Fetal adrenal gland biometry and cervical elastography as predictors of preterm birth: A comparative study

Evaluating the Efficacy of Cervical Tactile Ultrasound Technique as a Predictive Tool for Spontaneous Preterm Birth

Background

Premature cervical softening and shortening may be considered an early mechanical failure that predispose to preterm birth.

Purpose

This study aims to explore the applicability of an innovative cervical tactile ultrasound approach for predicting spontaneous preterm birth (sPTB).

Materials and Methods

Eligible participants were women with low-risk singleton pregnancies in their second trimester, enrolled in this prospective observational study. A Cervix Monitor (CM) device was designed with a vaginal probe comprising four tactile sensors and a single ultrasound transducer operating at 5 MHz. The probe enabled the application of controllable pressure to the external cervical surface, facilitating the acquisition of stress-strain data from both anterior and posterior cervical sectors. Gestational age at delivery was recorded and compared against cervical elasticity.

Results

CM examination data were analyzed for 127 women at 240/7 - 286/7 gestational weeks. sPTB was observed in 6.3% of the cases. The preterm group exhibited a lower average cervical stress-to-strain ratio (elasticity) of 0.70 ± 0.26 kPa/mm compared to the term group's 1.63 ± 0.65 kPa/mm with a p-value of 1.1 × 10-4. Diagnostic accuracy for predicting spontaneous preterm birth based solely on cervical elasticity data was found to be 95.0% (95% CI, 88.5 - 100.0).

Conclusion

These findings suggest that measuring cervical elasticity with the designed tactile ultrasound probe has the potential to predict spontaneous preterm birth in a cost-effective manner.

Association between Fetal Adrenal Gland Ultrasound Measurements in the 9th Month and Mode of Delivery

OBJECTIVE

Several studies have previously assessed the value of changes in the fetal adrenal gland to predict preterm labor. The aim of this study is to evaluate the correlation between fetal adrenal gland measurements after 36 weeks and obstetrical outcomes.

METHODS

Abdominal two-dimensional (2D) ultrasound is used to measure in the transversal plane the length of fetal zone (D1), the width (D2), and the length (D3) of fetal adrenal gland, and, subsequently, the fetal zone enlargement (FZE), in 98 primigravida women after 36 weeks. Labor and delivery outcomes were assessed and compared with these measurements.

RESULTS

FZE changes had no association with spontaneous onset of labor. No association was found between all adrenal gland measurements and delivery onset. There was a significant relationship between D1, D2, and D3 and the delivery method. Patients delivered by cesarean section had smaller fetal adrenal gland dimensions, defining D1= 0.16 cm, D2 = 0.7 cm, and D3 = 2.37 cm as cutoff levels based on receiver operator characteristics curves.

CONCLUSION

The 2D measurement of the fetal adrenal gland after 36 weeks seems to predict the delivery method in low-risk primigravida women.

KEY POINTS

· We evaluate fetal adrenal gland measurements after 36 weeks versus the obstetrical outcome.. · No association was found between all adrenal gland measurements and delivery onset.. · Patients delivered by cesarean section had smaller fetal adrenal gland dimensions..

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.

Diagnostic accuracy of cervical elastography for predicting preterm delivery: Systematic review and meta-analysis

OBJECTIVE

Cervical elastography has been used in pregnant women to diagnose preterm births. However, there is a variability in the measured elasticity parameters and imaging mode used. We evaluated the precision of cervical elastography in identifying preterm births.

METHODS

Extensive and methodical searches were made in the databases such as Scopus, Embase, Cochrane Library, PubMed Central, Medline, ScienceDirect, and Google Scholar from the inception until November 2022, for studies that report diagnostic accuracy of cervical elastography for preterm deliveries in antenatal women.

