancy with a short cervix receiving progesterone treatment at 18 to 24 weeks' gestation.

BACKGROUND: A short cervix in the second trimester is known to increase the risk of preterm birth, which can be reduced with the administration of vaginal progesterone. However, some studies have suggested that a significant number of cases still experience preterm birth despite progesterone treatment. OBJECTIVE: This study was aimed to investigate the potential value of transvaginal cervical elasticity measured by E-Cervix as a predictor for spontaneous preterm birth (sPTB) in singleton pregnancies receiving progesterone treatment for a short cervix (CL ≤ 2.5 cm) diagnosed at 18 to 24 weeks' gestation. STUDY DESIGN: This prospective study was conducted at a single center premature high-risk clinic from January 2020 to July 2022. Singleton pregnancies with a short cervix at 18 to 24 weeks' gestation were enrolled. Cervical elastography using E-Cervix was performed, and maternal and neonatal demographic characteristics, cervical length (CL), elasticity contrast index (ECI), cervical hardness ratio, mean internal os strain (IOS), and mean external os strain (EOS) were compared before and after progesterone treatment in sPTB and term birth groups. Multivariate logistic regression was used to analyze the association between elasticity parameters and spontaneous preterm birth. The screening performance of CL and optimal cervical elasticity parameters in predicting sPTB was evaluated using receiver-operating characteristic (ROC) curve analysis. RESULTS: A total of 228 singleton pregnant women were included in the study, among which 26 (11.4%) had sPTB. There were no significant differences in maternal characteristics and gestational age at enrollment between women with and without sPTB. At the start of progesterone treatment, there were no significant differences in cervical elasticity parameters between the two groups. After two weeks of progesterone treatment, women who had sPTB showed significantly higher levels of ECI, IOS, EOS (p = 0.0108, 0.0001, 0.016), and lower hardness ratio (p = 0.011) compared to those who had a full-term birth. Cervical length did not show significant differences between the two groups, regardless of whether progesterone treatment was administered before or after. Among the post-treatment cervical elasticity parameters, IOS and EOS were associated with a 3.38-fold and 2.29-fold increase in the risk of sPTB before 37 weeks (p = 0.032, 0.047, respectively). The AUROC of the combined model including CL, IOS, and EOS (0.761, 95% CI0.589-0.833) was significantly higher than the AUROC of CL alone (0.618, 95% CI 0.359-0.876). At a fixed false-positive of 13%, the addition of IOS and EOS in the CL model increased sensitivity from 34.6% to 57.6%, PPV from 25.7% to 36.5%, and NPV from 91.1% to 94.1%. CONCLUSION: When assessing the risk of sPTB in singleton pregnancies with a short cervix receiving progesterone therapy, relying solely on cervical length is insufficient. It is crucial to also evaluate cervical stiffness, particularly the strain of the internal and external os, using cervical elastography.

Reliability of the sonographic evaluation for cervical length and elastography with pelvic parameters in term pregnancy by experienced operators with varying levels of experience.

OBJECTIVE: To assess the reliability of sonographic measurements of six cervical and pelvic parameters by three sonographers with varying levels of experience. METHODS: A cross-sectional study was conducted in pregnant women with a gestational age of ≥39 weeks. Each pregnant woman was examined by two sonographers with different levels of experience. Six parameters were measured: cervical length (CL), cervical strain elastography (extrinsic type), posterior cervical angle (PCA), fetal head-to-perineum distance (FHPD), fetal head-to-pubic symphysis distance (FHSD), and angle of progression (AOP). Intra- and interobserver reliabilities were assessed using the intraclass correlation coefficient with a 95% confidence interval. Pearson pairwise correlation coefficients were used to analyze the correlation between the parameter values. RESULTS: In all, 66 pregnant women were enrolled in this study. We found excellent intraobserver reliability for measurements of CL, PCA, FHPD, FHSD, and AOP and good-to-excellent intraobserver reliability for cervical strain values in the cross-sectional view of the endocervix in the internal os area and cross-sectional view of the entire cervix in the internal os area. Interobserver reliability was excellent for all pelvic parameters, except for the FHPD. Strain values were moderate to excellent in the area of the internal os. A significant negative correlation between CL and strain values at the internal os was observed. CONCLUSIONS: Pelvic parameters, except for FHPD, have excellent intra- and interobserver reliabilities. The high reproducibility of CL and cervical strain elastography at the internal os level, with a negative correlation between these two parameters, may play an important role in predicting successful induction of labor.

Quantitative sonoelastography of the uterine cervix in predicting successful outcome of induction of labour.