RESULTS

The pooled sensitivity and specificity value of cervical elastography for preterm deliveries were 82% (95%CI: 73%-89%) and 77% (95%CI: 64%-86%), respectively with area under curve (AUC) of 0.87 (95%CI: 0.72-0.95). The diagnostic odds ratio (DOR) was 15 (95%CI: 8-28), positive likelihood ratio (LRP) was 3.5 (95%CI: 2.3-5.5) and negative likelihood ratio LRN was 0.23 (0.16-0.34). Pooled sensitivity and specificity of shear wave elastography was 88% and 71%, respectively. Pooled sensitivity and specificity of strain elastography was 80% and 79%, respectively. Heterogeneity was significant, as indicated by chi-square test and an I2 statistic of over 75.

CONCLUSIONS

Cervical elastography can be used for predicting preterm deliveries with moderate to high level of accuracy.

Evaluation of the stiffness of normal cervix and its change with different factors using transvaginal two-dimensional shear wave elastography under strict quality control

BACKGROUND

The usefulness of transvaginal two-dimensional shear wave elastography (2D SWE) for cervical lesions is still uncertain. This study was to explore the value of transvaginal 2D SWE in the evaluation of the stiffness of normal cervix and its change with different factors under strict quality control (QC).

METHODS

Two hundred patients with normal cervix were included in this study and were examined using quantitative 2D SWE to evaluate cervical stiffness and its change with different factors under strict QC.

RESULTS

Intra-observer concordance of transvaginal 2D SWE parameters in midsagittal planes were acceptable with intraclass correlation coefficients higher than 0.5. Transvaginal 2D SWE parameters were significantly higher than the corresponding transabdominal parameters. 2D SWE parameters of internal cervical os were significantly higher than the corresponding parameters of external cervical os in a transvaginal midsagittal plane. 2D SWE parameters of external cervical os increased significantly over 50 years old, while these parameters of internal cervical os didn't change significantly with increasing age. 2D SWE parameters of internal cervical os of horizontal position cervix were significantly higher than those of vertical position cervix. SWE parameters of normal cervix did not change according to different menstrual cycles, parities and human papilloma virus test results.

CONCLUSIONS

Transvaginal 2D SWE under strict QC could provide quantitative, repeatable and reliable cervical stiffness information. Internal cervical os was stiffer than external cervical os. Menstrual cycles, parities and human papilloma virus test results wouldn't affect cervical stiffness. However, age and cervical positions should be taken into condition while interpreting 2D SWE results of cervical stiffness.

The importance of fetal adrenal gland volume measurement in successful labor induction with oxytocin

AIM

We aimed to show the predictive value of fetal adrenal gland volume (FAGV) measurement in the success of labor induction with oxytocin.

METHODS

This is a prospective cohort study that included a total of 103 term nulliparous. Immediately after deciding to induce labor with oxytocin, the fetal right and left adrenal gland measurements were obtained.

RESULTS

Induction success was achieved in 89 of 103 (86.4%) pregnant women. In comparison of the FAGV values of failed induction labor group, the total volumes of right and left fetal adrenal glands and the fetal zone volumes (FZV) were found to be statistically significantly higher in the successful labor induction group (p < 0.001). In predicting induction success, the cut-off value of fetal adrenal gland volume (cFAGV) was set as >230.2 mm³ /kg and area under curve (AUC) value of 0.872 (95% confidence interval [CI], 0.736-1.000) for right total adrenal gland (p < 0.001). The cut-off value of cFAGV was set as >236.7 mm³ /kg and AUC value of 0.891(95%CI, 0.768-1.000) (p < 0.001) for left total adrenal gland. The cut-off value of cFAGV was set as >12.6 mm³ /kg and AUC value of 0.952 (95%CI, 0.905-0.999) for right FZV(p < 0.001). The cut-off value of cFAGV was set as >7.8 mm³ /kg and AUC value of 0.884 (95%CI, 0.752-1.000) for left FZV (p < 0.001).

CONCLUSIONS

Two-dimension ultrasonographic measurement is an easy-to-access and noninvasive method that can be integrated into the algorithms to predict the success of induction based on FAGV measurement.

Second-Trimester Cervical Shear Wave Elastography Combined With Cervical Length for the Prediction of Spontaneous Preterm Birth

The goal of this study was to explore the value of shear wave elastography (SWE) combined with cervical length (CL) in the prediction of spontaneous preterm birth (sPTB) between 18 and 24 weeks of gestation. In this study, SWE was used to evaluate four regions of the cervix: the external and anterior lip (region A1), the external and posterior lip (region A2), the internal and anterior lip (region A3) and the internal and posterior lip (region A4). The cervical Young's modulus (YM) was compared between women who spontaneously delivered prematurely (<37 wk) and those who delivered full term. Finally, the predictive power of SWE was evaluated using receiver operating characteristic analysis. Overall, 773 patients were included in this study, of whom 60 (7.8%) had a sPTB. In the univariate analysis, prior sPTB, history of spontaneous abortion, history of cervical surgery, CL and YM at the anterior portion of both the internal and external os and the posterior portion of the internal os were associated with sPTB (p < 0.05). Multiple regression analyses were performed to develop the prediction probability for sPTB. YM and CL were independent predictors of sPTB in asymptomatic women, and the combination of YM and CL improved the ability to predict sPTB (area under the receiver operating characteristic curve = 0.98, 95% confidence interval: 0.97-0.99, p < 0.001). The interventions had relatively little impact on the outcome indicators measured. Cervical YM added to the CL may improve the predictive performance of second-trimester transvaginal ultrasound for sPTB.

Screening for spontaneous preterm birth by cervical length and shear-wave elastography in the first trimester of pregnancy

BACKGROUND

First-trimester cervical length for the prediction of spontaneous preterm delivery remains controversial. A better method for the measurement of the first-trimester cervical length and additional cervical ultrasound parameters for the identification of women at high risk for spontaneous preterm delivery are needed.

OBJECTIVE

This study aimed to compare the predictive value of cervical length measured by 2 different methods in the first trimester of pregnancy to predict spontaneous preterm delivery and to explore the potential value of first-trimester cervical shear-wave elastography for the prediction of spontaneous preterm delivery.

STUDY DESIGN

This was a prospective study in unselected singleton pregnancies at 11⁺⁰ to 13⁺⁶ weeks' gestation. Cervical length was measured by the following 2 methods in the base-cohort population: (1) a linear distance between the 2 ends of the glandular area around the endocervical canal (single-line method: cervical length-s) and (2) a sum of the linear distance from the internal os to the greatest cervical curvature and the linear distance from this point to the external os (2-line method: cervical length-t). In a substudy, cervical shear-wave elastography scores for 9 regions of interest (inner, middle, and external parts of anterior lip, endocervical canal, and posterior lip) in midsagittal plane were also obtained by transvaginal ultrasonography. The screening performance of the first-trimester cervical length measured by the 2 different methods for the prediction of spontaneous preterm delivery was assessed by receiver operating characteristics curve analysis. The areas under the curves were compared using a DeLong test. The predictive performance of a soft cervix (mean elastography scores with multiple of median <5th, 10th, 15th, 20th, and 25th percentile) for spontaneous preterm delivery was also determined.

RESULTS

Among a total of 2316 included pregnancies, spontaneous delivery at <37 and <34 weeks' gestation occurred in 111 cases (4.8%) and 20 cases (0.9%), respectively. In the total study population, when compared with the term delivery group, the median cervical length-t was shorter in women with spontaneous delivery at <34 weeks' gestation (36.9 mm vs 35.1 mm; P=.015), but there was no clear correlation for cervical length-s. Receiver operating characteristics curves demonstrated that cervical length-t achieved better performance in predicting spontaneous delivery at <34 weeks' gestation (area under the curve, 0.658 vs 0.573; P<.01) than cervical length-s. The best combined model to predict spontaneous delivery at <34 weeks' gestation was provided by cervical length-t and history of preterm delivery (area under the curve, 0.692). In the substudy, a soft cervix with a mean elastography scores multiple of median <10th percentile had a relative risk of 7.8 (95% confidence interval, 2.1-28.6) for spontaneous delivery at <34 weeks' gestation; the detection rate was 44.4% at a false-positive rate of 9.0%.