Objectives: The aim of the study was to evaluate the stiffness of cervix and determine its significance in predicting successful outcome of induction of labour. The primary objective was to determine the differences in elastography indices of different areas of cervix between the outcome groups of successful and failed induction of labour. A secondary objective was to find out the correlation of these elastography indices with Bishop's score and cervical length. Methods: This was a prospective, observational study conducted over a period of 6 months on pregnant women admitted in the labour room for induction of labour. Establishment of adequate regular uterine contractions - at least three contractions lasting 40-45 s in a 10-min period - was taken as end point for successful outcome of induction of labour. Even after 24 h of initiation of induction of labour, regular, adequate and painful uterine contractions were not established, then induction of labour was described as having failed. Prior to induction, cervical length measurement, Bishop's scoring and elastographic evaluation of the cervix were done by stress-strain elastography. A colour map was produced from purple to red and a five-step scale - the elastography index - was used to describe the various parts of the cervix. The differences between elastography indices of different parts of cervix were estimated using Mann-Whitney U test. Correlation of the indices with cervical length and Bishop's score was determined by Spearman's correlation coefficient. Results: A total of 64 women were included in the study. A significant difference (p < 0.001) was found in the elastography index of internal os between the two outcome groups of success (1.76 ± 0.64) and failure (0.54 ± 0.18). However, the elastography index of central cervical canal, external os, anterior lip and posterior lips did not differ significantly across the outcome groups. A significant positive correlation was found between elastography index of internal os and cervical length (Spearman's correlation coefficient, r = 0.441, p < 0.001) and between elastography index of external os and cervical length (r = 0.347, p = 0.005), whereas a negative correlation was seen between elastography index of external os and Bishop's score (r = -0.270, p = 0.031). Conclusion: Elastography index of internal os can be used to predict outcome of induction of labour. Cervical elastography is a promising new technique for cervical consistency assessment. Further larger studies are required to determine some cut-off point for elastography index of internal os in prediction of outcome of induction of labour and to strongly establish the usefulness of cervical elastography for pregnancy management, preventing preterm delivery and establishment of cut-off points to determine successful induction.

Cervical elastography during pregnancy: a critical review of current approaches with a focus on controversies and limitations.

In normal pregnancy, the cervix functions as a protective mechanical barrier that must remain tight and closed. Premature remodeling and consecutive shortening occur in many cases of spontaneous preterm birth. Although the complex underlying physiology of normal and abnormal cervical remodeling is not fully understood, it is clear that cervical softening occurs prior to delivery, and inappropriate timing seems to be associated with preterm delivery. Also, degree of cervical softness is a component of the Bishop score currently used clinically to predict successful induction of labor. Therefore, the assessment of changes in cervical stiffness with ultrasound elastography techniques might be useful in the prediction of preterm delivery or successful induction of labor. Two different approaches for cervical elastography for quantitative determination of the physical properties of the pregnant cervix have been developed: strain elastography and shear wave elastography. Recently, several feasibility studies showed the reliability of these cervical elastography techniques for the prediction of preterm delivery and successful labor induction. In this review, we contrast strain elastography, which determines only relative values of tissue stiffness because the applied transducer pressure is unknown, with shear wave elastography, which provides, in principle at least, a more objective description of tissue softness. While more promising preliminary results involving these approaches to assessing cervical softness have been recently published, current limitations in technical implementation need to be addressed before elastography techniques will become clinically useful. We discuss these limitations and present challenges for future studies and equipment development.

Quantitative cervical elastography during pregnancy: influence of setting features on strain calculation.

AIM: To evaluate the influence on feasibility and reliability of quantitative tissue Doppler imaging (TDI)-based cervical elastography of the cycle phase and of the derivative pitch (DP) selected during tissue strain (TS) calculation across all three trimesters of pregnancy. MATERIALS AND METHODS: The pilot study included 17 patients collected between the 12th and the 42nd week of gestation. The TS was measured by a single operator by quantitative elastography. The influence of DP values (5, 10, 15, and 20 mm) and phase (compression versus relaxation) was tested after a cycle of freehand compression and relaxation of the cervix through the vaginal probe. Feasibility and intra-operator intraclass correlation coefficient (ICC) agreement for strain measurement were also evaluated for every setting used. RESULTS: TS values were inversely correlated with DP and were slightly higher if measured during a compression phase. TDI-based cervical elastography was feasible in all cases. Reliability for the process of strain calculation of different raw datasets was very good (ICC agreement ranging between 0.79 and 0.87), while excellent considering the same raw dataset (ICC agreement ranging between 0.93 and 0.95). CONCLUSIONS: The DP and cycle phase influenced the strain values calculated. Nonetheless, TDI-based cervical elastography was feasible and reliable for all the settings considered.

Measuring cervical strain with tissue Doppler imaging depending on the shape and placement of the region of interest and its correlation with cervical consistency index.

OBJECTIVES: We want to evaluate tissue Doppler imaging (TDI) for measuring cervical strain. We compare three different methods for measuring strain depending on the region of interest (ROI) placement and evaluate patient discomfort. We correlate the strain measured through TDI with cervical consistency index (CCI), cervical length and width of both cervical lips. STUDY DESIGN: This is a prospective study in 30 singleton primigravida pregnancies without obstetrical risks between 40+0 and 41+3 weeks of gestation. The CCI was calculated according to Parra-Saavedra et al. We tested three methods of measuring cervical elasticity depending on shape and location of ROIs. RESULTS: The CCI ranged between 36.4% and 71.9% with an average of 50.78%. The CCI shows negative correlation with strain and no correlation with cervical length or with the width of either cervical lip. The strain measurements regardless of tested method were reproducible and independent on cervical length. The average strain was higher in outer cervical regions. The ROIs placed on the anterior lip had higher reproducibility than those placed on the posterior lip. The average score for patient discomfort during examination was 3.7/10. CONCLUSION: The strain depends on the size and location of ROIs. The circular ROIs with diameter equal to the width of the cervical lip are recommended. There is a correlation between CCI and TDI. The cervix shows heterogeneous consistency with increased stiffness from the outer to the inner sections. The TDI seems to be an easy to learn, quickly to perform, acceptable and reproducible method for measuring cervical elasticity. There is room for optimization and refinement of measuring methods before being tested for clinical significance.