CONCLUSION

The 2-line approach provides a better estimate of the actual first-trimester cervical length and achieves better performance as a screening tool for spontaneous preterm delivery at <34 weeks' gestation than the conventional measurement. A soft cervix as determined by shear-wave elastograpthy in the first trimester is associated with an increased risk for subsequent spontaneous preterm delivery.

Predictive value of cervical length by ultrasound and cervical strain elastography in labor induction at term

OBJECTIVE

This study aimed to examine whether addition of cervical elastographic parameters measured by ElastoScan for the cervix (E-cervix) improves the predictive value of cervical length (CL) in induction of labor at term by dinoprostone.

METHODS

We conducted a prospective, observational study between January 2020 and June 2020 in term primiparous women (n = 73) who were scheduled for labor induction by a 10-mg dinoprostone vaginal insert. The time intervals from the start of labor induction to regular uterine contractions and to vaginal delivery were calculated as the primary outcomes. We divided subjects into two groups using a threshold of 24 hours. Ultrasound measurements were compared between the two groups and the area under the curve (AUC) of the prediction model was calculated.

RESULTS

Women who delivered vaginally within 24 hours had a shorter CL and softer cervix than those who delivered after 24 hours. The combination of CL and elastographic parameters increased the AUC to 0.672 compared with CL alone (AUC = 0.637).

CONCLUSIONS

Measurement by E-cervix is relatively reproducible. Addition of cervical strain elastography slightly improves the predictive performance of CL in vaginal delivery within 24 hours. This technique is a promising ancillary tool for use with ultrasound.

Use of shear wave elastography on the maternal cervix to recognise cervical insufficiency using a transabdominal ultrasound approach

INTRODUCTION

The ramifications of preterm birth on society and the role of cervical length in identifying cervical insufficiency are well known. The main goal of this work was to apply shear wave elastography to the maternal cervix to assess the stiffness of the cervix and identify cervical insufficiency, using a transabdominal ultrasound approach.

METHODS

Measurements of shear wave speed were obtained using a transabdominal ultrasound approach, at the anterior and posterior portions of the internal and external cervical os on 504 participants. A total of 455 participants were contacted following the expected date of birth of the fetus and birth details were obtained.

RESULTS

The anterior and posterior portions of the internal os showed a significant correlation between shear wave speed and time until delivery of the fetus for women who gave birth spontaneously, with R 2 Linear being 0.024 (P = 0.012) and 0.017 (P = 0.05) respectively, and these correlations increased for the group of participants that were scanned between the 18th and end of the 20th week of pregnancy to R 2 Linear = 0.043 (P = 0.001) and 0.021 (P = 0.040) respectively. A ratio of internal os/external os anteriorly also showed a correlation of R 2 Linear = 0.030 (P = 0.009).

CONCLUSION

A transabdominal ultrasound technique has identified a reduction in shear wave speeds at the internal os in the mid-trimester, in women who had a subsequent preterm birth.

Shear Wave Elastography of the Maternal Cervix: A Comparison of Transvaginal and Transabdominal Ultrasound Approaches

OBJECTIVES

This work aimed to compare the use of shear wave elastography on the maternal cervix with transvaginal (TV) and transabdominal (TA) ultrasound approaches to assess differences in shear wave speeds (SWSs) obtained for possible clinical use.

METHODS

In both TV and TA ultrasound approaches, SWS measurements were attempted at the anterior and posterior portions of the internal and external cervical os on 38 gravid participants.

RESULTS

A larger number of SWS measurements were obtained at the anterior portion of the cervix by both approaches. The numbers of reliable measurements of the SWS obtained at the anterior and posterior portions of the internal and external os were 99, 65, 103, and 77 in the TA approach and 93, 53, 110, and 87 in the TV approach, respectively. The mean difference in -the SWS obtained between the TV and TA ultrasound approaches was statistically significant at the anterior and posterior portions of the internal os, with differences of 0.67 and 0.52 m/s (P < .05). Differences were not significant at the external os both anteriorly and posteriorly, with differences of 0.15 and - 0.07 m/s (P > .05).

CONCLUSIONS

Both TA and TV ultrasound approaches may be used to obtain SWSs in the maternal cervix. This study has shown that SWSs obtained by each approach need to be considered independently, as the TV approach produced significantly greater SWSs at the internal os compared to the TA approach, but the values were similar at the external os.

Uterocervical Angle and Cervical Length as a Tool to Predict Preterm Birth in Threatened Preterm Labor

Objective

To evaluate the diagnostic performance of uterocervical angle (UCA) and UCA with cervical length (CL) in predicting preterm delivery in threatened preterm labor.

Methods

A multicenter prospective observational cohort study was conducted in 160 pregnant women having threatened preterm labor at Srinagarind and Udonthani Hospitals in Thailand between March 2019 and June 2020. Researchers measured UCA and CL by transvaginal ultrasonography. Medical records were reviewed for patient characteristics, and patients were followed up until the date of delivery to assess for the outcome of preterm birth. The cut-off point of UCA was determined from receiver operating characteristic curve analysis. The sensitivity, specificity, likelihood ratio, positive and negative predictive values (PPV and NPV) of UCA and of UCA with CL for predicting preterm birth were determined.

Results

The incidence of preterm birth in women having threatened preterm labor was 27%. The sensitivity, specificity, PPV and NPV of UCA ≥110.97 degrees for predicting preterm birth were 65.1%, 43.6%, 29.8% and 77.3%, respectively. The sensitivity, specificity, PPV and NPV of UCA ≥110.97 degrees with CL <3.4 centimeters for predicting preterm birth were 48.8%, 68.4%, 36.2% and 78.4%. The specificity and NPV of UCA with CL were higher than for UCA alone.

Conclusion

With adequate sensitivity and high NPV, UCA by TVS can be supplemented with CL measurement in threatened preterm labor management to increase the diagnostic performance for predicting preterm birth.

Relationship between cervical elastography and spontaneous onset of labor

Cervical elastography might be an objective method for evaluating cervical ripening during pregnancy, but its usefulness has not been fully investigated. We examined the significance of cervical elastography in the last trimester of pregnancy. Cervical elastography was performed at weekly checkups after 36 weeks of gestation in 238 cases delivered at our hospital from 2017 to 2018. The correlation with the onset time of natural labor, which is an index for judging maternal delivery preparation status, was examined. A total of 765 examinations were conducted, and cervical stiffness determined by cervical elastography was positively correlated with the Bishop score (r = 0.46, p < 0.0001). When examined separately for each week, only the examinations performed at 39 weeks were associated with the onset of spontaneous labor up to 7 days later (p = 0.0004). Furthermore, when stratified and analyzed by the Bishop score at 39 weeks of gestation, cervical elastography was associated with the occurrence of spontaneous labor pain for up to seven days in the groups with Bishop scores of 3–5 and 6–8 (p = 0.0007 and p = 0.03, respectively). In conclusion, cervical elastography at 39 weeks of pregnancy is useful for judging the delivery time.

Longitudinal adrenal gland measurements and growth trajectories as risk markers for late preterm delivery

BACKGROUND

The fetal adrenal gland receives rising awareness as a predictor of spontaneous preterm birth. We hereby provide longitudinal growth assessments of the fetal adrenal gland in a low risk population with an additional focus on trajectories in fetuses born preterm.

METHODS

Fetal adrenal gland was assessed via transabdominal ultrasound at gestational weeks (gw) 24-26, 28-30, and 34-36 in a low-risk pregnancy cohort. Longitudinal trajectories of the total gland and the mark (so called fetal zone) as well as ratio of fetal zone width/ total widths (w/W) were analyzed using repeated ANOVA analyses. To compare trajectories of the ratio w/W for preterm and term fetuses respectively, as well as women with and without clinical signs of preterm labor, the propensity score method was applied.

RESULTS

Fetal zone width increased over the course of pregnancy (p < 0.0001), while the ratio w/W decreased (p < 0.0001) (n = 327). Comparing the trajectories of the ratio w/W in fetuses born preterm (n = 11) with propensity-score matched term born fetuses (n = 22), a decrease between gw 24-26 and 28-30 was observed in both groups, which continued to decrease for the term born fetuses. However, in preterm born fetuses, the ratio increased above the term born values at gw 34-36.

CONCLUSION

Our study provides for the first time longitudinal growth data on the fetal adrenal gland and supports the hypothesis that fetal zone enlargement is associated with preterm birth which could play an important role in risk-prediction.

Role of placenta accreta index in prediction of morbidly adherent placenta: A reliability study

Objective

To estimate the level of interobserver agreement in the calculation of placenta accreta index (PAI) as well as to evaluate the accuracy of PAI in prediction of morbidly adherent placenta.

Materials and methods

This was a prospective study where 45 pregnant women (from 28 to 37 weeks of gestational age) with at least one previous Caesarean section and ultrasound-proven placenta previa were included. A known and previously published scoring system, the PAI, was evaluated independently by two radiologists and the cases were followed for the delivery and histopathology outcome. The accuracy of the PAI and the level of interrater agreement was analysed using cross-table analysis, intraclass correlation efficient and Cohen's kappa as statistical variables.

Results

Adherent placenta was found in 15 patients accounting for 33% of cases. The PAI showed nearly 90% sensitivity, specificity and the predictive values. Interrater agreement in calculation of PAI by the two radiologists was perfect with an intraclass correlation efficient of 0.959. An easy-to-use morbid adherent placenta score was also predicted to simplify the results of PAI, which showed moderate agreement (κ = 0.746).

Conclusions

The PAI can be helpful in stratifying the individual risk of placental invasion above the baseline risk. The PAI-derived, simplified scoring system called morbid adherent placenta score can be used as a simple tool to interpret and convey the results of PAI.

Shear wave elastography of the uterine cervix under different conditions with inter-operator agreement analysis

Purpose

Shear wave elastography (SWE) is a relatively new technique for measuring tissue elasticity. Its implementation for assessing the tissue of the cervix is evolving, and SWE analyses of healthy, nonpregnant cervixes is the first step in understanding other SWE changes related to cervical pathologies; nevertheless, some challenges in the use of the technique still require investigation. We aimed to target the consistency of healthy cervix shear wave elastography measurements and examine the changes induced by patient-related factors.

Material and methods

Elastograms were obtained at the internal and external os in the anterior (IA, EA) and posterior (IP, EP) portions of the cervix using a transvaginal approach in eight postmenopausal and 25 premenopausal women. Measurements with a standard deviation of over 20% and patients who presented with colour loss or heterogeneity were excluded from the study. Shear wave elastography assessments were performed using a Toshiba Aplio 500 version 6. Statistical significance was defined as a p value less than 0.10, due to the small number of patients.

Results

The mean speeds obtained at the external os on the anterior and posterior aspects was 3.17 ± 0.85 m/s and 3.18 ± 0.84 m/s, respectively, and at the internal os, the results on the anterior and posterior aspects were 3.38 ± 0.73 m/s and 3.53 ± 0.81 m/s, respectively. The difference in speed among all regions was statistically significant (p < 0.05). Fifteen patients were also analysed by a second radiologist with a similar experience level as that of the first. Nine measurements for IP, 13 measurements for IA, 11 measurements for EP, and 15 measurements for EA were performed. The correlation coefficients between the two sets of measurements were 0.46, 0.30, 0.67, and 0.51, respectively. There was no difference in the SWE values with respect to age, parity, and gravidity for any of the regions. The SWE values at the IA, IP, and EA regions between the postmenopausal and premenopausal women were significantly different (p = 0.038, p = 0.059, p = 0.065).

Conclusions

The posterior portion of the internal os is most likely to undergo inaccurate SWE measurement among the different anatomical positions. The correlation between radiologists was found to be different for different locations in the cervix. More studies are needed to determine the SWE values of the healthy cervix and the agreement levels between radiologists.

Cervical Characterization with Tactile-Ultrasound Probe

BACKGROUND

Premature cervical softening and shortening may be considered an early mechanical failure that predisposes to preterm birth. Preliminary clinical studies demonstrate that cervical elastography may be able to quantify this phenomenon and predict spontaneous preterm delivery.

OBJECTIVE

To explore a new approach for cervix elasticity and length measurements with tactile-ultrasound probe.

METHODS

Cervix probe has tactile array and ultrasound transducer designed to apply controllable load to cervix and acquire stress-strain data for calculation of cervical elasticity (Young's modulus) and cervical length for four cervix sectors. Average values, standard deviations, intraclass correlation coefficients and the 95% limits of agreement (Bland-Altman plots) were estimated.

RESULTS

Ten non-pregnant and ten pregnant women were examined with the probe. The study with non-pregnant women demonstrated a reliable acquisition of the tactile signals. The ultrasound signals had a prolonged appearance; identification of the internal os of the cervix in these signals was not reliable. The study with pregnant women with the gestational age of 25.4 ± 2.3 weeks demonstrated reliable data acquisition with real-time visualization of the ultrasound signals. Average values for cervical elasticity and standard deviations of 19.7 ± 15.4 kPa and length of 30.7 ± 6.6 mm were calculated based on two measurements per 4 sectors. Measurement repeatability calculated as intraclass correlation coefficients between two measurements at the same cervix sector on pregnant women was found to be 0.97 for cervical elasticity and 0.93 for the cervical length. The 95% limits of agreement of 1) cervical elasticity were from -22.4% to +14.9%, and 2) cervical length from -13.3% to +16.5%.

CONCLUSIONS

This study demonstrated clinically acceptable measurement performance and reproducibility. The availability of stress-strain data allowed the computation of cervical elasticity and length. This approach has the potential to provide cervical markers to predict spontaneous preterm delivery.

Quantitative Sonoelastographic Assessment of the Normal Uterus Using Shear Wave Elastography: An Initial Experience

OBJECTIVES

To describe the sonoelastographic characteristics of the normal endometrium, myometrium, and cervix and to assess their variability with age and different menstrual phases.

METHODS

A total of 56 women were enrolled in this prospective study, who underwent transvaginal ultrasound examinations, including B-mode imaging and shear wave elastography. The elasticity parameters (in kilopascals) of the normal endometrium, myometrium, and cervix were studied. The variability of the mean elasticity value of the endometrium in different menstrual phases and age groups was analyzed. The variability of the mean elasticity of the cervix across different age groups was also studied.

RESULTS

The mean age of the participants was 40 years (range, 25-69 years). The normal mean elasticity values ± SDs were 25.54 ± 8.56 kPa for the endometrium, 40.24 ± 8.59 kPa for the myometrium, and 18.90 ± 4.22 kPa for the cervix. A mean endometrial-to-myometrial elasticity ratio was calculated, which was found to be 0.65 ± 0.22. There was no significant difference in the mean endometrial elasticity values for women in different menstrual phases (P = .176) or in different age groups (P = .376). There was no significant difference in the mean cervical elasticity with age (P = .192).

CONCLUSIONS

Shear wave elastography is a promising adjunct to ultrasound for the evaluation of the uterus, and the results from this study may provide normal data, which may further help in diagnosing various uterine diseases.

Transvaginal Real-time Shear Wave Elastography in the Diagnosis of Cervical Disease

OBJECTIVES

To explore the value of shear wave elastography in the diagnosis of cervical disease.

METHODS

This work was a retrospective analysis of 246 cases of cervical lesions confirmed by transvaginal conventional ultrasound, shear wave elastography, and a cytologic test. The lesions were divided into 2 groups according to the final pathologic results: a malignant cervical group and a benign cervical group. In addition, the normal cervix was set as the control group.

RESULTS

The maximum and mean shear wave velocity values ± SD were 5.24 ± 1.11 and 4.91 ± 1.12 m/s for the malignant cervical group, 3.93 ± 0.39 and 3.53 ± 0.52 m/s for the benign cervical group, and 3.27 ± 0.31 and 2.86 ± 0.23 m/s for the normal cervix, respectively. The areas under the receiver operating characteristic curves for the maximum and mean shear wave velocity in the differential diagnosis of a normal cervix and benign cervical tumors were 0.909 and 0.878 (both P < .001), whereas in the differential diagnosis of benign and malignant cervical tumors, they were 0.909 and 0.895 (both P < .001).

CONCLUSIONS

Shear wave elastography can quantitatively analyze the elastic characteristics of cervical diseases, help differentially diagnose cervical diseases, accurately determine the extent of tumor invasion, and improve effective clinical staging and treatment.

Quantitative assessment of cervical softening during pregnancy with shear wave elasticity imaging: an in vivo longitudinal study

We report here the results of a longitudinal study of cervix stiffness during pregnancy. Thirty women, ages ranging from 19 to 37 years, were scanned with ultrasound at five time points beginning at their normal first-trimester screening (8-13 weeks) through term pregnancy (nominally 40 week) using a clinical ultrasound imaging system modified with a special ultrasound transducer and system software. The system estimated the shear wave speed (its square proportional to the shear modulus under idealized conditions) in the cervix. We found a constant fractional reduction (about 4% per week) in shear wave speed with increasing gestational age. We also demonstrated a spatial gradient in shear wave speed along the length of the cervix (softest at the distal end). Results were consistent with our previous ex vivo and in vivo work in women. Shear wave elasticity imaging may be a potentially useful clinical tool for objective assessment of cervical softening in pregnancy.

Fetal adrenal gland size and the ability to predict spontaneous term labor

OBJECTIVE

The objective of this study was to evaluate whether ultrasound measured fetal adrenal gland size can be a predictor of spontaneous term labor.

STUDY DESIGN

This study was a diagnostic test accuracy study using a prospective cohort design evaluating the ability of 2-dimensional ultrasound measurement of fetal adrenal gland total length, total width, fetal zone length and fetal zone width in women in the third trimester to predict the primary outcome of spontaneous term labor. Secondary outcomes were vaginal delivery, length of labor, and maternal and neonatal morbidities.

RESULTS

Of 43 patients recruited, 3 were excluded. 11 (25.6%) presented in spontaneous labor and 29 (67.4%) underwent induction of labor. Patient demographics were similar for all included except for admission cervical exam and oxytocin use. A receiver operative curve was created to assess test predictability. Weighted width of fetal adrenal gland was the best predictor of spontaneous labor amongst variables measured with an area under the curve of 0.674, p = 0.93. w/W ≥ 0.41 had a sensitivity of 91.0%, specificity of 44.8%, positive predictive value of 38.5% and a negative predictive value of 92.3%. Maternal and neonatal morbidities were not different between the spontaneous labor group and the induction of labor group.

CONCLUSION

Ultrasound measured fetal w/W was moderately predictive of spontaneous labor.

Diagnostic accuracy of cervical elastography in predicting preterm delivery: A systematic review and meta-analysis

BACKGROUND

The aim of the study was to evaluate the diagnostic accuracy of cervical elastography in predicting preterm delivery (PTD).

METHODS

We searched the PubMed, EMBASE, and Cochrane databases to identify relevant studies that applied ultrasound (US) elastography to assess cervical stiffness and predict PTD. All the studies were published before December 11, 2018, and only studies published in English were collected. The cervical length (CL) was considered a comparator, and the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool was applied to assess the quality of the included studies. Summary receiver operating characteristic (SROC) modeling was performed to evaluate the diagnostic performance of cervical elastography in predicting PTD. Subgroup analyses were also performed.

RESULTS

Seven studies, including 1488 pregnant women, were included in this meta-analysis. Cervical elastography showed a summary sensitivity of 0.84 [95% confidence interval (CI): 0.68, 0.93], a specificity of 0.82 (95% CI: 0.63, 0.93), a diagnostic odds ratio of 25 (95% CI: 7, 93), and an area under the curve (AUC) of SROC of 0.90 (95% CI: 0.87-0.93). CL measurement showed that the AUC of SROC was 0.60 (95% CI: 0.56-0.64). The results of subgroup analysis showed that the summary sensitivity and specificity were different in the QUADAS-2 score subgroups.

CONCLUSION

Cervical elastography is a promising and reliable method to predict PTD. Cervical elastography showed better diagnostic performance to predict PTD than CL measurement.